Effects of restoration practices on biodiversity in temperate and boreal forests

Several restoration practices are used to mitigate and compensate for the negative effects of large-scale forestry on biodiversity in temperate and boreal forests. A comprehensive synthesis of the benefits of these practices across taxa is missing. We conducted a systematic review and meta-analysis on this topic. We identified 93 relevant studies in which the effects of partial harvest, thinning, understory removal, prescribed burning, deadwood addition, or a combination of these were examined. Overall, restoration practices had a positive effect on richness and abundance of forest species, though effects varied among practices and taxa. The most consistent positive responses were found for plants and flying invertebrates. For other taxa, the response was not statistically significant, and in several cases, there were also negative responses. For instance, thinning and understory removal negatively affected birds, and prescribed burning had negative effects on bryophytes and lichens. Effects of restoration practices often became more positive over time, but 83% of data points were from within 10 years since the start of restoration, meaning the long-term impacts of restoration practices remain to be explored. Because different restoration practices benefit different taxa, promoting forest biodiversity requires a variety of restoration practices applied across forest landscapes. So far, evaluations have been done only at local scales, and evaluations of effects on landscape-scale biodiversity are needed.