Use prescribed fire to control problematic plants: freshwater swamps
Overall effectiveness category Awaiting assessment
Number of studies: 1
Background information and definitions
Prescribed burns can be used to manage problematic plants that may overgrow and outcompete desirable vegetation. By removing above-ground vegetation, fire can also be used to manage the physical vegetation structure (Flores et al. 2011). Prescribed burns may have only temporary effects: many plants can regrow from remaining stumps, roots or rhizomes (underground horizontal stems).
Potential benefits of management by prescribed burning should be weighed up against potential risks. For example, it can be difficult to control the intensity, duration and area of a prescribed burn: burning when the ground is wet and/or cold might be safer (Hackney & de la Cruz 1981). Burning can damage seed banks, and might produce apparently desirable changes in vegetation over the short term followed by a rapid return to a degraded state. Burning can also damage the physical habitat (e.g. by exposing sediments, increasing erosion and reducing accumulation of organic matter; McKee & Grace 2012) and may be harmful to animals like amphibians (Smith & Sutherland 2014) and birds (Flores et al. 2011).
The timing and duration of monitoring might be particularly important when evaluating the effects of this action. Burning might produce apparently desirable changes in vegetation over the short term, followed by a rapid return to a degraded state.
For this action, “vegetation” refers to overall or non-target vegetation. Studies that only report responses of target problematic plants have not been summarized.
Flores C., Bounds D.L. & Ruby D.E. (2011) Does prescribed fire benefit wetland vegetation? Wetlands, 31, 35–44.
Hackney C.T. & de la Cruz A.A. (1981) Effects of fire on brackish marsh communities: management implications. Wetlands, 1, 75–86.
McKee K.L. & Grace J.B. (2012) Effects of Prescribed Burning on Marsh Elevation Change and the Risk of Wetland Loss. U.S. Geological Survey Open-File Report 2012-1031.
Smith R.K. & Sutherland W.J. (2014) Amphibian Conservation: Global Evidence for the Effects of Interventions. Pelagic Publishing, Exeter, UK.
Supporting evidence from individual studies
A replicated, randomized, controlled study in 2002–2004 aiming to restore a swamp in a reed canarygrass Phalaris arundinacea stand in Wisconsin, USA (Hovick & Reinartz 2007) found that burning after spraying herbicide increased plant diversity more than spraying alone, but that burning had no additional effect on plant richness or the number of tree seedlings. After two growing seasons, the vegetation was more diverse in burned/sprayed plots than in plots that had only been sprayed (data reported as a diversity index). The treatments did not significantly differ in overall plant richness (burned/sprayed: 9.3; sprayed: 6.6 species/m2), native plant richness (burned/sprayed: 6.3; sprayed: 4.0 species/m2) or density of non-planted tree seedlings (burned/sprayed: 21; sprayed: 25 seedlings/m2). The study also reported differences between treatments in the abundance of individual plant species(statistical significance not assessed). For example, eastern willow herb Epilobium coloratum was more abundant in burned/sprayed plots (70% of quadrats; 10% cover) than sprayed plots (40% of quadrats; 6% cover). Reed canarygrass was less abundant in burned/sprayed plots (80% of quadrats; 34% cover) than sprayed plots (100% of quadrats; 73% cover). Methods: Twelve plots were established in a canarygrass-invaded wetland. All 12 plots were sprayed with herbicide (Roundup®) in November 2002, and planted with tree/shrub seedlings (roughly 1 seedling/m2) in spring 2003. Four random plots were also burned, before planting, in spring 2003. In August 2004, plant species and their cover were surveyed in ten 1-m2 quadrats/treatment, ignoring planted trees/shrubs.Study and other actions tested