Quantifizierung des Zeitlichen Verhaltens der Wasserhaushaltskomponenten eines Buchen- und eines Fichtenaltholzbestandes im Solling mit Hilfe Bodenhydrologischer Methoden

Abstract

Ecological research programs of the German Research Association (Deutsche Forschungsgemeinschaft) enabled us to investigate the water budget of a beech and a spruce stand in the mountainous part of northern central West-Germany. Both stands are timbersize and site conditions are comparable. All components of the water budget equation were determined quantitatively as functions of time over a continuous period of almost 5 years (1968–1972). Soil moisture measurements were carried out by means of a great number of tensiometers. Mathematical simulation was used as an helpful tool.

The results are presented as balance statements for annual and monthly periods. Spruce turned out to have an average 135 mm/a higher total evaporation (evapotranspiration + interception) than beech and a correspondingly smaller deep seepage. Considerable deviations from the average values were observed for all of the components of the water budget.

The monthly rates of evapotranspiration and seepage exhibit a strongly seasonal course (Fig. 3). There are typical differences between beech and spruce: although spruce transpires in general at a lower rate during the summer months the total evapotranspiration is nevertheless normally higher due to the longer transpiration period. Furthermore, spruce was found to intercept in average about 100 mm/a more of the rainfall water than beech.

From Fig. 4 and 5 it was concluded that the results reported here must not be generalized. The figures indicate that the difference in water consumption between beech and spruce as found in this investigation is likely to become smaller with an increasing level of soil water suction in the root zone.