Logging That Retains Trees Also Retains Biodiversity

Leaving some live trees standing after logging benefits biodiversity, concludes a review of over 200 scientific studies. In nearly three-quarters of the studies, green-tree retention harvesting lowered losses of populations or individuals compared with clearcut logging. In no instances did retaining trees have negative consequences for plants or animals.

Those that benefit most from retention harvesting are birds and ectomycorrhizal fungi. Patches of forest that remain after logging serve as "lifeboats", providing habitat for forest-dependant species until cut areas regenerate. Lifeboats work best for maintaining soil fungi, tree lichens and small ground-dwelling animals. Tree patches are less successful at safeguarding mosses and vascular plants.

Research consistently found that the effectiveness of green-tree retention in preserving biodiversity was always influenced by what tree species were kept on the cutblock. In most cases the density of trees, and in half of the studies the arrangement of tree patches, also affected how well green-tree retention maintained native populations.

Altogether, the meta-analysis of harvesting pattern research considered 214 studies, of which 173 were in North America and the rest in Europe.