Potential Effects of Climate Change on Mortality of the Invasive Species Hemlock Woolly Adelgid (Adelges tsugae) in Nova Scotia, Canada
MetadataShow full item record
Hemlock woolly adelgid (HWA) kills hemlock trees by injecting poison into their stems as the feed on sap, defoliating the trees. This insect has caused widespread eastern hemlock death across the northeastern United States (US) and its presence was confirmed in Nova Scotia in 2017. Eastern hemlock trees are foundation species, creating unique ecosystem dynamics in their habitats, and they are also a defining species of tolerant coniferous old-growth Acadian forests, which are valuable biodiversity hubs in Nova Scotia. HWA mortality after exposure to extreme low winter temperatures has been well studied, and 91% mortality has been found to keep HWA populations under control. This study used an equation developed for northeast US forests to determine theoretical HWA mortality using mean winter temperatures for a past (1981-2010) scenario and representative concertation pathway (RCP) 2.6, 4.5, and 8.5 scenarios for the near future (2041-2070) and distant future (2071-2100). Stands containing hemlock are also shown in the maps to depict areas of concern. It was found that some high-elevation, northern regions of Nova Scotia would have kept HWA populations under control, causing >90% HWA mortality, but stands containing hemlock are generally not present in these areas. Areas with >90% mortality were not found in any of the future scenarios. The differences between the near future and distant future scenarios were lowest for RCP 2.6 and highest for RCP 8.5, with RCP 4.5 falling in the middle. Because this study used equations developed for the northeastern US, future research should focus on developing HWA mortality equations for Nova Scotia. Future studies should also consider more variables that have been linked to HWA population distributions.