Variations of the ectomycorrhizal community in high mountain Norway spruce stands and correlations with the main pedoclimatic factors

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.