Effect of local species composition on topsoil properties in mixed stands with silver fir (Abies alba Mill.)

Abstract

This study was carried out in three stands with fir and spruce (Picea abies L. Karst.), pine (Pinus sylvestris L.) and beech (Fagus sylvatica L.). The objectives were to characterize the spatial pattern of topsoil variation; to determine the contribution of local stand density and local species composition to small-scale variation in topsoil morphology, pH and gravimetric water content during mild midsummer drought; and to compare the effect of spruce, pine and beech vs fir. Although local stand density was related to soil properties, only in the case of single soil characteristics could this variable explain more than 10 per cent of their variation. Compared with fir, increasing density of pine exerted a stronger effect on an increase in organic horizon thickness and a comparable effect on a decrease in pH, but a weaker effect on decrease in topsoil moisture. Irrespective of the soil characteristics, the effect of spruce was approximately twice as strong as that of fir. Beech, however, had a much weaker effect on a decrease in topsoil moisture than did fir and the influence of this species on topsoil pH was the opposite.