Inventory and Ventilation Efficiency of Nonnative and Native Phragmites australis (Common Reed) in Tidal Wetlands of the Chesapeake Bay

Nonnative Phragmites is among the most invasive plants in the U.S. Atlantic coast tidal wetlands, whereas the native Phragmites has declined. Native and nonnative patches growing side by side provided an ideal setting for studying mechanisms that enable nonnative Phragmites to be a successful invader. We conducted an inventory followed by genetic analysis and compared differences in growth patterns and ventilation efficiency between adjacent native and nonnative Phragmites stands. Genetic analysis of 212 patches revealed that only 14 were native suggesting that very few native Phragmites populations existed in the study area. Shoot density decreased towards the periphery of native patches, but not in nonnative patches. Ventilation efficiency was 300 % higher per unit area for nonnative than native Phragmites, likely resulting in increased oxidation of the rhizosphere and invasive behavior of nonnative Phragmites. Management of nonnative Phragmites stands should include mechanisms that inhibit pressurized ventilation of shoots.