Ecotone Changes
Ecotones are transitional zones between two habitats or ecosystems. For example, the change from land to sea or river, or the change from
forest to grassland is an ecotone. These zones can shift over time, as one species expands and the other contracts. Ecotones do not only
depend on the area occupied by individual species, but the changes in the area covered by a habitat is driven by the presence or absence
of particular vegetation species.
An area of mountain ecotone showing the transitions from forest to scrub to grass and finally to bare ground with increasing elevation.
Source: GEOLAND project
As the elevation increases the types of vegetation change, as it can be seen on the image above. Why do you think that is?
Answer
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As the altitude increases, temperature is reduced and vegetation species cannot grow outside a certain region of temperatures. Other
factors are the intensity of the wind, the increasing amount of rain or snow that falls at higher elevation, the slope gradient and other
less important factors.
Frequently, the summits of mountains are bare of vegetation. The reason is that the extreme temperatures, wind and rainfall/snowfall
prohibit the growing of most vegetation species, and without vegetation cover the soil is susceptible to soil erosion, which removes the
top soil layer, revealing the bare rock underneath.
A map of ecotone transition in an Austrian alpine treeline, produced from SPOT satellite data.
Source: GEOLAND project