Invasive species research is focused on developing best management practices of invasive plants, including evaluating the efficacy of chemical and biological control and examining the subsequent restoration of native plant communities.
Leafy spurge (Euphorbiaceae: Euphorbia esula)
is an invasive plant threatening the structural and functional integrity of wildlands
throughout much of northern North America. Biological control agents, specifically Aphthona flea beetles, have successfully reduced the foliar cover and density of leafy spurge below and ecological and economic threshold shortly after release. However, the long-term efficacy of flea beetles on the target plant are unknown; consequently, we have several long-term monitoring sites used to investigate not only the efficacy of flea beetles, but also the target and non-target effects of using herbicides to control leafy spurge.
- Once controlled, the residual effects of leafy spurge infestations on the remaining native species and communities are unknown. Leafy spurge appears to have a strong filtering effect on plant species composition, which has important implications for restoration management following successful control. We are working to increase our understanding of how these residual effects may potentially alter success ional trajectories, which is needed as a part of a complete management plan for leafy spurge.
- Severe disturbances of natural landscapes incurred by timber harvest creates new habitat for invasive plants. Large infestations of several plant species (e.g. Canada thistle, spotted and Russian knapweeds, musk thistle, and common mullein) have resulted from extensive timber harvest, both spatially and temporally, on the Black Hills National Forest. In order to develop a sound management plan for invasive plants, we must have a thorough understanding of the dynamics of the understory plant community following three common timber harvest methods. Additionally, the current weed management plan instituted by the Black Hills NF had not been quantified. Consequently, managers need information that rigorously evaluates the effectiveness of current strategies to control invasive plants.
- Sickleweed (Brassicaceae: Falcaria vulgaris) has been present on the South Dakota grasslands since the 1940s. However, the species was not considered an ecological problem because it never reached infestation levels until recently. Currently, the Fort Pierre National Grasslands has several thousand acres heavily infested by this exotic species. Very little is known about sickleweed, so in order to successfully combat it, we must understand the basic biology and ecology, and its response to herbicide treatments.