Healthy grasslands are generally identified by the plant community. At the core of any plant community assessment is an inventory of native plants. When assessing a native plant community, you must consider both the number of native plants and the diversity of native plants. As an example, a native pasture might have thousands of individual grass plants. If all those individual plants only represent three species, you might have a lot of individual native plants but very little native diversity. This might be considered an unhealthy native grassland that could be subject to invasion.
Alternatively, if you have hundreds of individual native plants, but those plants are comprised of dozens of species, you might have a grassland with reasonable diversity, but is also suffering from poor reproduction or poor soil health with a lot of open space between plants. Again, this might be symptomatic of an unhealthy grassland that is ripe for invasion of non-native plants.
What is desirable in a native plant community are many robust individuals of various species competing amongst themselves for space on the landscape, thus leaving little opportunity for unwanted invasive species to enter the community. Ironically, grasslands that are resistant to invasion and those that are ripe for invasion are both the result of management decisions.
Once invaded, grasslands can shift dramatically toward dominance of exotic species and require an integrated approach to species control that considers all tools such as mechanical (cutting, burning), cultural (grazing), or chemical alternatives. Each of these tools may have positive and negative consequences, especially regarding the native plant community. In temporary or semi-permanent planted grassland systems or hayfields, unintended consequences of more aggressive techniques, such as chemical applications, are not as far reaching as those in diverse native systems. Work with a trusted local grassland expert to develop a management strategy for invasive species prevention and control in your grasslands.
The Healthy Grasslands article series is provided by the South Dakota Grassland Coalition in partnership with SDSU Extension. Contributing editors: Sandy Smart (SDSU Extension Rangeland Management Specialist), Pete Bauman (SDSU Extension Range Field Specialist), and Joshua Lefers (South Dakota Grassland Coalition Board Member, 2015–2017). © South Dakota Grassland Coalition 2017. View the full document for more information.