Exotic Plants May Dominate After a Fire, But Not for Long


exotic_grasses_Wikimedia.jpgLand managers expect that exotic invasive plants will quickly move in following a disturbance, especially after a fire. Though exotics initially might have an edge over native plants on burned ground, this may not always be so as time goes on, according to a recently published study. Eastern Threat Center research ecologist Qinfeng Guo made this discovery after re-analyzing post-fire plant data from a southern California chaparral community that burned in November 1993 during the Old Topanga Fire. “I hypothesized that the same community may show different relationships between exotic and native plants at different points in time as vegetation regrew after the fire,” says Guo. He was correct. For two years after the fire, the number, or richness, of both native and exotic plant species increased, but exotic species made up a larger proportion of all the plant species. The richness of both exotic and native species then gradually declined, and within four years after the fire, native plant species began to dominate the larger proportion of vegetation on the site. Though this is a case study of just one fire and the resulting vegetation dynamics, “More studies like this one can help managers understand the best timing for actions that can prevent the establishment of exotic plants following fire,” says Guo. Read more in CompassLive...

Pictured: Annual grasses, including Bromus diandrus (ripgut brome) and Vulpia myuros (rat's tail fescue), were among the exotic plants that dominated the study site soon after the fire. Photo by Matt Lavin, Wikimedia Commons.


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