Effect of invasive species on abundance and diversityof native flora.

Abstract

Wetlands are a very unique and fragile ecosystem supporting a wide variety of rare endemic flora. Human disturbances are having a large negative effect on wetlands. Not only construction but introduction of invasive species is detrimental to wetlands. Many of these invasive species are imported for garden use then escape into wetlands and change components of the ecosystem. In our study we examined potential allelopathic effect of invasive species. Allelopathy may be one way invasives take over a landscape. Volatiles and leachates from purple loosestrife (Lythrum salicaria), European swamp thistle (Cirsium palustre), and glossy buckthorn (Rhamnus frangula) were used to test effects of rate and germination of lettue can radish seeds. The volatiles had no effect on either rate nor germination. Leachate from the purple loosestrife had no effect on seed germination. The European swamp thistle negatively affect lettuce seed germination. Glossy buckthorn inhibited seed germination of both lettuce and radish seeds. The leachates from all invasive species had an effect on rate of germination of lettuce seeds. Glossy buckthorn has the strongest effect on seed germination and has potential allelopathic effects on native wetland plant species. Allelopathy may be working in concert with other factors to crowd out native plants. Chemical compounds from the plants may combine with compounds in the soil and then have an allelopathic effect. Studies in the field would provide more practical data on allelopathy and if it plays a role aiding invasives.