Vegetative Nutrient Pools in a Constructed Wetland in Southeastern Idaho

ABSTRACT

We examined the vegetative pools of carbon (C), nitrogen (N), and phosphorus (P) in constructed wetlands receiving irrigation return flows in southeastern Idaho. Seven native wetland plant species were introduced into the wetlands in 1999. Carex nebrascensis, Eleocharis palustris, Juncus balticus, and Scheonoplectus maritimus were planted in replicate wetland meadows (primary filters), and Scheonoplectus acutus, Scheonoplectus pungens, and Typha latifolia were planted in replicate experimental marshes (shallow wetlands). The elemental percentages of C, N, and P for aboveground biomass and litter varied among species, and the pattern of temporal change for each element in plant tissues was unique. At the end of the 2003 growing season, J. balitcus had more C and S. maritimus had less N and P than other species in the primary filter cells. No differences were detected in shoot N and P content among shallow wetland species, but litter from shallow wetlands had greater percentages of N and P than did standing biomass. C. nebrascensis aboveground biomass represented the largest pool of N and P (7.65 g/m² and 0.45 g/m²). Litter nutrient pools contributed considerably to the total aboveground nutrient pool, and this was especially true for J. balticus patches where the pool for litter N (17.2 g/m²) was four times larger than the pool for biomass N (4.3 g/m²). This work suggests that larger nutrient pools were associated with areas of higher production rather than areas containing species with higher concentrations of nutrients.