Do forest fires encourage the spread of invasive plants?

A number of invasive plants thrive in forested and grassland areas disturbed by fire, floods, erosion, wind, insects, or diseases, so increases in disturbed areas associated with climate variability and altered land-use could assist in the spread of this group of invasive plants. Cheatgrass (Bromus tectorum), one of the most invasive species in the western shrublands and woodlands of the U.S., has been common on severely burned areas. Recent studies suggest that increased wildfire activity in the western U.S. in recent decades is associated with increasing spring and summer temperatures and earlier spring snowmelt. If such trends continue, the concern is that a number of invasive plants will spread out of control in response to these large landscape-level disturbances.

The timing and amount of precipitation, especially in dryland areas, is a major factor determining how well nonnative invasive species establish themselves then persist and spread. Postfire invasions by plants are influenced by

    ♦ Resource Availability and Interactions Between Plant Species
    ♦ Site conditions (moisture, nutrients, light, and disturbance history)
    ♦ Fire Severity
    ♦ Fire Frequency
    ♦ Spatial Extent and Uniformity of Fire
    ♦ Fire Season and Plant Phenology
    ♦ Weather Patterns
    ♦ Availability of Seed(2).

Changes in any of these factors can influence the success of an invasive plant however, the key in the future will be understanding the complexity of how these factors interact (1) for any given plant in different vegetation communities.


Authors: Tom DeGomez, Area Agent and Regional Specialist, University of Arizona; and

Sarah Workman, US Forest Service, Eastern Forest Environmental Threat Assessment Center  


Cheatgrass in Invasive Species and Climate Change briefing paper, prepared for 2010 National Invasive Species Awareness Week

Fire Effects Information by plant category and specific species

1 Kerns, B. Guo, Q. 2012. Climate change and Invasive Plants in Forests and Rangelands. US DA Forest Service, Climate Change Resource Center.

2 Zouhar, Kristin; Smith, Jane Kapler; Sutherland, Steve; Brooks, Matthew L. 2008. Wildland fire in ecosystems: fire and nonnative invasive plants.  Gen. Tech. Rep. RMRS-GTR-42-vol. 6. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 355 p. This volume synthesizes scientific information regarding wildland fire and nonnative invasive plant species, identifies the nonnative invasive species currently of greatest concern in major bioregions of the United States, and describes emerging fire-invasive issues in each bioregion and throughout the nation.