Non-native Phragmites can now be found in all of the lower 48 states of America and all Canadian provinces. It colonizes natural wetlands throughout the continent, but also human-made habitats such as roadsides and agricultural ditches. The non-native Phragmites is now the dominant subspecies of Phragmites throughout the eastern parts of United States and Canada, while the native Phragmites is scattered across its historical distribution and mainly confined to natural wetlands.
Non-native Phragmites is likely to be found in disturbed and linear habitats such as roads, dikes, and ditches.
This has been attributed to a broader tolerance to a variety of environmental conditions such as salinity level, soil type, nutrient levels, and heavy metals. Movement of non-native Phragmites through these disturbed areas appears to facilitate spread.
- Roads increase the level of landscape connectivity, thus facilitating the transport of propagules (i.e. seeds, fragments) from invaded to non-invaded wetlands. Roadsides are harsh environments, frequently disturbed and with high inputs in salts and contaminants, which favor the establishment of disturbance-adapted species such as non-native Phragmites.
- Drainage ditches and canals facilitate spread by providing favorable habitats and by facilitating the dispersal of vegetative parts to downstream areas during floods or other disturbances.
- Agricultural areas commonly have high levels of non-native Phragmites due to soil disturbance and high nutrient levels from fertilizer run-off.
Non-native Phragmites is limited by water depth.
Water levels have been identified as one of the very few limiting factors of non-native Phragmites. High water level and continued flooding may successfully limit the spread of non-native Phragmites. While the water level tolerance of non-native and native Phragmites has not been yet compared, studies of large and small scale patterns of distribution demonstrated that native Phragmites is more frequently observed near rivers and wetter marshes.
- Catling, P. M. and S. Carbyn. 2006. Recent invasion, current status and invasion pathways of European Common Reed, Phragmites australis subspecies australis, in the Southern Ottawa District. Canadian Field-Naturalist, 120(3): 307-312. Abstract
- Lambert, A. M. and R. A. Casagrande. 2006. Distribution of Native and Exotic Phragmites australis in Rhode Island. Northeastern Naturalist, 13(4): 551-56. Abstract (Visit Dr. Lambert publication page to obtain a copy)
- Meadows, R. E. and K. Saltonstall. 2007. Distribution of native and non-native populations of Phragmites australis in oligohaline marshes of the Delmarva Peninsula. Journal of the Torrey Botanical Society, 134(1): 99-107. Abstract
- Taddeo, S. and S. de Blois. 2012. Coexistence of introduced and native common reed (Phragmites australis) in freshwater wetlands. Ecoscience, 19(2): 99-105. Abstract (Visit the Phragmites research group website to request a reprint)
Non-native Phragmites can be found in undisturbed natural habitats.
While disturbed areas, areas with high nutrient inputs, or newly exposed bottomlands are likely candidates for hosting non-native Phragmites, these plants have found their way into all variety of natural wetlands and shorelines.