ALPECOLE
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Why treelines?

Architecture sets the limit

 

Why should trees suffer more from cold climate than grasses, dwarf shrubs and herbaceous plants which reach 4000 m in the temperate and up to 6000 m in the subtropical zone?

The answer is simple: Trees are designed to compete for light with neighbours, not to thrive in the cold.

  • With their crowns reaching into the free atmosphere they become closely coupled to the harsh alpine climate and do not profit from the warm boundary layer close to the ground.
  • By shading their own root zone they prevent the sun from heating the ground. Roots stay cold because of self shading once the canopy is closed.

A cold "crown" and cold "feet" is the price to be paid for being a tree in the mountains.

Low vegetation profits from heat capture and heat storage in the soil.

Architecture determines the tree limit at high altitudes.

 

energy flux

1 - Energy flux in forests and adjacent low stature alpine vegetation in midsummer.

 

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29 August 2011
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