Underneath the Litter

Abstract

ECOLOGY/EVOLUTION The European beech is one of the predominant trees of the natural forests in Europe. Over the past several centuries, foresters have replaced many of the beech-dominated forests with plantations of Norway spruce. Spruce needles and beech leaves produce litter with different structures and patterns of decay. Under spruce, soils are more acidic, and inorganic nutrients become locked up in organic matter, with ultimately deleterious consequences on food webs of soil organisms. In order to assess whether these consequences could be mitigated by planting mixed stands of beech and spruce, Scheu et al. have compared the soil communities of pure and mixed forests. Although microbial biomass was similar in the two types, that of most soil animal groups decreased under pure spruce and under mixed stands as compared to pure beech. However, the structures of food webs, in terms of the ratio of predators to prey, were more similar in the pure beech and mixed stands, suggesting that mixed stands might enhance the preservation of ecological interactions.— AMS Oikos 101 , 225 (2003).