Get reliable science

Native plant species are not generally known to be weeds. Many even question whether native species can be invasive in the full extent of the definition. However, there are many native species in rangeland ecosystems that decrease habitat availability and forage quality and increase wildfire intensity. Many of these native species are woody, secondary succession species. A primary reason for native species becoming weedy is because of effective fire suppression strategies following European settlement of the western U.S. Suppressing historical wildfires has many times led to native woody species dominance of mixed plant ecosystems. In many cases, sites invaded by native woody species cross a threshold to a woody plant dominated state that is irreversible without significant management inputs. Across the Great Plains, native weedy species have become dominant in areas where wildfire frequency has decreased and led many grasslands to now be dominated by woodlands. Alternatively, in Great Basin ecosystems, historical fire suppression has led to dense woodland forests with low forage availability at high elevations and a buildup of fine fuel at low elevations, which increases fire intensity and spread. High intensity wildfire is particularly devastating to low elevation bunchgrasses and shrub species that keep their growing points above ground. Adding fuel to these wildfires is the increased dominance and spread of invasive annual grasses that decrease forage quality and wildlife habitat and both increase wildfire frequency and are increased by wildfire occurrence. Restoring structure and function these ecosystems can take a considerable amount of money and management efforts, many times with low success rates. A greater understanding of these rangeland ecosystems currently invaded by native weedy species and those that have been devastated by historical mismanagement should lead to better management strategies for restoring ecological structure and function to these vulnerable rangelands.