Submerged harvest reduces invasive Typha and increases soil macronutrient availability

Aims We examined how mechanical management of invasive macrophyte, Typha x 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 mu g C-CO2 and 2.44 +/- 0.85 mu g 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.