The response of a northeastern temperate forest to future scenarios of climate change and energy policies through the 21st century

Northeastern temperate forests provide essential ecosystem services that are increasingly threatened by climate change and air pollution. To evaluate integrated ecosystem responses to these changes, we applied the PnET-CN-daily model to project carbon, nitrogen, and water cycling dynamics at Harvard Forest (Petersham, MA, USA) throughout the 21st century. The projections were based on future climate scenarios (RCP4.5, RCP8.5) and different energy policies scenarios (current U.S. policies, decarbonization policies). Simulations suggest that carbon storage in forest ecosystems will continue to increase throughout the 21st century, but the increase will become increasingly limited by nitrogen availability. The energy policy scenarios are projected to continue a decline in atmospheric nitrogen deposition, which will slow carbon accumulation and further accelerate the ongoing nitrogen oligotrophication. Therefore, future management may need to consider the effects of increasing nitrogen limitation on the carbon sequestration potential and the structure and function of northeastern temperate forests.