Abstract

The species composition of ectomycorrhizal (ECM) fungal communities can be strongly influenced by abiotic and biotic factors, which determine interactions among the species such as resource partitioning, disturbance, competition, or relationships with other organisms. In order to determine the influence of environmental features on ECM community, soil bedrock pH, exposure, humus features and sampling points locations were taken into account as the most representative and influencing factors in these soil ecological dynamics. In summer 2003, 2004 and 2005, in 10 [165(±10)-year-old] Norway spruce [Picea abies (L.) Karst.] stands located in the Province of Trento (northern Italy), root tips were collected according to an experimental sampling method designed and statistically tested on purpose. The investigation of the ECM community composition (species richness and abundance) in relation to the main pedoclimatic factors revealed the importance of bedrock pH and site exposure as variables at a macro-scale level. A spatial niche differentiation of ECM species and ecological ECM groups, based on similar organization and extent of the extramatrical mycelium, were mostly associated to organic layers (OF), pH and N tot variables at a vertical micro-scale level of study. The results suggest that bedrock pH, exposure and humus dynamics play a primary role in the adaptive selection of ECM species constituting the consortium.