CANCELLED - Manipulating shade levels to control Phalaris arundinacea and promote native species diversity in a wet meadow

Background/Question/Methods This study examines the invasive grass species Phalaris arundinacea (Reed canary grass or RCG) and attempts to control its growth and vigor through the use of shading and grazing techniques. Simultaneously, plugs and seeds of native grass species (Elymus riparius and Panicum virgatum) were introduced to examine their establishment rates under these same conditions. Shade levels of 0%, 40%, and 80% were established through the use of nylon mesh shade cloth placed over a structure 8 feet in height. Because RCG has become a nuisance in the Midwest and the Pacific Northwest by forming extensive monocultures, the development of successful control methods is vital in maintaining species diversity in the wetland areas it is prone to successfully establish. Plant heights and light readings were taken throughout the growing season, and plants were harvested at the end of the season to determine dry weights. These measurements were used to determine relative success rates of establishment or control. It is hoped that this experiment will allow for control of the invasive RCG with a minimization of disturbance. Also, the successful establishment of seedlings combined with seed germination is anticipated under these conditions.

Results/Conclusions

Initial results showed successful establishment by plugs of both native species. Under periodic grazing, both species had larger dry weights by the end of the season. Elymus dry weights, however, were notably larger when 80% shade was combined with periodic grazing. There did not appear to be much difference in dry weights for Panicum under the varying light levels. Slightly higher dry weights were noted under periodic grazing than without. In contrast, seeds germinated with greater success under full sun conditions for both species than under shade. However, there did not appear to be a significant difference in seedling height among the varying shade level conditions. The presence of data points with zero readings from either plug disappearance or failure of seeds to germinate necessitated a second season of analysis. A fresh series of plugs and seeds will be planted in an attempt to improve on the study results. This will also be done to determine overwintering success as well as second year growth and control success.