Download Aripo Savannas

Environmentally Sensitive Area:
Aripo Savannas Strict Nature Reserve
Trinidad and Tobago
Introduction
The Aripo Savannas has long been recognised for its unique ecosystem and
biological diversity. In 1934 the Long Stretch Forest that also consists of the
Aripo Savannas was proclaimed a Reserve. In 1980 the area was proposed
as a Scientific Reserve and in 1987 the Savannas was declared a Prohibited
Area under the Forests Act. The Aripo Savannas is also internationally renowned
for its unusual flora and vegetation communities. It is one of the more intensively
studied areas of natural ecosystems in Trinidad.
Through the Environmentally Sensitive Areas Rules, 2001 (ESA Rules 2001),
the Environmental Management Authority (EMA) has been declaring terrestrial
and marine areas of Trinidad and Tobago to be protected according to criteria
set out in the ESA Rules. The ESA Rules were made under Sections 41, 42
and 43 of the Environmental Management Act, 2000 (EM Act).
In June 2007 the Aripo Savannas was declared an Environmentally Sensitive
Area. It was designated as a Strict Nature Reserve because it is one of
the areas in Trinidad and Tobago with high scientific value, as it is the best
remaining example of the types of ecosystems found within its boundaries.
This designation makes the area eligible for special protection and management
under the laws of Trinidad and Tobago.
Location and Boundaries
The Aripo Savannas Strict Nature Reserve lies in North Central Trinidad between
Arima and Sangre Grande. Its general boundaries are:
• the Valencia River, excluding a 12 hectare parcel of land in Kangalee on the north
• the Eastern Main Road Valencia on the east
• a disused railway line on the south and
• survey control points along the Aripo River on the west
Fig. 1: Location Map of Aripo Savannas
Soil
Old alluvial terraces fanning out from the foothills of the Northern Range and
uplifted during the Pleistocene era are the geological setting of the Aripo
Savannas. The alluvial terraces consist of layers of gravel, sands and clays
representing different depositional environments.
Weathering and ground water movements have subsequently modified the
alluvial sediments, creating a hardpan layer of cemented clays that is impervious
to water infiltration. Weathering has also created an infertile soil A-horizon
(fine sands and sandy clays) that overlies the hardpan.
The hardpan and the infertility of the soils are the two most important features asdfthat have determined the natural savanna ecosystem. The hardpan prevents the vertical movement of water creating alternating conditions
of drought and waterlogging where the hardpan is close to the surface. In
these areas the only vegetation able to survive are grasses, sedges and
herbs. Where the hardpan is found at greater depths, trees and other woody
vegetation are able to grow and create a forest ecosystem.
(a)
(b)
(c)
Fig. 2 a-c: Soils of the Aripo Savannas
Flora
The complex of habitats making up the Aripo Savannas possess characteristics not
seen elsewhere in the country. This ecosystem can be considered unique
as there is a high density of rare, threatened, endemic and possible endemic
species. According to the available data (Schwab 1988), a total of 457 plant
species have been identified thus far, 38 are restricted to the Aripo Savannas
with 16 to 20 that are rare or threatened, and 2 endemic floral species.
The habitats that have been identified in Aripo Savannas are based on the
dominant vegetation type. These have been categorised into six vegetation
communities each having distinct characteristics as follows: open
savanna, palm marsh, marsh forest, palm island, intermittent open water and
trackside.
(a)
(b)
Fig. 3 a-c: Vegetation in Aripo Savannas
(c)
Fauna
In terms of fauna, there are five resident species of birds including Rufescent Tiger-heron (Tigrisoma lineatum), Red-bellied macaw (Orthopsittaca
manilata), Epaulet (Moriche) Oriole (Icterus cayanensis chrysocephalus),
Sulphury flycatcher (Tyrannopsis sulphurea) and the Fork-tailed Palm-swift
(Tachornis squamata). There are also several mammals, fishes, reptiles,
amphibians insects and crustaceans.
(a)
(b)
(c)
Fig.4 a-d: Fauna in Aripo Savannas
Open Savannas
There are ten discrete areas or savannas of varying size (only eight are identifiable)
with a very distinctive community of open, low growing herbaceous vegetation
on a flat plain. The low stature of the vegetation is caused by the impervious
hardpan layer a few centimeters beneath the soil that prevents larger plants
establishing in anything but isolated individuals. In addition, the soils on the
open savanna have a very poor nutrient status.
To cope with this stressful environment, plants have adopted a number of
characteristics to help them survive such as trapping and eating insects and
nematodes. Ninety-five (95) species of plants are found in the open savanna
community, some of which are confined to the Aripo Savannas Scientific
Reserve (ASSR).
The most common species in the open savannas are grasses, and sedges.
Other notable plants of the open savanna include the carnivorous Sundew
Plant (Drosera capillaris) and many terrestrial orchid species such as Pogonia
tenuis or Epistephium parviflorum.
(d)
Marsh Forest
Marsh forest is the community that covers the most of the land area of the
ASSR. This is a forest that grows on land that becomes waterlogged or
marshy during the wet season. It is a relatively low forest, with a closed canopy
populated by species that can tolerate a period of the year waterlogged. The
hardpan layer found under the open savannas is also found under the marsh
forest (although thinner and at greater depth) and is responsible for the flooding of the marsh forest as water cannot drain away through the impervious
hardpan layer. There are a few species that are restricted to the marsh forest
in Trinidad (e.g. the Lady Slipper Orchid Selenipedium palmifolium.) There are
approximately 118 species of plants found in the marsh forest.
Palm Marsh
The palm marshes and palm islands communities are found around the fringes
of the open savannas and in isolated clumps or islands in the middle of the
savanna. They are dominated by the Moriche Palm (Mauritia flexuosa) that
forms evenly spaced stands with a thick understory of shrubs (e.g. Clidemia
neglecta or Miconia ciliata) or tall sedges and grasses (Seleria bracteata or
Panicum parvifolium).
Endemic, Threatened, Rare and Native Species
The Aripo Savannas is believed to be home to two (2), but maybe as many as
fifteen (15) endemic plant species (Schwab 1988) to Trinidad. A comprehensive
biological survey is currently being conducted by UWI which would provide
updated data on the status of any of the species thought to be endemic to
Trinidad and Tobago. The two tentatively confirmed endemic plant species are
Rhynchospora aripoensis and Xyris grisebachii that are both restricted to the
open savannas.
In addition to the endemic species of Aripo, there are a number of species
that are threatened or rare, or its status is unknown. A list was compiled by M.
Oatham based on work by Schwab (1988), Comeau (1989-1990) and Jodhan
& Johnson (1997-1999).
(a)
Drosera capillaris
(b)
Cyrtopodium parviflorum
Fig. 5 a-b: Rare and endangered Species in Aripo Savannas
Threats
A comparison of aerial photographs of 1969 and 1994, indicated that the
marsh forest and palm marsh in the Aripo Savannas have shown marked
deterioration. This has been as a result of human induced activities. Only
small patches of the ecosystems appeared intact with a smooth and continuous
canopy. The majority of the marsh forest and palm marsh ecosystem had
broken, lower canopies, which were interpreted as fire damaged. The major
threats to the area are fires; quarrying; residential and agricultural squatting;
and poaching.
Management
The history of management of the Aripo Savannas has been varied ranging
from management of resource extraction to efforts to conserve the unique
ecosystem. The day-to-day management is undertaken by officers attached
to the National Parks Section. In addition, an Aripo Savannas Stakeholders
Management Committee (ASSMC) has been convened as a multi-stakeholder
advisory body under the ESA Rules (2001). In 2002, the EMA prioritized the
Aripo Savannas for designation as an Environmentally Sensitive Area. In
2003, the then Director of the Forestry Division set up a Working Group focused
on the management of the Aripo Savannas to put forward recommendations
that could be implemented by the Forestry Division to properly manage the
area.
In 2006, the EMA contracted the Caribbean Natural Resources Institute
(CANARI) to develop a comprehensive framework to guide and manage a
participatory process for the development of updated management plans
for the Aripo Savannas. The planning process involved the Aripo Savannas
Stakeholders Management Committee (ASSMC), management personnel
of the Forestry Division, members of the community and other critical stakeholders who were identified during the process. The Updated Integrated
Aripo Savannas Environmentally Sensitive Area Management Plans
were completed in 2009. These plans outline the long term direction for the
protection, development, management and use of the area’s resources for
a 10-15 year period. The Integrated ASESA Management Plans comprise
four detailed plans, an Implementation Plan and a popular version Management
Plan.
Fig. 6: Aripo Savannas Stakeholders Management Committee
References
EMA (2005), Administrative Records for the Environmentally Sensitive Area: Aripo Savannas
Strict Nature Reserve. Port of Spain
Schwab, S (1988), Floral and faunal composition, phenology and fire in Aripo Savannas
Scientific Reserve. Wisconsin, USA University of Wisconsin
Cooper, F (Unpublished) Mid-Terms Report of the baseline botanical survey of the Aripo
Savannas Environmentally Sensitive Area (ASESA). Document prepared for EMA
For further information
The Environmental Management Authority
#8 Elizabeth Street, St. Clair, Port of Spain
Tele: (868) 628-8042 / 8044-5; Fax: (868) 628-9122
Email: [email protected]
Website: ema.co.tt