Risk analysis of effects of whole-tree harvesting on site productivity

The increased removal of biomass from the forest sites with whole-tree harvesting has raised concern over the sustainability of site productivity. In this study, the results from eighty-six studies that quantify the short-term effects of whole-tree harvesting as compared with stem-only harvesting on soil- and tree-based indicators of site productivity were reviewed with the aim of estimating the risks of both negative and positive impacts on site productivity. The risk was defined as the combination of the probability of occurrence of an impact in an indicator of site productivity and the magnitude of the impact. According to risk analysis of this study, soil pH, P, K, Ca, Mg and tree diameter were priority indicators of site productivity on which to act to mitigate risks of site productivity decline following whole-tree harvesting. Following clear-cutting, the probability of occurrence of a negative effect of whole-tree harvesting on these indicators of site productivity was 31–39% and the mean decrease 13–60%. The results showed that the risk level of change in indicators of site productivity following clear-cutting with whole-tree harvesting might be high enough to justify a need for mitigation measures. Following thinning with whole-tree harvesting, the probability of occurrence of the negative effects and the risk levels were lower in comparison to clear-cutting. Therefore, mitigation measures at thinning may not be needed.

► The risk of site productivity decline from whole-tree harvesting was estimated.
► Soil pH, P, K, Ca and Mg had the highest risk level.
► Risk mitigation measures may be needed at clear-cutting.
► The proposed method allows risk elements to be evaluated in a precise way.