We investigate the response of ecosystems in the northwest United States and southwest Canada to projected future climate change. The dynamic global vegetation model LPJ-GUESS was used to simulate vegetation and carbon flux patterns using modern climate (1961-1990 means) and two end-of-century scenarios (2.6 and 8.5 RCP projections). The simulated results include estimates of changes in net ecosystem exchange as well as variations in different components of the carbon cycle for a set of 7 plant functional types.
Results/Conclusions
Overall, net ecosystem exchange remained fairly consistent across the three scenarios. While the potential amount of carbon stored in vegetation increased, this was compensated for by increased sources of carbon, in particular through increased respiration. The simulated carbon balance showed marked spatial heterogeneity in the northern portion of the study region with distinct sink and source locations, in contrast to a highly homogeneous southern region, with net ecosystem exchange near zero. Carbon flux from fire differed spatially from patterns in vegetation and soil. The results have implications for land management as they suggest which areas may release or sequester carbon under future climates.