Losing trees despite the forest

When we think of human impacts on forests, we usually think of whole-scale destruction from logging or other habitat destruction. However, loss of individual trees within a persistent forest can have unforeseen effects. Such losses occur through drivers such as disease and drought and can occur within a specific tree species or across species. Fleming et al. conducted a large meta-analysis of mostly North American and Australian studies and found both positive and negative impacts on forest animal abundance. Species that rely on specific living tree resources such as nectar and pollen declined, whereas those that rely on resources such as tree cavities, open canopies, and ground resources increased. Impacts also shifted over time, with individual tree deaths leading to increases that eventually shifted to overall decline. Although sometimes occurring in opposite directions, species responses were substantial enough that increased tree loss could lead to altered forest communities.

Biol. Rev. Camb. Philos. Soc. 10.1111/brv.12725 (2021).