Simulated Emerald Ash Borer Induced Changes in Western New York Forests

Abstract

Invasive pests and pathogens are among the biggest threats currently faced by Northeastern forests. The emerald ash borer (Agrilus planipennis) is one such pest and targets trees in the genus Fraxinus. The primary goal of this research was to determine the ecological effects of EAB on forests in Western New York, emphasizing forest composition, succession, and carbon cycling. Each ash-dominated site contained two 20 x 20 m plots, an experimental plot where ash trees were girdled to simulate the effects of EAB and a control plot with ash trees left intact and healthy. Forest composition was examined in each of the plots to examine how composition and succession would change as a result of EAB. The effect of EAB on carbon dynamics and microclimate was also determined by quantifying soil organic matter, decay rate, soil respiration, tree productivity, soil and air temperature, and soil moisture. Ash was prevalent in all three woody strata (seedlings, saplings, and trees) at the examined sites; however, once these sites are impacted by EAB, ash will not be able to remain the dominant species. Although it remains unclear how different species will respond to the gaps left by ash, it is likely that invasive shrubs will benefit the most from EAB attack due to their current presence in examined sites. Ultimately, these invasive shrubs will likely alter the successional trajectories of the sites they invade. These changes in composition, as well as the loss of ash, will have an impact on ecosystem 2 functioning. Overall, the results of this study suggest that, in the short term (at least two years based on my results), sites impacted by EAB will become C sources as suggested by the slightly increased soil CO2 efflux (one year after girdling) and decomposition rates that were observed in the girdled plots. Additionally, there is a loss of ash productivity in the girdled plots and this loss is not being fully compensated by other species. Based on the results of this study, EAB will have a substantial impact on the composition of the sites it impacts in Western New York, resulting in altered functioning and decreased C sink strength. However, it is important to note that these responses will be site-specific, and therefore, the response of sites will vary with environmental conditions. Finally, EAB will result in altered species composition and, consequently, ecosystem functioning over longer time scales as other species completely fill the gaps left by ash.