Transcript Alpine vegetation lecture

Alpine Vegetation
reference: Körner, Ch. 1999. Alpine Plant Life. Springer Verlag, Berlin
Some slides courtesy of Bill Bowman
Mountain Research Station, INSTAAR
MOUNTAINS
• 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
Mixed Aspen - Lodgepole Pine
Forest : 8,500 to 10,000 feet
•yellow - green color
foliage
•dense trees
•straight, pole-like
•Used by humans since prehistoric times
•light construction, finishing lumber, poles
Lodgepole pine
• needles attached to
twigs in bunches
• paired, twisted
• long, green
Aspen
• only deciduous tree at
this altitude
• grow in a variety of
soil conditions from
wet to dry
Subalpine Forest:
10,000 -11,000 ft
spruce and fir dominate.
narrow crowns
dark green color
cool,dark, humid
E.g. Engelmann Spruce
Humans have seldom used these forest due to their remoteness
Engelmann Spruce
• short needles attached
to twigs
• rounded, spiky
• Spruce bark is reddish
and outer layer flakes
off
Rocky Mtn. Douglas Fir
• short needles attached
to twigs;
• flat needles
• smooth bark
Forest- Tundra Transition:
CLIMATE
• Situated between timberline and treeline
(lower)
(upper)
• Windier and colder
• mean annual soil temps ~ 0 deg.
• Snow covered
Forest-tundra transition:
VEGETATION
Wind
snow
"Krummholz”: crooked wood
slow growth (few inches trunk)
”Flag trees”
Forest-tundra transition:
TREE ISLANDS
• Trees grow into bands
• form microsites -- reproduction occurs
Lee side:
snow
Windward side:
wind
World’s highest tree?
Quenual, up to 4,800m
Nival
Alpine
Subalpine
treeline
Montane
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
Nival
Alpine
treeline
Subalpine
Montane
Alpine Tundra: 11,200 to 12,000 ft
• Definition:
windswept, treeless
area found at highest
altitudes in the
mountains
Niwot Ridge in May
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
•
•
•
•
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
Incas used them as
fuel source
Cushion plants – Coropuna, Peruvian altiplano
Note the leaves
Puya Raimondi, Pastoruri (Peru)
Blooms evey 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:
•
•
•
•
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
– e.g. Groundsel
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) Grow in balls that roll around
w/frost heave, eg. Kenya moss
deal w/expansion and contraction
of soil due to freezing and thawing.
Stone circles
Adaptations to cold
6) Rosette plants
• cabbage-like
• leaves surround a
central bud
• 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
• Heaths: hard
evergreen leaves that
can withstand drying
winds and cold
temperatures.
• Common heaths:
cranberries,
blueberries, and
rhododendrons
II. Adaptations to dry conditions
• Many high
mountains plants
are succulents,
with water stored
in thick leaves;
• minimize
evaporation
E.g. cactus
Adaptations to High UV
irradiance
• Cover their leaves with
white hairs (reflect the
suns rays).
• 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
Adaptation:
•start to grow as soon as
the snows melts
•store food during the
summer months
•pollination strategies?
The 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
• Cold
•
•
•
•
wind
low nutrients
UV
low growing seasons
• dry
ADAPTATION
- grow short, close to ground
- grow horizontally
-cushion trees
- grow in clumps (island trees)
-carnivorous
-white hairs; antocyanin
- grow fast; store nutrients;
-pollination strategies
-wax leaves