Posted 23 June 2011, by Staff, Source: Allen Press Publishing Services, NewsWise, newswise.com
Newswise — Nature can have its own solutions to offer against invasive plant species. In the case of the weed cogongrass, woody vegetation at the forest’s edge may stop its progress. By catching seeds blowing in the wind, shrubs can prevent or lessen the impact of an invasion of weeds that will strangle native plants.
A study reported in the current issue of the journal Invasive Plant Science and Management found that woody vegetation may form a natural barrier to the dispersal of seed. Cogongrass is an invasive species that displaces native vegetation and adapts to varying conditions of shade and moisture, making its spread hard to stop. Researchers put a natural barrier to the test against cogongrass.
Pine forests within the Gulf Coastal Plain of Mississippi served as the study site. Two kinds of barriers were tested: (1) frequently burned areas with an open canopy of pine and tallgrass understory and (2) areas that have not experienced frequent fires where there are closed canopies of pines and hardwoods with a dense midstory of shrubs and small trees. The study utilized three forest sites, each containing both barriers.
A minimum of 50 cogongrass spikelets were released at each location and allowed to be dispersed by the wind into the forest sites. Tallgrass sites saw more spikelets dispersed farther into the forest than sites with dense woody vegetation. The shrubs and trees served to reduce wind speed and intercept the spikelets before they could become established within the forests.
However, cogongrass that is already established may continue to spread on the ground, without the aid of the wind. Woody vegetation cannot defend against this type of invasion, and the study’s authors recommend that forest managers use additional means of control.
Fire increased the spread of cogongrass in both types of study sites. This poses a dilemma for managers seeking to maintain more open forests for other reasons, such as biological diversity. The solution may be to “seal” the edges of the forests with woody vegetation while maintaining the open canopy within.
Full text of the article, “Woody Shrubs as a Barrier to Invasion by Cogongrass (Imperata cylindrica),”
Invasive Plant Science and Management
Vol. 4, No. 2, April-June 2011,
is available at http://www.wssajournals.org
About Invasive Plant Science and Management
Invasive Plant Science and Management is a broad-based journal that focuses on invasive plant species. It is published four times a year by the Weed Science Society of America, a nonprofit professional society. The Weed Science Society of America promotes research, education, and extension outreach activities related to weeds; provides science-based information to the public and policy makers; and fosters awareness of weeds and their impacts on managed and natural ecosystems. For more information, visit http://www.wssa.net