Progress 09/01/03 to 08/31/06
Outputs
No progress reported this period
Impacts
Efforts to control weeds on wildland areas have, in the past, concentrated on destroying weed populations after they become large enough to impact productivity greatly. More recently, researchers recognized the importance of integrated approaches to pest management that incorporates the establishment of native species after removal of weeds. This research investigates native community response to weed competitors. By targeting surviving native plants within very old weed invasions, the study offers the ability to re-vegetate using competitive native plants that will be more successful at limiting weed return promoting sustainability of wildlands.
Publications
- Mealor, B.A. and Hild, A.L. 2006. Potential selection in native grass populations by exotic invasion. Molecular Ecology 15: 2291-2300.
- Mealor, B.A. 2006. Native Plant Population Resilience to Exotic Invasion. Ph.D. Dissertation. University of Wyoming, Laramie. 108 p.
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Progress 01/01/05 to 12/31/05
Outputs
Researchers located very old (25-40 years) weed invasion sites to document remaining native species. Soils and native plants were collected on the sites and on comparable areas just outside the weed invasions (inside and outside invasions). Remnant native species were identified and seed collections from individuals were used for a greenhouse grow-out study. Soils collected beneath long-standing Russian knapweed invasions was different chemically and physically (organic matter) than soils from adjacent, non-invaded areas. Although zinc (cited as an allelopathic chemical) was not at high enough concentration to have adverse affects on plant growth. Germination and growth of four native species was greater in soils collected from long-standing Russian knapweed invasions than in soils from non-invaded areas, a result contradictory to predictions based on previous literature. Molecular genomics analyses (AFLP) of two native grass species with and without previous history
of coexistence with Russian knapweed revealed loci that may be linked to divergent selection between two habitat types: invaded by Russian knapweed and non-invaded, native rangelands. As a follow-up to the genomic analyses, greenhouse and experiments were performed to test for differential performance of native grasses collected from invaded and non-invaded communities. Preliminary results suggest that native grasses from within invasions may be less suppressed by presence of Russian knapweed in a greenhouse setting. Long-term field data indicate that overall performance, measured as a combination of growth and survival, of native grasses from invaded communities may be better than those from non-invaded communities when grown inside existing knapweed invasions. Additional materials for native species propagation and evaluation of their ability to tolerate invaded conditions were also undertaken and are currently in progress. The M.S. student funded by this grant graduated in
December, 2005. The doctoral student will graduate in spring 2006.
Impacts
Efforts to control weeds on wildland areas have, in the past, concentrated on destroying weed populations after they become large enough to impact productivity greatly. More recently, researchers recognized the importance of integrated approaches to pest management that incorporates the establishment of native species after removal of weeds. This research investigates native community response to weed competitors. By targeting surviving native plants within very old weed invasions, the study offers the ability to re-vegetate using competitive native plants that will be more successful at limiting weed return promoting sustainability of wildlands.
Publications
- Mealor, B.A., Hild, A.L. and Shaw., N.L 2004. Native plant community composition and genetic diversity associated with long-term weed invasions. Western North Amer. Nat. 64(4): 503-513.
- Mealor, B.A. and Hild, A.L. 2006. Potential selection of native grass populations by exotic invasion. Molecular Ecology. In Press.
- Tyrer, S.J. 2005. Germination and Establishment of Four Native Species in Soils from Russian Knapweed Invasions. M.S. Thesis, University of Wyoming, Department of Renewable Resources.
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Progress 01/01/04 to 12/31/04
Outputs
Researchers located very old (25-40 years) weed invasion sites to document remaining native species. Species richness and weed densities were documented on the sites and on comparable areas just outside the weed invasions. Vegetation monitoring and site characterization were completed for all sites in the two locations (inside and outside invasions). Remnant native species were identified and seed collections from individuals were used for a greenhouse grow-out study. Preliminary results were presented at Wyoming Chapter, Society for Range Management meetings held in Casper, Wyoming in 2003. A second student (Tyrer) was added to the project to document seed germination of native species in knapweed infested soils. In 2003 and 2004, researchers returned to weed invasions to collect extant native plants for continued competitive and genetic characterization. In 2004, clones of these plants were placed into a field competition study. In 2003, the M.S. student (Mealor)
completed his thesis. In 2004 we published the genetic results. Tyrer presented germination results to the national SRM meetings at Ft. Worth, Texas in Feb. 2005.
Impacts
Noxious weeds have devastated productivity and function of most native wildland ecosystems of western North America. One GAO report to Congress (July 2001) suggests that there is insufficient rapid response to invasive species in natural areas, since controls have primarily targeted croplands and forest production. Efforts to control weeds on wildland areas have, in the past, concentrated on destroying weed populations after they become large enough to impact productivity greatly. More recently, researchers recognized the importance of integrated approaches to pest management that incorporate the establishment of native species after removal of weeds. This research begins a new line of investigation to procure native seed sources that are superior competitors against weeds. By targeting surviving native plants within very old weed invasions, we obtained native plants that remain inside weed invasions. In this way, the study offers the ability to re-vegetate using
competitive native plants that will be more successful at limiting weed return promoting sustainability of wildlands. Our work will greatly improve the ability to contain weedy invaders in extensive natural areas where native ecosystem integrity is most threatened.
Publications
- Mealor, B. A., Hild, A.L. and Shaw, N.L. 2004. Native plant community composition and genetic diversity associated with long-term weed invasions. Western North Amer. Nat. 64(4): 503-513.
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