Alpine Vegetation

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Alpine Vegetation reference Körner, Ch. 1999.
Alpine Plant Life. Springer Verlag, Berlin
Some slides courtesy of Bill Bowman Mountain
Research Station, INSTAAR
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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

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Regional scale plant diversity in S. Rockies the
influence of mountains
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Nival
Alpine
treeline
Subalpine Montane
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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

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Lodgepole pine

• needles attached to twigs in bunches
• paired, twisted
• long, green

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Aspen

• only deciduous tree at this altitude
• grow in a variety of soil conditions from wet to
  dry

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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
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Engelmann Spruce

• short needles attached to twigs
• rounded, spiky
• Spruce bark is reddish and outer layer flakes off
  

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Rocky Mtn. Douglas Fir

• short needles attached to twigs
• flat needles
• smooth bark

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Forest- Tundra Transition CLIMATE

• Situated between timberline and treeline
• (lower)
  (upper)
• Windier and colder
• mean annual soil temps 0 deg.
• Snow covered

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Forest-tundra transition VEGETATION
"Krummholz crooked wood slow growth (few inches
trunk)
Flag trees
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Forest-tundra transition TREE ISLANDS

• Trees grow into bands
• form microsites -- reproduction occurs

Lee side snow
Windward side wind
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Worlds highest tree?
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Nival
Alpine
Subalpine Montane
treeline
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Elevation of treeline corresponds with

• 1) minimum growing season temperature around 6 C
• 2) wind zone
• 3) geomorphic disturbance- avalanches

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Global distribution of treeline
from Körner, 1999
associated with continentality- treelines lower
in moist, maritime locations
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Nival
Alpine
treeline
Subalpine Montane
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Alpine Tundra 11,200 to 12,000 ft

• Definition
• windswept, treeless area found at highest
  altitudes in the mountains

Niwot Ridge in May
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Alpine environmental conditions CLIMATE

• cold (lt0 deg C)
• temperatures may change rapidly
• windy (mainly temperate zone)
• 100 mph at Niwot Ridge!
• Precipitation as snow

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Alpine environmental conditions SOIL

• low nutrients in soil
• Rocky
• Thin soil cover
• low soil temperature

ice present in the ground -- creates periglacial
features polygons
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Alpine Tundra distribution
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Alpine is a globally distributed biome- plants
have similar "growth forms" graminoids
(grasses, sedges) forbs (broad leaved
plants) prostrate shrubs
flowers
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Major life forms of alpine vegetation
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Incas used them as fuel source
Cushion plants Coropuna, Peruvian altiplano
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Note the leaves

Puya Raimondi, Pastoruri (Peru) Blooms evey 40
years!
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Alpine environment summarized

• Cold windy
• snowy!
• short growing season
• low nutrient availability
• High UV radiation

How do plants survive in these conditions?
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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

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4 things plants need

• Liquid water
• nutrients
• warmth
• light

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Adaptations to cold

• 1) Cushion plants grow in small, rounded humps
• conserve heat
• reduce wind chill

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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

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Adaptations to cold

• 3) Keep dead leaves on the stem
• prevents ground from freezing
• e.g. Groundsel

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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.

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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
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Adaptations to cold

• 6) Rosette plants
• cabbage-like
• leaves surround a central bud
• winter central bud is protected by the
  remaining vegetation.

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More adaptations to cold

• high investment into belowground biomass (high
  rootshoot ratio)
• tolerance to low temperatures
• ( intolerance of high temperatures)

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Cold-tolerant species examples

• Heaths hard evergreen leaves that can withstand
  drying winds and cold temperatures.
• Common heaths cranberries, blueberries, and
  rhododendrons

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II. Adaptations to dry conditions

• Many high mountains plants are succulents, with
  water stored in thick leaves
• minimize evaporation

E.g. cactus
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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.

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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 plume- shaped. This
allows them to ride on the wind before falling
to the ground where they can take root.
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Summary
LIMITATIONS ADAPTATION

• 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