Soil bacterial communities in native and regenerated perhumid montane forests

Forest management often results in changes in soil properties and microbial communities. In the present study, we characterized differences in soil bacterial communities caused by forest management practices using 16S ribosomal RNA (rRNA) gene clone libraries. The communities were from a disturbed Chamaecyparis (DCP) forest subjected to harvesting of snags and downed logs, a secondary Chamaecyparis (SCP) plantation subjected to harvesting of old-growth trees, and a secondary cedar plantation (SCD). These forests were compared to a nearby native Chamaecyparis (NCP) forest in a perhumid montane ecosystem. At this locality, the elevation is from 1500 to 2100 m a.s.l., the mean annual precipitation >4000 mm, the mean annual temperature about 12 °C, and the soil pH <4. The phyla Acidobacteria and Proteobacteria predominated among the three disturbed forest soil communities. Several diversity indices and rarefaction curves revealed that the diversity of the SCD community was higher than that of the DCP soils. The diversity of the SCP community was intermediate. The bacterial diversity of the NCP community was lower than communities in the three disturbed forest soils. Analysis of molecular variance revealed that the bacterial community in SCD soils significantly differed from those in the three Chamaecyparis forest soils. Some of the abundant operational taxonomic units (OTUs) significantly differed among the four forest soils. Compared to the three disturbed forest soil communities, the NCP community was dominated by Proteobacteria, which accounted for more than half of the community. These results suggest that the disturbance of forest harvesting and tree species conversion influence the composition of bacterial communities in natural and disturbed forests and increase the diversity of the disturbed forest soil community.

Research highlights▶ We study soil bacterial communities from one native and three disturbed forests. ▶ Bacterial rRNA gene diversity increased with disturbance in forests. ▶ Bacterial community composition differs significantly between all forests. ▶ Forest management practices clearly influence soil bacterial community composition.