Information About

Krummholz




The tree-line or '''timberline''' is the edge of the habitat at which Tree s are capable of growing. Beyond the tree-line, they are unable to grow due to inappropriate environmental conditions. There are several types:

  • Arctic tree-line The furthest North in the Northern Hemisphere that trees can grow; further north, it is too cold to sustain trees.

  • Antarctic tree-line The furthest South in the Southern Hemisphere that trees can grow; further south, it is too cold to sustain trees.

  • Alpine tree-line The highest Elevation that trees can grow on Mountain s; higher up, it is too cold, soil too poor, or snow cover too much of the year to sustain trees.

  • Exposure tree-line On Coast s and isolated mountains, the tree-line is often much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because high Wind s reduce tree growth.

  • Desert tree-line The Driest places that trees can grow; drier Desert areas having insufficient Rainfall to sustain trees.

  • Wetland tree-line The wettest ground on the margins of Muskeg s and Bog s that trees can grow in, below which the ground is too saturated with water, excluding Oxygen from the soil that tree Root s need to grow. However, no such line exists for Swamp s, where trees, such as Bald Cypress and the many Mangrove species, are adapted to growing in permanently water-logged soil.


, Poland.]]
At the tree-line, tree growth is often very stunted, affected by wind, with the last trees forming low, densely matted bushes. These are known as krummholz, from the German for 'twisted wood'. The tree line, like many other natural lines ( Lake boundaries, for example), looks sharp from a distance, but upon sufficiently close inspection, it becomes a more gradual transition. Trees grow shorter towards the inhospitable climate until they simply stop growing.

The Climate above the tree-line is called an Alpine Climate . See that article for more details on what climatic factors prevent trees from growing.


Typical tree-line species

growing close to the arctic tree-line in the Kolyma region, arctic northeast Siberia.]]
Some typical tree-line tree species (note the predominance of Conifer s):


Table of alpine tree-lines

The alpine tree-line at a location is dependent on local variables, such as Aspect of slope, Rain Shadow and proximity to either Geographical Pole . Given this caveat, here is a list of average tree-lines from locations around the globe:


Table of arctic and antarctic tree-lines

Like the alpine tree-lines shown above, polar tree-lines are heavily influenced by local variables such as Aspect of slope and degree of shelter; trees can often grow in river Valleys at latitudes where they could not grow on a more exposed site. Maritime influences such as Ocean Currents also play a major role in determining how far from the equator trees can grow. Here are some typical polar treelines:

, 55°S.]]


REFERENCES

  • Arno, S. F. & Hammerly, R. P. 1984. ''Timberline. Mountain and Arctic Forest Frontiers.'' The Mountaineers, Seattle. ISBN 0-89886-085-7

  • Ødum, S. 1979. Actual and potential tree-line in the North Atlantic region, especially in Greenland and the Faroes. ''Holarctic Ecology'' 2: 222-227.

  • Ødum, S. 1991. Choice of species and origins for arboriculture in Greenland and the Faroe Islands. ''Dansk Dendrologisk Årsskrift'' 9: 3-78.

  • Beringer, J., Tapper, N. J., McHugh, I., Lynch, A. H., Serreze, M. C., & Slater, A. 2001. Impact of Arctic treeline on synoptic climate. ''Geophysical Research Letters'' 28 (22): 4247-4250.