Physical, chemical, and biological interactions in wetlands: A case study using Fairview Constructed Wetland in southeastern Idaho

In the western U.S., wetlands are being constructed to treat runoff and agriculturally impacted water. The Fairview Constructed Wetland, a complex of replicated wetland cells built in 1999, was planted with seven macrophyte species. Establishment patterns varied among species and cells. In primary filter cells, where Juncus balticus and Carex nebrascensis dominated the plant community, aboveground biomass increased from 443 to 560 g/m2 and root mass increased from 387 g/m 2 to 1108 g/m2 (2000-2003). Litter mass increased from 230 g/m2 to 829 g/m2 (2001-2003). In shallow wetland cells, aboveground biomass increased from 82 to 391 g/m2 and root mass increased from 108 g/m2 to 574 g/m2 in (2000-2003), while litter mass increased from 68 to 214 g/m2 (2001-2003).; The chemical composition of macrophytes varied among species. In primary filter cells, J. balticus had more carbon (C) and Scheonoplectus maritimus less nitrogen (N) and phosphorus (P) than other species. No differences were detected in shoot N and P content among shallow wetland species. In general, litter from shallow wetlands had greater N and P than did standing biomass.; Interactions between C. nebrascensis and J. balticus were evaluated from 1999 to 2004. Total biomass was similar for each species for the first three years. In 2003, C. nebrascensis patches had twice the biomass of J. balticus patches, yet, J. balticus invasion of C. nebrascensis patches progressed more rapidly than C. nebrascensis into J. balticus. Complementarity was observed in 2003, when patches containing both species contained greater biomass than patches with either species growing alone.; My investigations on the effect of water level fluctuations on arbuscular mycorrhizal (AM) colonization of T. latifolia indicated that AM colonization occurred during flooded and unflooded periods. Two forms of AM colonization, hyphal and arbuscular, were positively correlated with the length of the unflooded period and drawdown represented a period of marked declines in AM colonization.; Previous work showed that AM colonization influences the elemental composition and above and belowground production of T. latifolia. Combined with the work reported herein, I provide compelling evidence for the interrelatedness of flooding, plant-fungal interactions, plant production, and the elemental composition of plant tissues. These interactions are manifested in the pools of nutrients associated with biomass and litter in wetlands.