Download Alpine plant biodiversity. Part 2: Functions and threats

ALPINE PLANT BIODIVERSITY
Part II
Functions and Threats
H.J.B. Birks
NOMA 2011
ALPINE PLANT BIODIVERSITY
Ecosystem services in alpine habitats
Functional significance of alpine
biodiversity
Threats to alpine biodiversity
Conclusions
Acknowledgements
ECOSYSTEM SRVICES IN ALPINE
HABITATS
Three main types:
1. Provision services – extractable resources that
primarily benefit lowland populations (water for
drinking, irrigation, timber) and ecosystem production
(crops, medicinal plants)
2. Regulatory and support services – biodiversity,
watershed and catchment protection, soil fertility, soil
as store of water and carbon
3. Cultural services – spiritual role of mountains,
biodiversity (biophilia), recreation, cultural and
ethnological diversity.
Ecosystem services in alpine habitats globally
Downslope
safety
Water
Food
Fibres
Medicinal
Cultural
Körner et al.
(2005)
Safety
Dams
Freshwater
Energy
Grazing
Crops
Fuel
Timber
Wild
Cultivars
Recreation
Spiritual
Ethnology
Alpine
Terr
Aq
+++
+++
+
+++ +++
+++ +++
++
+++
++
+
+++
+
+++
-
Montane
Hills/Plateaux
Terr
Aq
Terr
Aq
+++
+
+
+
+
+++ +++
+
+
+++ +++
+
+
+++
+++
+++
+
++
++
++
++
++
++
+++
+
+++
+
++
++
+++
+
++
+
+
+
+++
++
-
- not relevant; + relevant; ++ important; +++ very important
Will vary from area to area (e.g. European Alps, Himalaya, Andes)
Human population in mountains
Population
(x 103)
Asia
Former USSR
597,714
34,851
Percent of
total
Density
(per km2)
49%
65.2
3%
6.4
South America
173,549
14%
37.7
North Africa
141,113
12%
52.3
Central Africa
119,559
10%
18.3
Europe
152,613
13%
43.1
100%
38.2
Total
1,219,399
World population 6 billion, so global mountain
population (1.2 billion) is about 20% of total
global population.
Data from Körner et al. (2005)
FUNCTIONAL SIGNIFICANCE OF
ALPINE BIODIVERSITY OR
WHY IS ALPINE BIODIVERSITY SO
IMPORTANT?
1. Catchment slopes depend on soil stability
2. Soil stability depends on near continuous plant cover
3. Plant species diversity ensures a sustained plant cover and
hence soil stability
4. Biodiversity therefore provides insurance – intact systems
provide insurance against system failure (Körner 2002)
5. Ecosystem functioning (plants, animals, micro-organisms coexisting and functioning together)
6. Cultural heritage argument – diverse, man-made
ecosystems are historical treasures of our society
7. Ethical aspects (the right of all species to exist)
8. Aesthetic values (the beauty of alpine plants)
Concentrate on ‘Körner’s Insurance of
Intact Systems' Idea
Alpine terrain (alpine + montane) covers 24% of the
global land area
All mountains have slopes, sometimes very steep slopes
Slopes (and the peaks behind them) not only capture
water but channel it to the foothills and, via large river
systems, feed the lowland plains
Mountains therefore provide water for half of mankind,
directly or indirectly. Hold about 66% of world's
freshwater as snow or ice
Runoff and associated sediment load are beneficial
(water supply, mineral nutrients) and also non-beneficial
(floods, mud-flows, etc.)
Slopes are the key to so much of alpine
landscape ecology
1. Provide gravitational power to water, some of
which can be converted to electric energy
(hydroelectric power)
2. Guard, guide, constrain, or endanger traffic
routes for people and animals
3. Stop clouds (advection) or create clouds
(convection)
4. Exert mechanical forces on organisms
Unless made of solid rock, the only way loose substrates
are secured to slopes is through VEGETATION.
Alpine vegetation provides the 'screws' and 'nails' that
maintain slopes and prevent slope dangers and disasters.
Slopes are only as stable and safe as the integrity and
stability of their vegetation.
Körner (2002)
Integrity of alpine up-slope vegetation is thus the
basic core or control of much, if not all, of downslope lowland welfare and society in many parts
of the world.
Easy to forget basic link between remote
mountains and densely populated lowlands.
Recurring floods in China and mud slides in
Philippines or Andes are result of uncontrolled upslope instability.
Much lowland productivity is required to support the
needs of up-slope society and to maintain sustainable
management in the uplands.
Down-slope

Up-slope interdependencies
"Lowland – Upland Contract of Society" (Körner 2002)
Needs the effectiveness of alpine vegetation, natural
or cultural, to control slope and soil erosion.
Körner
(2004)
Intact alpine vegetation provides slope safety.
As there are many risks and threats on slopes, require
many SAFEGUARDS.
Threats include damage by heavy rain or hail, surface
run-off, mechanical sheer of loose ground, exploitation of
deep-substrate moisture, over-trampling and grazing by
herbivores, snow-gliding, etc.
Plants with their range of life-forms and growth habits
provide the safety 'tools' and 'services'. At any time
these may fail because of natural disease, divergent life
cycles, senescence, stress, disturbance, and chance
factors.
Need all key 'tools' to be present in various combinations
at all times to provide 'emergency' help, to maintain
ecosystem 'services'.
Not really known if ecosystems with more
species are less at risk of loss of integrity than
systems with less species.
Depends on absolute numbers of species
identity, growth-form, and ecology
of species
environmental conditions
Insurance hypothesis proposes that one of the
benefits of biological richness is that it insures
against system failure.
Functional redundancy may not play any role for long time
periods but a single extreme event can cause functional
redundancy to be the 'safety mechanism' of fragile alpine slopes.
Alpine slopes are very susceptible
to extreme events. Maintaining
alpine biodiversity (microbes to
herbivores) is thus a high priority
as alpine slopes and their stability
are so important globally for the
'Lowland – Upland Contract of
Society'.
Functional diversity of species are Nature's insurance against
system failure (loss of substrate on mountain slopes) and secures,
at the same time, other 'services' such as
- provision of medicinal plants, food, fodder, fibres, and other
montane forest products
- clean run-off water
- attractive landscapes
How many species are needed to ensure ecosystem
integrity and slope stability?
Answer depends on the time-frame but the more the
better is a safe generalisation.
We do not know what future disturbances and stresses
will be. Best to play safe now!
As gravity does not compromise or cease, there is little
hope for repair once alpine slopes are damaged and
'wounded'
May take thousands of years for new soils to develop in
an eroded landscape. End-result of slope damage may
be bare rock.
Mountain desert, Andes, S America
Grabherr (1997)
Central Tibet, 4520 m
Miehe et al. (2008)
Ghimire (2008)
Peak of medicinal plant
richness about 1000 m
but medicinal plants (up
to 100 species) occur up
to 6000 m (e.g. Rheum
nobile, Saussurea spp.)
Rokaya et al. (unpublished)
Major topic in itself – several books
Jha et al. (2008)
Ghimire et al. (2008)
Emphasises the central role of medicinal plants in
Himalayan ecosystem services
Evidence for human-induced dwarfing
of Saussurea laniceps in the Himalaya
Decline in height of S.
laniceps since 1900
Height of plants at
heavily harvested and
low harvest sites – 9cm
smaller
Law & Salick (2005)
Nepal Biodiversity
Plan 2004
Unique in recognising
people as part of the
systems from
lowlands to alpine
summits
Ram P. Chaudhary
POTENTIAL THREATS TO ALPINE
BIODIVERSITY
Last 100 years
Decline of traditional grazing practices has resulted in
regrowth of scrub and forest. Tree-lines have risen in the
last 50 years - ? land-use changes or climate changes or
both.
Hydroelectric development, flooding of valleys, and river
regulation.
Tourism, trampling, ski centres, use of artificial snow,
mining -generally rather localised.
In northern areas, lichen- and bryophyte-rich vegetation
has declined because of trampling and too much or too
little grazing. Perhaps also because of changes in
atmospheric inputs as a result of 'global change'.
Reports on seedling establishment and shift of
tree-line in last 50-100 years
Area
Since
Shift (m)
Genus
Chile
1850
10
Nothofagus
NW Canada
1850
10-20
Picea
N Urals
1920
100-500
Larix
New Zealand
(South Island)
1950
10
Nothofagus
Sweden
1960
120-375
Betula, Picea,
Pinus
Spain
1955
70
Fagus
Australia
1967
15
Eucalyptus
Bulgaria
1950
130
Pinus
Oregon, USA
1980
10
Abies
Montana, USA
1973
10-15
Abies, Picea,
Pinus, Larix
Global Change
Körner (1998)
In last 150 years, atmospheric CO2 concentrations and
global temperatures have increased, as have
atmospheric nitrogen levels.
Are alpine plants responding to these changes?
Jotunheimen mountains of central Norway
24 mountains surveyed in 1930-1931 by
Reidar Jørgensen
Re-located over 400 of his localities in 1998
Could see how flora had changed in 68 years
Kari Klanderud and John Birks
Galdhøppigen, Norway
Map of Jotunheimen, central south Norway, showing the 25
mountains studied by Jørgensen (1933) and this study. Three
local glaciers are indicated by stars.
Klanderud & Birks (2003)
Little
change
Some
increase
>2,000 m
1,800 – 2,000 m
Changes in
species
numbers
 1930-31
 1998
1,600 – 1,800 m
Big
increase
Klanderud &
Birks (2003)
Some plants have extended their altitudinal
limits in last 70 years by 200-300 m.
1. Dwarf-shrubs –
Phyllodoce caerulea Vaccinium myrtillus
Empetrum nigrum
Vaccinium vitis-idaea
Salix lapponum
2. Grasses –
Festuca vivipara
Deschampsia flexuosa
Phyllodoce caerulea, Norway
Vaccinium myrtillus
Norway
Vaccinium vitis-idaea
Swedish Lapland
Empetrum nigrum
Norway
Salix lapponum
Scotland
Some summit plants have declined in frequency in
last 70 years (e.g. Saxifraga cespitosa, Cerastium
alpinum, Erigeron uniflorus, Ranunculus glacialis).
Decline because of direct warming or, more likely,
increased competition from faster-growing species
expanding from lower altitudes.
Cerastium alpinum
Norway
Erigeron uniflorus
Norway
Saxifraga cespitosa
Norway
Similar floristic changes reported from Swiss and
Austrian Alps, the Swedish mountains, north-east
Greenland, and Glacier National Park, Montana.
Long-term future for high alpines is not good if they
continue to decline, even on the highest mountains in
the Alps or Scandinavia.
If global change and global warming continue to the
extent predicted by climatologists, the Alpine World will
be a very different place in 2100 compared to 2008.
Many species may have gone extinct or be committed to
extinction because of climate warming, loss of
specialised habitats (e.g. snow-beds), the absence of
anywhere higher or cooler to spread to, and competition
from larger, faster growing dwarf-shrubs and grasses
that are rapidly moving upwards in response to climate
warming.
Attempt to assess
species status by 2080
under various future
climate scenarios. Main
drivers are
temperature and
moisture changes.
Excess species loss
(red) in Alps,
Pyrenees, central
Spain, Balkans,
Scandinavia,
Carpathians, and
Corsica.
Alpine flora 60% loss
Thuiller et al. (2005)
Four different climate scenarios
EU scale extinction
Local scale extinction
MRI
(2007)
AT=Austrian Alps, FR=French Alps, CHB=Swiss Central Alps1,
AP=Apennines, IPE=Pyrenees1, CHV=Swiss Western Alps, NO=Norway,
P=Pyrenees2, SCO=Scotland, CAR=Carpathians, CHZ=Swiss Central Alps2
Extinction rates generally >10%. At local scale, highest
extinctions are predicted to be Pyrenees1 & Scotland
Projected warming by 2055 in alpine and arctic areas
according to IPCC Fourth Assessment Report. Average of
five climate predictions under two different future scenarios
Nogués-Bravo
et al. (2008)
Order of temperature change (1=high, 13=low)
2055
2085
Northern Asia
1
1
N American Arctic
2
2
European Arctic
3
4
Central Asia (Himalaya, etc)
4
3
N Africa
5
6
N American Rockies
6
5
European Alps
7
7
N and Central Andes
8
9
Equatorial Africa
9
8
South Africa
10
10
Low Asia (e.g. Borneo)
11
11
Southern Andes
12
12
Australia/New Zealand
13
13
Why is there little or no evidence for local
extinction of high-altitude species?
Need to assess an alpine landscape not at a
climate-model scale or even at the 2 m height of
a climate station, but at the plant level.
Use thermal imagery technology to measure land
surface temperature.
Körner 2007 Erdkunde
Scherrer & Körner 2010 Global Change Biology
Scherrer & Körner 2010 Journal of Biogeography (in press)
Land-surface temperature across an
elevational transect in Central Swiss
Alps shown by modern thermal
imagery. Forest has a mean of 7.6°C
whereas the alpine grassland has a
mean of 14.2°C. There is a sharp
warming from forest into alpine
grassland
Körner (2007)
In two alpine areas in Switzerland (2200-2800 m),
used infrared thermometry and data-loggers to
assess variation in plant-surface and ground
temperature for 889 plots.
Found growing season mean soil temperature range
of 7.2°C, surface temperature range of 10.5°C, and
season length range of >32 days. Greatly exceed
IPCC predictions for future, just on one summit.
IPCC 2°C warming will lead to
the loss of the coldest habitats
(3% of current area). 75% of
current thermal habitats will be
reduced in abundance
(competition), 22% will
become more abundant.
Scherrer & Körner (2010 in press)
Warn against projections of alpine plant species
responses to climate warming based on a broadscale (10’ x 10’) grid-scale modelling approach.
Alpine terrain is, for very many species, a much
‘safer’ place to live under conditions of climate
change than flat terrain which offers no short
distance escapes from the new thermal regime.
Landscape local heterogeneity leads to local
climatic heterogeneity which confers biological
resilience to change.
In Himalaya, highest known vascular
plants are
Saussurea gnaphalodes at 6400 m
Ermania himalayensis
at 6300 m
Arenaria bryophylla at 6180 m
Highest stand of vegetation (9 species) at 5960 m
Highest closed sward of vegetation at 5500 m
Often sharp transition at 5500 m, plants become
much more sparse. Potentially 900 m available for
occupation today (assuming no climate change),
about 6°C
Photos: Toshio Yoshida
Upland Land-Use and Biodiversity
Montane and alpine areas have been subject to land-use,
particularly grazing, for many thousands of years.
Not a new factor.
Problems arise when the tolerable dose is exceeded by overstocking and over-grazing.
Who knows what the tolerable dose is?
Who knows the point of no return?
Who knows what is sustainable, in the sense that the system
remains intact?
Traditional shepherds knew of course, but this knowledge has
been lost or was never incorporated into any management plan
for alpine and montane areas.
Plans based on lowland areas are almost
certainly not applicable to upland areas.
Potential disaster!
Des
Thompson
Many montane and low-alpine areas in Alps, Carpathians,
Caucaus, Hindu Kush, Himalaya, South Africa, Tibet,
Karakorum, Altai, Scotland, and possibly Scandinavia are
man-made ecosystems or 'cultural landscapes' from many
thousand years of utilisation.
Cultural heritage – wooden fences, stone walls, shrines,
wooden or stone dwellings, drainage and irrigation systems,
very specialised flora and fauna, etc.
Traditional and thus commonly sustainable management
very rarely leads to erosion.
These traditional land-uses are currently disappearing due
to population growth, increasingly intense agriculture, and
large extension of land-use areas for marginal economic
gain.
Result - major changes in ecosystem functioning & biodiversity
Essential to secure sustainable agriculture in
traditional alpine areas near the tree-line so as:
1. to conserve biologically highly diverse, stable,
and attractive plant communities
2. to maintain a healthy, unpolluted food and
water source for future generations
3. to retain part of our cultural heritage
4. to ensure soil stability and water supply for
down-slope human communities
Things can go wrong in three ways:
1. uncontrolled, non-traditional (patchy)
grazing, causing spot-impacts under
otherwise low stocking rates
2. over-stocking beyond carrying capacity or
introduction of excessively heavy cattle
3. sudden abandonment of pastures
Can all affect soils and induce slope erosion
Introduction of invasive species can also be a
major threat in some areas. Such species grow
faster and out-compete native, slow-growing alpines
(e.g. New Zealand).
Millennium Ecosystem Assessment
MEA (2005)
Major threats in alpine areas world-wide
1. Habitat and land-use change
2. Climate change (global warming)
3. Invasive introduced species
4. Over-exploitation (agriculture, grazing,
hydro-electric development)
5. Pollution (nitrogen phosphorus)
also
6. Recreation (e.g. ski development)
Potential threats different in different alpine
areas, a point not really emphasised by MEA
North
America
South
America
Introduced species
+
++
-
-
Land-use changes
-
+
++
++
Hydroelectric
development
+
-
+
+
Ski development
+
+
+
+
Atmospheric nitrogen
deposition
++
-
++
-
Global warming
++
+
++
+
-
+
-
++
Over-exploitation
++ = high threat
+ = some threat
European Turkey &
Alps
Iran
- = no likely threat
Australia
New
Zealand
Introduced
species
+
++
-
+
-
-
Land-use
changes
+
-
++
++
++
++
Hydroelectric
development
-
-
-
+
-
+
Ski development
+
+
-
-
-
?
Atmospheric N
deposition
-
-
-
-
-
+
Global warming
+
+
+
++
++
++
Over-exploitation
-
-
++
++
++
++
++ = high threat
East Southern
Himalaya China
Africa
Africa
+ = some threat
- = no likely threat
Threats in Drakensberg Mountains,
Southern Africa
3% in Lesotho and 97% in Natal Drakensberg are protected
as Nature Reserves, National Parks, and Wilderness Areas.
Major threats by overstocking and soil erosion in Lesotho.
Also threats from invasive exotic plants and clearance for
crops in an area very poorly suited to arable agriculture in
Lesotho.
At present alpine areas (nearly all in Lesotho) are
unprotected.
Urgent need for whole areas as Biosphere Reserve or World
Heritage Site.
But conservation is not the major problem facing southern
Africa……
Besides problems of overstocking, soil erosion,
and hydroelectric development in Lesotho, major
threat is from 'global warming'.
McDonald et al.
(2002) defined
climate
envelopes for 16
alpine species
today, to define
the modern
'alpine' climate.
McDonald et al. (2002)
Predicted the extent of the 'alpine' climate under
future scenario of IPCC for 2150.
See major reduction in 'alpine' climate, confined to
the few highest areas. Would become very
fragmented. Major loss of species.
Much reduced snow cover, loss of available water.
Major ecological and economic effects. Lesotho’s
‘economy’ depends on selling its water to South
Africa. What is there is less water and more soil
erosion?
Disaster!
Nepal Biodiversity
Plan 2004
Recognises people
as part of the
systems from
lowlands to alpine
summits
Ram P.
Chaudhury
Species Action Plans in Europe
Because of land-use changes and hence
habitat loss and also deliberate collecting
in 19th and early 20th century, some alpine
species in Europe are locally extinct.
Major attempts by conservation bodies to reintroduce species in Scotland, Sweden,
Switzerland, and elsewhere.
So-called 'Species Action Plans'.
Pinguicula
alpina, Norway
Extinct in UK
Local in Alps and
Scandinavia
Woodsia ilvensis, Scotland
Nearly extinct in UK
Locally common in central and eastern Norway
Saxifraga
cotyledon,
Norway
Nearly extinct in
Sweden but
common in
Norway
Saxifraga
hirculus, Yukon
Nearly extinct
in Switzerland
but common on
Svalbard
Conservation in High Mountains globally
Mountain Park*
(number)
Area
(106 ha)
Afro-tropical
42
20.4
Antarctica
15
3.2
Australian
3
2.6
Indo-Malayan
42
7.2
Neo-arctic
96
153.8
Neo-tropics
Oceanic islands
103
8
34.5
3.6
Palaeo-arctic
164
39.1
Total
473
264.5
*IUCN Management Categories I-IV, with at least 1500 m
relief and minimum size of 10,000 ha
Körner et al. (2005)
Global Mountain Biodiversity Assessment
www.unibas.
ch/gmba
Within the Global Mountain Diversity Assessment,
change in emphasis from diversity in ‘pristine’
alpine areas to a recognition of alpine areas as
‘cultural landscapes’
2002
2006
“Highlands are more valuable in terms of resources
of medical plants than lowlands”
Aditya Purohit, India
“Mountain crop systems: below the tree-line highaltitude agro-ecosystems become more reliable with
spatially diverse crop rotational cycles”
Alejandro Camino, Peru
“When poverty is the driver of human life in the
uplands, how can we guarantee sustainable land use?
Mountain economies must create added value beyond
the production of raw materials if they are to survive.
Mohamed Saleem, Ethiopia
“An important human dimension of global mountain
biodiversity is the diversity of the human species
itself. Indigenous populations seem to have better
functional capacity than newcomers when measured
in terms of traits such as health, physical work
capacity, and reproductive success, that are
important for long-term success. Andean and Tibetan
populations have different physiological adaptations
to high altitude and illustrate biodiversity in this
sense.”
Cynthia Beall, USA
“We cannot separate people from nature anymore”
Fausto Sarmiento, USA
CONCLUSIONS
1. Alpine plant biodiversity is higher than one would
expect on a simple species:area relationship.
2. Some alpine areas are particular 'hotspots' of
biodiversity.
3. Alpine biodiversity declines at a remarkably constant
rate with elevation (about 40 species decrease per 100
m).
4. High alpine biodiversity in certain areas appears to be
a result of many factors, including centuries of lowintensity land-use, topographical isolation, and high
geological and topographical diversity.
5. Alpine biodiversity is globally important because of
the importance of stable alpine slopes and the 'Lowland
– Upland Contract' for society.
6. There are many potential threats to alpine
biodiversity. The most important are land-use
changes, global warming and atmospheric nitrogen
deposition, and invasive species.
7. Species re-introduction plans are in progress in parts
of Europe, as part of 'species action plans'.
8. Mountain biodiversity is not only a scientific theme of
great interest, but also it is perhaps the best
'indicator value' of the integrity of mountain
ecosystems.
9. As a cultural heritage, diverse alpine grazing areas
deserve more attention and respect. They are of real
and potential value ecologically, economically, and
aesthetically.
ACKNOWLEDGEMENTS
Ram P. Chaudhury
Hilary Birks
Harry Jans
Khem Raj Bhattarai
Christian Körner
Ian Green
Ole Reidar Vetaas
Kari Klanderud
Des Thompson
John-Arvid Grytnes
Oriol Grau
Bill Baker
The late Derek Ratcliffe
Peter Erskine
John Grimshaw
Mark Hanger
Guido Vittone
Cathy Jenks
Royal Botanic Garden Edinburgh Herbarium Staff
Alpine Garden Society and Scottish Rock Garden Club members
for help, sharing data, ideas, and pictures, and
for help in preparing these lectures