European beech forests create an impressive diversity of forest floors

Forest floors are the interface between vegetation and soil and are therefore often neglected by science. Wrongly so, because they are highly sensitive and integrative indicators of ecosystem processes and fulfil important functions. Using an interdisciplinary approach, we analyse the properties and functioning of organic layers at 12 temperate forest sites, dominated by European beech and differing in P-status and mean annual air temperature. In agreement with literature, we found increasing mass of FF with decreasing temperature and P availability in the mineral soil. However, we found no significant differences in FF mass and C stocks between calcareous (n=3) and silicate (n=9) sites. The range of FF properties found by far exceeds the range of mineral soil properties. The pH(KCl) values of organic layers (OF and OH horizons) varied between 2.6 and 6.6. The FF mass ranged from 17 to 81 t ha^-1, the C-stock from 6.2 to 38.8 t ha^-1, the C/N ratio from 16 to 44, the concentrations of citrate extractable P from 66 to 487 mg kg^-1 and the cation exchange capacity from 186 to 634 µmol_c g^-1. Gross FF turnover calculated based on litterfall and FF mass ranged from 3.0 to 22.9 a. The fine root biomass showed close correlation with FF mass and precipitation at the studied sites. Cool and wet sites showed the highest root biomass. The identification and analyses of controlling factors and interrelationships with the microbial community and soil fauna at the study sites are currently in progress and will be presented. Based on the results obtained so far we conclude that the huge plasticity of European beech is mirrored by the heterogeneity of beech forest floor properties.