Altering succession and improving habitat at created wetlands in Wyoming.

摘要

In northeast Wyoming over 1,500 wetlands have been created through bentonite mining. These wetlands ranged in age from one to over 50 years old and represent one of the largest wetland creation projects in the world. They also served as a large experiment in self designing ecosystems. I found that waterfowl used wetlands in this region that (1) are located within complexes of >5 within 1 km, (2) have variable depths to accommodate various feeding strategies, and (3) have abundant submersed and emergent vegetation. I evaluated 48 wetlands in three age classes to determine aquatic plant succession. These wetlands were dominated by wind-dispersed emergents and generally have low species richness and plant biomass. During the reclamation process no attempt was made to introduce aquatic plants into these wetlands, most of which were isolated from other wetlands and sources of propagules by 50 km or more. I designed several experiments using greenhouse microcosms and field trials to identify plants that could be propagated at these wetlands using bentonite substrates or bentonite mixed with native topsoil. Plant species for experimental trials were selected based on their adaptations to the high salinity, pH, and alkalinity common among these wetlands. Generally, all plants (10 species of both submersed and emergent plants) had higher growth weights and survival in microcosms with the topsoil or topsoil and bentonite mixed soil, suggesting that reclamation should include the addition of topsoil into these wetlands. Several plants did well under various treatments and in field trials, including some that are of high value to wildlife (Potamogeton pectinatus, Vallisneria americana, Scirpus validus, Scirpus maritimus, Eleocharis palustris). I also evaluated the use of salvaged-wetland soil in six newly-created wetlands as a technique to introduce propagules of native aquatic plants. The use of salvaged-wetland soil increased (1) the number of plant species present at a wetland over time (richness), (2) the total vegetation coverage in a treated wetland over time, and (3) the total plant biomass in a treated wetland. I recommend that future reclamation include the use of topsoil and salvaged-wetland soil to improve aquatic plant growth as well as plantings of select wetland species to improve plant diversity and biomass at these wetlands.