Hydrologic variability in black ash wetlands: Implications for vulnerability to emerald ash borer

Black ash (Fraxinus nigra) wetlands are widespread, forested landscape features in the western Great Lakes region. However, future of these ecosystems is threatened due to impending spread invasive emerald borer (EAB), which results tree mortality, decreased transpiration, and potential shifts wetter, non-forested conditions. The vulnerability such ecohydrologic likely varies according local hydrologic regimes controlled by settings, but this site-dependent our ability predict it unknown. Here, we assessed as a function site hydrology 15 undisturbed black from their three most common hydrogeomorphic settings northern Minnesota: lowland, depression, transition. Further, used high-resolution (1-cm) surface elevation models assess spatial variability water levels at subset 10 sites. Although observed similar ET groundwater exchange rates among lowland sites were generally drier because elevated position greater level drawdowns (via lower specific yield). We that will exhibit increases following EAB-induced compared wetter where open evaporation shallow-rooted understory transpiration offset losses transpiration. Moreover, sites, exhibited minimal microtopographic variation, limiting number microsites for establishment eventual canopy recovery after loss. These suggest wetness simple effective predictor wetland regime change. To end, terrain metrics wetness, providing tool target vulnerable areas active management efforts.