Publikationen
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| Manderscheid, B; Matzner, E: Auswirkungen unterschiedlicher Feinwurzelverteilungen und -biomassen auf das Risiko für Trockenstreß und Nadelverluste in Fichtenbeständen - Ergebnisse von Simulationsrechnungen zum Wasserhaushalt, Forstwissenschaftliches Centralblatt, 115, 350-362 (1996) | |
Abstract:
Chronic needle and leaf losses of major tree species, called "novel forest damage", are widespread in
Central Europe. Air pollutants are often blamed for this kind of damage. The influence of air pollutant
deposMon, soil chemical changes and the increasing nitrogen availability may cause a shallowing of the
root system and decreasing fine root blomass. We hypothesize that the changes in the root system
cause decreasing drought susceptability of the trees and needle or leaf losses.
Using computer models for the watercycle in a mature Norway spruce stand over a period of 18
years we quantified the influence of different rooting patterns on the transpiration and the risk of
drought stress. Here we compared the dry year 1976 with the wet year 198t. In 1976 the simulated
xylem water potenuals indicate severe drought stress under conditions of shallow rooting and low root
biomass. Under these rooting conditions the drought stress in 1976 would have been avoided, if the
trees had lost about 30% of the needle mass. During the wet year 1981 rooting patterns also influenced
xylem water potentials, but severe drought stress did not occur. |
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