Evidence for a Recent Growth Increase in Eastern Forests

Recent studies have shown increases in biomass across many forest types.  Often, this increase has been attributed to climate change.  However, since change in biomass can reflect normal recovery from previous events, it is important to know the disturbance history of a forest to understand the causes of change.  Using a unique dataset of tree biomass collected over the past 23 years from 55 temperate forest plots with known land-use histories and stand ages ranging from 5 to 250 years, we found that recent biomass accumulation greatly exceeded the expected caused by natural recovery.  Long records of local weather and of on-site atmospheric CO₂ measurements showed increases consistent with globally observed climate-change patterns. Combined, these observations suggest that changes in temperature, growing season length and CO₂ that have been observed worldwide can fundamentally alter the rate of critical natural processes.