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Abstract

Invasive species are problematic for wetland managers, but little is known about how common management treatments influence nutrient cycling or plant responses. This study tested three experimental treatments (mowing, herbiciding, and harvesting (i.e., removal of aboveground biomass)) on several response variables: wetland soil porewater nutrient content (NO3-, NH4+, PO4-), native plant and invasive-Typha density, and light attenuation through the plant canopy. Seventeen days post-treatment, herbiciding resulted in higher porewater phosphate concentrations (55.63 µg-P/L) than harvesting (8.95 µg-P/L). After 24 days, herbicide had higher porewater phosphate concentration (72.03 µg-P/L) than all other treatments (control=15.15 µg-P/L, harvest=12.48 µg-P/L, mow=24.75 µg-P/L). After 32 days, harvest treatments promoted higher native density (333.2 stems/m2) than mowing (29.05 stems/m2) or herbiciding (31.85 stems/m2), which may have resulted from the increased light penetration to the soil surface (70%) associated with removing the aboveground biomass. Together, these data suggest that harvesting should be considered by managers aiming to reduce Typha density, increase native abundance, and avoid eutrophication downstream.