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PLANTS AND LIFE PROCESSES  
Dynamics of subalpine forests

Environmental conditions | Factors influencing the Alpine environment

The subalpine environment

 

Environmental conditions

At their upper limit (tree limit, tree line, forest limit, timberline, timberline ecotone) subalpine trees and forests exist under harsh conditions of life. Forests are characterized by a steady climate, by typical soil formation processes and by a forest flora adapted to these conditions.

  Select the factors that define the subalpine environment.

For detailed information about these parameters see the links to other lessons.

 


Wind Erosion 1 Avalanches 2 Debris flow 3 Fire 4

 
Captions
1 -Wind eroded Loiseleuria procumbens (wild azaleae spalier shrub)on a snow free mountain ridge in the subalpine belt (Schams valley, 2100m, Grisons, Switzerland). Photo: C. Burga (150K)
2 - Avalanches, Klosters/Monbiel. Photo: H. Holzhauser (178K)
3 - Debris flow cone on a forest free slope (coniferous forest of Pinus mugo s.l. / mountain pine on calcareous rocks, Swiss National Park). Photo: C. Burga (172K)
4 - Subalpine Pinus contorta (lodgepole pine) forest ("toothpick forest") six years after the severe forest fire of 1988. Seedlings of rejuvenation grow between dead trees (Yellowstone N.P., Wyoming/USA). Photo: C Burga (172K)
 
Factors influencing the Alpine environment
 
Topography Duration of the Growing Period Precipitation Temperature Solar Radiation Geomorphology Soil Snow Avalanches Wind and storms Rockfalls Frost Building Deforestation Building Farming Tourism Fire Herbivores Insects

factors influencing the sub-alpine environment chart

 Click on factors to find out more.

What strengths do the settlers (trees and stand of trees) show and what survival strategies are required ?

Subalpine trees and forest plant communities are very fragile biocoenosis; they use various survival strategies. Important parameters are:
  1. rate of growth / growth characteristic, longevity

  2. horizontal stock structure (stock strength, stand density)

  3. vertical stock structure (canopy density)

  4. survival strategies against severe environmental impacts (see lessons Dynamic mountain climate, Snow and perennial ice, Slope processes and alpine soils,  Disturbance as an ecological factor)
Having identified the most important parameters limiting or inhibiting tree growth, the following section will focus on the habitus (facies) of the timberline ecotone.

 

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29 August 2011
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