Acidity, nutrient stocks, and organic-matter content in soils of a temperate deciduous forest with different abundance of European beech (Fagus sylvatica L.)

Weinheim

2009

S. 500-511

7 Abb., 5 Tab., 37 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200159106

The production and composition of leaf litter, soil acidity, exchangeable nutrients, and the amount and distribution of soil organic matter were analyzed in a broad-leaved mixed forest on loess over limestone in Central Germany. The study aimed at determining the current variability of surface-soil acidification and nutrient status, and at identifying and evaluating the main factors that contributed to the variability of these soil properties along a gradient of decreasing predominance of European beech (Fagus sylvatica L.) and increasing tree-species diversity. Analyses were carried out in (1) mature monospecific stands with a predominance of beech (DL 1), (2) mature stands dominated by three deciduous-tree species (DL 2: beech, ash [Fraxinus excelsior L.], lime [Tilia cordata Mill. and/or T. platyphyllos Scop.]), and (3) mature stands dominated by five deciduous-tree species (DL 3: beech, ash, lime, hornbeam [Carpinus betulus L.], maple [Acer pseudoplatanus L. and/or A. platanoides L.]). The production of leaf litter was similar in all stands (3.2 to 3.9 Mg dry matter ha-1 y-1) but the total quantity of Ca and Mg deposited on the soil surface by leaf litter increased with increasing tree-species diversity and decreasing abundance of beech (47 to 88 kg Ca ha-1 y-1; 3.8 to 7.9 kg Mg ha-1 y-1). The soil pH(H2O) and base saturation (BS) measured at three soil depths down to 30 cm (0-10 cm, 10-20 cm, 20-30 cm) were lower in stands dominated by beech (pH = 4.2 to 4.4, BS = 15% to 20%) than in mixed stands (pH = 5.1 to 6.5, BS = 80% to 100%). The quantities of exchangeable Al and Mn increased with decreasing pH and were highest beneath beech. Total stocks of exchangeable Ca (0-30 cm) were 12 to 15 times larger in mixed stands (6660 to 9650 kg ha-1) than in beech stands (620 kg ha-1). Similar results were found for stocks of exchangeable Mg that were 4 to 13 times larger in mixed stands (270 to 864 kg ha-1) than in beech stands (66 kg ha-1). Subsoil clay content and differences in litter composition were identified as important factors that contributed to the observed variability of soil acidification and stocks of exchangeable Ca and Mg. Organic-C accumulation in the humus layer was highest in beech stands (0.81 kg m-2) and lowest in stands with the highest level of tree-species diversity and the lowest abundance of beech (0.27 kg m-2). The results suggest that redistribution of nutrients via leaf litter has a high potential to increase BS in these loess-derived surface soils that are underlain by limestone. Species-related differences of the intensity of soil-tree cation cycling can thus influence the rate of soil acidification and the stocks and distribution of nutrients.