Asymmetric influence of forest cover gain and loss on land surface temperature

The direct biophysical effects of fine-scale tree cover changes on temperature are not well understood. Here, we show how land surface temperature responds to subgrid gross tree cover changes. We find that in many forests, the biophysical cooling induced by enhanced evapotranspiration due to tree cover gain is greater in magnitude than the warming from tree cover loss. Therefore, the goal of no biophysical warming effects from tree cover changes could be achieved by regaining a fraction of previously lost tree cover areas. This percentage differs between different forest biomes, ranging from 75% in tropical to 83% in temperate forests. Neglecting this asymmetric temperature effect of fine-scale tree cover change ignores the fact that biophysical feedbacks continue to cause surface temperature changes even under net-zero tree cover changes. Thus, it is necessary to account for gross, rather than net, tree cover changes when quantifying the biophysical effects of forests. Changes in tree cover can change surface temperatures in multiple ways. Here, the authors show an asymmetric direct biophysical effect of tree cover change, as the cooling due to tree cover gain is greater in magnitude than the warming from tree cover loss in most forests.