Original paper

The effects of tree species richness and composition on leaf litter decomposition in a Danube oxbow lake (Gemenc, Hungary)

Ágoston-Szabó, Edit; Schöll, Károly; Kiss, Anita; Dinka, Mária

Abstract

The breakdown dynamics of three monospecific leaf litters originating from two native species, Quercus robur and Ulmus laevis, and an invasive species, Acer negundo and all possible two- and three-species combina- tions were examined in an oxbow lake of River Danube at Gemenc, a forested floodplain, in order to test the ef- fects of litter diversity on the decomposition processes. Decomposition of U. laevis leaf litter was fast, A. negundo intermediate and Q. robur slow. In litter mixtures, the differences in initial single C, N, P concentrations and stoichiometric ratios significantly influenced the interaction strengths between the various species. The diversity component of species richness showed a non-significant effect on litter mass, nutrients and quality, while the effects of species composition displayed both additive and non-additive features. Q. robur had a significant non-additive effect on the AFDM, C, N, P, C:P and N:P ratios of remaining litter, while A. negundo had a similar effect on the C:N, C:P, N:P ratios, and in the case of U. laevis, this effect was on remaining N. The main effect of time was significant in each of the performed repeated measures ANOVA analyses. The presence/absence of Q. robur and U. laevis had a significant effect on breakdown and C, N, P release rates. The invading A. negundo influenced the litter associated nutrient dynamics rather than the rate of decomposition. The stability of the decomposition process increased with litter species richness. Litter mixing confirmed the diversity effects. Changes in the tree species composition of the floodplain forests due to species invasion or loss of native species can have a significant impact on the decomposition process and might affect the ecology and the biogeochemical cycling of floodplain waters.

Keywords

decompositioninvasive speciesbiodiversitylitter qualityspecies losslitter mixing