Restored Prairies Resist Non-Native Grasses

Newswise — Invasive species continue to pose a threat to ecosystem restoration. Prairies, already reduced to 1% of their original area, face competition from non-native cool-season turfgrass species (short grasses with two growing seasons-one in spring and one in fall) used for lawns, sports fields or golf courses. Although these non-native species have been reported in remnant and restored prairie, it is yet unclear how they got there.

A team of researchers from the University of Wisconsin, led by John C. Stier, investigated the ability of turfgrasses to compete against established prairie vegetation. Ten different species of turfgrass were transplanted into two restored prairie sites in Wisconsin. Colonies of non-native turfgrasses either declined in size or remained constant in size over two years. One native turfgrass colony tripled in size. The results demonstrate an inability of non-native species to compete in established prairies. The study was published in the January-February 2010 edition of Crop Science. Non-native grasses tended to show strong evidence of herbivory, likely by small rodents, rabbits, and turkey, and had to be protected by wire downspout guards. Native grasses also showed a competitive edge due to their deeper and more developed root systems. The shade from the native grasses was also a factor in limiting the growth of the sun-loving turfgrasses. Although most of the turfgrasses didn’t grow enough to produce seeds, the researchers did compare the viability of seeds of the non-native turfgrasses to the native prairie grasses. Non-native turfgrasses showed survival rates of 12% to 30% over 22 months, with rates for native grasses only about 1%. The researchers suggest that the existence of non-native grass species is most likely the result of inadequate prairie restoration and human disturbance. The results of the research suggest that non-native cool-season turfgrasses can’t compete with native grasses in prairie ecosystems. Their presence can be explained by their lengthier seed survival rates and insufficient controls during restoration efforts. Turfgrasses could become more prevalent with a consistent source for seed recruitment, such as a seeded roadside. The researchers suggest the study will help develop invasive species regulations and control measures. Funding was provided by University and Federal Hatch fund sources. The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://crop.scijournals.org/cgi/content/abstract/50/1/345.

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