Invasive plant cover and density following emerald ash borer-induced mortality in southern Ontario forests

Abstract

The emerald ash borer has caused widespread ash mortality in eastern North American forests, where forest managers are also facing challenges due to invasions of undesirable exotic plant species. This study aims to explore relationships between the two phenomena based on existing evidence that disturbance caused by insect pests may facilitate invasive plant colonization. The presence of invasive species was analyzed in the context of ash mortality following emerald ash borer infestation in four forests in the Region of Waterloo in Ontario. Multivariate analysis with generalized linear models was used to detect relationships between invasive plants and various environmental variables. Significant relationships with invasive plant cover and density are found for decline in ash basal area, ash mortality occurrence, change in total basal area, current basal area, canopy closure, regeneration density, and tree species composition. Potential effects of competitive exclusion and site richness on invasive plant species are discussed.