Differential effects of forestry plantations on bird diversity: A global assessment

Planted forests are becoming increasingly common worldwide, replacing natural forests and compromising their associated biodiversity. However, not all forest plantations are the same. Aiming to identify key plantation features that could be managed to improve bird diversity, we conducted a meta-analysis examining the differential effects of several kinds of plantations on bird species richness and abundance. Our literature survey provided 123 case studies (68 cases for species richness and 55 for abundance), which showed that, although forest plantations have negative effects on both richness and abundance, there is a large heterogeneity of responses among plantation types. The least negative effects were found at plantations established with native tree species and mixed arrangements, along with those intended for protective uses. Moreover, exotic monocultures for commercial purposes were found to be the most negative plantations for bird diversity. Likewise, small (<36 ha) stands, those with large rotation times, as well as plantations connected with native forest remnants at the landscape level were more avifauna-friendly. However, the presence of understory vegetation and the lack of management were not beneficial to bird diversity, as was also previously suggested by local studies. These global patterns of change in bird diversity in forest plantations hint which features could be managed to reduce their negative effects on bird diversity, making these productive lands friendlier to biodiversity in the long-term.