Responses of soil quality indicators to innovative and traditional thinning in a beech (Fagus sylvatica L.) forest

Soil has a pivotal role in keeping high the productivity of forest ecosystem but its physical and chemical properties are highly influenced by changes in forest species composition and forest management practices. Thinning is the most effective silvicultural practice used in Europe to increase the ecological and economic value of forest stands. The aim of this study was to identify the most appropriate forestry practice to preserve soil fertility and biodiversity in a beech (Fagus sylvatica L.) forest in Calabria, southern Italy. The effects of innovative (T3) and traditional (T2) thinning on soil properties with respect to unmanaged forest (T1) were assessed by using biological indicators. Results showed that T2 had the highest dissolved organic carbon (DOC) and the lowest water content (WC), organic carbon (OC) and nitrogen (N) amount. The humification index was the highest in T2 as well as fungi, ergosterol, fluorescein diacetate hydrolase (FDA) and catalase (CAT). The highest values of NO3−, SO4−, Na+, Mg2+ and Ca2+ were found in the T2. QBS-ar was significantly higher in T2 and T3 than in the T1. In short, our results evidenced that organic matter, total nitrogen, C/N ratio and water content cannot be considered alone or in combination indices of quality to evaluate the effect of thinning on soils. Rather, is the data crossing of microbiota and ions with organic matter pools (stable and labile) that can give important and accurate information on how thinning can affects soil biological properties that are strictly correlated to soil fertility and quality.