PS 19-180 - The Future Vulnerability of New England Forest Carbon to Ecological Disturbances

Background/Question/Methods

Climate change is expected to increase the ecological impacts of disturbances. With New England being among the fastest warming regions in the world, changes to disturbance regimes may be particularly significant. Invasive insects and hurricanes are among the main ecological disturbances faced by New England forests, the impacts of both are widely expected to be exacerbated by climate change. New England is among the most heavily forested regions in the United States (80% of total land cover), and these forests serve as a critical carbon sink. We seek to understand the potential future impacts that ecological disturbances will have on tree community composition, and carbon stocks of New England Forests. To quantify the potential impacts of climate change, invasive insects, and hurricanes on the region’s forests, we use the HURRECON and LANDIS-II models to simulate the forested landscape for the duration of the 21st century under an RCP 8.5 climate scenario. We identify the live forest carbon risk due to hurricanes informed by the historical range of variation along with two prevalent invasive insects, Adelges tsugae (hemlock woolly adelgid) and Agrilus planipennis (emerald ash borer).

Results/Conclusions

Our results showed an average 45% (±16.7%) reduction in stand biomass immediately following a simulated hurricane in our test landscape compared to the scenarios without hurricane disturbance. 15-years post hurricane, forest biomass recovered to pre-hurricane levels, but was 29% less than the no-hurricane scenario. The stand-level factors that were most important for predicting hurricane susceptibility were: stand age, conifer biomass fraction, and proximity to the forest-edge. Hemlock woolly adelgid and emerald ash borer caused a major reduction in the mean stand biomass of Tsuga canadensis (50%) and Fraxinus americana (89%) in southern New England (Connecticut, Rhode Island, and Massachusetts) within the first 10 years of the simulations. However, this biomass was largely replaced by succeeding species. In contrast, impacts were less pronounced across the rest of the region (New Hampshire, Vermont, and Maine) where these invasive insects and/or host species are less prevalent. While New England forests currently serve as a carbon sink, the long-term effects that ecological disturbances (along with anthropogenic forces on the landscape) will have on the composition and carbon of New England forests for the remainder of the 21st century remain uncertain.