Fungal community response to forest restoration thinnings in a Pinus tabuliformis plantation in northern China. tree metagenome

Forest restoration thinning can alter stand structure and soil abiotic properties, which have the potential to change wood-inhabiting fungal community structure. To determine the effects of thinning on wood-inhabiting fungi, wood stakes of Chinese pine (Pinus tabuliformis), loblolly pine (Pinus taeda), and trembling aspen (Populus tremuloides) were placed horizontally on the soil surface and inserted vertically in the mineral soil of a Chinese pine plantation in northern China. The stand was thinned at age 35 and treatments consisted of three levels of overstory removal (30%, 41% and 53% of the standing biomass) plus an unthinned control. Fungal species were identified from decomposed wood stakes after 1, 2 and 3 years using high-throughput amplicon sequencing (HTAS). Across all species of wood stakes on the soil surface, Operational Taxonomic Unit (OTU) richness averaged 138 OTUs per thinning treatment. Significantly greater OTU richness (p<0.01) on surface pine stakes was observed in the unthinned control as compared to the moderate and heavily thinned plots. In the mineral soil, wood stakes averaged 57-141 OTUs, with no clear OTU pattern for thinning treatment or sample time for richness. Furthermore, aspen stakes had significantly lower (p<0.01) OTU richness than both pines. Although richness was not strongly affected, fungal community composition in the mineral soil was significantly altered by thinning treatments, wood stake species and sampling time. Understanding the long-term effects of stand thinning on fungal communities is critical for determining if these changes will have functional implications for nutrient cycling, C:N, and organic matter decomposition.