Download Impact Assessment of Invasive Plant Species in Selected

Impact Assessment of Invasive Plant Species in
Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
An Ecosystem-based Adaptation in Mountain Ecosystem in Nepal
supported by:
Impact Assessment of Invasive Plant Species in Selected Ecosystems
of Bhadaure Tamagi VDC, Kaski
Research Team:
Ripu M Kunwar
Ram P Acharya
Technical Advisor Team of IUCN Nepal:
Anu Adhikari
Rajendra Khanal
Racchya Shah
Sony Baral
Dr. Yam Malla
The designation of geographical entities in this book, and the presentation of the material, do not imply the expression
of any opinion whatsoever on the part of IUCN concerning the legal status of any country, territory, or area, or of its
authorities, or concerning the delimitation of its frontiers or boundaries.
The views expressed in this publication do not necessarily reflect those of IUCN.
Published by: IUCN Nepal, Kupondole, Lalitpur, Nepal
Edited by: Amit Poudyal & Anu Adhikari, IUCN Nepal
Designed by: Naresh Subba (Limbu), IUCN Nepal
Language editing: Dr. Bishnu Hari Baral
Copyright: © July, 2013 International Union for Conservation of Nature and Natural Resources
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Available from:
IUCN Nepal
Kupondole, Lalitpur
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Tel: (977-1) 5528781
Fax: (977-1) 5536786
E-mail: [email protected]
Website: www.iucn.org/nepal
This Report has been published under ‘Ecosystem-based Adaptation in Mountain Ecosyestem’ Project, jointly
implemented by International Union for Conservation of Nature (IUCN), United Nations Development Programme
(UNDP) and United Nations Environment Programme (UNEP) with financial support from Germany’s Federal
Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU).
supported by:
Impact Assessment of Invasive Plant Species in
Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
An Ecosystem-based Adaptation in Mountain Ecosystem in Nepal
ACKNOWLEDGEMENTS
IUCN, International Union for Conservation of Nature, is thankful to Practical Solution Consultancy
Nepal Pvt Ltd (PSPL) for conducting this study on “Impact Assessment of Invasive Plant
Species in Selected Ecosystems of Bhadaure Tamagi VDC , Kaski ” and support to prepare
this document in the present form. Precisely, Mr. Ripu M Kunwar and Mr. Ram P Acharya of
PSPL are sincerely acknowledged.
The residents of Bhadaure Tamagi VDC, Kaski are highly appreciated for their supports to carry
out the field study. We are also indebted to those organizations and individuals, who spent their
precious time during consultations, discussions, meetings and field observations.
Last but not least we would like to express our gratitude to all individuals who helped us in one way
or another.
July, 2013
I
EXECUTIVE SUMMARY
The Convention on Biological Diversity (CBD), 1992 underlines that the biological invasion of
alien species is the second worst threat after habitat destruction and set global priorities and
guidelines to collect information and coordinate international actions on invasive alien species
management. However, approaches taken to combat invasive species and even the data on
which they should be based are clearly inadequate to deal with the onslaught of invasive
species in Nepal. Building resilience against climate change and invasive species in both human
and ecological systems to an optimum level is the best possible way of adaptation. Therefore,
Ecosystem-based adaptation (EbA) is gaining momentum as a cost-effective means of protecting
human and ecological communities against the impact of climate change and emerging biological
invasions. The present study was the first attempt to identify EbA options for building resilience of
nature and communities against climate change and biological invasions in Bhadaure Tamagi
VDC of Panchase through a study of various dynamics of invasive species and their management.
In particular, biological invasions of nilo gandhe (Ageratum conyzoides) and kalo banmara (Ageratina
adenophora) were studied and their management through EBA options was scoped.
Field visits were made in December 2012 and a total of 58 respondents from 10 study sites
(Bhadaure, Bhanjyang, Chainpur, Damdame, Ghatichina, Harpan, Kutmidanda, Sidhane, Tamagi
and Thulakhet) were interacted with. Questionnaires were administered to collect data on the
existing colonies of selected species, their introduction, establishment and spread, impacts,
and management measures. In addition to questionnaire surveys, six focus group discussions
were held at Bhanjyang, Chainpur, Ghatichina, Harpan, Tamagi and Thulakhet. The colonies
with different population intensity of the selected species were identified as dense, moderate and
fair/sparse during discussions and each was sampled in 13 different sites at altitudes between
821m and 2096 m. Altogether 54 transects were laid for a vegetation study. Some transects were
laid perpendicular to the road and others parallel to the road at 10 m to 100 m distance. Each
transect was studied for its vegetation by laying one or two quadrats measuring 10 m x 10 m,
depending on field situations. Diversity and distribution of Ageratum and Ageratina were accounted
in 1 m x 1 m and 2 m x 2 m quadrats respectively. Soil, precipitation and temperature were
analyzed with respect to diversity, distribution and invasion trend of the selected IAS. To locate
the study area and sites, and trace the distribution of species and model of the potential area
of invasionability, geo-coordinates were synchronized with Geographic Information System
(GIS) mapping. River, road, land use data (settlements, forests and agricultural lands) and
plant diversity and distribution were used to find the suitability index for invisibility.
Impacts of A. conyzoides and A. adenophora were well observed through out Bhadaure Tamagi
VDC and none of the ecosystems was found free from this menace. Edges of forests, agricultural
lands, wetlands and roads deteriorated due to invasion. The abandoned agricultural lands and
forests served as a good refuge for A. conyzoides and A. adenophora respectively. Roadsides,
grazing lands, edges of wetlands were co-invaded. A total of 140 plant species were recorded
during field visits, among them 52 invasive and 18 high risk possessing. There were 12 potentially
competitors invasive species which can establish where and when habitats are poorly nurtured
and abandoned. Local communities were aware of only about the invasion of nine IAS: A. conyzoides,
A. adenophora, Chromolaena odorata, Phalaris minor, Conyza japonica , Borreria alata, Eichhornia
crissepes, Parthenium hysterophorus and Lantana camara. The first IAS in Bhadaure Tamagi
VDC were ratnaulo (P. minor) and salah jhar (C. japonica) that came into account some 30 years
ago. Badame jhar (B. alata) was introduced and established on agricultural lands some 20 years
ago. Recently, seto jhar (C. odorata) has been introduced in the roadsides and fallow lands of the
VDC. A. adenophora was introduced and established a decade ago in the VDC and colonized
along the roadsides at first. With the help of vectors, it was spread in grazing lands and forest
periphery. Later, it was outcompeted by A. conyzoides. A. conyzoides was introduced in Bhadaure
III
Tamagi about 5-7 years ago. It has aggressively spread as low quality fertilizers with high nitrogen
content were used. Along with these nuisance invasive species, there were introduction and
establishment of Jalkumbhi (E. crissepes), Madhesi pati (P. hysterophorus) and Kande banmara
(L. camara) in and around Bhadaure Tamagi VDC, possessing a potential risk to the local biodiversity
and socio-economy. As increasing number of IAS and temperature of Bhadaure Tamagi are
concomitant, the intensive spread of IAS is likely unless the current management system is
strengthened. Chainpur, Sidhane, Harpan, Tamagi and Kutmidanda were prone to further invasion.
Therefore, all preventive, controlling and adaptation based measures are requisite to offset the
invasion.
Chainpur, Harpan and Kutmidanda of the VDC were more susceptible to invasion of A. conyzoides
and again Chainpur, Harpan and Tamagi were likely to be abraded by A. adenophora. A. adenophora
was most successful in sites above 1400 m, but in lower sites it was co-invaded by A. conyzoides.
Species like pati (Artemisia), kantakari (Solanum xanthocarpum) and sisnu (Urtica) on roadsides
and fallow lands, and banso (Setaria pallidesesca), samo (Panicum colonum), phurke (Pittosporum
napaulense), mallido (Ischaemun rugosum), siru (Imperata cylindrical), etc. on agricultural lands
were particularly threatened by A.conyzoides and A. adenophora. A. conyzoides is more harmful
to the local livelihood and biodiversity than A. adenophora. Neither cattle nor goats feed on Ageratum,
and the areas traditionally used for grazing in the upper areas of the VDC were deteriorated.
Incidents of livestock mortality were common in the village because of accidental consumption of
Ageratum and its flowers by livestock while feeding grasses. In the last five years, there were three
casualties of livestock mortality only in Harpan of Bhadaure Tamagi. Agricultural crops, particularly
ginger, millet and rice and grasses were outcompeted by Ageratum and their productivity was
declined. Poor agricultural productivity was one of the reasons of depopulation of the rural
areas. Inadequate human resources in the VDC have led to agriculture and grasslands less
nurtured and unattended, inducing rampant spread. Current livelihood pattern amplified
introduction of non-native species because of more interest in off-farm activities, new species and
varieties, and less interest in seeds, fertilizers, land and soil fertility. Consequently, farmers of
Bhadaure Tamagi VDC have been plagued by an increasing number of invasive weeds. Despite a
number of impacts of IAS have been witnessed, a detailed species specific impact assessment
for each habitat and ecosystem is yet to be carried out.
With changing population and declining productivity of farmland, generating alternative sources
of income is essential. It is important to promote activities that balance the need for conserving
biodiversity and meeting the requirements of local communities on the one hand and promoting
technology and skills that can offset the invasion of IAS on the other. Effective management of
biological invasion should consist of three main steps : prevention, early detection and
eradication. Then the control of invasion should be backed up by integrated management. The
precise management measures adopted for any plant invasion will depend upon factors such
as institutional mechanism, policy structures, terrain, the cost and availability of labour, the
severity of the infestation and presence of other invasive species.
The first and foremost principle of prevention is avoiding invasive species. For this, a list of invasive
species of an area should be enumerated and widely circulated through the media for awareness
of the general public. The participation of communities should be promoted by raising their
awareness and involving them in efforts to address IAS through promotion of the Public-Private
Partnership (PPP) approach. Guiding local communities and stakeholders to the judicious uses
of materials that limit introduction and spread of invasive aliens is important. The land use of
the VDC needs to be monitored and nurtured regularly for controlling invasion of species. A.
adenophora cannot invade dense canopy forests, shrub lands, and well-managed plantations.
Therefore, plantation, afforestation and promotion of native fodder and forage species in
abandoned and fallow lands should be encouraged to maintain canopy and ground coverage.
Plantation of F. glaberrima complements the open canopy, chokes the introduction of invasive
aliens and provides fodder to livestock. Until there is any firm conclusion to indicate otherwise,
plantation of non-native and invasive species should be discouraged (Tiwari et al. 2005).
IV
As Ageratum and Ageratina are useful for various purposes, their extensive use may control
their rampant spread. Extensive utilization is important as the strategy is called a win-win strategy
and it has a good scope for enterprise development, employment generation at the local level,
and long-term management of invasive species. Complete uprooting, including all roots and
rootlets, before flowering is mandatory and controlled burning, composting, manuring and using
is necessary. Integrated crop management with prescribed burning, regular weeding, hoeing
and uprooting invasive alien species generally results in an increase in abundance and diversity
of native species and crops.
Overall institutional facilities and human capacity need to be improved by providing essential
technical support, strengthening coordination and sharing IAS information among the agencies
concerned and stakeholders. Invasive alien species are a global issue that requires collaboration
among governments, the economic sector and non-governmental and international
organisations. Establishment of baseline data and regular monitoring of alien species dynamics
are essential to fully understand IAS problems and their impacts. Therefore, extensive and
intensive research should be promoted. Scientific research is necessary to prepare basic data of
species, biology, ecology, impact assessment and management guidelines.
V
ACRONYMS & ABBREVIATIONS
a.s.l.
Above Sea Level
BMU
Federal Ministry of Environment, Nature Conservation and Nuclear Safety, Germany
BRH
Biotic Resistance Hypothesis
CABI
Centre for Agricultural Bioscience International,
CBD
Convention on Biological Diversity
CBO
Community Based organization
CF
Community Forest
CITES
Convention on International Trade in Endangered Species of Wild Fauna and Flora
CNP
Chitwan National Park
CO2
Carbon dioxide
DHM
Department of Hydrology and Meteorology
ERH
Enemy Release Hypothesis
FAO
Food and Agricultural Organization
FGD
Focus Group Discussion
GIS
Geographic Information System
GISD
Global Invasive Species Database
GISP
Global Invasive Species Programme
GoN
Government of Nepal
GPS
Global Positioning System
IAS
Invasive Alien Species
ICM
Integrated Crop Management
IPCC
Intergovernmental Panel on Climate Change
ISSG
Invasive Species Specialist Group
IUCN
International Union for Conservation of Nature
KIS
Key Informant Survey
MEA
Millennium Ecosystem Assessment
mm
Milli meter
MoFSC
Ministry of Forests and Soil Conservation
MoSTE
Ministry of Science, Technology and Environment
NBS
Nepal Biodiversity Strategy
NTFPs
Non Timber Forest Products
NWH
Novel Weapon Hypothesis
PSPL
Practical Solution Consultancy Nepal Pvt. Ltd
VII
SM
Social Mobilizer
SSC
Species Survival Commission
UNDP
United Nations Development Programme
UNEP
United Nations Environmental Programme
UNFCCC United Nations Framework Convention on Climate Change
VDC
Village Development Committee
VIII
TABLE OF CONTENTS
ACKNOWLEDGEMENTS .......................................................................................................... I
EXECUTIVE SUMMARY .......................................................................................................... III
ACRONYMS & ABBREVIATIONS ......................................................................................... VII
CHAPTER ONE: INTRODUCTION
........................................................................................... 1
1.1 Background
........................................................................................... 1
1.2 Invasive Alien Species (IAS)
........................................................................................... 1
1.3 Invasive Alien Plant Species
........................................................................................... 1
1.4 Management Measures
........................................................................................... 2
1.5 Ecosystem-based Adaptation in Nepal ......................................................................................... 3
1.6 Objectives of The Study
........................................................................................... 3
1.7 Scope of The Study
........................................................................................... 4
1.8 Limitations of The Study
........................................................................................... 4
1.9 Organization of The Report
........................................................................................... 4
CHAPTER TWO: METHODOLOGY
........................................................................................... 5
2.1 Study Area: Panchase
........................................................................................... 5
2.2 Study Site: Bhadaure Tamagi VDC ........................................................................................... 6
2.3 Study Approaches
........................................................................................... 6
2.3.1
Multi-disciplinary and cross-sectional ............................................................................ 6
2.3.2
Participatory and consultative ........................................................................................ 6
2.3.3
Ecology and field-based
........................................................................................... 7
2.4 Study Methods
........................................................................................... 7
2.4.1
Desk review
........................................................................................... 7
2.4.2
Focus group discussion
........................................................................................... 7
2.4.3
Household survey
........................................................................................... 7
2.4.4
Ecological assessment
........................................................................................... 8
2.4.5
Soil test
........................................................................................... 9
2.4.6
Meteorological study
........................................................................................... 9
2.4.7
Geographic Information System (GIS) mapping ........................................................... 9
2.4.8
Data analysis
......................................................................................... 10
CHAPTER THREE: FINDINGS
......................................................................................... 11
3.1 Socio-economy
......................................................................................... 11
3.2 Biophysical Setting
......................................................................................... 11
3.3 Climate
......................................................................................... 11
3.4 Biodiversity
......................................................................................... 12
3.5 Invasive Alien Plant Species
......................................................................................... 13
3.6 Invasive Alien Plant Species: Ageratum conyzoides and Ageratina adenophora ...................... 14
3.6.1
Profile of selected species ......................................................................................... 14
3.6.1.1 Ageratum conyzoides ................................................................................................ 14
3.6.1.2 Ageratina adenophora .............................................................................................. 16
3.6.2
Diversity and distribution
......................................................................................... 19
3.6.3
Potential invasion
......................................................................................... 20
3.6.4
Characteristics of invasive alien species ..................................................................... 22
3.6.5
Mechanism of invasion
......................................................................................... 23
3.6.6
Causes of invasion
......................................................................................... 23
3.6.7
Invasion trend of alien species .................................................................................... 24
3.6.8
Impacts
3.6.8.1
3.6.8.2
3.6.8.3
3.6.8.4
3.6.8.5
of invasive species ......................................................................................... 25
Biodiversity threats .................................................................................................. 26
Impacts at ecosystem level ....................................................................................... 26
Impact on soil
.................................................................................................. 27
Impacts at species level ............................................................................................ 29
Impacts at socio-economic level ............................................................................... 29
3.6.8.5.1Negative impacts ........................................................................................ 30
3.6.8.5.2 Positive impacts ......................................................................................... 32
3.6.9
Climate change and invasive species ......................................................................... 33
3.7 Management of invasive species
......................................................................................... 34
CHAPTER FOUR: CONCLUSION AND WAY-FORWARD ...................................................................... 35
4.1 Conclusion
......................................................................................... 35
4.2 Recommendations
......................................................................................... 36
4.2.1
Preventive Measures
......................................................................................... 36
4.2.2
Controlling Measures
......................................................................................... 37
4.2.3
Actions
......................................................................................... 39
CHAPTER FIVE: BIBLIOGRAPHY
......................................................................................... 41
ANNEX
......................................................................................... 48
Annex 1. List of respondents for study of IAS in Bhadaure Tamagi VDC, Panchase ................ 48
Annex 2. Questionnaire used for survey ..................................................................................... 50
Annex 3. Per Month Maximum Temperature Record ................................................................. 54
Annex 4. Per month minimum temperature record .................................................................... 55
Annex 5: Total Species and their Frequency in Different Habitats ............................................. 56
Annex 6. List of invasive plant species in Bhadaure Tamagi, Panchase and Nepal ................. 60
Annex 7: Definitions of key terms
......................................................................................... 66
LIST OF FIGURES
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Study area and sites .................................................................................................................. 5
Group discussion at Bhadaure .................................................................................................. 7
Layout of transect and sample quadrat ..................................................................................... 9
Ecological sampling ................................................................................................................... 9
Temperature and precipitation at Lumle station, close to Bhadaure Tamagi VDC ................. 12
A threatened plant species Cythea spinulosa (tree fern) at Tamagi and orchids
at Harpan, Panchase ............................................................................................................... 13
Distribution of A. conyzoides in Bhadaure Tamagi VDC ........................................................ 15
A. conyzoides, a weed is dominating agriculture fields when they are less nurtured ............ 16
Distribution of A. adenophora in Bhadaure Tamagi VDC ........................................................ 17
A. adenophora growing along the edges of roads, canals, rivers and ponds ........................ 17
Importance Value Index of IAS in Bhadaure Tamagi VDC, Panchase ................................... 18
Invasion maps for A. conyzoides, A. adenophora and both species ...................................... 21
Characteristics of invasive alien species ................................................................................. 22
Mechanism of invasion of IAS ................................................................................................. 22
History of introduction of invasive alien plant species in Bhadaure Tamagi VDC .................. 24
Impact of IAS on different habitats ........................................................................................... 26
A house owned by a Gurung left unattended for long at Tamagi, Bhadaure Tamagi VDC .... 30
Ginger has been outcompeted by Ageratum at Chainpur and grassland has been
relegated by Ageratina at Tamagi ............................................................................................ 31
Uses of A. adenophora: tender shoots are as forage, green manuring and green fuel ........ 33
Relationship of IAS introduction and increasing temperature in Bhadaure Tamagi VDC ...... 33
Ficus glaberrima (Pakhuri) controlling invasive aliens in its shade ........................................ 37
A gall made by Procecodocharis utilis, gall fly in A. adenophora ........................................... 38
LIST OF TABLES
Table
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Details of quadrats laid at the sites of Bhadaure Tamagi VDC ................................................ 8
Research plots and area sampled ............................................................................................. 8
Temperature characteristics of Lumle, a nearby station of Bhadaure Tamagi VDC ............... 11
Worst IAS and their frequency in Nepal and Panchase .......................................................... 13
Density and frequency of the selected IAS (A. conyzoides and A. adenophora) ................... 19
Potential invasion map ............................................................................................................. 20
Causes and factors for invasion (N = 28) ................................................................................ 24
Information about the first sight of IAS in the Panchase area by local communities
(N =28) ..................................................................................................................................... 25
Physical characteristics of soil of Bhadaure Tamagi VDC ...................................................... 28
Chemical characteristics of soil of Bhadaure Tamagi VDC ..................................................... 28
Correlation analysis among soil characters, altitude and IVI of A. conyzoides and
A. adenophora ......................................................................................................................... 28
Impact of invasive alien species at species level .................................................................... 29
Impacts of A. conyzoides and A. adenophora ......................................................................... 31
Usage of different plant species as green manuring ............................................................... 32
Comparative use of A. conyzoides and A. adenophora .......................................................... 32
Management measures to control IAS in Bhadaure Tamagi VDC (N = 28) ........................... 34
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
CHAPTER ONE: INTRODUCTION
1.1 Background
Climate change and invasive species present two of the greatest threats to biodiversity and the
provision of valuable ecosystem services (Burgiel and Muir 2010). Climate change contributes
to erratic rainfall, drying up of local springs and streams, adjustment of species distribution,
phenology and morphology, shift in agriculture calendar, emergence of invasive species and
outbreak of diseases and pests, etc (IPCC 2007). Precisely, climate change impacts, such as
warming temperatures and changes in CO2 concentrations, are likely to increase opportunities
for introduction of invasive species because of their adaptability to disturbance and to a broader
range of biogeographic conditions and environmental controls (Mooney and Hobbs 2000).
Warmer temperature may also facilitate the movement of invasive species along previously
inaccessible pathways of spread in both natural and human-made environments (Engel et al.
2011), because invasive species have a broader range of tolerance (Walther et al. 2009).
It is estimated that biological invasions can have strong effects on structure and function of
ecosystems that are responding to a changing climate and climate change is also changing the
context in which potential invasive species succeed or fail (Husain and Agnihotri 2009). However,
relationship of biological invasion of alien plant species and climate change and their management
are hitherto unknown in Nepal, despite Article 8(h) of CBD urged parties to prevent the introduction
of, control or eradicate those alien species which threaten ecosystems, habitats and species
(CBD 1992) (www.biodiv.org).
1.2 Invasive Alien Species (IAS)
IUCN (2000) defines IAS as an alien species, which becomes established in natural or seminatural ecosystems or habitat, an agent of change, and threatens native biological diversity. IAS
occurs in all major taxonomic groups. Within each taxon, numerous species including perhaps
as many as 10 per cent have potential to invade other ecosystems (Rejmanek et al. 2000). IAS
can transform the structure and species composition of ecosystems (Ricchardi et al. 2000) by
establishing viable populations with growth rates enough to displace elements of native biota
(Rejmanek 1999) or to modify disturbance regimes (Brooks et al. 2004), thereby potentially
changing ecosystem structure and functioning (Dukes and Mooney 2004), or by outcompeting
native denizens for resources by changing the way nutrients are cycled through the system.
IAS endangers the environment, economy and human welfare (Lodge et al. 2006). It also reduces
biodiversity, replaces important native species and increases investment in agriculture and
silviculture (Ricchardi et al. 2000), disrupting prevailing vegetation dynamics and nutrient cycling
(Richardson 1998). The estimated damage from invasive species worldwide totals more than
US $1.4 trillion a year (5 percent of the global economy) with impacts across a wide range of
sectors, including agriculture, forestry, aquaculture, transportation, trade, power generation and
recreation (Stern 2006). Since the 17th century, IAS contributed to nearly 40 percent of all animal
extinctions for which the cause is known (CBD 2006). The share of invasive plants to damage is
around 10 percent of the total.
1.3 Invasive Alien Plant Species
A list of invasive alien plant species is available for most regions, though the list is to be updated
and reviewed routinely. Nepal is not exempt and there are handful studies of invasive species.
Though the first study of invasive alien species of Nepal was carried out for over five decades
1
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
(Banerji 1958), impacts and management studies of IAS at species, ecosystem and socioeconomic levels through eco-friendly approaches were parsimoniously carried out. Poudel and
Thapa (2012) reviewed 43 studies so far conducted in Nepal related to invasive plant species,
and they recommended for more researches on documentations and impacts of invasive alien
plant species. A total of 166 invasive alien plants species of Nepal were noted by IUCN (Tiwari
et al.2005). However, in a milieu of changing climate, introduction and aggressiveness of invasive
alien species is being increased, urging more researches and updates on IAS.
The world’s 100 worst invasive aliens (Lowe et al. 2000) include 11 plant species (Arundo
donax, Chromolaena odorata, Eichhornia crissepes, Hedychium gardnerianum, Hiptage
benghalensis, Imperata cylindrica, Lantana camara, Leucaena leucocephala, Mikania micrantha,
Opuntia stricta and Rubus ellipticus) that are found in Nepal. However, they are not equally
invasive. Seven toppers alien invasive in the list for Asia Pacific region include: Ageratina
adenophora, Ageratum conyzoides, Chromolaena odorata, Eichhornia crissepes, Lantana
camara, Mikania micrantha and Parthenium hysterophorus (Sankaran et al. 2005). All these
seven species are problematic in Nepal.
The impacts of those invasive plant species may be more severe as they increase both in
numbers and extent, and as they compete for diminishing resources such as water and soil
minerals. Invasive alien plant species can threaten those basic needs and compromise ecosystem
functions by taking advantage of habitat disturbance, species under stress and other chinks in
the armor of otherwise healthy systems. This affects the multiple roles of ecosystems in providing
provisioning, regulating, supporting and cultural services (MEA 2005, Vila et al. 2009). Therefore,
global efforts are being made to control these invaders. Whatever the cost may be, the unintended
spread of invasive species continues unabated, despite the earnest efforts are being made to
manage them (Sankaran et al. 2005).
1.4 Management Measures
Article 8(h) of the CBD states : “Each contracting party shall, as far as possible and as appropriate,
prevent the introduction of, control or eradicate those alien species which threaten ecosystems,
habitats or species”. The CBD (1992) sets global priorities, guidelines, collects information and
helps to coordinate international action on invasive alien species. However, approaches taken
to combat invasive species and even the data on which they should be based are clearly
inadequate to deal with the onslaught of invasive species in Nepal. Similarly, from a conservation
perspective, there is little point to addressing climate change if the biodiversity we are trying to
protect has already been lost to invasive species. Because the numbers of invasive plant species
and the extent of invasions are rapidly increasing at multiple scales resulting grown concerns
about the stability of ecosystems (Hobbs et al. 2006). Therefore, the management of invasive
species demands a hierarchical perspective where the preference, resources and capacity are
most; first to prevent, second to control and third to eradicate biological invasions (CBD 2002,
Wittenberg and Cock 2001).
Again building resilience in both human and ecological systems to an optimum level is the best
possible way to adapt to climatic variation.Therefore, Ecosystem-based Adaptation (EbA) is
gaining momentum as a cost-effective and eco-friendly means of protecting human and ecological
communities against the impacts of climate change and biological invasion (Heller and Zavaleta
2009, Mooney et al. 2009). EbA is described as building nature’s resilience to the impacts of
climate change, while also helping to meet people’s basic needs. Such an approach can also
provide an integrative framework to address impacts from both climate change and invasive
species (Burgiel and Muir 2010).
2
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
1.5 Ecosystem-based Adaptation in Nepal
Ecosystem-based Adaptation (EbA) is the use of biodiversity and ecosystem services as part of
an overall adaptation strategy to help people to adapt the adverse effects of climate change. It
aims at maintaining and increasing the resilience and reducing the vulnerability of ecosystems
and people in the face of the adverse effects of climate change. It can generate significant
social, economic and cultural co-benefits, contribute to the conservation of biodiversity, and
build on the traditional knowledge and practices of indigenous peoples and local communities,
including the important role of women as custodians of local knowledge (www.iucn.org). In
promoting the sustainable use of nature and biodiversity, EbA strategies provide policy coherence
with national and international commitments.
The EbA Project for Mountain Ecosystems in Nepal, Peru and Uganda aims at strengthening
capacities of these three countries which are particularly vulnerable to climate change impacts.
The project targets to strengthen ecosystem resilience of these countries and reduce vulnerability
of local communities with particular emphasis on mountain ecosystems. It is designed on the
premises that social/human adaptation is best achieved by ensuring continued provision of
ecosystem services and enhancing human capacities to address current climatic challenges
and future uncertainties. With funding from German Government, Federal Ministry of Environment,
Nature Conservation and Nuclear Safety (BMU) through its International Climate Initiative, the
EbA project is jointly implemented by the International Union for Conservation of Nature (IUCN),
the United Nations Environmental Programme (UNEP) and the United Nations Development
Programme (UNDP). In Nepal, the Ministry of Forests and Soil Conservation (MoFSC) is the
implementing agency at the national level, and the Ministry of Science, Technology and
Environment (MoSTE) plays an overall coordinatiing role. The project has four major components
(i) development of methodolgy and tools for mountain ecosystems; (ii) application of above
tools and methodology at the national level; (iii) implementation of pilot EbA at the ecosystem
level; and (iv) formulation of national policies and building an economic case for EbA at the
national level.
The pilot site for this project in Nepal is the Panchase area, a cross-point of Kaski, Parbat and
Syangja districts. The area is vulnerable to climate change, with negative impacts on forests,
water resources, agriculture and biodiversity. Panchase is a protected forest and has been the
focus of national, regional and local development strategies and plans considering its high
natural resource significance as well as its potential for tourism, preferably eco-tourism (GoN
2012a). With increasing trend of abandonment of previously productive land, Bhadaure Tamagi
VDC of Panchase is largely witnessing invasion of alien plant species, especially with apparent
impacts on connected ecosystems (UNDP/MDO 2006). Therefore, this VDC has been selected
for the present assessment of climate change and plant species invasion for developing EbA
options for building resilience of local communities and ecosystems.
1.6 Objectives of The Study
The main objective of the study was to assess the impact of major invasive plant species of
Bhadaure Tamagi VDC of the Panchase area and recommend potential Ecosystem-based
Adaptation options for resilience of local ecosystems and communities to address the impact
and maintain ecosystem. The specific objectives of the study were to:
• assess the current status of invasive plant species in Bhadaure Tamagi VDC;
• find out the trend and various dynamics of invasion of two major invasive alien
plant species (Ageratum conyzoides and Eupatorium adenophorum);
• study the impact posed by A. conyzoides and E. adenophorum on major
ecosystems (forests, agriculture, grazing lands and wetlands); and
• recommend potential EbA options for resilience of local ecosystems and
communities following the assessment.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
1.7 Scope of The Study
Scope of the study was to analyse the impact of two major invasive alien plant species
(A. conyzoides and A. adenophora) of Bhadaure Tamagi VDC of Panchase area, and propose
potential Ecosystem-based Adaptation options for resilience of local ecosystems and communities
to address the prevailing impacts and threats posed by them and other associated determinants.
The study was also meant to assess the current status and invasion trend of these species in
Bhadaure Tamagi VDC, and recommend a set of management prescriptions that are practical,
doable and implementable in the context of the Panchase ecosystem.
1.8 Limitations of The Study
The study was carried out between 15 to 25 December 2012, with a very short period for the
field visit. As December is a post-harvesting season of rice, there were constraints to observe
the impact of IAS on agricultural crops, including rice. As the field visit was conducted in winter,
the assessment of reproductive biology of selected species and the cross-cutting impact of the
species were also limited.
Limited field visit led to limited sampling and consultations. Only the frequency of associated
species and the frequency and density statistics of sample species were enumerated because
of limited field visit. Community perception and literature were frequently used for impact
assessment and trend dynamics. The species sampled were habitat specific and the study area
was physiographycally complex. Therefore, varied transects were laid for sampling.
1.9 Organization of The Report
This report has been divided into five chapters. Chapter one deals with introduction, background,
objectives and scope of the study, and organisation of the report. Chapter two outlines the study
area and sites, study approaches, materials, and methods adopted. Chapter three presents
findings of the study such as biodiversity and invasive species of the area, accounts of invasive
species and their impact and prevailing management measures, and Chapter four portrays
major conclusions, actionable management options and recommendations. In the report,
Ageratina adenophora is interchangeably used with Eupatorium adenophorum because they
are synonyms. Again, the generic names of Ageratum conyzoides and Ageratina adenophora
or Eupatorium adenophorum are sometimes abbreviated.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
CHAPTER TWO: METHODOLOGY
2.1 Study Area: Panchase
The Panchase area was selected as a study area and its Bhadaure Tamagi VDC as a study site
(Figure 1). Panchase is situated at the junction of Kaski, Parbat and Syangja districts.
Geographically, it is located in the mid- hills of Nepal, just west of Pokhara, between latitudes
280 12’ and 280 18’ N, and longitudes between 830 45’ and 830 57’ E. This region is densely
populated by subsistence farmers and livestock rearing is an integral part of their livelihood.
Altitude ranges from 815 m at the Harpan River to 2517 m at the peak of the Panchase hill.
Forests are located at 1450 m and above. Annual precipitation in here is 5000mm (UNDP/GEF
2006).
Figure 1: Study area and sites
The Panchase hill is the origin of many rivers and tributaries that supply water to lowland villages,
and a primary source for Phewa Lake. The lower limit of Panchase is enriched by flooded rivers
and agricultural lands. Panchase has a variety of terrain and climatic variations ranging from
upper tropics to moist temperate. It also has a great diversity of ecosystem and plant species.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
The Panchase area has hill sal forests, pine forests, Schima-Castanopsis forests, alder forests,
lower temperate oak forests, and oak-laurel forests. At present, 68.69 percent of the forests of
the area is conserved as protected forests and the rest as community forests (Aryal and Dhungel
2009).
Common fodder trees of the Panchase area are: pakhuri (Ficus glaberrima), dudhilo (Ficus
nerifolia), nimaro (Ficus roxburghii), kabhro (Ficus lacoor), khanyu (Ficus semicordata), gogan
(Sasaurrea napalensis), badahar (Artocarpus lakoocha), bedulo (Streblus asper), etc. tejpat
(Cinnamomum tamala), sugandhkokila (Cinnamomum glaucescens), amriso (Thysanolaena
maxima), chiraito (Swertia chirayita), timur (Zanthoxylum armatum), lapsi (Choerospondias
axillaris), kurilo (Asparagus racemosus), etc are common NTFPs of the area. Besides these,
chiraito (Swertia chirayita), satuwa (Paris polyphylla) and Kurilo (Asparagus Racemosus) are
important medicinal plants with high market value. The Panchase area holds immense potential
for establishing micro-enterprises based on several NTFPs like lokta (Daphne bholua), mollah
(Viburnum mullaha), allo (Girardinea diversifolia), nigalo (Arundinaria species), etc. Lokta can
be used for making Nepali paper, allo for weaving cloth, nigalo for making bamboo products,
and mollah for extracting valuable juice with sweet and sour taste.
Ethnic composition of the Panchase area constitutes Brahmin, Kshetri, Gurung, Bishwokarma,
Nepali, Pariyar, Magar, Thakali, etc. Gurung communities reside at higher elevations and Brahmin
and Kshetri at lower elevations. Of these, Gurung and Magar are indigenous to the area and
Bishwokarma, Nepali and Pariyar are disadvantaged groups. Approximately 40,000 people live
in and around the Panchase area, sustaining their livelihood from exploitation of local resources
and products (fodder, firewood, timber, edible, medicinal plants, etc) (Bhattarai et al. 2012).
2.2 Study Site: Bhadaure Tamagi VDC
Bhadaure Tamagi VDC is one of the largest VDCs of Panchase and it is dominated by the
Gurung ethnic group. The total area of the VDC is 15.07 km2. As in entire Panchase, Gurung
and other ethnic groups reside at upper elevations and Brahmin and Kshetri at lower elevations.
Most of the disadvantaged groups live at higher elevations. The VDC stretches at latitudes
between 280 12’ 35" and 280 16’ 34", and longitudes between 830 48’ 14" and 830 52’ 52", and
spans within 814 m to 2517 m. It has upper tropical to moist temperate bio-climate.
2.3 Study Approaches
2.3.1 Multi-disciplinary and cross-sectional
In accordance with the study goal, multi-disciplinary approaches as exploratory as well as crosssectional in its content were used for the study. Literature review, community consultations,
individual interviews, field observations, GIS mapping and cross-checking were used.
2.3.2 Participatory and consultative
Participatory and consultative approach was used to incorporate views and concerns of local
communities (farmers, users, community forest user groups and stakeholders) who have long
been inhabited in Panchase and utilized local resources for their livelihood. The approach was
adopted to reflect wider views and concerns of local communities who are directly or indirectly
encountered with invasive alien species during the course of livelihood.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
2.3.3 Ecology and field-based
Information generated in a participatory and consultative manner was recorded and verified at
the field level. Participatory cluster mapping was followed and information about abundance
and species threatened by invasive species were discussed in a participatory manner. Field
observations and sampling were useful in data and information verification and recording.
2.4 Study Methods
2.4.1 Desk review
Extensive desk review was done and data in general and of selected species was consolidated.
In particular, species invasion, distribution, impacts, management and factors for spread of the
selected species were appraised. About 100 literature were reviewed and used as references
for analysis of invasive aliens and their management.
2.4.2 Focus group discussion
Six focus group discussions were held after
establishing prior oral informed consent with
participating communities. Discussions were held
in Bhanjyang, Chainpur, Ghatichina, Harpan,
Tamagi and Thulakhet based on consultations
with IUCN and MDO staff members. Colonies with
different population intensity of selected species
as dense, moderate and sparse were identified
during discussions and each was sampled.
Participatory mapping and recall methods were
used to elucidate the history of introduction and
trend of invasion and distribution. Informal
meetings were held in Bhadaure, Bhanjyang,
Harpan and Thulakhet. Information from the
consultations was further cross-checked and
verified with five key informants—school teacher,
elderly person, woman, village representative and
forest guard (Annex 1).
Figure 2: Group discussion at Bhadaure
2.4.3 Household survey
A field visit was made in December 2012 and a total of 58 respondents from 10 study sites
(Bhadaure, Bhanjyang, Chainpur, Damdame, Ghatichina, Harpan, Kutmidanda, Sidhane, Tamagi
and Thulakhet) were consulted. A total of 28 individuals were interviewed during a household
questionnaire survey and the rest during focus group discussions, using simple random and
purposive sampling techniques respectively (Annex 1). Information about existing colonies of
species, their introduction, establishment and spread, impacts, and management measures,
etc were sought particularly from women, forest guards, elderly people and disadvantaged groups
during the household questionnaire survey (Annex 2).
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
2.4.4 Ecological assessment
Following the participatory mapping of species specific population intensity, a rapid ecological
assessment was carried out in 13 different sites (Table 1) following transect A-A’ (10-20 m wide
and 50-100 m long based on physiography) study. Altogether 54 transects were laid for vegetation
study. Some transects were laid perpendicular to the road and others parallel to the road at 10
m to 100 m distance. In particular, the perpendicular transect was laid for Ageratum study and
the parallel transect was subjected to Eupatorium study. Each transect was studied for its
vegetation by laying one or two quadrats measuring 10 m x 10 m depending on field situation at
the left and right of the transect middle line in a spiral manner (Figure 3). One quadrat was laid
in transects perpendicular to the road and two in parallel to the road. The quadrats were meant
to study frequency and distribution of plant biodiversity. In each quadrat, two micro quadrats
measuring 1 m x 1 m and 2 m x 2 m were laid respectively for the study of Ageratum and
Ageratina (Table 2).
Table 1: Details of quadrats laid at the sites of
Bhadaure Tamagi VDC
Figure 3: Layout of transect and sample
quadrat
Table 2: Research plots and area sampled
229
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
2.4.5 Soil test
Physicochemical properties of soil were analysed to see whether the selected species Ageratum
and Ageratina are related to soil characters for their diversity and distribution. To assess the
physiochemical properties of soil underneath of Ageratum and Ageratina, a total of five soil
samples from Bhadaure-1 (northern part), Tamagi-3 (highest elevation of study sites), Chainpur5 (east and lowlands of the VDC), Kutmidanda-7 (abandoned agricultural lands), and Sidane-8
(west part of the VDC) were collected (Figure 4). Soil texture, pH and moisture of the samples
were analysed in laboratory.
Figure 4: Ecological sampling
2.4.6 Meteorological study
Precipitation and temperature records of Bhadaure Tamagi VDC were collected from Lumle
meteorological station and the Department of Hydrology and Meteorology. Records from 1981
to 2011 were available and collected for further analysis. Maximum and minimum temperatures
and rainfall were analyzed and plotted in a graph and a linear regression model was plotted to
illustrate a trend in the last three decades. The missing data were not treated in any of the
calculations in this study.
2.4.7 Geographic Information System (GIS) mapping
Garmin Etrex Global Positioning System (GPS) was used to record the geo-coordinates of
sampling sites. The geo-coordinates were synchronized with Geographic Information System
(GIS) mapping to locate the study area and sites, and trace the distribution of species and
model of the potential area of invasionability of the selected species. River and road networks,
and land use data (settlements, forests and agricultural lands) were used to find the suitability
index for invasionability, as the area with good moisture, road networks, nearby wetlands, and
edges of forests and agricultural lands are the best conduits for invasive alien species. The
following procedures were applied to model the invasion of the selected species:
•
Field geo-coordinate points of the sampled species were collected.
•
Landsat TM satellite imagery of 2012 was used for land use classification on
the basis of field training samples.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
•
On the basis of classified image, the suitable area was identified through expert
and grass roots- level knowledge and from the spatial analysis of several
parameters such as land use, river, road network, settlements, etc.
•
Multi-criteria evaluation was performed on the basis of parameters selected for
potential area of invasion.
•
Majorly overlay tools of ArcMap 10 were used for the overall analysis of potential
sites of IAS invasion in the study area.
•
Suitability analysis of IAS was carried out on the basis of distance and frequency
of existing species in relation to land use, river and road. Spatial join was
performed in the ArcMap 10 for distance analysis from river, road and particular
land use such as forest, agriculture and settlement.
•
The weighted overlay analysis was performed in the model builder to assign
the weight and scale range for each parameter based on the existing scenario
such as how far a particular species is found in the field from river and road and
in which land use class it is available.
•
A potential invasion map of Eupatorium and Ageratum species was prepared
from the analysis performed and further classified into four categories: highly,
moderately, less and least potential sites of IAS.
2.4.8 Data analysis
Both quantitative and qualitative techniques were used for data analysis. The analysis was
designed specifically to triangulate the sources of evidence, rationalise information and interpret
in a simple and understandable form. Climatic characteristics of the study area were assessed
in terms of average annual maximum and minimum temperatures and annual precipitation by
analyzing the data recorded by DHM for Lumle station. GIS mapping was used for a graphical
presentation of distribution and potential invasionability of the selected species. Field ecological
sampling of vegetation and soil was carried out to see the relationship between soil and invasive
species. Relevant photographs were taken and used as references for report.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
CHAPTER THREE: FINDINGS
This chapter discusses socio-economic, biophysical setting, climatic characteristics, biodiversity
and invasive species of Bhadaure Tamagi VDC.
3.1 Socio-economy
Approximately 40,000 people live in the villages of the Panchase area and depend upon the
forests for their livelihood (fodder, forage, fuelwood, timber, edible and medicinal plants). Bhadaure
Tamagi, one of the largest VDCs of Panchase, has a population of 3,257 people living in 875
households with average 3.72 members per household, which is less than national average(4.88)
and district average (3.92) (GoN 2012b). About 50 percent of people depend on agriculture for
their livelihood. The lower area of VDC is densely populated by subsistence farmers and livestock
rearing is an integral part of their livelihood (Bhattarai et al. 2012). The upper area of the VDC is
dominated by Gurung and other ethnic groups. The area is also for temporary sheds (goths) for
livestock. There is a tradition to leave buffaloes temporarily in the higher pasture called Lek and
bring them back to the village once they begin milking (Upadhyay 2012).
3.2 Biophysical Setting
The lower belt of Bhadaure Tamagi VDC is dominant as settlement and agriculture land use
whereas the upper one is used for forests, grazing land and protected system. As Panchase is
a protected forest and pilgrimage site, almost all upper areas are under protection (GoN 2012a).
As the Panchase forest represents a relic of extensive forests, it is necessary that conservation
efforts are made to ensure its survival. Both lowland and upperland of the VDC are under pressure
of invasive species. The forests and unattended lands at higher elevations were covered by a
nuisance weed, banmara (Eupatorium adenophorum), whereas the lower part was used for
settlements and agriculture purposes, and this part was heavily invaded by Ageratum conyzoides.
As the lower part of the VDC is an entry point from Pokhara Sub-metropolis, it is at high risk of
alien species introduction while bringing goods and commodities for livelihood.
3.3 Climate
Both maximum and minimum temperatures were plotted against a period and they were found
increasing over thirty years; however, their trend was gradual. Average maximum and minimum
temperatures at Lumle were 20.22 0C and 11.99 0C respectively (Table 3). Precipitation in
Bhadaure Tamagi VDC was erratic and increasing in trend with some extremes (Figure 5). The
average precipitation was 5723.8 mm per annum. Maximum precipitation was recorded in 1995
and extreme maximum in 1998. The lowest annual precipitation was recorded in 2006 (4162
mm) during a period of thirty years. This variation in precipitation within a decade may be
associated with climate change (Annex 3, 4).
Table 3: Temperature characteristics of Lumle, a nearby station of Bhadaure Tamagi VDC
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Figure 5: Temperature and precipitation at Lumle station, close to Bhadaure Tamagi VDC
3.4 Biodiversity
The Panchase area is rich in biodiversity (Koirala 1998), possessing a total of 589 flowering
plants including 107 NTFPs (Bhattarai et al. 2012) and 113 orchids (Subedi et al. 2007) including
three endemic and three threatened species (Subedi et al. 2011). In the present assessment, a
total of 140 plant species were recorded from a 10-day field visit to Bhadaure Tamagi VDC,
including threatened species like tree fern (Cythea spinulosa), bhyakur (Dioscorea species)
and orchid (CITES II species) (Figure 6) (Annex 5). All these threatened plants are on the verge
of collapse due to invasion of alien plant species and anthropogenic disturbances; deforestation
and open free grazing. According to Pimentel et al. (2000), about 42 percent of the threatened
or endangered species are at risk primarily due to alien species.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Figure 6: A threatened plant species Cythea spinulosa (tree fern) at Tamagi and orchids at Harpan,
Panchase
3.5 Invasive Alien Plant Species
There are 100 worst weed species in the world (Lowe et al. 2000), among them eleven worst
invasive alien species are found in Nepal. Of the seven important alien invasive species for the
Asia Pacific region, all are pertinent to Nepal and six species except Mikania are found in the
Panchase area. Among the 14 worst species, nine species were prevalent in Bhadaure Tamagi
VDC, Panchase (Table 4), and Ageratum and Ageratina were the most problematic.
A note of 166 alien invasive plants species of Nepal was made by IUCN, Nepal in 2005 (Tiwari
et al. 2005); however, in a pursuit of changing climate, the list was outnumbered. The present
Table 4: Worst IAS and their frequency in Nepal and Panchase
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
study compiled literature, updated the list and catalogued it into 194 for Nepal (Annex 6). Out of
194 invasive species 52 were recorded from the VDC, some of them highly invasive and others
less invasive. There were 18 highly invasive plant species in and around the Panchase area,
but local communities were aware of the impact of only nine of them (Annex 6). The communities
need better management to controlling such pants. There were 12 competitor invasive species
established in the VDC, but they have not spread aggressively in the area at present but are
likely to spread and invade aggressively unless management is immediately strengthened. There
were 22 invasive species introduced in the area and are likely to establish if management is
poor. Among the nine highly invasive alien species recognized by the local communities, Ageratum
conyzoides and Ageratina adenophora were more frequent and dense in distribution (Table 5)
and severe in possessing detrimental impacts to livelihood and biodiversity. They were noted
for massive invasion and fast spread in Bhadaure Tamagi VDC.
3.6 Invasive Alien Plant Species: Ageratum conyzoides and
Ageratina adenophora
3.6.1 Profile of selected species
3.6.1.1
Ageratum conyzoides
Taxon name: Ageratum conyzoides L.
Synonyms: Ageratum album Willd. Ex Steud., A. caeruleum Hort. ex. Poir., A. caeruleum Desf.,
A. conyzoides var hirtum (Lam.) DC., A. cordifolium Roxb., A. hirsutum Lam., A. hirtum Lam., A.
humile Salisb., A. latifolium Car., A. maritimum H.B.K., A. mexicanum Sims., A. nanum Hort. Ex
Sch. Bip., A. obtusifolium Lam., A. odoratum Vilm., A. suffruiticosum Regal, Cacalia mentrasto
Vell.
Family : Asteraceae (Compositae)
Common names: Ageratum, Billy-goat weed, Blue ageratum, Blue flowered groundsel, Blue
top, Chick weed, Goat weed, Invading ageratum, White weed, Winter weed.
Local names: Gandhe, Nilo gandhe, Raunne, Hanumane, Paino (Gurung), Jhang noniba
(Tamang), Jhorijhyang (Tharu).
Local name in Bhadaure Tamagi VDC: Gandhe, Nilo gandhe, Maobadi jhar and Paino.
First report in Nepal: Burkill in Rec. Bot. Ind. 4:114.1910; Nepalgunj, 25.10.1972, N.P.
Manandhar 9857 (KATH).
Description: A. conyzoides is an annual erect, branching, soft, slightly aromatic hispid herb
with shallow, fribrous roots. It grows up to 1 m tall. Stems and leaves are covered with fine white
hairs; the leaves are egg-shaped with broad end at base up to 7.5 cm long. The flowers are
purple, blue, pinkish or white, < 6 mm across, with around 30-50 flowers, arranged in close
terminal flower-heads. Fruits are small brown one-seeded achene. The roots and rootlets are
densely fibrous and branched and tightly anchored the soil.
Habitat: A. conyzoides commonly grows in the proximity of habitation, thrives in any garden
and agricultural soils, and is very common in disturbed sites and degraded areas. It invades
forests, woodlands, grasslands, cultivated lands, and banks of water courses. It is an important
weed of plantation crops and overgrazed pastures.
Reproduction and dispersal: This species reproduces mainly by seeds, which are dispersed
on the hairs of livestock and wild animals, clothes and agricultural machinery. It can complete its
life cycle (germination to flowering) in less than two months. The plant flowers almost throughout
the year, precisely from June to March. The seeds germinate in response to light (photoblastic)
and are often no longer viable within 12 months. Ageratum conyzoides is sometimes confused
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Ageratum houstonianum Mill.
It is common in barren fields in association with A. conyzoides
Linn. It has numerous sticky hairs on bracts surrounding its flowerheads. The invulucral bracts are hairy and glandular and differ
from those of Ageratum conyzoides. Each of the tiny flowers/
florets which makes up the flower-heads has two short and
narrow projections that are about 1-2 mm long. The bases of the
flower-heads are relatively small (3-6 mm across).
with Ageratum houstonianum (blue billy-goat weed). It can be distinguished as follows by only a
few hairs on the bracts surrounding its flower-heads (the involucral bracts are glabrous or sparsely
pubescent). Each of the tiny flowers/florets (make up the flower-heads) has two long and narrow
projections that are about 5 mm long. The bases of the flower-heads are relatively large (5-8
mm across).
Distribution: It is native to Central and South America and the West Indies. In Nepal, it is
distributed throughout the country from 75 to 2000 masl.
In Bhadaure Tamagi VDC, A. conyzoides was observed in wards no. 1, 4,5,6,7 and 8, i.e. it was
recorded from Bhadaure, Harpan, Chainpur, Damdame, Kutmidanda and Sidane at altitudes
between 821 m and 1699 m (Table 5), but its availability above 1400 m was low and above 1700
m nil. A. conyzoides was most dense in Kutmidanda, Harpan and Chainpur (Figure 7) and most
frequent in Kutmidanda, Harpan and Thulakhet. In particular, the abandoned agricultural fields
of Harpan, Chainpur, Kutmidanda and Thulakhet were severely invaded by Ageratum. The least
managed or unattended agricultural fields with moisture and partial shade were favourable for
the growth and spread of A. conyzoides (Figure 8).
Figure 7: Distribution of A. conyzoides in Bhadaure Tamagi VDC
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Figure 8: A. conyzoides, a weed is dominating agriculture fields when they are less nurtured
3.6.1.2
Ageratina adenophora
Taxon name: Ageratina adenophora (Spreng.) R.M. King and H. Rob.
Synonyms: Eupatorium adenophorum Spreng., E. glandulosum Kunth.
Family: Asteraceae (Compositae)
Common names: Crofton weed, Hemp agrimony, Mexican devil, Sticky agrimony, Sticky
eupatorium, Sticky snake root, White thoroughwort
Local names: Kalo banmara, Kalimunte, Mohini (Chepang), Thangpa maran (Tamang).
Local name in Bhadaure-Tamagi VDC: Banmara, Banmasa, Kalo banmara, Kangres jhar.
First report in Nepal: Banerji in J. Bomb. Nat. Hist. Soc. 55: 259.1958 (E. glandulosum); Manichur
forest, 2134 m, 28.03.1961, P.N. Suwal & Party (KATH)
Description: A long-lived erect, tufty, semi-shrubby, perennial herbaceous plant of about 1–2 m
tall, but sometimes attains up to 3 m. It produces numerous upright stems from a woody rootstock.
The branched stems are densely covered in sticky hairs when young and may be green, reddish
or purplish. They become slightly woody and turn brownish-green or brown when mature. Leaves
are diamond-shaped rhomboid or almost triangular and oppositely arranged along the stems.
They have sharply pointed tips and are mostly hairless, but their stalks are often covered in
sticky hairs. The leaf blades 4-15 cm long and 3-9 cm wide are diamond-shaped with bluntly
toothed margins.
Small white flower-heads consist of several tiny flowers surrounded by two rows of greenish
bracts 3-5 mm long. These flower-heads (5-8 mm across) are borne in large numbers and
arranged in clusters at the tips of the branches in terminal corymbose iflorescense. The seeds
are slender, reddish-brown or blackish-brown, and slightly curved. These ‘seeds’ (1-2 mm long
and 0.3-0.5 mm wide) have four or five slight ribs which run length-wise (longitudinally) and their
bodies are hairless. However, they are topped with a ring pappus of numerous whitish hairs (34 mm long), which are readily shed. Its roots are yellowish and give off a distinct carrot-like smell
when broken or damaged.
Habitat: It is a weed of roadsides, pastures, fence-lines, disturbed sites, and banks of water
courses in subtropical and warmer temperate regions. It is also commonly found in open
woodlands, forest margins and forest clearings. It prefers a warm and wet environment, but its
ability to adapt to wide environmental conditions is very strong. It can grow in environments with
temperature ranges from 5°C to 42°C. It grows on dry and barren hills, and can even grow in
cracks in stone walls, road edges and houses. It also grows more vigorously in a fecund soil
with moisture. It has a shallow rooting system spreading horizontally in the top soil.
Reproduction and dispersal: A. adenophora propagates by seed, with each plant producing
30,000–45,000 seeds, and sometimes as many as 100,000 seeds (Jianghua 2005). It maintains
16
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
and spreads its population along rivers and roads, mainly by means of its seeds. Wind, flowing
water, vehicles, people and livestock are mediums for spread. Seed germination requires light,
but its seedlings can grow in shady environments, which is an advantage to its invasiveness
into other plant communities. It can also reproduce by asexual reproduction through adventitious
roots.
Distribution: It is native to Mexico and possibly Central America, although it is now distributed
widely in the United States, Australia, New Zealand and many countries of south-east Asia. It
was introduced in India after 1948 (Biswas 1934) and it is likely that it was introduced in Nepal
from India through eastern border (Banerji 1958) for agricultural purposes probably before 1950.
It is expected to spread at the rate of 20 km per year (Jianghua 2005).
In Bhadaure Tamagi, it was observed throughout the VDC except Kutmidanda. The Kutmidanda
area was heavily populated by Ageratum conyzoides and may be due to its suppression, A.
adenophora could not compete and sustain in the area. It was also most frequent in Harpan
(1214-1241 m), Thulakhet (920-929 m), and areas above 1400 m. Deurali, Chisapani, Bhanjyang,
Ahaldada were most for frequency and Chainpur, Tamagi, Sidane and Harpan for density of the
species. As Ageratina is found up to 2500 m elevation (Kunwar 2003), the transition lands
between agriculture and forests, fallow lands and road sides above 2000 m of Bhadaure Tamagi
VDC are likely to be invaded, if prompt preventive and controlling measures are not in place.
Figure 9: Distribution of A.
adenophora in Bhadaure Tamagi
Figure 10: A. adenophora growing
along the edges of roads, canals,
rivers and ponds
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Chromolaena odorata (seto banmara)
Chromolaena odorata, Siam weed, a fast-growing perennial shrub, native to South America and Central
America, has spread widely in the last 150 years into the tropical regions of Asia, Africa and the Pacific
(Gautier 1992). The first report of the plant was noted in Nepal by D.Don in his Prodromus Florae Napalensis
(Don 1826) and its voucher specimen was collected in 1964. It forms dense stands that prevent the
establishment of other plant species. It is an aggressive competitor and may have allelopathic effects. It is
also a nuisance weed in agricultural land, commercial plantations, road sides and forest edges.
Chromolaena odorata is a large upright shrubby plant 1.5-5 m tall with relatively broad, egg-shaped with
broad end at base or triangular leaves and young stems that are sparsely covered in fine hairs. Its seeds
are relatively large (4-5 mm long), and are topped with a ring pappus of whitish or brownish hairs (about 5
mm long). It is a tropical weed and found between 75 and 1540 m (Tiwari et al. 2005). In Bhadaure Tamagi
VDC, it has been introduced in Ghatichina, 820 m, lower elevation of the VDC. Very few scattered patches
can be seen along the river edges, agricultural fields and road sides. It is well grown in sunny, open and
well drained areas such as forest margins, fallow lands and roadsides whereas the A. adenophora (kalo
banmara) prefers moisture and wetlands and swamps for its growth. It is a typical pioneer species of
secondary forest succession with a strong heliophilic character and vigorous vegetative development
(Hoevers and Mboob 1996). It requires disturbances to native vegetation in order to become established.
Shoots start rooting once in contact with ground. C. odorata is entomophilous and yields a mass of lightweight seeds that are easily dispersed by wind courtesy of the aviation of a buoyant pappus. The fruits
have hooks and could be transported to other locations by sticking to the bodies of fauna and to farm
machinery (Adebayo and Uyi 2010). It flowers between December and April. Sexual reproduction starts
when the plant is one year old. Seed production is prolific and reported up to 87,000 seeds per mature
plant (www.issg.org/database).
It easily invades disturbed habitats and smothers native plant stands. It reduces species diversity both due
to competition and allelopathic effects (Ambika and Jayachandra 1980). Its foliage is reportedly flammable
(contains essential oil), making it a threat to indigenous species which are not resilient to forest fire (Witkowski
and Wilson 2001). It also affects the nesting sites of crocodiles (Pant and Sharma 2011). However, its
leaves contain insect repellent compounds, and root exudates may have nematocidal effects, resulting in
better yields of maize and ground-nut (Hoevers and Mboob 1993). It is, however, obvious that with its
abundant biomass production, C. odorata contributes significantly to the build up of organic matter and
substantial amount of nutrient-rich litter to the soil and improving chemical and physical properties of soil
(Lucas 1989). C. odorata also inhibits the development of another IAS Imperata cylindrica (Bani and Gall
1996).Smoke from C. odorata repels mosquitoes (Yehouenou 1996).
C.odorata can be effectively reduced by burning and weeding. Chemical control by using herbicides (e.g.
triclopyr) may be effective, but it is impracticable, expensive and counter-productive to environment. Biological
control is possible by introduction of natural enemies, arctiid moth, Pareuchaetes pseudoinsulata. It effectively
defoliates pure stands, but it is less successful in scattered patches. Other natural enemies, the flies
Cecidochares connexa, Aphis gossypii, A. citricola, Homona coffeariahave also been identified as potential
biological control agents of Siam weed (Kluge 1989, Muniappan and Nandwani 2002). In Srilanka, Tephrosia
purpurea was introduced to control C. odorata (Ooi et al. 1988). Plantation of Brachiaria decumbens Stapf
cv. Basilisk (Signal grass) and legumes as biological control on a large scale could considerably reduce the
Chromolaena in pastures (Wu and Xuejun 1991, Wu et al. 1996).
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
3.6.2 Diversity and distribution
Of the 13 sampling sites, they were categorized into two zones as 800-1400 m asl and 14002100 m asl. There were five sites within 800-1400 m asl, six within 1400-2100 m asl and two
were mixed or overlapped within 1200-1600 m asl. The sites at lower elevation i.e. 800-1400 m
asl were co-invaded by Ageratum and Ageratina species except at Kutmidanda. A. conyzoides
was found in Bhadaure at the least extent. Based on frequency, density and importance value of
both IAS, importance value index was highest for lowlands six sites: Harpan (1214-1441 m),
Chainpur (1036-1136 m), Kutmidanda (1337-1361 m), Thulakhet (920-929 m), Sidhane (13261690 m) and Ghatichina (821-975 m). Therefore, the lowland areas of the VDC were more
susceptible to biological invasion. The lowland sites Kutmidanda, Harpan, Chainpur, Thulakhet
and Ghatichina were more susceptible to Ageratum invasion.
Table 5: Density and frequency of the selected IAS (A. conyzoides and A. adenophora)
Figure 11: Importance Value Index of IAS in Bhadaure Tamagi VDC, Panchase
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
A. adenophora was homogeneous in distribution throughout the VDC except Kutmidanda, and
the ecosystems of Chainpur (1036-1136 m), Tamaghi (1440-1908 m), Harpan (1214-1441 m),
Chisapani (2058-2063 m) and Sidane (1326-1690 m) were compounded by invasion of A.
adenophora. It was most successful in invading sites above 1400 m but in lower sites, it was
rivaled by A. conyzoides and the lower sites were co-invaded by both species. Five sites above
1400 m: Ahaldada (1860-2096 m), Deurali (1410-1822 m), Bhadaure (1502-1699 m), Bhanjyang
(2001-2048 m) and Chisapani (2058-2063 m) were the least affected.
3.6.3 Potential invasion
Abandoned agricultural lands and grazing lands of Bhadaure Tamagi were quite refuge for
Ageratina adenophora and Ageratum conyzoides. Ageratum conyzoides was a common weed
in all crops apart from those under deep shade. It is also a first species to colonize in degraded
areas and so able to prevent other plants from establishing.Grazing land was the most vulnerable
to both Ageratum and Ageratina species invasion because it was frequently browsed by both
domestic livestock and wild animals. The grazing lands, fallow lands and roadsides are less
nurtured for personal use. Therefore, the areas are more prone to biological invasion. Cattle
grazing and trampling has allowed more invasive alien species to take root. Ageratina adenophora
has colonised forest margins, stream banks, road sides, fallow lands and disturbed areas,
preferring shaded and wetter areas but also growing in open sunny sites. It was luxuriant in
damp areas such as wetland margins, drainage lines, gullies and in clearings in wetter forests.
Fallow lands: roadsides, uncultivated lands, disturbed grasslands, and marginal lands of forests
are favourable for colonisation of invasive alien species. Therefore, unless the existing land
management system is strengthened, IAS are likely to be introduced and established in other
areas of the VDC. Following the GIS and habitat suitability mapping, the following areas were
found more susceptible to invasion of A. conyzoides and A. adenophora.
Table 6: Potential invasion map
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Figure 12: Invasion maps for A. conyzoides, A. adenophora and both species
21
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
3.6.4 Characteristics of invasive alien species
Common characteristics of IAS include rapid reproduction and growth, high dispersal ability,
phenotypic plasticity (ability to adapt physiologically to new conditions), and ability to survive on
various food types and in a wide range of environmental conditions, etc. Invasive alien species
display strong vegetative growth, abundant seed production capacity, high seed germination
rate, long-lived seeds, rapid maturation of a sexually reproductive stage and high ability to
establish over large areas. The alien species are too abundant and dominant even in poor soil
and disruptive to the other native species reducing their variability. Some characteristic features
of IAS are as follows:
•
They grow rapidly and reach maturity early.
•
Many species are capable of vegetative reproduction via stolon (e.g.
Alternanthera philoxeroides and Eichhornia crissepes), rhizomes, bulbs (e.g.
Oxalis latifolia) and rooting at the tips of stem (e.g. Ipomoea carne and Mikania
micrantha) and root fragments (e.g. Ageratina adenophora, Ageratum
conyzoides and Chromolaena odorata).
•
They are highly adapted to wind and insect pollination.
•
Their seeds get widely dispersed by winds, water, birds and other means,
enabling them to colonise in new areas at distances far from their original home.
•
They often have a different phenology for leafing to dormant stages that provide
better opportunities to take nutrients from soil.
•
They usually are not attacked by parasites, diseases, herbivores, etc. in the
newly introduced area.
Figure 13: Characteristics of invasive alien species
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
3.6.5 Mechanism of invasion
Absence of predators and parasites in alien habitat helps in advancing invasive alien species,
otherwise IAS are under control in native habitat. It is supported by the Enemy Release Hypothesis
(ERH) - the idea that species are more likely to become invasive when they are free from their
natural enemies (Torchin et al. 2003). The Biotic Resistance Hypothesis (BRH) argues that
diverse communities, particularly forests, are highly competitive and readily resist invasion
because of interactions with native species, including natural enemies, limit invaders’ impacts
(Darwin 1859, Maron and Vila 2001). As a result, forests, which are more diverse than any other
ecosystem are resistant to ecological invasion (Pimm 1984); however, the dense forest with
monospecific stands are vulnerable to biological invasion. The success of invasive alien plants
is also due to their allelopathic competitive strategy - Novel Weapon Hypothesis (NWH) (Rai
and Tripathi 1982).
The biological invasion usually follows a sequence beginning with introduction, progressing to
establishment and culminates into spread and invasion (Figure 14) (Keam et al. 2009). Not all
introduced species are invasive. Rule of Ten suggests that only 10 per cent of introduced species
will survive and 10 per cent of them will become established. Among the established aliens,
only 10 per cent will spread and become invasive over time (Keam et al. 2009). So, as a rule of
thumb, about 1 per cent of introductions is likely to become invasive (Williamson 1996).
Figure 14: Mechanism of invasion of IAS
3.6.6 Causes of invasion
Determinants of plant invasiveness per se are extremely complex (Rejmanek et al. 2005).
Anthropogenic and natural factors act together to facilitate the introduction and spread of alien
species. The consensus of local communities on the causes and factors of invasion/spread was
on biology of invasive plants and their adaptability, land use management and seed dispersal by
biotic and abiotic factors (Table 7).
Major causes of spread and invasion of alien species observed by local communities were
modes of plant reproduction, large number of seed production, plant allelopathy, etc. as biotic
factors and wind dispersal mechanism, land use change, depopulation, road and transportation,
etc. were abiotic factors. Small seeds, wind dispersal, plant with high competitive ability, etc. are
other important factors that accelerate plant introduction and establishment. Roads function as
prime corridors for establishment and spread of invasive plant species. Marginal land areas,
especially fallow agricultural fields, became source pools for new infestations and spread. Land
fragmentation and degradation also helps in enabling the spread of invasive aliens. Availability
of moisture and dispersal of propagules by water helps to increase plant introduction,
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Table 7: Causes and factors for invasion (N = 28)
establishment and spread. According to Pysek and Prach (1994), soil moisture and water courses
are complementary to IAS invasion. Many invasive plant species release chemical compounds
into the environment, which are not generally harmful to them, but those chemicals suppress
the growth of other plants growing in close proximity of invasive species. This negative effect
(often referred to as allelopathic effect) of invaders on the native species confers a tremendous
competitive advantage.
Land degradation and low productivity were major factors leading to depopulation of the VDC.
The migrated people are likely to bring desirable crops, domestic animals, and ornamental
species to their new homes, potentially speeding dispersal of new non-native species to other
areas. According to Reiter (2001), population migration, increases in density, as well as poor
sanitary conditions induce spread of invasive species and diseases. Less care about use of
seeds, fertilizers, land and soil fertility and un-routinely control of weeds and invasive aliens led
to rampant spread of invasive aliens. High nitrogen levels provide an advantage to invasive
species (Brooks 2003).
3.6.7 Invasion trend of alien species
Impact of invasive alien plant species was apparent for over a period of three decades in Bhadaure
Tamagi VDC when salah jhar (Conyza japonica) was problematic about 25 years ago. According
to local communities, Conyza, Phalaris, Borreria, Ageratina, Ageratum and Chromolaena are
consecutively invading the VDC and Panchase. Agricultural land was first worsened by Conyza
and was exacerbated by invasion of Phalaris minor. Later, Borreria was established and menaced
agricultural productivity. Roadsides, forests and agricultural periphery close to wetlands, ponds,
streams, and wells were invaded by Ageratina about 15 years ago and its impact is still increasing
(Figure 15).
Figure 15: History of introduction of invasive alien plant species in Bhadaure Tamagi VDC
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Table 8: Information about the first sight of IAS in the Panchase area by local communities (N =28)
In household surveys and group discussions, Damdame and Chainpur/Harpan areas were
identified as the first introductory points for Ageratum and Andherikhola and Chiandanda for
Ageratina. Other probable areas of introductions are given in Table 6. There were 9.32 Ageratina
stands/m2 in Hemja and Lahachok VDCs of Kaski district in 2005 (Kunwar and Uprety 2005),
but in 2012 in the Bhadaure Tamagi area, it was about 11.49/m2. Despite their insisting invasion,
they have been emaciated in agricultural fields because of aggressive invasion of A.conyzoides.
Agricultural fields and even roadsides are being invaded by A. conyzoides and it is now being a
serious menace to agricultural production and local biodiversity. Since 5 to 7 years, all the
unattended fields, farm plots and adjoining areas with inadequate nurture have been intruded
by A. conyzoides.
Chromolaena odorata (seto banmara) is being introduced in open sunny and well-drained
areas such as forest margins, fallow lands and roadsides of lowlands of Panchase.Therefore,
invasive aliens are increasing over time in the Panchase area. The area was assaulted by
Ageratina adenophora at higher elevations and forest fringes, by Ageratum conyzoides at mid
elevations and agricultural systems, and by Chromolaena odorata at lower elevations and
roadsides and fallow lands. Local communities think that the increasing invasion of alien species
was likely due to less land management interventions and increasing temperature.
3.6.8 Impacts of invasive species
Invasive alien species threaten the environment, economies, and human welfare (Lodge et al.
2006). They reduce biodiversity, replace economically important plant species and increase the
investment in agriculture and silviculture (Ricchardi et al. 2000), disrupt prevailing vegetation
dynamics and alter nutrient cycling (Richardson 1998). They can promote fire and alter water
and nutrient availability. They have a major impact on catchment hydrology; 30 to70 per cent of
lower water runoff is reported from watershed areas with dense stands of alien species
(Geldenhuys 1986). Plant invasions dramatically affect the distribution, abundance and
reproduction of many native species (Sala et al. 1999). Therefore, impacts of invasive alien
species are immense, insidious and irreversible (Mcneely 2000).
Impacts of invasive alien plant species A. conyzoides and A. adenophora were well observed
throughout Bhadaure Tamagi VDC and none of the ecosystems was free from this menace.
Edges of forests, agricultural lands and wetlands were severe in IAS intrusion. As a result of
invasion, socio-economic impacts were more apparent. Despite a number of impacts of IAS
25
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
have been witnessed, a detailed species specific impact assessment for each habitat and
ecosystem is yet to be carried out.
3.6.8.1
Biodiversity threats
The transport of organisms through increased levels of travel, trade and tourism is leading to
the widespread breaching of natural biogeographic barriers at unprecedented rates.
Consequences can be severe, especially in naturally isolated ecosystems. The ecosystems
particularly forests, wetlands and grazing lands of the VDC were deteriorated due to invasion of
alien species. Species such as Artemisia, Solanum xanthocarpum and Urtica sp. of fallow lands
and banso, samo, phurke, mallido, siru, etc of agricultural lands were threatened by invasive
alien speies in Bhadaure Tamagi VDC. Again, IAS are also considered as biological polluters
(Westbrook’s 1991) and are capable of hybridising with native plant relatives that result in
unnatural changes to a plant’s genetic make-up. Therefore, the biodiversity of Bhadaure Tamagi
VDC is in great peril because of IAS.
3.6.8.2
Impacts at ecosystem level
Although all ecosystems are susceptible to invasion, the ecosystems intertwined with higher
level of human interventions (Yan et al. 2001) (eg forestry, agriculture, grazing lands) are likely
to pose greater susceptibility. In Bhadaure Tamagi VDC, grazing, agriculture and fallow lands
and road sides were highly susceptible to invasion (Figure 16). In these productive ecosystems,
fast growing opportunistic alien species more benefited because of their mode of reproduction
and greater adaptability.
Figure 16: Impact of IAS on different habitats
Abandoned agricultural lands and grazing lands of Bhadaure Tamagi were a refuge for Ageratina
adenophora and Ageratum conyzoides. A. conyzoides was a common weed in all crops apart
from those under deep shade. It is also a first species to colonise in degraded areas and so able
to prevent other plants from establishing. Ageratum reproduces mainly by seeds, which are
26
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
dispersed by livestock, clothes and agricultural machinery. It can complete its life cycle
(germination to flowering) in less than two months, compounding the agro-ecosystems by
production of outnumbered propagules. Its competitive ability has impacts on native biodiversity
and it is also poisonous. It was considered as low risk posed species by Tiwari et al. (2005);
however, in Bhadaure Tamagi VDC, it was one of the serious menaces for agricultural fields. It
was introduced about 7 years ago in Bhadaure Tamagi VDC and has aggressively spread in
agricultural fields because of application of excessive nitrogen chemical fertilizer, according to
local communities.
Grazing land was the most vulnerable to both Ageratum and Ageratina species invasion because
it was frequently browsed by both domestic livestock and wild animals. Again, the grazing lands
of the VDC at higher elevations have open access (Upadhyay 2012) and management care
from government, community and individual levels is almost insignificant. The grazing lands,
fallow lands and roadsides are less nurtured for personal use. Therefore, the areas are more
prone to biological invasion. Cattle grazing and trampling has allowed more invasive alien to
take root (NEPA 1998).
Forests of Bhadaure Tamagi VDC were least affected by invasive alien species (Figure 16) as
they are more diverse (Bhattarai et al. 2011) and close canopied. Invasive alien species are
shaded out by trees and lianas in forests (Rouw 1996) and their invasion is slowed down
(Tjitrosemito 1996). As a result, dense and diverse forests are more resistant to ecological
invasion (Pimm 1984).
However, forest edges and plantation/secondary forests were disturbed by invasive species.
The plantation forests of Ranibas of Paudur VDC and Peribasti of Bhadaure Tamagi VDC were
considered as the first entry points of Ageratina adenophora. It has colonised forest margins,
stream banks, road sides, fallow lands and disturbed areas, preferring shaded and wetter areas
but also growing in open sunny sites. It was luxuriant in damp areas such as wetland margins,
drainage lines, gullies and in clearings in wetter forests. It grows in large dense clumps and will
eventually outcompete all other plants in an area, choking out native vegetation and forming a
monoculture. Therefore, grazing lands, roadsides, disturbed forests and wetlands of Bhadaure
Tamagi VDC are common niches of A. adenophora. Expansion of IAS into forest ecosystems of
Nepal in last few decades has posed a serious threat to forest health with a possible impact on
carbon balance (GoN 2011a).
Fallow lands, roadsides, uncultivated lands, disturbed grasslands, and marginal lands of forests
are favorable for colonisation of invasive alien species. Other potential invasive competitors
such as Parthenium hysterophorus, Lantana camara, Chromolaena odorata, Cassia tora, etc
are likely to invade Bhadaure Tamagi VDC unless the existing land management system is
strengthened because they are easily introduced in fallow lands. Other invasive aliens of Nepal
are Mikania mikrantha, Bidens pilosa, Amaranthus viridis, A. spinosus, C. sophera, etc which
can alter the species composition of fallow and cultivated lands (NBS 2002).
3.6.8.3
Impact on soil
Invasion by alien plant species affects the dynamics and composition of soil and have impact on
ecosystem functions such as soil nutrient cycling (Yelenik et al. 2007), hydrological flows and
soil chemistry (Randall and Marinelli 1996). With abundant biomass production, Ageratina
adenophora also contributes positively to build up the soil organic matter and soil pH (Hoevers
and Mboob 1996), but analysis of biomass of Ageratina and soil pH was not in the scope of the
present study
In Bhadaure Tamagi VDC, invasive alien species (A. conyzoides and A. adenophora) were
growing in a wide range of soils but not flourishing in shade. At the land use level, Ageratum
was common in agricultural fields and Ageratina in fallow lands and roadsides. Soil texture
27
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Table 9: Physical characteristics of soil of Bhadaure Tamagi VDC
analysis of soil samples of fallow lands and cultivated lands showed that coarse sand was
highest in cultivated fields and gravel in fallow lands (Table 9). Silt clay was higher in cultivated
fields. Since cultivated fields and barren/fallow lands were heavily invaded by Ageratum and
Ageratina respectively, physical soil data of these two sites did not reveal significant relationship.
However, all types of soil even gravel to fecund were supportive to establishment of Ageratina.
Therefore, their diversity and distribution were homogenous throughout the VDC. Ageratina
was well grown in dry and barren hills, and even in cracks of roads, stone walls and houses.
Ageratum conyzoides were common in the proximity of habitation and gardens and introduction
and establishment of Ageratum could be supported by more silt and clay of the soil of these
habitats. The agricultural fields with adequate soil moisture and partial shade were favorable for
growth of Ageratum but closed canopy was even lethal to seedlings. The sites (Chainpur,
Kutmidada) with highest density and frequency of A. conyzoides were also possessing highest
soil moisture content (Table 10). The areas were also possessing highest soil pH.
Table 10: Chemical characteristics of soil of Bhadaure Tamagi VDC
The correlation study between altitude and soil characters and plant IVI was negative. Soil pH,
soil moisture, and IVI of both IAS were negative to altitude (Table 11). Whereas, IVI of IAS was
positively correlated to soil pH and moisture, as soil moisture enhances introduction of IAS.
Table 11: Correlation analysis among soil characters, altitude and IVI of A. conyzoides and A.
adenophora
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Damp areas such as wetland margins, drainage lines and gullies densely covered by Ageratina
showed that Ageratina favors soil moisture for establishment. Availability of moisture and the
dispersal of propagules by water may increase establishment of Ageratum and Ageratina along
the water courses. As lowlands of the VDC have been exploited for agricultural production,
applications of chemical fertilizer were common resulting in increment in soil pH and IAS. Soil
pH was negatively correlated to altitude and it was positive to IAS importance value.
3.6.8.4
Impacts at species level
Household survey revealed that roadsides and fallow lands previously dominated by Artemisia,
Solanum, Urtica, etc. have now been invaded by aliens. Artemisia, Solanum and Urtica became
fail to maintain their biomass in the changing climate and their dominance was fairly slacked off
by invasive alien species particularly Ageratina. Ageratina contains cadinene sesquiterpenes
which plays a role of allelopathy and control associated vegetation. It is also poisonous to horses
(Bohlmann and Gupta 1981, Baruah et al. 1994). Similarly in agricultural fields, invasive alien
species precisely Ageratum conyzoides, Borreriaalata, Phalaris minor, etc. were known to replace
the native species as well as prevent their natural regeneration. The grasses such as Banso,
Samo, Phurke, Mallido and Siru etc. have been threatened because of invasion of A. conyzoides,
Borreriaalata, Phalaris minor in agriculture fields (Table 12).
Table 12: Impact of invasive alien species at species level
3.6.8.5
Impacts at socio-economic level
Lower area of Bhadaure-Tamagi VDC is densely populated by subsistence farmers and livestock
rearing is an integral part of their livelihood (Bhattarai et al. 2012). As livestock comprises a
major part of agro-ecological system of Panchase, fodder collection is the second most important
biomass outtake, especially in dry and lean periods when on-farm fodder is particularly sparse.
Preferred species for lopping fodder were Brassiopsis heinla, Ficus lacoor, F. glaberrima, F.
hispida, Streblus asper, Eurya accuminata, Prunus species , Quercus lamellosa and Q.
semecarpifolia (Bhattarai et al. 2012), however, their productivity was constrained by Ageratina
and Ageratum by outcompeting for nutrients. Livestock rearing was possible by stall-feeding
and foraging at lower elevation and by free grazing at upper area.
Upper area of the VDC is dominated by Gurung and other ethnic groups and their livelihood
differs to inhabitants of lower area. Out-migration is one of the characteristics of the VDC and it
is more common in upper part of VDC. Again the Gurung households of upper part of the VDC
29
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
have been allured for abroad and cities for various reasons, resulting in depopulation in the
VDC. The outcome of out-migration has multi-folds; agricultural fields are laid fallow, lack of
labor (Maren et al. 2013) and decreased productivity. All these factors are inherent to spread of
invasive aliens. Out-migration is less extensive in lower areas where Brahmin and Kshetri are
dominant because these ethnic groups are less eligible for Gurkha recruitment (Maren et al.
2013). Three limiting factors to agricultural production in Bhadaure Tamagi VDC are namely
labour, water and fertilizer (Thapa 1996). Inadequate labor in the VDC led the agriculture and
grasslands less nurtured and unattended, resulting in rampant spread of invasive species.
3.6.8.5.1 Negative impacts
Present study found that invasive species have deleterious effects to socio-economy in Bhadaure
Tamagi VDC. The current livelihood pattern amplified introduction of non-native species because
of more interest towards off-farm activities, less care about seeds, fertilizers, land and soil fertility
and untimely control of weeds and invasive aliens of farmlands. As a consequence, farmers of
Bhadaure Tamagi VDC are plagued by invasive weeds and lost their properties.
Figure 17: A house owned by a Gurung left unattended
for long at Tamagi, Bhadaure Tamagi VDC
As the species abrades agricultural crops, negative impacts to livelihood are apparent. According
to the local communities, A. conyzoides is more harmful to the local livelihood and biodiversity
than A. adenophora (Table 12). Neither cattle nor goats eat Ageratum, and areas traditionally
used for grazing in Tamagi area of the VDC were deteriorated, forcing villagers to walk farther in
search of grazing pastures. The increased time spent on this activity translates into a substantial
economic loss. Incidences of livestock mortality were common in village because of accidental
consumption of Ageratum and its flowers by livestock particularly cows and buffaloes while
feeding other grasses. In last five years, there were three casualties of livestock mortality only in
Harpan, Bhadaure Tamagi VDC.
Morbidity and mortality of livestock by A. conyzoides (Nilo gandhe)
Impact of A. conyzoides is more severe in Harpan, Chainpur and Kutmidada of Bhadaure Tamagi VDC. There are a number of
impacts of by A. conyzoides, but the cases of livestock mortality particularly of buffalo in Harpan – 4, Bhadaure Tamagi VDC
were noticeable. In last five years, there were three cases of livestock mortality in Harpan and two cases in Chainpur. In all
cases five buffaloes were assailed.
Mr. Uma Lal Poudel, Mr. Nar B Khatri and Mrs. Vishnu K Khatri of Harpan – 4 and Mr. Deepak Parajuli and Mr. Tek B Sunar of
Chainpur – 5, Bhadaure Tamagi VDC got lost their buffaloes because of feeding A. conyzoides by their buffaloes. In general,
buffalo and other livestock except goat did not forage A. conyzoides but in sometimes, they inadvertently feed A. conyzoides
while feeding other grasses. The cases were generally happened in spring season when the plant flowers in full bloom. After
feeding A. conyzoides, abdomen is enlarged, and there is no defecation and rumination (Ugraunu). In folklore, leaf or seed of
radish, wild garlic, sil timur (Litsea species), timur (Zanthoxylum armatum), nirmasi (Delphinium species) and byakur (Dioscorea
species) are mixed and fed immediately after diagnosing.
30
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
In Bhadaure Tamagi VDC, A. conyzoides has adverse impacts on most of the agricultural crops
as the nutrients and fertilizers supplied to the main crop are being exploited by this species.
Agricultural crops particularly ginger, millet, rice and grasses were outcompeted by Ageratum
and their productivity was declined (Table 13). According to local communities, there was about
3 muri (273 kg) rice productions in a ropani (0.0509 ha) agricultural land at Chainpur but after
invasion by A. conyzoides, the production was reduced to about two muri (182 kg). Reduction in
production of cereals and grasses by A. conyzoides, Ageratina adenophora, and C. odorata in
Kaski district was also discussed (Bhusal 2009). According to Oerke et al. (1994), there was a
loss of 13% in agricultural output due to weeds.
Table 13: Impacts of A. conyzoides and A. adenophora
Ageratum is allergic and produces foul smell, which often results in giddiness, vomiting, fever
and headache (Singh and Singh 2009). Wetlands, roadsides and forests and species Artemisia,
Urtica, Solanum were aggressively threatened by Ageratina. Although the Ageratina have
pesticidal properties (Chettri 1986) which have been applied in a few areas of Nepal, no
commercially viable applications have been found in Bhadaure Tamagi VDC.
Figure 18: Ginger has been outcompeted by Ageratum at Chainpur and grassland has been relegated
by Ageratina at Tamagi
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
3.6.8.5.2 Positive impacts
Along with negative impacts, there are several positive impacts of these two species and almost
have been capitalized by local communities of Bhadaure Tamagi VDC. The technology of using
Ageratina was already in place in VDC as a green energy resource, composting and income
generation offsetting the household firewood deficit, promoting soil fertility of farmland and
complementing livelihood of rural poor. The practice of using Ageratina in particular and Ageratum
conyzoidesas green manure is in increasing trend in the VDC. Increment of rice and wheat yield
was observed on other areas of the country when green manuring of Ageratina was used
(Bhattarai et al. 2006) (Table 14), because it contains 0.372% total nitrogen, 0.062%total
phosphorus, and 0.580% total kalium, as well as calcium, magnesium, iron, sulfur, silicon, zinc,
boron (Sun et al. 2004). Therefore promotion of utilization of Ageratinaas green manuring is
important in Bhadaure-Tamagi VDC.
Table 14: Usage of different plant species as green manuring
Again, Ageratina has long been used as cattle bedding material, as found in other parts of the
country (Shrestha 1989). The apical leaves are crushed and its paste and juice are used for
bleeding control. Ageratum was also utilized for treatment of various ailments (Oladejo et al.
2003), but it was not in practice in Bhadaure Tamagi. Bio-briquette made from Eupatorium was
used as green energy fuel in Bhadaure Tamagi VDC; however it was merely a demo version.
Production of bio-briquette is potential in Bhadaure Tamagi VDC because it helps arrest plant
invasion, enrich the biodiversity and supply employment and additional income to locale.
Table 15: Comparative use of A. conyzoides and A. adenophora
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Figure 19: Uses of A. adenophora: tender shoots are as forage, green manuring and green fuel
3.6.9 Climate change and invasive species
Interacting dynamics with climate change and invasive species ranges from global patterns to
local sites and communities of species (Burgiel and Muir 2010). Climate change may include
alterations in species distributions and changes in abundance within existing distributions,
resulting from direct physiological impacts on individual species, changes in abiotic factors,
changes opportunities for reproduction and recruitment and alters interactions among species
(Karieva et al., 1993). Invasive species may find that changes in climate produce more conduits
for their establishment andspread (McNeely 2000). Climate change is therefore a pervasive
element of the multiple forcing functions which maintain, generate and threaten biodiversity and
induce biological invasion.
Over a period of 30 years, maximum temperature has been increased from 19°C to 20.5°C and
rainfall 5300 mm/yr to 5600 mm/yr in Bhadaure Tamagi VDC. As a coincidence, during the
years, there was an exponential increase in IAS, according to local communities. At present
there were 54 IAS and among them 18 were highly invasive. There were no recorded archive
data about the history and number of IAS of Panchase over a period neither with local communities
nor with government organization. However consecutive invasion of IAS Conyza, Phalaris,
Borreria, Ageratina, Ageratum and Chromolaena was accounted and nine high risks possessed
species Lantana camara, Eichhornia crissepes, Parthenium hysterophorus and above six species
were noted. Increasing temperatures and changes in precipitation compounded by invasion of
alien species posed the additional impacts on agricultural productivity, grazing lands, and forest
biodiversity. Climate change therefore could alter almost very facets of invasion dynamics and
every interaction between different factors (Thuiller et al. 2007).
Figure 20: Relationship of IAS introduction and increasing temperature in Bhadaure Tamagi VDC
33
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
3.7 Management of invasive species
Effective management of IAS is clearly a priority for biological conservation worldwide. As local
communities were aware about invasive species and their management, local initiatives as
conventional measures to control them were common. Manual uprooting, burning and controlling
through uses and weeding, hoeing and ploughing were applied as controlling measures and
plantation of fodder trees and grasses was used ascontrolling and preventive measure. Multiple
methods were often applied for controlling, however almost were controlling focused. Manual
uprooting, a classical tool for controlling weeds, was easy for Ageratina because it has a shallow
rooting system spreading horizontally in the topsoil, but it was labor intensive to Ageratum
conyzoides because A. conyzoides has profusely branched root system. Burning was the second
common management measure to control weeds (Table 16).
Table 16: Management measures to control IAS in Bhadaure Tamagi VDC (N = 28)
According to Rejmanek (2005), effective management of biological invasion should follow three
main steps from prevention, early detection and eradication and control backed up by integrated
management. Prevention is the best form of invasive species management. If prevention is no
longer possible, it is best to treat infestations when they are small to prevent them from
establishing. Controlling the weed before seeds will reduce future problems. Control is generally
best applied to the least infested areas before dense infestations are tackled. Consistent followup work is required for sustainable management.The precise management measures adopted
for any plant invasion will depend upon factors such as institutional mechanism, policy structures,
terrain, the cost and availability of labor, the severity of the infestation and presence of other
invasive species.
Nepal has various national and international legislative measures to conserve country biodiversity
through IAS addresal. The IUCN Guidelines for Preventing Biodiversity Loss due to IAS (2000)
has been designed to increase awareness and understanding of the impact of IAS. It provides
guidelines for prevention of introduction, re-introduction and control as well as eradication of
IAS (IUCN 2000). Despite these arrangements, Nepal so far does not have any specific institutions
responsible for invasive alien species research and management and it yet remains an overlooked
environmental problem. Impact of IAS in the country has not been properly studied, albeit some
adverse environmental impacts like alteration of habitat and species composition have been
experienced through their invasion (GoN 2011b).
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
CHAPTER FOUR: CONCLUSION AND WAY-FORWARD
4.1 Conclusion
Climate change impacts, such as warming temperatures, erratic rainfall, are likely to increase
opportunities for invasive species because of their adaptability to disturbance and to a broader
range of biogeographic conditions and environmental controls. Although all ecosystems are
susceptible to invasion, the ecosystems intertwined with higher level of human interventions
(e.g. forestry, agriculture, grazing lands) of Bhadaure Tamagi VDC were highly susceptible.
Invasive alien species Ageratum and Ageratina were luxuriant in these habitats however they
were habitat specific.
Despite the Bhadaure Tamagi VDC is rich in plant diversity (a total of 140 plant species were
recorded during field), it is seriously plagued by invasive aliens. A total of 52 invasive alien plant
species were recorded from the VDC, of them, 18 were highly invasive. There were 12 potentially
competitors invasive species and they can establish where the habitats are poorly nurtured and
already degraded.Impacts of invasive alien plant species A. conyzoides and A. adenophora
were well observed throughout the Bhadaure Tamagi VDC and none of the ecosystems was
free from this menace. Edges of forests, agricultural lands, wetlands and roads were bereaved
due to invasion of IAS. Species such as Artemisia, Solanum xanthocarpum and Urtica species
of fallow lands and Banso, Samo, Phurke, Mallido and Siru etc. of agricultural lands were
particularly threatened by A. conyzoides and A. adenophorain Bhadaure Tamagi VDC.
The fallow lands and less attended agricultural plots were invaded by invasive aliens particularly
by A. conyzoides at lowlands and by A. adenophora at higher elevations along roads. Lowlands
such as Kutmidada, Harpan, Chainpur of the VDC were more susceptible to invasion of A.
conyzoides. Ageratina adenophora was homogeneous in distribution throughout the VDC except
Kutmidada and the ecosystems of Chainpur, Tamagi, Harpan were compounded. It was most
successful in sites above 1400 m but in lowlands, it was co-invaded by A. conyzoides.
History of introduction of IAS in Bhadaure Tamagi dates back to 25-30 years. The first IAS were
Phalaris minor (Ratnaulo) and Conyza zaponica (Salah jhar). Borreria alata (Badame jhar) was
introduced about 20 years ago in Bhadaure Tamagi. A. adenophora was introduced and
established before a decade in Bhadaure Tamagi and colonized almost of the habitats but in
later it was outcompeted by A. conyzoides. A. conyzoides has introduced in Bhadaure Tamagi
for about 5-7 years. It has been aggressively spread as increasing the usage of nitrogen chemical
fertilizer in the VDC. Recently Chromolaena odorata (Seto banmara) has been introduced along
the roadsides and fallow lands of the VDC. Along with these nuisance invasive species, there
were introductions and establishments of Eichhornia crissepes, Parthenium hysterophorus and
Lantana camara in and around Bhadaure Tamagi VDC, possessing potential risk to the local
biodiversity and socio-economy.
A. conyzoides is more harmful to the local livelihood and biodiversity than A. adenophora. Neither
cattle nor goats eat Ageratum, and the areas traditionally used for grazing in upper areas of the
VDC were deteriorated. Incidences of livestock mortality were common in the village because
of accidental consumption of Ageratum and its flowers by livestock while feeding grasses. In
last five years, there were three casualties of livestock mortality only in Harpan, Bhadaure Tamagi.
Agricultural crops particularly ginger, millet, rice and grasses were outcompeted by Ageratum
and their productivity was declined.
Less production is more likely lead to depopulation at rural areas. Again the migrated population
may bring desirable crops, domestic animals, and ornamental species to other areas, potentially
speeding dispersal of aliens. Inadequate human resource in the VDC led the agriculture and
grasslands less nurtured and unattended, inducing rampant spread of invasive species. Current
35
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
livelihood pattern amplified introduction of non-native species because of more interest towards
off-farm activities, less care about seeds, fertilizers, land and soil fertility and untimely control of
weeds and invasive aliens of farmlands. As a consequence, farmers of Bhadaure Tamagi VDC
are plagued by increasing number of invasive weeds and lost their properties. Despite a number
of impacts of IAS have been witnessed, detail species specific impact assessments for each
habitat and ecosystem are yet to be carried out.
With increasing population and falling productivity of farmlands, generating alternative sources
of income is essential. It is important to promote activities that balance the need for conserving
biodiversity and meet the requirements of local communities, on the one hand, and promote
technologies and skills that can provide additional income through wise and cautious uses of
invasive species on the other.Invasive alien species are a global issue that requires collaboration
among governments, economic sectors and non-governmental and international organizations.
Establishment of baseline data and regular monitoring of alien species dynamics are essential
to fully understand the IAS problems and their impacts. Therefore, extensive and intensive
research should be promoted.Plantation of native plants species available in the country should
be encouraged. Until there is any firm conclusion to indicate otherwise, plantation of non-native
and invasive species should be discouraged (Tiwari et al. 2005).
4.2 Recommendations
4.2.1 Preventive Measures
Legislation and institution development: There is a lack of specific regulations, manual,
guidelines, laboratory, taxonomic capacity, etc. for the identification of IAS in Nepal (Tiwari et al.
2005). The overall institutional facilities and human capacity need to be improved by providing
essential technical support, strengthening coordination and sharing IAS information among
concerned agencies and stakeholders. Legislation and regulatory procedures regarding
quarantine, inspection, and cautious introduction of plants need to be strengthened, with more
attention to risk assessment before approval and follow-up monitoring after introduction (Bista
and Chaudhary 2005). Coordinated approaches at national level are important through a
responsible government institution to identify and understand the biology and ecology of IAS
and their monitoring and management.
Building awareness and capacity and promote community participation: It is recognized
that public awareness plays a key role in combating invasive species as the species create
ecological and economic havoc including damages of human health. It is essential that awareness
needs to create among wider stakeholders so that prevention, control, monitoring and eradication
are possible. TV, newspapers, internet and other forms of media are best to utilize to inform and
educate the general public on the impacts of invasive species. Promote community participation
through awareness generation and involvement in efforts to address IAS through promotion of
Public-Private Partnership (PPP) approach.
Promote scientific research: Almost of the ecosystems are invaded by IAS, threatening species,
ecosystem and genetic diversity. Again the limited research and management interventions
compounded the situation. Introductions of new species are continued in the name of economic
development. Therefore, scientific research is necessary to prepare basic data of species, biology,
ecology, impact assessment and management guidelines.
Avoid using the known invasive species: This is the first and foremost principal of prevention
is avoiding the invasive species. For this, a list of invasive species of an area should be catalogued
and widely circulated through media for awareness of general public. Identify the worst alien
species that have invaded the natural ecosystems and assess their distribution, rates of invasion,
their population dynamics and indigenous management practices, if any (Paudel and Kaini
2003).
36
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Judicious use of inputs: Many studies have shown that high nitrogen levels and low quality
fertilizers provide an advantage to invasive species that are better adapted to using plentiful
nutrients for rapid growth and establishment as compared to native species. Introduction of
Eupatorium might be due to plantation materials/seedlings used in plantation of erosion of
Ranibas, Paudur. Therefore, the judicious uses of the materials limit the introduction and spread
of invasive aliens.
Minimizing landscape disturbance and plantation of native species: All land uses need to
be monitored and nurtured regularly for controlling the invasion of species. Scouting at regular
interval helps in preventing spread of invasive species. Particularly, seedlings need to be checked
by uprooting. Removal of invasive species when the population is small and before flowering
helps native species to occupy the empty niche.
Plantation and afforestation of native species: A. adenophora cannot invade dense forest,
shrub lands, and well-managed plantations, therefore plantation, afforestation and promotion of
native plant species is imperative to offset the invasion. The invasive alien species are pioneer
of secondary forest succession with a strong heliophilic character and vigorous vegetative
development. Opened canopy due to logging or disturbance results in increased light intensities,
inducing heliophilic invasive species (Joshi et al. 2011). Again closed canopy retards the growth
of invasive aliens. Plantation over invaded sites is also beneficial because the soil moisture is
maintained by weed by covering the soil and it will be gradually replaced by routinely management
of planted species.
According to local communities, shade of Ficus glaberrima deters invasive aliens. Again plantation
of F. glaberrima checks the open canopy, chokes the introduction of invasive aliens and provides
fodder to livestock. Though it is premature to say, it seems that F. glaberrima preempts the
introduction of invasive aliens in roadsides and transition areas. However, a study about
allelopathic effect of F. glaberrima is prerequisite before implementation.Plantation and promotion
of other fodder trees, Brachiaria decumbens (Signal grass),trifolium, and legumes could
considerably reduce weed infestations (Wu and Xuejun 1991, Wu et al. 1996).
Collaboration: The problem of IAS is a global concern. The isolated and unilateral actions may
be insignificant to address the prevention and control IAS. Collaboration and networking among
peer organizations, government institutions and national and international government
organizations is essential to design the programs, share the information, resources and
technologies, and institutionalize the best management interventions. Trans-boundary
collaboration is also necessary to manage the species invasion.
Figure 21: Ficus glaberrima (Pakhuri) controlling invasive aliens in its shade
4.2.2 Controlling Measures
Exploration and management of uses: As Eupatorium and Ageratum are useful for various
purposes, extensive uses of these plants may control rampant spread. Species currently has
been used as ethnomedicinal, bedding material, green manuring, forage for goat, green fuel as
37
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
bio-briquette, etc. in the VDC. Extensive utilization is important as the strategy is called win-win
strategy and it is a good scope of enterprise development, employment generation at local
scale and long run management of invasive species. Eupatorium contains much fibrin that can
be used to produce paper and board after deodorization treatment (Sun et al. 2004).
Uprooting: Uprooting cannot be applied independently because of the abundant seed in soil
and strong asexual propagation of the plant. Again it cannot be perished effectively by one
single way because of the topography of study area, changing climate type and big flexibility of
species itself. Complete uprooting including all roots and rootlets before flowering is mandatory
and controlled burning or composting or manuring or using is necessary. Once the species is
eradicated and habitat is cleared, the area must be planted with fast growing grasses and
fodder trees against seedling re-growth.
Integrated Crop Management (ICM): Integrated crop management involves combination of
measurements such as prescribed burning, regular weeding, hoeing and uprooting invasive
alien species generally results in an increase in abundance and diversity of native species and
crops. Uprooting is suggested to pursue before flowering. This is the most simple and efficient
method, but a tedious, very labor-intensive and costly (Matthew et al. 2000). However, mechanical
and manual weeding of Ageratum is limited due to its allergic effects and strong foul smell,
which often results in giddiness, vomiting, fever and headache (Singh and Singh 2009). Mowing
and tillage provide some measure of control, but are impractical in some situations.
Chemical control: The Alachlor at 1.5 kg/ha was found to be effective in controlling Ageratum
conyzoides in maize crop (Singh and Singh 2009). Glyphosphate, dicamba and 2,4-D butyl
have proven to be effective chemical treatments for Ageratina. Triclopyr may be effective for
controlling Chromolaena odorata and Ageratina adenophora, but chemical control is impracticable
and expensive and may turn counter-productive to the environment (www.hear.org./pior/species/
chromolaena_odorata.htm). It is expensive due to resprouting weeds from rootstocks or root
crowns. Chemical control is one of the effective means of control, but single applications will
generally not provide complete control and they are expensive and contaminate environment
and fail to give season-long control. The use of chemical control must becarried out wisely to
avoid the possible negative effects to the environment.
Biological control: Collection, multiplication and redistribution of gall making fruit fly
Procecidochares utilis was the first used for suppression of Banmara (Ageratina adenophora)
weed in 1945 in USA (Julien 1992). In 1987, fungi Mycovelosiella species and Entyloma
compositarum were found to be effective than gall fly (Wan and Wang 2001). Biological control
of Ageratum conyzoides by bioagents viz. Liothrips mikaniae,Epiblema sternuana, Zygogramma
bicolorata, Listronotus setosipennis, Puccinia species, etc is widely introduced. Biological control
is long term approach to controlling IAS and it is effective only to slow down the invading process
(Sun et al. 2004). The combined use of natural enemies has proven to be effective as biological
control against weeds. However, these natural enemies themselves will have chances of
becoming IAS in due course of time. Therefore biological control can be considered merely as
a placebo to control invasive species.
Figure 22: A gall made by Procecodocharis utilis, gall fly in A. adenophora
38
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
4.2.3 Actions
Based on recommendations, following actions are suggested to initiate in Bhadaure Tamagi
VDC at respective time interval:
Short term
•
Awareness, understanding and participation of local communities on IAS need to create
among wider stakeholders so that prevention, control, monitoring and eradication of the IAS
are possible.
•
Promote plantation of Amrisho and other fodder trees in farmlands and support in-situ
conservation of grasslands (kharbari). Plantation and grassland conservation is feasible in
Damdame, Kutmidada, Harpan and Chainpur areas.
•
Promote plantation of Ficus glaberrima (Pakhuri), a fodder tree provides fodder in lead
periods and may control alien species in transition areas, roadsides and fallow lands of
Sidhane, Bhadaure, Kutmidada, Tamagi, Bhanjyang areas of the VDC.
•
Support and train famers to do integrated crop management: farm with prescribed burning,
hoeing, utilization of bio fertilizers, regular weeding, green manure, composting etc.
•
As Eupatorium and Ageratum are useful for different purposes, scope their extensive uses
and start to use it. Extensive utilization is important as it is win-win strategy and a good
scope of enterprise development, employment generation at local scale, management of
invasive species at long run and involvement of disadvantaged, marginalized and dalit groups.
•
Support local communities to do manual uprooting of Ageratum conyzoides and Ageratina
adenophorabefore flowering and equip them to use the products as energy/fuel potential
bio-briquette. Promote and develop bio-briquette/green energy development initiatives.
•
Design training courses for building capacity to deal with IAS including identification,
prevention, control and eradication management methods, risk assessment and exploration
and uses of IAS.
•
Develop guiding principles for prevention, introduction and mitigation of impacts of IAS.
Mid-term
•
Promote to control use of chemical fertilizers, pesticides and hybrid species because the
chemical fertilizers, pesticides and hybrid species were supposed to introduce Ageratum
and Ageratina in the area and support to use bio-fertilizers, compost manure and green
manure.
•
Explore uses and applications of IAS and their products and manage to use them to control
their spread.
•
All land uses need to be monitored and nurtured regularly for controlling the invasion of
species.
•
Identify key institution responsible for overall management of IAS and capacitate it with
adequate resources, technology and information.
•
Prohibition of further species introductions without prior information and evaluation is
imperative, so that further deterioration of agricultural, forest and other ecosystems and
environment is prevented.
Long-term
•
Define the relationship of climate change (temp, rainfall, humidity, soil data) and invasive
species through participatory action research for building resilience for both local communities
and plant species.
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
40
•
Incentives on researches of biological control of Ageratina adenophora (Kalo banmara)
using gall fly Procecidochares utilis.
•
Strengthen coordination and information sharing mechanism among the national agencies
of forestry, agriculture, trade, environmental protection and research institutions in dealing
with forest invasive species. Promote sharing of information about invasive alien species
through databases and workshops.
•
Collaborate among peer organizations, government institutions and national and international
government organizations to design the programs, share the information, resources and
technologies, and institutionalize the best management interventions.
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
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ANNEX
Annex 1. List of respondents for study of IAS in Bhadaure
Tamagi VDC, Panchase
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Annex 2. Questionnaire used for survey
Impact Assessment of Invasive Ecosystem in Selected Ecosystems of BhadaureTamagi VDC of Panchase Area, Nepal
Date:
District:
VDC:
Name of the interviewer:
1.
50
Ward:
Village:
Name of the respondent:
Are you familiar with invasive species?
Well known .........
general ...........
little ...........
2.
Have you observed any invasive species in your area?
Yes……………….. No…………
3.
If yes, please mention the name of these invasive species
4.
Since when you had observed the first invasive species in your area?
a. Less than 5 years
b. 6-10 years
c. 11 above
5.
May we have more information of IAS in your area (species specific)?
6.
Indicate your idea about the IAS (Tick one).
7.
If yes, what are the problems/benefits?
8.
Which are the factors affecting your livelihood and biodiversity? (Tick appropriate)
9.
What are the factors responsible for introduction and spread of Invasive Species?
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
10.
Please give us some plants/wildlife that are particularly threatened by invasive alien
plants and precisely by Ageratum and Eupatorium?
11.
If Ageratum is harmful, to what extent the ecosystems are affected?
12.
If Eupatorium is harmful, to what extent the ecosystems are affected?
13.
Where are they abundantly seen?
14.
From your experience, where is the potential cover of these species in your VDC?
15.
What are the other natures of these two species? (give data/Information)
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16.
Their infestation/spreading rate in your VDC?
17.
How was the fast spread of these species possible?
18.
Three major problems/impacts you have faced/seen/heard due to these two species?
19.
Other associated/hidden impacts of these two species?
20.
What are the likely threats/challenges of these two invasive species?
21.
·
What are the preventive/controlling measures have you followed?
·
22.
52
·
·
The best three strategies we should run to manage IAS?
Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
23.
Are there community/eco-friendly best options or biological control of these species?
24.
Have you seen any possibilities or options to utilise these invasive species such as Bio
Briquette, fertiliser, etc. Yes……………….. No…………
25.
If yes, what are they?
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Annex 3. Per Month Maximum Temperature Record
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Annex 4. Per month minimum temperature record
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Annex 5: Total Species and their Frequency in Different Habitats
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Impact Assessment of Invasive Plant species in Selected Ecosystems of Bhadaure Tamagi VDC, Kaski
Annex 6.
60
List of invasive plant species in Bhadaure Tamagi,
Panchase and Nepal
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Annex 7: Definitions of key terms
Alien species (synonyms: non-native, non-indigenous, foreign, exotic): a species, subspecies,
or lower taxon introduced outside its normal past or present distribution; includes any part,
gametes, seeds, eggs, or propagules of such species that might survive and subsequently
reproduce.
Casual alien species: Alien species that may flourish and even reproduce occasionally in an
area, but which do not form self-replacing populations, and which rely on repeated introductions
for their persistence (Richardson et al. 2000).
Eradication: The extirpation of the entire population of an alien species in a managed area;
eliminating the IAS completely.
Establishment: The process of a species in a new habitat successfully reproducing at a level
sufficient to ensure continued survival without infusion of new genetic material from outside the
system.
Intentional introduction: The purposeful movement by humans of a species outside its natural
range and dispersal potential (such introductions may be authorised or unauthorised) (IUCN,
2000) (c.f. unintentional introduction).
Introduction: The movement, by human agency, of a species, subspecies, or lower taxon
(including any part, gametes, seeds, eggs, or propagule that might survive and subsequently
reproduce) outside its natural range (past or present). This movement can be either within a
country or between countries (IUCN, 2000).
Invasive alien species: An alien species whose establishment and spread threaten ecosystems,
habitats or species with economic or environmental harm. These are addressed under Article
8(h) of the CBD.
Native species (synonym: indigenous species): a species, subspecies, or lower taxon living
within its natural range (past or present), including the area which it can reach and occupy using
its own legs, wings, wind/water-borne or other dispersal systems, even if it is seldom found
there.
Naturalized species: alien species that reproduce consistently (cf. casual alien species) and
sustain populations over more than one life cycle without direct intervention by humans (or in
spite of human intervention); they often reproduce freely, and do not necessarily invade natural,
seminatural or human-made ecosystems.
Pest: “Any species, strain or biotype of plant, animal or pathogenic agent injurious to plants or
plant products” (IPPC).
Suppression: reducing population levels of the IAS to an acceptable threshold.
Unintentional introduction: a species utilizing unwitting humans or human delivery systems
as vectors to disperse and become established outside its natural range (IUCN, 2000).
Weeds (synonyms: plant pests, harmful species; problem plants): Plants (not necessarily alien)
that grow in sites where they are not wanted and have detectable negative economic or
environmental effects; alien weeds are invasive alien species.
66
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