- What are the crucial environmental conditions for the establishment
of a subalpine forest?
Beside local environmental conditions (microclimate,
soil, avalanches, fire, parasites) there is the average summer (July) mean temperature at the treeline which
defines the establishement of trees or a forest in the subalpine belt (average temperature at the treeline: ca. 6.5 ± 1 °C).
- Which parameters define the altitudinal zonation of the alpine timberline
ecotone?
Both forest and tree limits are mainly determined
by the average summer (July) mean temperature (ca. 6.5 ± 1 °C, length of growing season,
heat sums)at the treeline, further by water balance and dessication damage in frozen
soil.
- What are the main features of human impact on mountain forests?
Mountain forests are affected by clearcutting and
other methods of use like grazing, alpine pastures, domestic lifestock
and skiing grounds. After deforestation started different secondary
plant successions which replace the former forests (e.g. subalpine meadows,
extended stands of Alpine rose and other dwarf shrubs or spread of green
alder).
- According to which aspects can Swiss Alpine forest communities be
classified?
A Swiss Alpine forest community is characterized
by its dominant forest-buildung tree species and by some characteristic
accompanying herb, fern and moss species. Further parameters are: stand
c
- Why do trees forme only one tree ring within a year?
Trees in climatic zones with distinct seasonal changes
are forming during the vegetative period (spring to autumn) one tree
ring per year. In winter tree growth is temporaly suspended.
- What conditions other than climate can affect tree growth?
These factors are: competition, wind, site, insects,
avalanches, debris flows, rock fall, fire and slope movement.
- What kinds of external influences on a tree can be deduced from the
tree's shape without making an analysis of it's core or cross-section?
The follwing external influences can easily be deduced
from the tree's shape: wind, slope movement and avalanches.
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