The impacts of global change drivers (GCDs), such as invasive insects, climate change, and land use have significant effects on forest ecosystems. The interactions between GCDs are substantial. New England (NE) is one of the most forested regions in the US, with >80% of its lands forested, but also the most densely populated, with a majority of these lands owned and managed by a patchwork of small family forest owners. Often, management decisions in response to GCDs are made at the parcel level but have implications for landscape-scale forest biomass and composition, climate, as well as invasive insect spread. Limitations in computing and model structure have previously inhibited our ability to model future scenarios of the effects of insects, climate, and land use interactively at relatively high spatial resolutions. Therefore, our question is: can we model how the GCDs of invasive insects, climate change, and the coupled human management decisions may alter NE forests in the next 50 years? As a test case, we seek to model the spread of Hemlock Woolly Adelgid (Adelges tsugae, HWA) within the Connecticut River Watershed at a 100m resolution, where parcel management decisions are relevant.
Results/Conclusions
We successfully modeled 50 years of HWA spread throughout the Connecticut River Watershed, including population dynamics that vary yearly due to both climate and land use change. We simulated a 78% loss of Eastern hemlock (Tsuga canadensis) biomass in cells with only HWA and climate pressures, and an 86% loss of hemlock within cells modeled with additional management due to pest presence. Oaks (Quercus spp.) tended to benefit most from the loss of hemlock in the southern part of the region, with more than double the biomass in the simulations with HWA spread versus a test simulation with no HWA spread. In this example system, we demonstrate the importance of including the interactions of GCDs to better simulate disturbances affecting future forest growth and composition.