Overview

          In North America, an invasive, European genotype of common reed (Phragmites australis (Cav.) Trin. Ex. Steudel) is now abundant in habitats once colonized by native genotypes (1). The native genotypes (P. australis subspecies americanum) can be distinguished from the exotic genotype based on morphological and genetic characteristics (2). Population decline and local extinctions of the native genotypes may be a result of competitive displacement by the exotic genotype (3) and/or anthropogenic disturbance (4,5). We found that the few remaining native populations are more susceptible to exotic insect herbivores than exotic P. australis - the vector for exotic insect introductions (6). Our objectives for this research include 1) determining the distribution of native and non-native P. australis in New England, 2) assessing differences in susceptibility to native and non-native herbivores among native and non-native P. australis genotypes, and 3) finding a genotype-specific biological control agent that will safely and permanently control non-native P. australis. This is a collaborative research project among the University of Rhode Island Biological Control Lab, Bernd Blossey's lab (Cornell University), and the RIVR Lab at UCSB.

GIS maps and data for native and non-native Phragmites australis distribution in Rhode Island

     
Exotic Phragmites invading coastal scrub in Rhode Island (left). Exotic Phragmites (in background with flowerheads visible) invading a native Phragmites stand (in foreground without flowerheads) on Block Island, RI (right).

References

(1) Saltonstall, K., P.M. Peterson and R.J. Soreng. 2004. Recognition of Phragmites australis subsp. americanus (Poaceae: Arundionideae) in North America: Evidence from morphological and genetic analyses. SIDA 21: 683-692.
(2) Saltonstall, K. 2002. Cryptic invasion by a non-native genotype of Phragmites australis into North America. Proceedings of the National Academy of Sciences, USA. 99: 2445-2449.
(3) Meyerson, L.A., K. Saltonstall, L. Windham, E. Kiviat, and S. Findlay. 2000. A comparison of Phragmites australis in freshwater and brackish environments in North America. Wetlands Ecology and Management 8: 89-103.
(4) Chambers, R.M., L.A. Meyerson, and K. Saltonstall. 1999. Expansion of Phragmites australis into tidal wetlands of North America. Aquatic Botany 64: 261-273.
(5) Bertness, M.D., P.J. Ewanchuk, and B.R. Silliman. 2002. Anthropogenic modification of New England salt marsh landscapes. Proceedings of the National Academy of Science 99: 1395-1398.
(6) Lambert, A.M. 2005. Native and exotic Phragmites australis in Rhode Island: distribution and differential resistance to insect herbivores. Ph.D. Dissertation, University of Rhode Island, USA.