Abstract
Forest disturbances can result in very different canopies that carry elevated albedo, thus causing substantial cooling effects on the climate. Unfortunately, the resulting dynamic global warming potential from altered albedo (GWPΔα) is poorly understood. We examined and modeled the changes in albedo over time after disturbances (i.e., forest age) by forest type, disturbance type and geographic location using direct measurements from 107 sites in temperate and boreal regions. Albedo in undisturbed forests was used as the reference to calculate albedo changes (Δα) and GWPΔα after a disturbance. We found that age is a significant factor for predicting albedo amid the obvious regulations from forest type and geographic locations. We found the strongest cooling GWPΔα in the first 10 years after a disturbance, but it decreased rapidly with time. The changes in GWPΔα were very different from the chronosequence of net ecosystem production (NEP). In the first decade after disturbances, GWPΔα was negative (i.e., cooling) and surprisingly larger in magnitude, with an average of −0.609 kg CO2 m−2 yr−1, compared to NEP of −0.166 kg CO2 m−2 yr−1. Albedo continued to decrease and approached pre-disturbance levels until around 50 years, resulting in a nearly zero GWPΔα. This research illustrates that many forests in temperate and boreal regions can be considered significant cooling agents by taking into account the high albedo of young forests following disturbances.