Forest management affects the functional traits of birds and mammals differently.

Forest management is an important component of global change as more than half of the world’s forests are managed for human use. Although the effect of forest management on taxonomic diversity is well-studied, we do not fully understand its impact on functional diversity. Understanding this is important to better predict how ecosystem processes will respond to global change scenarios and to implement efficient conservation actions. We conducted a large-scale (~81,800 km2), research project over 4 years in temperate forests of the northeast USA to investigate how the functional structure of bird and mammal communities are affected by forest disturbance. We surveyed 85 bird species distributed in 115 sites using point counts, and 14 mammal species across 197 sites using camera traps. For each species, we selected functional traits that summarize key features of their biology, and for each site, we collected data on the level of forest disturbance based on forest loss events. We found that functional richness increased with forest disturbance for mammals while it decreased for birds, with morphological (body mass) and physiological (litter size) factors being the main determinants of the observed patterns. These findings emphasize the complexity associated with making generalizations and predictions on how species and their traits respond to forest management since our empirical data suggests that this process is heavily dependent on the context and taxa studied. Overall we observed a limited response of functional diversity to forest management, which might indicate that the environmental changes generated by forest management are less extreme than changes resulting from other types of land-use change, especially deforestation or conversion of natural forest to plantations of exotic species.