Conclusions

The high elevation low temperature limit of trees results from the tree's growth form (architecture), which does not permit the tree to decouple from the cool high altitude atmosphere as low stature alpine plants do. Thus, trees experience lower mean daytime temperatures than adjacent alpine heath vegetation. The low mean temperatures limit tissue formation despite sufficient or even overabundant availability of photoassimilates.

Acknowledgements

Christian Körner

(Institute of Botany, Ecology - University of Basel)

Concept and content, photographs

Thomas Zumbrunn

(Institute of Zoology, Evolution - University of Basel)

Technical realisation, photographs

Glossary

abiotic: Not related to life, purely physical-chemical processes/conditions

biotic: Life related

boreal: Nordic; usually used to indicate the zone of the nordic coniferous forests

ecotone: The transition zone from one to another type of ecosystem (e.g. from forest to shrubland)

insolation: Incoming solar radiation

land use: Anthropogenic utilisation of vegetation and soils and their transformation

lee: Wind shade (little wind)

luv: Exposed to wind (windy)

meristem: A tissue layer or group of cells which produces new cells by cell division

microhabitat: The exact place where an organism lives

photoassimilate: Carbohydrate derived from photosynthesis

photosynthate: Product of photosynthesis (e.g. sugar)

subalpine: A term with many different definitions referring either to the transition between the upper montane forest to the alpine belt (a synonym to treeline ecotone) or the varying parts of the upper montane forest itself