Canadian Forest Service Publications
Biogeography and organic matter removal shape long-term effects of timber harvesting on forest soil microbial communities. 2017. Wilhelm, R.C.; Cardenas, E.; Maas, K.r.; Leung, H.; McNeil, L.; Berch, S.; Chapman, W.; Hope, G.; Kranabetter, J.M.; Dubé,S.; Busse, M.; Fleming, R.L.; Hazlett, P.W.; Webster, K.L.; Morris, D.; Scott, D.A.; Mohn, W.W. International Society for Microbial Ecology Journal. p1-17.
Available from: Great Lakes Forestry Centre
Catalog ID: 38839
CFS Availability: PDF (request by e-mail)
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The growing demand for renewable, carbon-neutral materials and energy is leading to intensified forest land-use. The long-term ecological challenges associated with maintaining soil fertility in managed forests are not yet known, in part due to the complexity of soil microbial communities and the heterogeneity of forest soils. This study determined the long-term effects of timber harvesting, accompanied by varied organic matter (OM) removal, on bacterial and fungal soil populations in 11- to 17-year-old reforested coniferous plantations at 18 sites across North America. Analysis of highly replicated 16 S rRNA gene and ITS region pyrotag libraries and shotgun metagenomes demonstrated consistent changes in microbial communities in harvested plots that included the expansion of desiccation- and heat-tolerant organisms and decline in diversity of ectomycorrhizal fungi. However, the majority of taxa, including the most abundant and cosmopolitan groups, were unaffected by harvesting. Shifts in microbial populations that corresponded to increased temperature and soil dryness were moderated by OM retention, which also selected for sub-populations of fungal decomposers. Biogeographical differences in the distribution of taxa as well as local edaphic and environmental conditions produced substantial variation in the effects of harvesting. This extensive molecular-based investigation of forest soil advances our understanding of forest disturbance and lays the foundation for monitoring long-term impacts of timber harvesting.
Plain Language Summary
Soil microbial communities are key to maintaining nutrient cycling and soil productivity and more intensified forest land-use has the potential to modify these communities. This study determined the long-term effects (11-17 years post-harvest) of timber harvesting and organic matter removal on bacterial and fungal populations at 18 Long-Term Soil Productivity (LTSP) sites across North America. Using genomics methods the authors determined that the majority of taxa were unaffected by the harvest treatments. Plots with forest floor removal had increases in heat-tolerant organisms and decreases in ectomycorrhizal fungi. This molecular-based study advances our understanding of the effects of forest disturbance on soil microbial communities
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