Upload
krista-creasey
View
221
Download
1
Tags:
Embed Size (px)
Citation preview
Alpine Vegetation
reference: Körner, Ch. 1999. Alpine Plant Life. Springer Verlag, Berlin
Some slides courtesy of Bill BowmanMountain 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
Boulder County: 1550 species(50% of flora of Colorado)
Weld County: ~600 species
Regional scale plant diversity in S. Rockies; the influence of mountains:
Nival
Alpine
treelineSubalpine
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
"Krummholz”: crooked woodslow growth (few inches trunk)
”Flag trees”
Windsnow
Forest-tundra transition: TREE ISLANDS
• Trees grow into bands
• form microsites -- reproduction occurs
Windward side:wind
Lee side:snow
World’s highest tree?
Quenual, up to 4,800m
Nival
Alpine
treeline
Subalpine
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
large variation in altitude at mid-latitudes
associated with continentality- treelines lower in moist, maritime locations
from Körner, 1999
Nival
Alpine
treelineSubalpine
Montane
Alpine Tundra: 11,200 to 12,000 ft
• Definition:
windswept, treeless area found at highest altitudes in the mountains
Niwot Ridge in May
cold (<0 deg C)
temperatures may change rapidly
windy (mainly temperate zone) 100 mph at Niwot Ridge!
Precipitation as snow
Alpine environmental conditions: CLIMATE
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 biome-plants have similar "growth forms:"
graminoids (grasses, sedges)
forbs (broad leaved plants)
prostrate shrubs
flowers
Major life forms of alpine vegetation
Cushion plants – Coropuna, Peruvian altiplano
Incas used them asfuel source
Puya Raimondi, Pastoruri (Peru)Blooms evey 40 years!
Note the leaves
Alpine environment summarized:
Cold + windysnowy!short growing seasonlow nutrient availabilityHigh 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
The Fireweed's seeds are plume-
shaped. This allows them to ride
on the wind before falling to the ground
where they can take root.
Adaptation:•start to grow as soon as the snows melts•store food during the summer months•pollination strategies?
Summary
• Cold - grow short, close to ground
- grow horizontally
-cushion trees
• wind - grow in clumps (island trees)
• low nutrients -carnivorous
• UV -white hairs; antocyanin
• low growing seasons - grow fast; store nutrients;
-pollination strategies
• dry -wax leaves
LIMITATIONS ADAPTATION