Transcript ALPINE PLANT BIODIVERSITY Part I Patterns and Processes H.J.B. Birks

ALPINE PLANT BIODIVERSITY
Part I
Patterns and Processes
H.J.B. Birks
NOMA 2008
ALPINE PLANT BIODIVERSITY
Introduction and Definitions
Alpine biodiversity patterns
Alpine biodiversity processes
(To be continued)
INTRODUCTION
What is an Alpine Plant?
A plant whose natural habitat is beyond the tree-line,
either above it in the mountains of the world, or beyond it
in the arctic tundra of the far north. I will refer to them all
as 'ALPINES'.
Based on our explorations in Alpine areas in Europe (Alps,
Scandinavia, Svalbard, UK, Iberia, Mediterranean islands,
Greece); Asia (China, Tibet, India, Bhutan, Iran, Turkey,
Kazakhstan); Greenland; North America (Rockies, Yukon,
Alaska, Cascades); South America (Patagonia);
Africa (Drakensburg Mountains of South Africa
& Lesotho, Bale Mountains in Ethiopia,
Mt Kenya); South Island New Zealand,
Tasmania, and the Australian Alps of Victoria.
Hilary Birks
What is Biodiversity?
The diversity of life from genes to whole ecosystems. Includes:
• richness in genes
• diversity of taxa of organisms (species, genera, families, etc.)
• variety of their assemblages
Biodiversity is the ‘variety of life’ - often oversimplified to
'species richness'
In reality, biodiversity is an expression of part of the 'quality of
life'. Significance has only been recognised relatively recently.
Convention on Biological Diversity in Rio de Janeiro on 5 June
1992 represented a watershed in conservation philosophy.
Signed by 150 nations. Came into force 18 months later.
Diversity of the Term 'Diversity'
Diversity  multiplicity – diversitas in Latin, diversité in
French, Diversität in German, diversidad in Spanish
Used as a technical term in French intellectual circles in
18th century
First entry is in a French encyclopaedia - Diderot &
D'Alenbert 1751-1752
Does not appear in any German encyclopaedia until 1966
Does not appear in Encyclopaedia Britannica until 15th
edition in 1979
Term 'biological diversity' first appeared in Norse &
McManus (1980)
Quickly shortened to 'biodiversity' and made popular by
E.O. Wilson in his 1988 book 'Biodiversity'
E.O. Wilson (1988)
Reaka-Kudla et al. (1997)
E.O. Wilson (1994 Naturalist) claims ‘no credit at
all’ for the term biodiversity.
The word was coined by Walter Rosen of the
National Academy of Science who organised the
1986 meeting that resulted in the 1988 book.
Wilson wanted to call the book ‘Biological
diversity’ as he felt that ‘biodiversity’ was ‘too
catchy and it lacks dignity’.
Rosen persisted and argued that biodiversity was
simpler, more distinctive, and would catch the
attention of the general public. Wilson gave in.
Wilson now admits he does not know why he
resisted the word ‘biodiversity’ as it very quickly
acquired dignity and influence.
Wilson had, in 1979, invented the word ‘biophilia’
as ‘the inborn affinity humans have for other
forms of life, an affiliation evoked by pleasure, or
a sense of security, awe, or even fascination
blended with revulsion.’
Wrote a book in 1984 called Biophilia.
Wilson does not define 'biodiversity'. In his
discussion he crosses the classical boundaries of
systematics, taxonomy, and evolutionary biology to
create a branch of science in its own right. Deals
analytically with the special problems of the variety
of living organisms principally on the basis of
species in a 'cause and effect' context.
Tends to mean
'species variety'
'species number'
'number of taxa in a certain region'
Also can consider relative abundances and
distributional patterns
Can see biodiversity as "the sum of genetic diversity
among living organisms, their abundance, and their
evenness within a specific study area."
"… the variability among living organisms from all
sources including inter alia, terrestrial, marine, and
other aquatic ecosystems and the ecological complexes
of which they are a part; this includes diversity within
species, between species, and of ecosystems".
UN Convention on Biological Diversity 1992
Biodiversity is thus the variety of life. Encompasses
all forms, levels, and combinations of natural variation.
It is a broad and valuable unifying concept in
ecology, systematics, molecular ecology,
palaeoecology, biogeography, conservation biology,
and macroecology.
Determinants of Biodiversity
Biodiversity of an area depends on
• historical factors
(climatic change, human impact,
vegetation history, palaeogeography,
evolutionary history, species pool)
• abiotic factors
(geology, climate, soils, landforms,
topography)
• biotic factors
(other biota, mutualisms, interactions)
• chance factors
(dispersal, establishment, etc.)
 BIODIVERSITY =
f (History + Ecodiversity (abiotic) + Biota (biotic) + Chance)
Ecological Definitions
Nival belt – Snow-line – Alpine belt - Tree-line – Montane belt
Alpine life-zone = Alpine belt + Nival belt
Only life-zone that occurs at all latitudes on the globe
Körner (2004)
Total Vascular Plant Species Richness
Current estimate
about 2.7 x 105 described species globally
Likely estimate of total richness
about 3.2 - 5 x 105 species
Global Biodiversity Assessment (1995)
ALPINE BIODIVERSITY PATTERNS
Global diversity – species number per 100 000 km2
(Malyshev 1975)
Barthlottt et al. (1996)
'Hotspots' of Plant Biodiversity
Long recognised that within the broad latitudinal gradients
of richness, there are areas of greatest richness, so-called
'hotspots'
Centres of Plant Diversity – A Guide and Strategy for their
Conservation Volumes I-III. eds. Vernon H. Heywood et al.
1997
1994
1995
Recognised 235 'hotspot' areas in 15 geographical areas
Heywood et al. (1994-7)
No. hotspots With alpine areas % alpine areas
South America
46
15
33
South East Malesia
41
10
24
Africa
30
10
33
China & East Asia
21
6
29
Middle America
21
5
24
Australia & New Zealand
14
2
14
Indian sub-continent
13
3
23
S.W. Asia & Middle East
11
8
73
Europe
9
8
89
Pacific Ocean Islands
8
1
13
North America
6
1
17
Central & northern Asia
5
3
60
Atlantic Ocean Islands
4
1
25
Caribbean Islands
3
0
0
Indian Ocean Islands
3
0
0
Alpine areas are within many 'hotspots' in Europe, South-west Asia
& Middle East, central & northern Asia, South America, and parts of
Africa.
Swiss Alps
Mediterranean
mountains
SE Turkey
Zagros Mountains
near Aligourdarz,
Iran
Sani Pass
Drakensberg
Makalu (8475 m), Tibet
Photos: Harry Jans
Qomolangma (Everest
8848 m), Tibet
Photos: Harry Jans
Cho Oyu (8201 m), Tibet
Min-Shan, Sichuan
China
Jhomolhari
(7,314 m)
Bhutan
Southern Alps
New Zealand
Torres del Paine
Patagonia, Chile
Mount Kenya
Beartooth
Mountains
Montana &
Wyoming
White Clouds
Peak, Idaho
St Elias Mountains
Yukon-Alaska border
Mt. Edith Cavell
Canadian Rockies
Alpine Zone
Körner
(2003)
Alpine areas within biomes and major vegetation types
MEA (2005)
Extent of Alpine and Arctic Environments
Alpine
4 million km2; 3% of earth’s land; only 18% in
Southern Hemisphere
Arctic
7 million km2; 5% of earth’s land
Arctic + alpine
8% global land area
(Boreal forest 8.1%; total agricultural land 9.4%)
Global arctic + alpine carbon pool only 2% of global terrestrial
biosphere carbon pool
Alpine and arctic areas hold about 66% of globe's freshwater in
the form of snow and glaciers
Provide water for half of mankind, directly or indirectly. Key role
in global hydrological cycle.
Species Diversity Patterns
1. Global scale
Alpine vascular plant flora 10,000-15,000
species, 2,000 genera, 100 ± 10 families.
About 6% of world’s flora (3% land is alpine)
Arctic flora 1,000-1,500 species, less than
1% world’s flora (5% land is arctic)
Alpine floras richer than most lowlands on an area
basis
Total
Species
number
above treeof species line*
Exclusive
alpine
species+
Area above
tree-line
4000
1900 (48%)
870 (22%)
19%
New Zealand 2200
620 (28%)
210 (10%)
10%
Switzerland
1280 (50%)
570 (22%)
23%
Chile
2570
* alpines + sub-alpine + montane species
+
exclusively or nearly so in alpine habitats
Main families – better represented than on areal proportional
representation
Asteraceae
Gentianaceae
Saxifragaceae
Poaceae
Brassicaceae
Caryophyllaceae
Rosaceae
Ranunculaceae
Ericaceae
Cyperaceae
Salicaceae
Alpine
Alpine
Alpine
Alpine
Alpine
Alpine
Alpine
Alpine
Arctic
Arctic
Arctic
Arctic
Arctic
Arctic
Arctic
Arctic
(Campanulaceae, Polygonaceae, Scrophulariaceae, Apiaceae,
Hypericaceae, Primulaceae, Epacridaceae – in some alpine areas)
Under represented:
Orchidaceae
Fabaceae
Liliaceae
2. Regional scale
Alpine flora in 20-200 km2 about 250-300
species in 40 families. About 20-25% of
total regional flora (including lowlands)
Arctic flora in same area about 150-200
species. Fewer total arctic species (10%) than
alpine species but much more widespread
than alpines. Very few arctic endemics,
very many alpine local endemics
Richness decreases with altitude and with
latitude. On average, decreases by 15-45
species per 100 m altitude or by about 10-30
species per 1ºC temperature drop in latitude.
Species Richness Decreases with Altitude
Decreases on
average, by
15-45 species
per 100 m.
Grabherr et al.
(1995)
Species richness and
temperature in
relation to altitude
(Odland & Birks 1999)
Körner (2002)
Körner
(2002)
40 species decrease per 100 m
? general 'rule'
1. N.E. Greenland, 2. Scotland, 3. W. Norway, 4. Central
Norway, 5. Polish Tatra, 6. Mount Olympus, Greece, 7-8 &
10. Swiss Alps, 9. French Alps, 11-12 Austrian Alps, 13-15.
Himalaya, 16. Karakorum, 17. Hindu Kush
Why is there a Regular Decline in Species
Diversity with Altitude?
Parallels the well-known latitudinal decrease in diversity.
Potential explanations for altitudinal gradient in biodiversity
1. Adaptation limits – successful evolutionary selection for
survival under alpine climates may be limited by the available
pool of adaptive or pre-adaptive taxa. Some physiological and
reproductive limitations have been identified in alpine species
compared to their lowland relatives.
Do not know if there would be more high elevation taxa if
there were no evolutionary constraints to adaptation.
Untestable.
2. Limited area – biodiversity-area relationship above treeline hardly changes with elevation across the globe ('mountain
geometry'). Species number thus declines in proportion to
declining land-area as elevation increases.
Global
pattern of
land area
outside
Antarctica in
100 m steps
starting at
1500 m
Körner (2007)
Körner (2004)
Area changes with elevation. Species number decreases
as available area decreases with increasing altitude.
Habitat diversity also decreases with decreasing area.
Körner (2002)
Above tree-limit, land area is halved, on average, for
every 167 m increase in altitude (150 m in Alps, 178
m in Andes)
3. Limited functional space – in addition to mountain
geometry, there is another space-related constraint,
ISOLATION. Missing or restricted corridors reduce the
functional space and hence the species pool that alpine
areas can exploit.
4. Seasonal-time constraints – a decline in season length
(drought, low temperature) restricts the period during
which evolutionary processes can occur. Vascular plants
adjust to this by fast reproduction and thus maintain one
reproductive event per year. Micro-organisms may
have several cycles per year in the lowlands but only a
few in alpine areas. Thus, options for microbial
diversification decline with altitude which could have
feedbacks on plants (e.g. symbionts). Life-history
dependence of diversification of different taxonomic
groups with altitude needs further study.
5. Geological-time constraints – short evolutionary
time due to eradication of habitats by glaciation
would diminish opportunities for diversification at
high elevations.
Given that these two time-constraints would, in
theory, be of less significance in humid tropics,
tropical high mountains with a 365 day season should
be richer in taxa than higher latitude mountains.
Not the case for the alpine and nival belts, at least
for perennial species up to 47°N.
Montane belt is much richer at lower latitudes.
Annual alpine plants are quite abundant in the humid
tropics but are nearly absent at higher latitudes.
If considered together, these five constraints should limit
species diversity MUCH MORE at high elevations than
they actually do.
Space (area) alone may not be sufficient to explain the
elevational decline. How does area act as an ecological
and evolutionary factor?
Factors at high elevations may counteract these five
constraints through:
1. habitat diversity
2. diversification
(endemism)
related
to
habitat
3. efficient breeding systems
4. environmental (climatic) forcing.
fragmentation
May never be possible to falsify the adaptation limit
hypothesis. Major challenge is to study space + time
as the driver of diversity.
Could be tested by comparing mountain systems of
different size, history, and climate.
Mountains in
relation to latitude
and main biomes
Körner (2002)
Körner (2002)
Nepal – longest altitudinal gradient in world
Ole Reidar Vetaas
Species richness of flowering
plants (4928 taxa) and altitude
(0-6000 m) in Nepal
John-Arvid Grytnes
Vetaas & Grytnes (2002)
400
300
200
100
0
Endemic species richness
500
Species endemic to Himalaya
0
1000
2000
3000
4000
Altitude
5000
0
1000
2000
3000
4000
5000
6000
6000
Altitude
Patterns very different – endemics have peak at
4000 m, whereas total species richness peaks
between 1500 and 2500 m.
Vetaas & Grytnes (2002)
Other groups of plants in Nepal
Khem
Bhattarai
Oriol Grau
=Vascular plants – peak 1500-2500 m
=Ferns – peak 1900 m
=Mosses – peak 2500 m
Bhattarai et al. (2004)
Grau et al. (2007)
=Liverworts – peak 2800 m
Rare species
(narrow ranges)
Himalayan
endemics
Nepal
endemics
Richness of rare and endemic species and
altitude in Nepalese Himalaya
Vetaas & Grytnes (2002)
Nepalese species-richness patterns all show a
humped pattern. Why?
Vetaas & Grytnes (2002) used Enumeration of the
Flowering Plants of Nepal as data source. Gives the
known altitudinal range of each 4928 species. Same
type of source used for fern, moss, and liverwort
data in other studies.
If the range is reported as 2100-3200 m, the
species is assumed to be present at all altitudinal
levels between 2100 and 3200 m, so-called
interpolation.
Is the hump-backed pattern real or is it an artefact
of interpolation?
When interpolating a species, a species is added to
levels where it may or may not be present, but it is
assumed to be present.
Endpoints of the gradient (e.g. 0-100 m, 5900-6000 m)
will not acquire any extra species, as only the species
recorded at those levels can be counted.
In the middle of the gradient, apparent species
richness = species observed + species interpolated.
Creates a humped pattern.
Vetaas & Grytnes (2002) did simulations to
investigate the effects of interpolation and also of
so-called hard boundaries.
Hard boundaries are boundaries that restrict
species dispersal and species ranges cannot extend
beyond these boundaries.
Species in the middle of the gradient (‘middomain’) can freely expand within domain, whereas
species outside the domain cannot enter the
domain. Thus species richness can increase in the
mid-domain by species dispersing from above or
below the domain (‘mass-effect’), whereas species
at sea-level and on mountain tops can only receive
species from one side.
When allowing for effects of interpolation and hard
boundaries in the Nepal gradient, the observed
patterns appear to be:
Decrease with
altitude
Hard-boundary
effect
Vascular plants
Endemics
+
+
+
?
Ferns
Mosses
+
+
(+)
Liverworts
+
(+)
+ Strong
(+) Weak
? Unsure
- No evidence
0.4
0.2
Isolation effect more and more
important at high altitudes
above 5000 m.
0.0
Ratio of endemics
0.6
Ratio of Himalayan endemics
to total species richness
steadily increases with
altitude.
0
1000
2000
3000
4000
5000
6000
Altitude
Saussurea bhutkesh
Rheum nobile
Recent studies in Norway by J.-A. Grythes, A. Odland, and others
Group
Vascular plants
Range (m)
0-1770
0-1270
0-540
0-500
300-1460
360-2060
450-1950
600-1700
Monotonic
Decrease
Humped
+
Decrease
Decrease
Oceanic
+
+
+
+
+
+
+
+
Vascular plants
Bryophytes
Lichens
300-1140
300-1140
300-1140
+
Vascular plants
250-1525
Dwarf shrubs
250-1525
Herbs
250-1525
+
Graminoids
250-1525
+
Lichens
250-1525
+
Mosses
250-1525
No pattern
Liverworts
250-1525
Increase
No pattern
Increase
+
Decrease
+
+
+
Humped
10/18
Monotonic
decrease or
low plateau
& decrease
4/18
Monotonic
increase
2/18
No trend
2/18
Oceanic:
decrease 3/7
humped 2/7
increase 1/7
no pattern
1/7
Worldwide and four groups of organisms
Grytnes & McCain
(2007)
Humped pattern commonest of all except for birds
Low plateau and decrease commonest in birds
Decreasing pattern frequent in bats, birds, and some
plants
Humped pattern may be more widespread than
previously thought, especially over long ecological
gradients (not always equivalent to long altitudinal
gradients).
Energy-water model ideas of O’Brien (1993, 1998,
2006), whereas richness is a function of water +
energy.
Species richness
Temperature (a energy)
decreasing with altitude
Water availability often
has a unimodal pattern
in some mountain areas
Species richness shaded
Grytnes & McCain (2007)
Appears that humped relationships most frequent
on dry, continental mountains where this is a midaltitude peak in water availability.
Monotonically decreasing patterns are most
frequent on wet, oceanic mountains (e.g. western
Norway, Mt Kenya, Ruwenzori).
In general, dry continental mountains are the most
species rich mountains. Alpines are intolerant of
oceanic conditions – need cold winters and a sharp
transition to summer growing season.
How does precipitation change with
altitude?
Polar mountains
(Greenland)
Temperate
mountains (40°60°) (e.g. W USA)
transition (30°40°) (e.g. Turkey,
Iran)
Subtropical (10°30°) (e.g.
Drakensberg,
Himalaya)
Equatorial (0°-10°)
(e.g. Mt Kenya,
Kilimanjaro)
Pakistan – rise then fall in
precipitation in monsoon season (1-5
are different mountain ranges)
Körner (2007)
3. Micro scale
At global scale, alpine diversity is about
average
At regional scale, alpine diversity is high
compared to other temperate areas
At micro scale (1m2), highest diversity of
anywhere – 50-60 species in 1m2, nearby
only 5 species in 1m2
High micro-habitat differentiation (ridges,
hollows, late-snow, cliffs, rock outcrops,
hydrology, geology, etc.)
34 species in alpine area 25 x 35 cm, northern
Sweden
Körner (2004)
ALPINE BIODIVERSITY PROCESSES
1. Climate zones are compressed
2. Slopes cause exposure and micro-climate to
vary over small distances
3. Gravity induced erosion fragments the
continuous vegetation into 'micro-islands'
4. Mountain summits are themselves 'islands' in
the sky or in the lowland 'sea'
5. Topography - climate – geography interactions
thus create a multitude of microhabitats, each
with its own specific set of organisms, and
hence high local and regional diversity
Altitude for Latitude Scales
Körner (2003)
100 m increase in elevation equivalent to 600 km
distance north.
Some Case Studies
1. European Alpine Flora
European alpine flora (species confined to or mainly above the
tree-line) contains over 2,500 species and subspecies.
Equals 20% of the European native flora in contrast to world's
alpine flora that is about 6% of the world's flora. European
mountains very rich.
About 250 species (10%) are endemic to single mountain ranges
or areas in Europe.
Very few introduced species grow in the European alpine zone
(cf. New Zealand).
European alpine flora is more special than is often realised.
Involves many genera
Primula
Campanula
Saxifraga
Papaver
Draba
Alchemilla
Ranunculus
Phyteuma
Aquilegia
Dolomites
North Italy
Grossglockner
Austria
Bernese Oberland, Switzerland
Dryas octopetala
Austria
Silene acaulis
Colorado
Androsace alpina
Switzerland
Eritrichium nanum
Switzerland
Ranunculus glacialis
Switzerland
Papaver kerneri
Austria
Papaver ernesti-mayeri
Slovenia
Papaver rhaeticum
Italy
Soldanella alpina, Switzerland
6 days later
Endemic species
in Europe
Piekos-Mirkowa et al. (1996)
Why so Rich?
1. High geological and topographical diversity
2. Mixture of floristic elements (alpine,
Mediterranean, continental, northern, etc.)
3. Large altitudinal range
4. Strong climatic gradients both regionally and
locally. Mountains not oceanic
5. Topographic isolation of mountains, especially in
the Southern Alps – 'islands of alpine areas' in a
'sea of Fagus forest', resulting in many local
endemics
6. Centuries of low-intensity land-use ('intermediate'
disturbance) in low-alpine areas (grazing, mowing,
pasturing, hay-making) over last 5000 years
7. Soils are generally infertile (low N, P, K) except
managed areas
8. Fine-scale topographical and ecological variation
with springs, flushes, screes, rock-outcrops, and
other open areas within alpine grasslands
9. Mountains run west to east and north and south
and are situated at the meeting of different
phytogeographical regions. High potential species
pool
10. Some areas probably ice-free in last glaciation
2. Drakensberg,
Lesotho, and
KwaZulu-Natal in
South Africa
van Wyk & Smith (2001)
Cathkin Peak
The Sentinel
The Sentinel
The Amphitheatre
Montane belt
1280–1830 m
Podocarpus
latifolius forest
Subalpine belt
1830–2750 m
Fynbos (= species-rich
heath); now mainly
grassland
Alpine belt
2750–3484 m
Erica–Helichrysum
'tundra' heath and
grasslands
Killick (1990)
Extent of alpine belt above 2750 m
Killick (1997)
About 2200 species, 4 endemic genera, 400
endemic species (ca. 18%)
Largest families
1. Asteraceae
5. Cyperaceae
2. Scrophulariaceae
6. Orchidaceae
3. Poaceae
7. Ericaceae
4. Iridaceae
Helichrysum (85)
Argyrolobium (18)
(Fabaceae)
Senecio (76)
Moraea (16)
(Iridaceae)
Erica (25)
Thesium (15)
Disa (24)
(Orchidaceae)
Hypoxis (15)
(Hypoxidaceae)
Selago (19)
(Scrophulariaceae)
Kniphofia (15)
(Liliaceae)
Crassula (19)
Life-study of Olive Hilliard and the late Bill Burtt,
Royal Botanic Garden Edinburgh.
Kniphofia caulescens, Drakensberg – sun birds
Zaluzianskya microsiphon,
Drakensberg – tangle-veined fly
H. ecklonis
H. herbaceum
H. flanagannii
H. trilineatum
Helichrysum
species
Drakensberg
H. milfordii
H. tenuifolium
Why so Rich?
Drakensberg is an international 'hotspot' of plant
biodiversity, not only of vascular plants (2200
species) but also of bryophytes (over 1000
species).
Nothing known about vegetational history.
Endemics (18%) are mixture of palaeo-endemics
and neo-endemics.
Some major disjunctions (e.g. Macowania –
Drakensberg, Ethiopia, Yemen; Thamnocalamus –
Drakensberg, east Asia).
Small area ca. 40 000 km2 ( Belgium)
Possible contributory factors for high diversity
1. Centuries of low-intensity ('intermediate') disturbance
from Bush-people.
2. Soils are infertile but not strongly acid and high in Al.
3. Mixture of floristic elements (Cape, Afromontane, etc.)
4. Altitudinal range of over 2000 m.
5. Climatic gradients within 1500 m from alpine
periglacial features to lush Podocarpus forest with
Streptocarpus.
6. Topographical diversification into distinct valleys and
watersheds, favouring isolation of species.
7. Fine-scale topographical variation with springs, flushes,
soaks, mires, etc. within well-drained grassland.
Other Reasons for High Alpine Diversity
1. Centres of origin, huge diversity of one genus (up to 300
species) in an area
e.g.
Pedicularis
Meconopsis
Rhododendron
Saxifraga
Primula
Gentiana
Calceolaria
Penstemon
Helichrysum
Swertia
Euphrasia
Celmisia
-
Sichuan, Yunnan, Himalaya
Sichuan, Yunnan, Himalaya
Sichuan, Yunnan, Himalaya
Himalaya
Himalaya
Himalaya
Andes
Western North America
Drakensberg
Ethiopia
Australia
New Zealand
Pedicularis oederi, Norway
Pedicularis tricolor, Sichuan
Pedicularis przewalskii, Qinghai
Pedicularis siphonantha, Bhutan
Photo:
Mike Grant
Pedicularis bella, Bhutan
Pedicularis decorissima, Sichuan
Meconopsis discigera, Bhutan
Meconopsis horridula ssp.
racemosa, Sichuan
Meconopsis
quintuplinervia, Sichuan
Meconopsis integrifolia
Sichuan
Meconopsis punicea
Sichuan
Meconopsis tibetica, Tibet
2. History – very poorly known anywhere about alpines, e.g. in
Americas
• Little direct fossil evidence – very few studies
• Higher frequency of endemics in South America
• Species ranges & genetic diversity generally smaller in S America
Beringia
plants
Ice-sheets in North
Circumarctic plants
Andean plants
Basin plants
Steppe
plants
Ice-free
mountain
areas
Ice-sheets
in West
and South
Circum-antarctic plants
3. Adaptations to extreme conditions, especially extreme cold
Alpine plants show a high degree of specialisation. They
are well adapted to these extremes.
Selected for small size and ability to cope with extremes.
Alpine plant life is an interplay of ADAPTATION and
INCREASING CLIMATIC LIMITATION ON PLANT
GROWTH
Alpine plants are not simply 'stressed' plants that tolerate
extreme conditions. They are SPECIALISED to thrive where
there is increasing CLIMATIC LIMITATION on plant growth;
close to the physiological limits for plant growth.
Alpine plants are TRUE specialists of an extreme world
(e.g. Ranunculus glacialis, nival species – see Plant Life in
the Cold Part II).
Summary
1. Reduced area does not seem to truly restrict alpine
diversity, as the numbers do not decline if based
on the ACTUAL AVAILABLE land area.
2. Reduced season length may restrict diversity as
all species show peak growth, flowering, and
reproduction at about the same time.
3. Reduced competition at high elevations may
play a role in the co-existence of high numbers of
taxa.
4. Habitat heterogeneity (fragmentation) permits
co-existence of many species in close proximity.
5. Alpine plants are usually small, so many
species can co-exist in a small area.
6. Genetic and breeding systems of alpine taxa
(polyploidy and self-incompatibility) permit high
genetic diversity despite spatial isolation.
7. Age of community does not seem to result in
high diversity in alpine areas. Late successional
'old' assemblages tend to be poor in species and
be dominated by a few persistent long-lived
species.
8. Much of the richness in mountains may result
from different types of disturbance (e.g. landuse, solifluction, small herbivores, etc.)