Microbial processes and fungal community structure in soils from clear-cut and unharvested areas of two mixedwood forests

Abstract

Decomposer fungi and microbial processes were examined in harvested and adjacent unharvested areas of two mixedwood forests in northwestern Ontario. Seven to 9 years following harvesting, organic and mineral soil from treated and control areas was sampled with the objective of examining the impact of clear-cutting and site preparation on soil basal respiration, microbial biomass carbon (C), metabolic quotients (qCO2), microbial C to organic C ratios (Cmic:Corg), nitrogen mineralization, and fungal community structure. Relative sensitivity of fungal community indices at species and genus levels was also examined. Soil microbial processes and fungal community structure were similar in harvested and unharvested stands. Although reductions were not significant, basal respiration, microbial biomass C, qCO2, Cmic:Corg, and nitrogen mineralization tended to be lower in organic soil from the harvested sites than the unharvested sites, with the exception of qCO2. Fungal community structure indicated by rank abundance curves and indices of fungal richness, diversity, evenness, and dominance was similar in harvested and unharvested soil. When comparing organic and mineral soil layers, fungal richness, diversity, and community composition corresponded more closely in the harvested sites than unharvested sites. The isolation frequencies of all frequently found fungal species were equivalent in harvested and unharvested soil. In this study, identifying fungi to the genus level instead of the species level did not alter any major conclusions.Key words: harvesting, fungal community, microbial processes.