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United States Department of Agriculture

Agricultural Research Service

Research Project: THE ECOLOGY AND MANAGEMENT OF MEDUSAHEAD IN THE GREAT BASIN AND SURROUNDING ECOSYSTEMS
2008 Annual Report


1a.Objectives (from AD-416)
Improve our ability to prevent invasion of rangeland by medusahead, determine the most ecologically sound and cost-effective methods for managing medusahead using herbicides, and develop landscape-scale restoration strategies for medusahead-infested rangeland using successional management.


1b.Approach (from AD-416)
This research will build upon existing efforts to develop ecologically-based invasive weed management strategies. This research will test ecological theories that have potential to become principles that guide invasive plant management and develop those principles into methods for managing weeds. Part of this effort will focus on understanding the key species and grazing strategies that minimize medusahead invasion. Since herbicides are one of the few effective tools for medusahead, this research will attempt to define ecological and economic thresholds for applying them. Finally, the studies will test two novel approaches to restoring medusahead infested rangeland using current ecological theory to guide the implementation. Decision-support tools will be researched and developed to assist land managers in applying existing and new knowledge associated with medusahead in the Great Basin and Columbia Plateau. Replacing 5360-22000-002-00D (5/05)


3.Progress Report
CRIS 304 project. In 2008 we continued to progressing toward achieving the objectives outlined above and the stated milestones describe the specific progress for the past year. In response to NP 304 Action Plan Component V, efforts were geared toward developing new prevention strategies, with an emphasis on determining the functional groups are important in minimizing invasion by medusahead. additionally, a conceptual framework for linking the ecology of seed dispersal with prevention management was developed. complementary to Component VI and VII, we continued collecting data and information from ongoing studies to determine the most economically sound and cost-effective methods for managing medusahead using herbicides. In support of Component X, maintenance and evaluation of studies aimed at rstoring medusahead infested rangeland were continued.


4.Accomplishments
1. Ecologically-based guidelines for preventing weed invasions Preventing plant invasions is the most cost-effective and efficient method for managing invasive species. Weed prevention consists of terse lists common sense things to consider that might help prevent invasions and are only linked to the ecology of seed dispersal in some vaguely intuitive way. ARS scientists in the Range and Meadow Forage Management Research Unit in Burns, OR have created a conceptual framework for preventing the spatial dispersal of invasive plants that links the ecology of seed dispersal with prevention management strategies. The framework identifies major potential vectors by incorporating invasive plant seed adaptations for dispersal through space and infestation locations relative to vector pathways. The framework then proposes preventing management designed to limit dispersal by those specific vectors. This provides managers ecology-based guidelines for developing effective prevention programs. The publication describing the framework was awarded “Outstanding Paper in Weed Science”. National Program 304; Component V, Problem c: Response to emerging pest issues, Component X, Problem a: Weed management systems, Component VI, Problem d: Implementation of practical integrated crop protection and production systems, Component VII, Problem a: Biology and ecology of serious weeds and other invasive plants

2. Ecologically-based restoration Heterogeneity in disturbance regimes, propagule pools, and factors affecting plant performance are a ubiquitous feature of wildlands. ARS scientists in the Range and Meadow Forage Management Research Unit in Burns, OR developed and tested a conceptual framework, termed augmentative restoration, aimed at identifying and selectively repairing or replacing damaged processes based on their predicted influence on three causes of succession: site availability, species availability, and species performance. In two of the three sites, using augmentative restoration to guide our management approaches improved our decision as to the treatment combinations that would maximize seedling establishment. Selectively augmenting successional processes that remain intact by repairing or replacing processes occurring at inadequate levels can advance successional management theory and provide a refined process-based theory for restoration across heterogeneous landscapes. Besides the clear economic advantages of lower management inputs associated with augmentative restoration, avoiding unnecessary management inputs has the additional advantage of minimizing unintended negative impacts on ecosystem processes. National Program Component 304; Component V, Problem c: Pest Control Technologies, Component X, Problem a: Weed Management Systems, Component VII, Problem a: Biology and ecology of serious weeds and other invasive plants

3. Prevention of annual grass invasion Prevention strategies for limiting annual grass invasion have been largely absent, or at least, not tested. In a comprehensive series of research projects by ARS scientists in the Range and Meadow Forage Management Research Unit in Burns, OR, specific prevention strategies were evaluated for their potential for minimizing invasion of desired plant communities by annual grasses. Planting tall vegetation around the borders of large infestations reduces wind dispersal of seeds. Borders seeding of tall tussock grasses would only have to be a few meters wide to be effective. Prescribed fall burning of a late-seral sagebrush community stimulated the herbaceous component and increased the resistance of the communities to cheatgrass invasion for years post-burn. National Program Component 304; Component V, Problem c: Pest Control Technologies, Component X, Problem a: Weed Management Systems, Component VII, Problem a: Biology and ecology of serious weeds and other invasive plants

4. Invasion and fire resistant soils Along with agricultural production losses and ecological damage, annual grass sponsored rangeland wildfires cost over $30 billion annually. ARS scientists in the Range and Meadow Forage Management Research Unit in Burns, OR discovered that an optimum level of plant available nitrogen favors native plant communities over those dominated by annual grasses. Altering plant available nitrogen by grazing, mowing, litter management, microbial alteration, and minimizing disturbances helps maintain weed resistant soils that favors native plant communities where they exist. Promoting native plant communities is central to minimizing wild fires in the Great Basin. National Program Component 304; Component V, Problem c: Pest Control Technologies, Component X, Problem a: Weed Management Systems, Component VII, Problem a: Biology and ecology of serious weeds and other invasive plants

5. Using functional traits rather than functional groups as a unit for restoration. Restoration of invasive plant dominated rangeland progressed from establishing grass communities to establishing diverse functional groups of species because they appear to convey some degree of invasion resistance. However, invasion resistance does not always occur. ARS scientists in the Range and Meadow Forage Management Research Unit in Burns, OR identified and developed the theoretical basis for using specific portions of the relative growth rate (RGR) of individual species to design desired plant communities that will maximize resource uptake and preempt resource acquisition by invasive weeds. The most important components of RGR with respect to invasion resistance are specific leaf area (SLA; leaf area per unit total plant mass) and leaf area ration (LAR; leaf area per total plant mass). SLA and LAR are plant traits that can be used to select species in restoration with the highest probability of resisting invasion by pests. National Program 304; Component V, Problem c: Pest Control Technologies, Component X, Problem a: Weed Management Systems, Component VII, Problem a: Biology and ecology of serious weeds and other invasive plants


5.Significant Activities that Support Special Target Populations
These studies may all potentially benefit small farms (including ranching families and holders of grazing allotments on public land) by maintaining the quality and quantity of the forage base, and by increasing the profitability of pasture and hay production.


6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings7
Number of Newspaper Articles and Other Presentations for Non-Science Audiences6

Review Publications
Sheley, R.L., Bingham, B.S., Svejcar, A.J. 2008. Crested wheatgrass defoliation intensity and season on medusahead invasion. Rangeland Ecology and Management. Rangeland Ecol Manage 61:211-217

Sheley, R.L., Carpinelli, M., Reever Morghan, K.J. 2007. Effects of imazapic on target and nontarget vegetation cover during revegetation. Weed Technology. 21:1071-1081

Mangold, J.M., Sheley, R.L. 2008. Controlling performance of bluebunch wheatgrass and spotted knapweed using nitrogen and sucrose amendments. Western North American Naturalist. 68(2)pp. 129-137.

Davies, K.W., Sheley, R.L. 2007. A conceptual framework for preventing the spatial dispersal of invasive plants. Weed Science. 55:178-184.

Sheley, R.L. 2007. Tolerance of meadow foxtail (alopecurus pratensis) to two sulfonylurea herbicides. Weed Technology 21:470-472.

James, J.J., Drenovsky, R.E. 2007. A basis for relative growth rate differences between native and invasive forbs. Rangeland Ecology and Management 60(4):1-7.

Last Modified: 10/23/2014
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