2007 Annual Report 1a.Objectives (from AD-416) 1: Investigate ecological mechanisms important for the development of bio-rational strategies for suppression of exotic and invasive weeds on western watersheds. Sub-objective 1.A. Conduct foreign exploration for natural enemies of saltcedar and cruciferous weeds, and evaluate candidate species for risk to non-target organisms. Sub-objective 1.B. Conduct organismal, population, and community-level ecological studies of weed natural enemies and their interactions with the environment. Sub-objective 1.C. Develop remote-sensing technologies useful in evaluating and characterizing weed biological control strategies. 2: Define ecosystem responses to integrated weed management and identify and test appropriate restoration technologies. Sub-objective 2.A. Determine the interactive effects of Diorhabda elongata herbivory and saltcedar defoliation on the ecohydrology of riparian ecosystems. Sub-objective 2.B. Monitor native plant and animal taxa as potential indicators of impacts of saltcedar control at successive trophic levels. Sub-objective 2.C. Investigate restoration and rehabilitation strategies following integrative control of invasive weeds in riparian ecosystems. 1b.Approach (from AD-416) New biological control agents of saltcedar will be identified, characterized, and evaluated for both efficacy and safety in conjunction with on-going projects on saltcedar biological control and management. This work will be accomplished with other projects within the Research Unit and with cooperators at other ARS locations. Additional linkages with overseas cooperators in areas native to saltcedar will also be developed to aid in the assessment of potential biological control agents prior to regulatory approval. New risk analysis techniques will be developed and applied to assess both pre- and post-release impacts of approved biological control agents on target and non-target organisms. Detailed studies will be conducted to assess natural enemy impact on the target plant along with similar impacts caused by other methods of integrated vegetation management strategies. Studies will be conducted in both agricultural and natural areas for vegetation characterization and change. New methods of revegetation of affected habitats will be conducted using ecological methods guiding plant succession toward desired beneficial species. Species complexes are expected to be different depending upon the specific habitats of concern, environmental conditions at affected sites, and the goals of the local land managers. Research procedures will strive to produce effective and economically viable methods of revegetation that are practical for both public and private land management agencies. 4.Accomplishments Conduct foreign exploration for new natural enemies. Riparian weeds are some of the most deleterious invaders of rangelands; they degrade wildlife habitat, use excessive amounts of groundwater, and increase fire hazards. Foreign exploration was conducted in eastern Europe and central Asia to collect and study potential biological control agents for riparian weeds of the western U.S., including saltcedar (Tamarix spp.), perennial pepperweed (Lepidium latifolium), and Russian olive (Elaeagnus angustifolia). ARS scientists in Albany, CA in collaboration with colleagues from Asia (Central Asian Biological Control Lab.) and Europe (Biotechnology and Biological Control Agency and CABI Biosciences), conducted field exploration for natural enemies of these weeds and field studies of their biology was conducted in Kazakhstan, Turkey, and China; for perennial pepperweed, faunistic surveys, geographic range assessment, and pest status surveys were begun in the U.S. as well. Several potential natural enemies of this target species were collected; specimens from these collection trips are now awaiting taxonomic determination and subsequent biological studies. Future releases of biological control agents of saltcedar, perennial pepperweed, and Russian olive will be incorporated into the expanded remote sensing efforts (see related accomplishment below) and be conducted in cooperation with state and federal collaborators to optimize suppression of these weeds. This research supports ARS National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds. Setup lab testing protocols for predation studies and select field sites. Exotic and invasive weeds are the most damaging pests in the Western Rangelands. ARS scientists in Albany, CA selected field sites, established laboratory methods, and initiated studies to investigate the impact of natural enemies on biological control agents of exotic and invasive weeds which are the most damaging pests in western rangelands. Field sites in Nevada, California, and Utah were selected for future field studies of natural enemy-biocontrol agent interactions, and laboratory investigations were conducted in collaboration with colleagues (USDA-ARS Pest Management and Biological Control Research Unit) to develop immunological labeling methods for weed biocontrol agents; subsequent studies evaluated important parameters, such as retention time of label, method of labeling insects, and effect of insect stage on label retention. This work will: identify the important natural enemies in the initial stages of biological control releases, permit an empirical understanding of predators on established agents, and may enhance future success rates by suggesting specific measures for reducing impacts of natural enemies on biological control insects. This research supports ARS National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds. Remote sensing of saltcedar leaf beetle impact. Aerial and satellite imagery was collected over test areas in three states to quantify biological control success against saltcedar. Saltcedar (Tamarix spp.) is one of the worst invasive shrubs in all of the western U.S., as it produces extensive monocultures in highly valued riparian areas, uses extensive amounts of water and increases fire danger. Scientists from the ARS Exotic and Invasive Weed Research Unit worksites in Albany, CA and Reno, NV, worked to assess the distribution and impact of Diorhabda elongata using aerial-based hyperspectral imagery and compared those data with satellite-based data collections made in California, Nevada, and Utah. This work documented the continued defoliation and spread of the saltcedar leaf beetle, D. elongata, across wide areas adjacent to the test sites. This work documents the practicality of assessment biological control impact over wide areas using more cost effective remote sensing compared to personnel intensive ground-based sampling. This research supports ARS National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds. Impact of saltcedar leaf beetle on plant growth and transpiration. Saltcedar is one of the most noxious weeds in the intermountain Western United States and strategies are needed for their control. ARS scientists in Albany, CA selected the field sites and instrumented for plant ecohydrology-herbivory studies with saltcedar (Tamarix spp.), and the saltcedar leaf beetle, an important biological control agent. A site was selected along the Truckee River in a dense Tamarix stand with little previous beetle impact, an eddy covariance tower was installed to measure carbon dioxide and water flux from the land surface, and three groundwater monitoring wells were installed to measure changes in water levels. At the Humboldt Sink, three sites were selected along a chronosequence of beetle infestation, four groundwater monitoring wells were installed along the chronosequence and micrometeorlogical station, and trees were sampled to determine plant water stress and plant water source use. Plants at these sites will be surveyed to determine changes in leaf area and canopy cover through time, effect of beetle defoliation on the ability of Tamarix to use groundwater, and plant water source use will be determined with stable isotopic methodology. This work will help to elucidate the mechanisms that lead to plant mortality, and will document ecosystem impacts of biological control of Tamarix. This research supports ARS National Program 304, Component:Weed Science, Problem Statement:Biological Control of Weeds. 5.Significant Activities that Support Special Target Populations None 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 6 Review Publications Snyder, K.A., Williams, D.G. 2007. Root allocation and water uptake patterns in riparian tree saplings: Responses to irrigation and defoliation. Forest Ecology and Management. 246:222-231.