Alpine Vegetation- patterns of biodiversity and response to environmental change
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Alpine Vegetation- patterns of biodiversity and response to environmental change Bill Bowman- Ecology and Evolutionary Biology Mountain Research Station, INSTAAR (william.bowman@colorado.edu) reference: Körner, Ch. 1999. Alpine Plant Life. Springer Verlag, Berlin. What is the alpine?

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Alpine vegetation patterns of biodiversity and response to environmental change

Alpine Vegetation- patterns of biodiversity and response to environmental change

Bill Bowman- Ecology and Evolutionary Biology

Mountain Research Station, INSTAAR

(william.bowman@colorado.edu)

reference: Körner, Ch. 1999. Alpine Plant Life. Springer Verlag, Berlin


Alpine vegetation patterns of biodiversity and response to environmental change

What is the alpine? environmental change

Is it tundra?

Nival

Alpine

treeline

Subalpine

Montane


Alpine vegetation patterns of biodiversity and response to environmental change

elevation of treeline corresponds environmental change

with:

1) minimum growing season

temperature around 6 °C

2) wind

3) geomorphic disturbance- avalanches

krummholz- "twisted wood"


Alpine vegetation patterns of biodiversity and response to environmental change

large variation in altitude at mid-latitudes environmental change

Global distribution of treeline

from Körner, 1999

associated with continentality- treelines lower in moist, maritime locations


Alpine vegetation patterns of biodiversity and response to environmental change

Alpine is a globally distributed biome- environmental change

plants have similar

"growth forms:"

graminoids

(grasses, sedges)

forbs

(broad leaved

herbaceous plants)

prostrate shrubs


Alpine vegetation patterns of biodiversity and response to environmental change

Alpine environmental conditions: environmental change

  • cold

  • temperatures may change rapidly

  • windy (mainly temperate zone)

  • soils often poorly weathered

  • low water and nutrient availability

  • high UV irradiance (although offset

    by cloud cover)

  • low p(CO2) - dependent on elevation


Alpine vegetation patterns of biodiversity and response to environmental change

Adaptations to the alpine environment include: environmental change

  • being short

  • high investment into belowground biomass (high root:shoot ratio)

  • low growth rates

  • tolerance to low temperatures (= intolerance of high temperatures)


Alpine vegetation patterns of biodiversity and response to environmental change

Greenhouse experiment- artificial imposition of N limitation environmental change

Dominant sedges

Common grasses

amount of growth is biologically constrained in some species




Alpine vegetation patterns of biodiversity and response to environmental change

interglacial (present) and plant distribution?

Continuous and isolated alpine habitat: Colorado

Glacial (ca. 20K BP)


Alpine vegetation patterns of biodiversity and response to environmental change

Biogeographic trends in Rocky Mountain alpine plant diversity

~ same number species

more Arctic species to north

more endemic species to south


Alpine vegetation patterns of biodiversity and response to environmental change

Biogeographic similarities ( diversityafter Hadley 1987)

Sørenson’s index

Beartooth

(50-83)

Absoroka

Big Horn

Gros Ventre

51

Teton

Wind River

58

51

54

Uintah

Medicine Bow

48

59

Indian Peaks

44

50

Sangre de Cristos

Needles

34

San Fransisco Peaks



Alpine vegetation patterns of biodiversity and response to environmental change

Weld County: ~600 species diversity

Boulder County: 1550 species

(50% of flora of Colorado)

Regional scale plant diversity in S. Rockies; the influence of mountains:


Alpine vegetation patterns of biodiversity and response to environmental change

Alpine Mesotopographic Gradient diversity(After Billings)

Prevailing wind

Fellfield

Fellfield

snow

Snowbed

Snowbed

Moist

Meadow

Dry

Meadow

Wet

Meadow

Similarity of flora among communities

(Sørenson’s index): 25-77%



Alpine vegetation patterns of biodiversity and response to environmental change

Alpine plant diversity relationship to soil N+P availability on Niwot Ridge

  • other factors:

  • disturbance (climate & animal)

  • water availability


Alpine vegetation patterns of biodiversity and response to environmental change

Environmental change on Niwot Ridge in alpine - primarily “indirect:”

climate, N deposition, stratospheric ozone degredation (↑UV)

locally most immediate threat is N deposition


Alpine vegetation patterns of biodiversity and response to environmental change

source: William Travis on Niwot Ridge

CU Geography

Colorado ranks 3rd in U.S. population growth, with most of the increase in the Front Range urban corridor:


Alpine vegetation patterns of biodiversity and response to environmental change

Moist meadows- elevated N on Niwot Ridge

inputs due to topographic location

Where in the alpine landscape is change most probable?

Snow is an effective reservoir of atmospheric N inputs


Alpine vegetation patterns of biodiversity and response to environmental change

} on Niwot Ridge

+ responder to N non responders

15N labeling experiment:


Alpine vegetation patterns of biodiversity and response to environmental change

Implications of differential N uptake by alpine vegetation: on Niwot Ridge

  • change in plant species composition ("weedy" native species)- may already be occurring

  • change in ecosystem properties:

    • > enhancement of N cycling (net N mineralization and nitrification) rates- loss of N from terrestrial to aquatic ecosystems

    • > greater climatic control (lower biological control) over variation in primary production