Invasive pests and pathogens as potential drivers of urban forest distributional inequalities and inequities

Abstract

Environmental injustices are influenced by socio-political and environmental legacies. Urban forest inequalities and inequities are often attributed to drivers like systemic racism and segregation. However, in recent decades, invasive pests and pathogens have substantially changed urban forests. It is not known how these invasive pests and pathogens act as a driver of urban forest inequalities and inequities. At the western range of Dutch elm disease (Ophiostoma spp.) and emerald ash borer (Agrilus planipennis), we examined how the loss of localized street tree monocultures of elm (Ulmus spp.) and ash (Fraxinus spp.) will result in changes to distributional justice. We examined street tree count and basal area distributions, applying the Gini Index and spatial autoregression to measure inequality and inequity, respectively, under current conditions and hypothetical pest-induced loss scenarios. Findings reveal that DED-related elm losses could improve distributional equality, likely due to the high density of elm in already greener areas, while EAB-related losses of ash could increase inequalities. Street tree losses to both DED and EAB dampen the magnitude of distributional inequities, but the inequities remain present in areas of high residential instability, economic dependency, and ethno-cultural composition. Our results indicate that pest-induced urban forest losses do not merely reduce canopy cover but may reshape distributional equality and equity in ways that align with socioeconomic disparities. This research highlights the need to incorporate principles of environmental justice in pest management approaches and replanting efforts, particularly prioritizing systemically marginalized communities. These findings underscore the critical role of diversity and strategic planning in urban forest resilience, advocating for practices that mitigate the social and ecological impacts of invasive pests and pathogens.