Download Alpine Tundra Flora

Alpine Tundra Flora
Körner, Ch. 1999. Alpine Plant Life. Springer Verlag, Berlin
Mountain Flora Diversity
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Have the highest plant species diversity
High mountain environments have a high
percentage of endemic plants
Alpine areas have a much high plant
diversity than forested areas
Regional scale plant diversity in S. Rockies; the influence of
mountains:
Weld County: ~600 species
Boulder County: 1550 species
(50% of flora of Colorado)
Nival
Alpine
treeline
Subalpine
Montane
Forest- Tundra Transition:
CLIMATE
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Situated between timberline and
treeline
Windier and colder
mean annual soil temps ~ 0 deg.
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Snow covered
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Forest-tundra transition:
VEGETATION
Wind
snow
"Krummholz”: crooked wood
slow growth (few inches trunk)
”Flag trees”
Forest-tundra transition:
TREE ISLANDS
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Trees grow into bands
form microsites -- reproduction occurs
Lee side:
snow
Windward side:
wind
World’s highest tree?
Polylepis tarapaca – Queñoa tree, circa 4,500 meters
Elevation of treeline corresponds
with:
1) minimum growing season temperature around
6 °C
2) wind zone
3) geomorphic disturbance- avalanches
Global distribution of treeline
from Körner, 1999
large variation in
altitude at midlatitudes
associated with continentalitytreelines lower in moist, maritime
locations
Alpine Tundra: 11,200 to 12,000 ft
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Niwot Ridge in May
Definition:
windswept,
treeless area
found at highest
altitudes in the
mountains
Alpine environmental
conditions: CLIMATE
 cold (<0 deg C)
 temperatures may change rapidly
 windy (mainly temperate zone)
100 mph at Niwot Ridge!
Precipitation as snow
Alpine environmental conditions: SOIL
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low nutrients in soil
Rocky
Thin soil cover
low soil temperature
ice present in the ground -creates periglacial features
“polygons”
Alpine Tundra distribution
Alpine is a globally distributed biomeplants have similar
"growth forms:"
graminoids
(grasses, sedges)
forbs
(broad leaved
plants)
prostrate shrubs
flowers
Major life forms of alpine vegetation
Cushion Plants on the Altiplano
Puya –
Raimondi
pastoruri
(Peru)
Blooms
every 40
years!
Alpine environment summarized:
Cold + windy
snowy!
short growing season
low nutrient availability
High UV radiation
How do plants survive in these conditions?
Plant adaptation to alpine
environment
(1) evolutionary adaptation
(2) ontogenetic modifications, which are
non-reversible during the life of an
individual
(3) reversible adjustment, often termed
“acclimation”
4 things plants need:
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Liquid water
nutrients
warmth
light
Limiting factors in alpine and arctic tundra
Limiting factor in arctic tundra only
Adaptations to cold
1) Cushion plants:
grow in small,
rounded humps
◦ conserve heat
◦ reduce wind chill
Adaptations to cold
2) Develop a blanket
of white hairs
◦ protect them from
cold at night
◦ White to reflect
radiation during the
day
◦ e.g. Giant Lobelia, in
Kenya
Adaptations to cold
3) Keep dead
leaves on the
stem
◦ prevents ground
from freezing
Adaptations to cold
4) Grow short and
small
◦ to avoid harsh
winds and crushing
snow
◦ the air temperature
is warmer 10-15cm
above the soil.
Adaptations to cold
5) Rosette plants

cabbage-like
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leaves surround a
central bud
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winter: central
bud is protected
by the remaining
vegetation.
More adaptations to cold
 high investment into
belowground biomass
(high root:shoot ratio)
 tolerance to
low
temperatures
 (= intolerance of high
temperatures)
Cold-tolerant species examples
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Heaths: hard
evergreen leaves
that can withstand
drying winds and
cold temperatures.
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Common heaths:
cranberries,
blueberries, and
rhododendrons
II. Adaptations to dry conditions
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Many high
mountains
plants are
succulents,
with water
stored in thick
leaves;
Adaptations to High UV irradiance
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Cover their leaves with
white hairs (reflect the
suns rays).
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Some plants contain a
red pigment called
anthocyanin which
absorbs UV sunlight
before it has a chance
to damage the leaves.
Short growing season
Cold nights
Short daylight
hours
 180 days/year
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Adaptation:
•Start to grow as soon as
the snows melts
•Store food during the
summer months
•Pollination strategies?
Fireweed's seeds are plumeshaped. This allows them to ride
on the wind before falling to the ground
where they can take root.
Summary
LIMITATIONS
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Cold
ground
ADAPTATION
- grow short, close to
- grow horizontally
-cushion trees
- grow in clumps (island
wind
trees)
 low nutrients
-carnivorous
 UV
-white hairs; antocyanin
 low growing seasons - grow fast; store nutrients;
-pollination strategies
 dry
-wax leaves
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