NEBC Meeting News

Abstract

December 2019. President Jesse Bellemare convened the 1142 meeting of NEBC in the Haller Lecture Hall at Harvard University on Saturday, December 7, 2019. Matt Charpentier introduced the speaker, Dr. Jaclyn Hatala Matthes, who is an Assistant Professor in the Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts. Her presentation was titled, ‘‘Forecasting the Ecosystem Impacts of Invasive Insects in Northeastern U.S. Forests.’’ Dr. Matthes studies herbivory and its effect on net primary productivity in forests, particularly the effect on the carbon cycle and CO2 sequestration. Forest insects and pathogens (FIPs) are transported around the globe through trade networks and thus introduced into new habitats (for example, accidentally in shipping pallets) where native plants lack defenses against them. These FIPs may reduce ecosystem services, create shifts in the invaded ecosystem and have high economic costs, yet they are not often represented in ecosystem models. Dr. Matthes believes that forecasting impacts of FIPs can provide foresight into ecosystem changes and facilitate adaptive management. An ecological forecast provides a near-term future prediction using models that can be iteratively updated as new data are available. The information is useful for planning adaptive management and for testing hypotheses so that better predictions can be made. Using data from remotely sensed imagery and field surveys, a dynamic vegetation model simulates competitive demography of tree species and predicts rates of spread and future forest structure. FIPs are grouped functionally based on how they disrupt carbon flows (defoliators, phloem feeders, xylem disrupters root rot and stem rot) in forest trees. Dr. Matthes presented two case studies in the northeast (a hotspot of diversity for introduced pests) that illustrate how she and her collaborators are using this approach to understand the impact of FIPs. In one study, she is forecasting the near-term impacts of the 2015–2018 gypsy moth (Lymantria dispar) outbreak in southern New England. The gypsy moth is a defoliator introduced to the US in 1869 that has periodic population irruptions. Landsat satellite images of defoliated areas show the spread of impacts from western Rhode Island (2016) to large areas of Rhode Island, Connecticut and Massachusetts (2017). Productivity was expressed as a proportion of baseline (no defoliation) for areas that experienced one, two or three sequential years of defoliation between 2015 and 2017. The modeling predicts that sites defoliated for one or two years will mostly recover by 2022, but