Alpine Tundra Flora. Körner, Ch Alpine Plant Life. Springer Verlag, Berlin

Transcription

1 Alpine Tundra Flora Körner, Ch Alpine Plant Life. Springer Verlag, Berlin

2 Mountain Flora Diversity 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

3 Regional scale plant diversity in S. Rockies; the influence of mountains: Weld County: ~600 species Boulder County: 1550 species (50% of flora of Colorado)

4 Nival Alpine treeline Subalpine Montane

5 Forest- Tundra Transition: CLIMATE Situated between timberline and treeline Windier and colder mean annual soil temps ~ 0 deg. Snow covered

6 Forest-tundra transition: VEGETATION Wind snow "Krummholz : crooked wood slow growth (few inches trunk) Flag trees

7 Forest-tundra transition: TREE ISLANDS Trees grow into bands form microsites -- reproduction occurs Lee side: snow Windward side: wind

8 World s highest tree? Polylepis tarapaca Queñoa tree, circa 4,500 meters

9 Elevation of treeline corresponds with: 1) minimum growing season temperature around 6 C 2) wind zone 3) geomorphic disturbance- avalanches

10 Global distribution of treeline from Körner, 1999 large variation in altitude at midlatitudes associated with continentalitytreelines lower in moist, maritime locations

11 Alpine Tundra: 11,200 to 12,000 ft Niwot Ridge in May Definition: windswept, treeless area found at highest altitudes in the mountains

12 Alpine environmental conditions: CLIMATE cold (<0 deg C) temperatures may change rapidly windy (mainly temperate zone) 100 mph at Niwot Ridge! Precipitation as snow

13 Alpine environmental conditions: SOIL low nutrients in soil Rocky Thin soil cover low soil temperature ice present in the ground -- creates periglacial features polygons

14 Alpine Tundra distribution

15 Alpine is a globally distributed biomeplants have similar "growth forms:" flowers graminoids (grasses, sedges) forbs (broad leaved plants) prostrate shrubs

16 Major life forms of alpine vegetation

17 Cushion Plants on the Altiplano

18 Puya Raimondi pastoruri (Peru) Blooms every 40 years!

19 Alpine environment summarized: Cold + windy snowy! short growing season low nutrient availability High UV radiation How do plants survive in these conditions?

20 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

21 4 things plants need: Liquid water nutrients warmth light Limiting factors in alpine and arctic tundra Limiting factor in arctic tundra only

22 Adaptations to cold 1) Cushion plants: grow in small, rounded humps conserve heat reduce wind chill

23 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

24 Adaptations to cold 3) Keep dead leaves on the stem prevents ground from freezing

25 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.

26 Adaptations to cold 5) Rosette plants cabbage-like leaves surround a central bud winter: central bud is protected by the remaining vegetation.

27 More adaptations to cold high investment into belowground biomass (high root:shoot ratio) tolerance to low temperatures (= intolerance of high temperatures)

28 Cold-tolerant species examples Heaths: hard evergreen leaves that can withstand drying winds and cold temperatures. Common heaths: cranberries, blueberries, and rhododendrons

29 II. Adaptations to dry conditions Many high mountains plants are succulents, with water stored in thick leaves;

30 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.

31 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? Fireweed's seeds are plumeshaped. This allows them to ride on the wind before falling to the ground where they can take root.

32 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