Impacts of Invasive Tree Species on Sustainability of Freshwater Resources

How invasive species affect the ecosystem

Forest watersheds in the Eastern United States supply ecosystem services that heavily regulate the quantity and quality of freshwater supplies. Specifically, the southern Appalachians are among the most diverse and productive ecosystems in the temperate climate region. However, the forests have experienced significant changes due to the presence of invasive species—including chestnut blight, hemlock woolly adelgid (HWA), princess tree, and more—over several centuries.

HWA is an invasive species that has functionally removed eastern hemlock and Carolina hemlock from the southern Appalachians to New England and has led to near-complete mortality in many forests. The invasive princess tree seedlings have rapidly recruited and are impacting the oak-pine communities—especially following wildfires. Many studies report that water use for the replacement species is usually higher than for native species and that invasive species alter seasonal streamflow and stormflow regimes due to changes in leaf phenology, plant water use, and subsequent freshwater yield.

Using multi-temporal remote sensing data and a distributed hydrological and biogeochemical model, IU Assistant Professor Taehee Hwang and his collaborators are studying the relationship between invasive species, the water cycle, and other ecosystem processes in Eastern US forests by characterizing landscape infestation and disturbance patterns and emergent watershed-scale hydrological behavior.