Phalaris arundinacea invades sedge meadow restorations, forming persistent monotypes that prevent community
establishment. Eradicating Phalaris, however, leaves restored ecosystems prone to reinvasion. In order to restore
desired plant communities, methods to control Phalaris are needed. To determine if reducing light by sowing cover
crops and reducing nitrogen by incorporating soil-sawdust amendments would prevent Phalaris invasions, a study
was conducted under conditions similar to a restored wetland in two experimental basins with controlled
hydrology. Seeds of a 10-species target community and Phalaris were sown in plots with high diversity, low
diversity, or no cover crops in soils with or without sawdust amendments. Nitrogen, light, tissue C:N ratios, firstyear
seedling emergence, establishment, and growth, and second-year above ground biomass were measured. Only
high diversity cover crops reduced light and sawdust reduced nitrogen for about 9 weeks. Similar trends in firstyear
seedling data and second-year biomass data suggested Phalaris control efforts should focus on establishing
perennial communities rather than implementing separate resource-limiting strategies. Sowing high diversity cover
crops resulted in Phalaris-dominated communities, making cover crops an ineffective Phalaris control strategy.
Using sawdust amendments did not reduce Phalaris invasion much beyond what the target community did but
resulted in a community similar to those of natural sedge meadows by increasing the abundance of seeded species
from the Cyperaceae family and colonization of non-seeded wetland species. The target community apparently
reduced Phalaris invasion by reducing both light and nitrogen. Regardless, no treatment fully prevented invasion,
making follow-up Phalaris control necessary to ensure community recovery.
Iannone III, Basil V.; Galatowitsch, Susan M..
Wet Meadow Revegetation Following Invasive Plant Control.
Minnesota Department of Transportation.
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