Assessment of benthic barrier products for submerged aquatic weed control

摘要

The use of biodegradable products as benthic barriers to control submerged aquatic weeds and their impact on desirable native plant species was assessed in a common garden study. Five introduced invasive species (Ceratophyllum demer-sum, Egeria densa,Elodea canadensis, Hydrilla verticillata, Laga-rosiphon major), a lesser weed (Potamogeton crispus, also introduced) , and desirable native species (Myriophyllum triphyllum, Potamogeton ochreatus, an assemblage of charophytes, and oospore rich sediment)were grown in pots under common conditions before being covered by one of three matting products. Two different grades of hessian (burlap) and a coconut fiber product were placed over the plants and anchored in the pots. Plant emergence through the barrier and biomass were assessed over a 5-month period. For all species, the trend was toward reduced emergence with increasing product density, with significantly fewer plants emerging from treated pots compared with untreated control pots for all speciesexcept C. demersum and the charophytes. Biomass data corroborated the trends observed in the emergence data, except that the biomass of the germling charophytes was significantly lower in the densest treatments compared with controls. There was, however,a variable response among plant species; some were inhibited by all of the products while others only had reduced emergence and biomass with the densest matting product. The variable response of the weeds and the native plants to the different productsprovides an opportunity for selective control of some weed species, while providing a recruitment opportunity for native charophytes species from the seed bank.