Submerged harvest reduces invasive Typha and increases soil macronutrient availability.
Aims: We examined how mechanical management of invasive macrophyte, Typha × glauca alters plant-soil interactions underlying carbon processes and nutrient cycling, which are important to wetland function but under-represented in restoration research. Methods: In the northern Great Lakes, we compared plant biomass, light transmittance, soil nutrient availability and carbon mineralization rates of Typha-dominated controls with Typha stands harvested above the waterline (harvest) and at the soil surface (submerged harvest). Results: Relative to controls, harvested stands had 50% less litter and twice as much light transmittance to the water surface after one year. However, Typha stems re-grew, and soil nutrient availability rates were similar to controls. Submerged harvest eliminated Typha litter and stems, and increased light transmittance through the water column. P and K soil availability rates were 70% greater with submerged harvest than in controls. Soil C mineralization rates were not affected by treatment (mean±1 SE; 40.11±2.48 µg C-CO2 and 2.44±0.85 µg C-CH4 g-1 soil C hr.-1), but were positively correlated with soil Fe availability. Conclusions: While submerged harvest effectively decreased invasive Typha biomass after one year, it increased soil nutrient availability, warranting further examination of macronutrient cycling and export during invasive plant management.