Litter decomposition in pure and mixed Quercus and Fagus stands as influenced by arthropods in Belgrad Forest, Turkey

Arthropod assemblages and decomposition rates were compared in the litter of pure and mixed Quercus ( Quercus petraea L.) and Fagus ( Fagus orientalis L.) stands. Litter was sampled on a monthly basis for 1 year and stored in litterbags of different mesh sizes. The experimental objective was to test the effect of mesh size on litter decomposition, decomposition rates of litter, and diversity of the invertebrate fauna between the two types of stands. Decomposition rates were measured by filling three fiber litterbags of different mesh sizes with pure Quercus litter (3 g) left in the pure Quercus stand, and litterbags with Fagus litter (3 g) were left in the pure Fagus stand. Mixed litter samples were prepared by mixing of equal amounts of each litter in the same litterbag and leaving them in the mixed stand. The residual mass of litter from the pure Quercus stand was significantly lower in fine- and coarse-mesh bags than in the medium-mesh bags in pure the Fagus stand. Carbon and nitrogen levels in the pure Quercus litter were significantly different among the mesh sizes at the end of the incubation period. Macroarthropods from 27 taxa were collected from pitfall traps every month. Their relative numbers differed significantly between the pure and mixed-stand litter samples. Litter-dwelling Isotomidae (Collembola) and Mesostigmata (Acarina), and soil-dwelling Mesostigmata were the most numerous in the mixed stand. It is significant that the abundance of macroarthropods contributed to the mass loss of litter in both the medium and coarse mesh sizes in the mixed stand, but did not significantly affect the mass of litter in the pure stands. In the mixed stand, there was a negative correlation between litter mass loss and total number of microarthropods in all mesh sizes. Mixed-stand litter decomposed more slowly than pure-stand litter.