Beech Forests: Relationships between Decomposition Processes, Microflora Activities and Soil Fauna Biodiversity.

Information about organic matter dynamics in the soil, particularly with regard to the way they are affected by changes in the climate, is still scanty. As is already known, climate controls litter decomposition and the quality and quantity of organic matter. On the other hand, the characteristics of the organic matter determine the composition and the activities of the microflora and the animal communities, which play key roles in the carbon cycle dynamic. The study was conducted in two beech forests (Fagus sylvatica) in nature reserves, the first located in the Northern Apennines (Riserva Naturale Guadine Pradaccio, Parma province) and the second in the Southern Apennines (Laceno, Monte Raiamagra, Avellino province). In each area, 6 sub-sites were identified and 12 soil cores, 6 (10x10x10 cm) for mesofauna investigation and 6 (to a depth of 40 cm) for chemical-physical and microbial analysis, were recovered from each of them in autumn 2010 and spring 2011. Litter horizon (O) was sampled distinguishing different phases of decomposition. Microarthropod extraction was performed using Berlese-Tüllgren funnels, the obtained specimens were identified and counted. Soil biological quality was estimated using the QBS-ar and QBS-c indices (based on the arthropods and collembolans communities respectively); the biodiversity of soil communities was evaluated using the Shannon diversity index (H’) and Pielou’s evenness index (J). The results revealed some important differences. The Pradaccio site showed a higher C content along the soil profile and displayed a greater quantity of soluble fraction and a lower C/N ratio in the organic matter. The analysis of the litter failed to show any significant difference in terms of lignin and cellulose contents, but the Pradaccio litter was richer in N. With regard to soil fauna, both of the sites displayed a well diversified microarthropod community, characterized by the presence of organisms well adapted to soil habitat. This points to a generally high soil biological quality. Multivariate statistical analysis showed that the most important differences between the two sites were explained by the fungal biomass, chitinase (enzymatic activity), QBS-c, P content and microbial carbon in the organic layer, and by fungal biomass, soluble and microbial carbon and by acid phosphatase and xylanase (enzymatic activity) in the mineral layer.