DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 13/2005 str. 41 <-- 41 --> PDF |
P. Kantor: POSSIBILITIES OF MOUNTAIN FORESTS IN REDUCING HIGH WATERS AND FLOODS Šumarski list SUPLEMENT (2005), 31-39 2. From the aspect of ecological stability and safety of yield and production, one of evident priorities of forestry is the transformation of spruce monocultures to mixed stands. However, research results have proved, that the increased proportion of broadleaves cannot decrease the danger of high waters and floods. Broadleaved species are able to retain and draw less precipitation water than coniferous species (particularly spruce) with respect to their leafless state out of the growing season and smaller biomass of assimilatory organs. 3. Upland and mountain forests (unlike all non-forest ecosystems) reduce very easily rainstorms up to 50 mm. Uninterrupted precipitation up to 100 mm manifests itself in the total amount of runoff from the forest but from the aspect of water-management effectiveness is still acceptable. A threshold of 150 to 200 mm of uninterrupted precipitation can be considered to be a critical limit for the effective reduction of floods by the forest. Under conditions of this precipitation total, forest soil is always completely saturated by water including depressions both in the soil surface and the parent rock stratum. Then, uncontrolled and spontaneous runoff occurs through the whole soil profile appearing often on the soil surface irrespective of a species composition or the method of management. In other words, also the forest soil body shows, similarly as eg reservoirs, its capacity possibilities which cannot be exceeded. |