Overview of research grants awarded from 2001-2007.


Year PI Institution State Title


2007 Cruzan, M (Rosenthal, D) Portland State University OR Population dynamics of a newly invasive species Studies integrating population genetics with demographic data are needed to address a fundamental paradox of biological invasions: if genetic bottlenecks are harmful, then why do so many successful invaders have depauperate gene pools in the invaded range when compared to their native range? Newly invasive species are particularly well suited to understand these phenomena as populations are expected to be highly genetically structured, with some harboring more variation than others. In spite of overall reduced genetic diversity in the invasive range, some populations will harbor more variation than others. Population genetic surveys of a newly invasive perennial grass false brome (Brachypodium sylvaticum) in Oregon confirmed this expectation. More genetically diverse invasive populations are expected to become more vigorous and produce more seeds and would have greater intrinsic population growth and increased propagule pressure contributing more to the invasion. This has not been tested in any invasive species. The PI proposes to initiate demographic surveys of invasive populations ranging in genetic diversity and spanning a range of regions with different invasion histories to identify the characteristics of populations that make them a more imminent threat (i.e., higher genetic diversity, growth rate, and fecundity).  
2007 Wallace, L Mississippi State University MS Understanding how landscape features influence population connectivity in Canada thistle (Cirsium arvense (L.) Scop.) by modeling gene flow across populations The researcher studied the degree of population connectivity and evaluated landscape features that may potentially serve as natural barriers to gene flow and dispersal in Canada thistle (Cirsium arvense). The proposed project would provide a genetic data set of population samples in the western United States based on microsatellite loci to test spatially explicit models of gene flow in Canada thistle and to identify landscape factors that influence connectivity among populations. By examining genetic variation on a local scale and in the context of environmental variables, the project puts a great emphasis on ecological context and provides a basis for inferring physical barriers to gene flow that can subsequently be tested through simulation modeling and field experiments in future studies. 4905
2007 Turner, G West Chester University PA The influence of garlic mustard (Alliaria petiolataon ectomycorrhizal fungi from Carya andQuercusseedlings Garlic mustard (Alliaria petiolata (Bieb.) Cavara & Grande) is an invasive exotic plant listed on noxious weed lists in several western states that is more commonly found in the eastern U.S. It has been shown to rapidly invade forest communities where it can displace native herbs and woody seedlings. Less is known, however, about how the plant may indirectly influence woody plant communities by affecting ectomycorrhizal (ECM) fungal communities. Because many tree species and ECM fungi are symbiotic, effects from exotic plants on ECM fungal abundance and diversity could affect native plant communities through indirect effects on seedling growth and survival. As a result, this proposed study seeks to examine how A. petiolata may influence ECM fungal communities associated with dominant canopy tree seedlings. To assess this, an examination of roots taken from hardwood bait seedlings grown under a range of A. petiolata density and from seedlings exposed to a range of phytochemical concentrations will be made. Specifically, an assessment of the potential effects of A. petiolata on ECM fungal abundance and diversity from mockernut hickory (Juglans nigra) and red oak (Quercus rubra) seedlings will be determined. This proposed study would provide a novel opportunity to address indirect effects of A. petiolata on the recruitment of important native tree species. A CIPM seed grant of $4435 would provide needed funding required to initiate the proposed project, present results of the study to the scientific community, and foster longer-term studies of A. petiolata influences on ECM fungi and forest tree composition in both eastern and western forests. 4435
2007 Krasahara, T Utah State University UT Nitrogen retention in cottonwood and Russian olive-dominated riparian systems Riparian areas serve as interfaces between terrestrial and aquatic systems worldwide and are critical for sustainable management of water resources. Intact riparian ecosystems are functionally connected to terrestrial and aquatic ecosystems, substantially altering hydrology via transpiration and biogeochemical cycling through the trapping of nutrients and sediments. Riparian areas, however, have been altered by flood control and withdrawal, key disturbances that have facilitated invasion by exotic species. In the arid and semi‐arid western US, riparian forests historically dominated by cottonwood (Populus spp.) and willow (Salix spp.) have yielded to the invasive tamarisk (Tamarix chinensis) and Russian olive (Elaeagnus angustifolia). Compared to tamarisk, the effects of Russian olive on riparian ecosystem processes are less well understood, but may be dramatic as Russian olive is a known nitrogen fixer.
The short‐term research objective was to identify candidate field sites and collect preliminary data examining hydrologic connectivity and nutrient retention in riparian ecosystems with native cottonwood trees versus the exotic Russian olive. The specific hypothesis predicted a reduction in riparian ecosystems capacity to filter nitrogen effluent from croplands due to Russian olive being an nitrogen fixer. Investigators suggested that the addition of atmospheric nitrogen into the ecosystem and subsequent deposition of high‐nitrogen foliage on the soil surface will reduce the uptake of nitrogen flowing from adjacent ecosystems into the riparian zone; nitrogen will pass through these invaded systems into the stream.
2007 Lambert, A University of California - Santa Barbara CA Plant-herbivore interaction with native and non-native genotypes of common reed Common reed (Phragmites australis Cav.) is a perennial wetland grass native to North America. Currently, there is insufficient data on the distribution of native genotypes in the United States to effectively control exotic populations without harming native ones. In the most recent invasive plant inventory of California, P. australis remained unscored as native/exotic because of a lack of information on its genetic distribution. Plants form monocultures along the canals and are invading desert oases adjacent to canal systems. Native P. australis populations are more susceptible to attack by the European aphid Hyalopterus pruni, which build significantly larger populations on native genotypes, causing leaf damage, pathogenic fungal growth, and mortality in native plants. In preliminary surveys in the southwest, all of the (potentially) Gulf Coast genotype populations and some native P. australis populations had exotic aphids on them. The Gulf Coast genotype is more resistant to aphid damage, and may be facilitating the spread of these aphids onto native populations throughout the southwest and compounding the adverse effects of the non‐native reed invasion.
Lambert’s primary objectives are to: (1) identify native, exotic, and Gulf Coast P. australis populations throughout the southwest US and use these data to build a GIS database for the management of exotic and Gulf Coast genotypes and conservation of native genotypes; (2) determine the distribution of exotic aphids (H. pruni) on native and Gulf Coast P. australis populations in the Southwest US; (3) quantify population sizes of aphids on and subsequent damage to the native and Gulf Coast genotypes in the southwest US; and (4) evaluate the potential for the invasive Gulf Coast genotype to facilitate the spread of H. pruni into native P. australis populations.
2007 Wang, X Indiana University-Purdue University IN A physiological assessment of the effects of environmental changes on the invasiveness of kudzu, a noxious and highly invasive species Kudzu (Pueraria montana) is a highly invasive plant species distributed mostly in the southeastern U.S., but it was recently found in Washington and Oregon. Kudzu may expand its territory eastward and southward from these two states and become a noxious weed in the northwest because of rising CO2 in the atmosphere and the increased water use efficiency in plants grown at higher CO 2levels.The physiological traits in kudzu grown under future environmental conditions were examined. The interactive effects of drought with CO 2 were concurrently studied in a growth chamber experiment. Results from this research will not only improve our understanding of environmental changes on the ecology of this exotic weedy species, but also contribute to more efficient control in the infested areas and pro-active management in the areas where it is not yet a serious threat. 4950
2007 Harrington, T USDA Forest Service, Pacific NW Research Sta. OR Evaluating competitive ability of native grasses to exclude Scotch broom

Scotch broom (Cytisus scoparius) is a highly competitive, non-native shrub that invades disturbed sites throughout the Pacific Northwest and elsewhere in the US. Competitive exclusion of one plant species by another is a vegetation management strategy that has the potential to limit the spread of Scotch broom. Two studies were conducted to evaluate this possibility. Study I evaluated the competitive abilities of three native grass species (spike bentgrass (Agrostis exarata), blue wild-rye (Elymus glaucus), and western fescue (Festuca occidentalis)) to exclude Scotch broom. A replacement series experiment (Study II) also was conducted to determine if high or low availabilities of soil water or nutrients influenced the competitive abilities of each grass species to exclude Scotch broom. Of the grass species compared in this study, blue wild-rye and spike bentgrass effectively suppressed biomass development of Scotch broom, regardless of broom density. Western fescue also was competitive with Scotch broom, but these effects diminished as density of Scotch broom increased. These results suggest that, when sown into an existing seedbank of Scotch broom, blue wild-rye and spike bentgrass are likely to inhibit development of this aggressive shrub species; however, western fescue will not be as aggressive at inhibiting Scotch broom. Nutrient amendments strongly stimulated biomass development of Scotch broom and grass; however, broom biomass was lowest when it was grown with grass without any nutrient amendments. Because relative competitive effects of the grass increased with nutrient amendments, the potential may exist to combine fertilization and mowing treatments to create an aggressive stand of grass that may effectively eliminate Scotch broom and inhibit further germination of the species.

2007 Hardesty, L Washington State University WA Evaluating the ecological amplitude of naturally occurring cheatgrass suppressive bacteria Cheatgrass (Bromus tectorum) is an invasive annual grass that out‐competes seeded and volunteer plants of more desiable species and currently occupies millions of acres in the western United States. No successful restoration strategy exists for infested sites. The naturally occurring rhizobacterium Pseudomonas flourescens strain D7 has been demonstrated to suppress both germination and growth of cheatgrass in wheat fields near where the organism was found but has not been tested on rangelands where ecological conditions vary considerably and where biotic communities are more complex than on croplands. The project proposal included plans to collect cheatgrass seed and soil from four locations in the interior Northwest and use these to test the effectiveness of the bacterium against locally adapted seed grown in native soil and representing a range of ecological conditions. 4925
2007 Cooper, D Colorado State University CO Does one invasion lead to another? In the southwestern US, riparian areas have been invaded by two exotic woody plant species: tamarisk (Tamarix ramosissima Ledebour, T. chinensis Loureiro, T. pentandra Karst, and their hybrids) and Russian olive (Eleagnus angustifolia L.). Seedlings of riparian plants need water, light, and suitable substrate to establish. Native cottonwood trees (Populus fremontii) and tamarisk need high light levels to establish. In contrast, Russian olive has a low light requirement and can establish in the shade. Russian olive could potentially dominate Southwestern floodplains by establishing in shadier and drier environments than tamarisk and cottonwood. There have been no previous comparisons of seedling requirements of tamarisk, Russian olive, and cottonwood together in controlled experiments. The seedling survival rates of tamarisk and cottonwood have been analyzed to show that under ideal conditions, cottonwood can out‐compete tamarisk. One study has shown that Russian olive seedlings are more successful than cottonwood in shadier environments; however, no studies have compared tamarisk and Russian olive directly or tested the seedling survival of tamarisk, Russian olive, and cottonwood under conditions drier than flooding. The PIs proposed an experiment to analyze the water and light requirements of tamarisk, Russian olive, and native cottonwood seedlings in order to test the following hypotheses:
(1) Russian olive, tamarisk, and cottonwood seedlings have the same survival rate regardless of light or water conditions; and
(2) Russian olive seedlings have higher survival rates in low light and low water conditions than tamarisk and cottonwood.
2007 Pai, A St. Lawrence University NY Examining weediness in Chinese medicinal plants: A comparison of the exotic Asian Coptis chinensis and the native congener Coptistrifolia The herbal supplements and nutraceutical industry in the USA is creating a demand for tradtional Chinese medicinals. Seeds and rhizomes of Chinese medicinal species are available through catalogues and the Internet. Horticulture and sale of exotic plants have been implicated in the large-scale spread of invasive speciest. The fact that many of these medicinal species are richly laden with allelopathic secondary plant compounds (of medicinal value to humans) makes them likely candidates for becoming weeds. The North American native Coptis trifolia (goldthread) and Coptis chinesis (Chinese goldthread; a Chinese medicinal currently undergoing small scale cultivation in the U.S) were compared to investigate whether C. chinensiscould displace C. trifolia. Rhizomes of each were grown in pure and mixed plantings under high and low light, moisture and nutrient conditions for three months. Seeds of C. trifolia and C. chinenesis were germinated using a “move along” experimental design in germination chambers that mimicked night and day temperatures for spring, summer, and fall in North America.
Results indicated that nutrient and moisture availability did not significantly impact the growth of C. trifoliaand C. chinensis. However, when grown in shade, C. chinensis increased biomass significantly more rapidly than C. trifolia.
2006 Bartuszevige, A Eastern Oregon Agriculture Research Center OR Are invasive species in western rangeland associated with stock ponds? This research tested the hypothesis that there is a higher percent cover of exotic species near stock ponds and that the cover of exotic species decreases as the distance from the stock pond increases. 25 ponds were selected from the Zumwalt Prairie Preserve for the research. It was concluded that exotic cover was always greatest at the edge of the stock ponds compared to plots further from the pond and cover at the edges of stock ponds was almost completely exotic, with very few native species at the edge of the stock pond. 5000
2006 Wurtz, T University of Alaska AK White sweetclover in Alaska: Can this invasive affect the floodplain vegetative community? Shading from sweetclover was hypothesized to physiologically stress and kill seedlings of native species that are accustomed to an open-light environment. Results showed that sweetclover patches can shade a substantial proportion of PAR along early successional floodplain surfaces. Furthermore, the amount of shading that occurs under sweetclover can physiologically stress each tested species. Sweetclover represents a barrier to the recruitment of common floodplain species through its ability to obstruct light to establishing seedlings. 4950
2006 Rice, P University of Montana MT

Model weed law provisions for management of new invaders, rapid response, and cost-effective allocation of public resources: Tiering noxious weed lists to invasion stage

As the threat of invasive weeds becomes more urgent and widely recognized, an increasing number of states are writing or updating comprehensive weed management statutes, rules, and regulations. The invasion stage of species is one factor by which states can organize and prioritize weed lists. Organizing by invasion stage emphasizes rapid response to new invaders which has been shown to be more cost-effective than prolonged management of widespread species. Only ten governments currently have noxious weed lists tiered in any degree to invasion stage. The provisions discussed in this report may be adopted to build or modernize a state noxious weed law to more effectively manage new invaders. Creating or changing state weed legislation is likely to require a long-term, multi-year effort. Often social, political, or economic issues must be considered along with biological factors such as a species’ invasion stage. However, the more that science can inform policy, the more likely it is that our nation’s natural and agricultural resources can be protected and maintained.

2006 Cronin, J Louisiana State University LA Landscape-level impact of invasive smooth brome on a native prairie plant, Spartinapectinata, and native invertebrates Research conducted in eastern North Dakota prairies was used to test the hypothesis that the invasive smooth brome would have higher germination rates and abiotic conditions, outcompete, and have higher success and reproduction than the native cordgrass. Results showed that cordgrass had higher rates of germination in cordgrass-dominant areas, and that brome did not outcompete of displace cordgrass, but was more capable of flowering than cordgrass, in all habitat types.  5000
2006 Pavlovic, N USGS Great Lakes Science Center MI Distinguishing an alien invasive vine from the native congener: Morphology, genetics, and hybridization The goal of the research was to use genetic analysis of the American bittersweet and Oriental bittersweet to aid in the identification of fruiting species, and hybridization of the two bittersweets to determine if the ploidy level of the hybrid is different than that of the parent plant. Hybrid creation was successful, as well as identifying the 50 unknown species with an RFLP analysis technique. 5000
2006 Rhode, J Georgia College and State University GA Potential for hybridization between an invasive seagrass species and its native congener The purpose of the research was to examine the impacts of an invasive seagrass species on the region's dominant native seagrass species using collections, morphological measurements, breeding trials, and molecular analyses to assess the potential for hybridization between these two closely-related species. There were distinct phenotypes for all three of the studied species, Z. marina, Z. japonica, and putative hybrids. The nonnative species seemed to have little ability to harm the native one but did reduce species diversity in the area, and hybridization of the two in the nature is unlikely. 4934
2006 Dudley, T University of California - Santa Barbara CA Developing the ecological basis for biological control of cape ivy (Delaireaodoratain southern California Research goals were to provide baseline information on the distribution of Cape ivy in coastal southern California, the ecosystems and native plants that are affected by its infestation, and conduct experiments to quantify these impacts. Several native species appeared to be displaced or strongly inhibited by Cape ivy, whereas those not as greatly affected were often other non-native taxa or other vine-like plants. Ecophysiological studies indicated that Cape ivy (DEOD) has a lower photosynthetic rate when compared to native vines; however, it is more efficient in its use of available water. 2500
2006 Havens, K The Chicago Botanic Garden IL The impact of invasive plants on pollinator assemblages and pollinator services: Effects of cheatgrass (Bromustectorum in the Great Basin We proposed to quantify the effects of cheatgrass invasion on native pollinator communities in the Great Basin through the completion of a survey of pollinator communities and introduction of potted flowering plants of native species to determine visitation rates. Research confirmed that the insect community within a non-disturbed site, with more plant diversity, supported the highest insect community. We found a large difference in visitation in disturbed, cheat-grass dominated site compared to the non-disturbed site, which was associated with a large difference in abundance and diversity. 5000
2006 Mulder, C University of Alaska AK Assessing wildfire burn susceptibility to invasive plant colonization in black spruce forests of interior Alaska We proposed to plant invasives in soils taken from burns of varying severity and age to predict susceptibility to invasion along the road system. Observations were focused toward answering questions in three main categories: dispersal from road, burn severity and moisture, and burn age. In general, cores from burned sites supported much greater germination and growth of exotic plants than do cores from unburned sites, supporting the hypothesis that burned areas are particularly susceptible to invasion. For young burns, the severity of the burn and the moisture level appear to have little effect on the growth of invasives. All three species grew better in soils from burned areas, all three species tended to grow better in soils from the Dalton Highway than from other areas, and all three tended to show reduced growth in high-severity burns in the Delta chronosequence. 5000
2006 Stark, J 
Rew, L
Dougher, T
Montana State University MT The use of a native plant sod buffer to reduce invasion of nonnative species from residential areas into wildland areas High and low-watering regimes for a native plant sod buffer were compared The high water treatment received an average of 2.54 cm of water per week (a typical watering rate for P. pratensis residential lawns) and the low water treatment received no supplemental irrigation, and natural precipitation was recorded. the overall density and spread of C. arvense was greatest in all of the low water treatments; the number of C. arvense propagules, and the maximum distance that they spread, was greatly reduced by a buffer of native sod. The results from the high water treatments in both the sod and bare-ground control plots indicate that supplemental irrigation reduces the overall density and spread of C. arvense. 5000
2006 Knops, J University of Nebraska - Lincoln NE Abandoned agricultural fields: competition between native and exotic plant species for soil resources Two experiments were established to examine the role of plant-microbe-resource interactions in determining the competitive ability of the exotic grass species. The first experiment found no significant differences across species with regard to gross rates of N mineralization and microbial NH4 consumption. There was evidence, however, of significant differences across the species with regards to nitrate dynamics and temporal variation in nitrate dynamics across species. Results of the second experiment supported our prediction that the soil microbial associated with the different species determine the level of N available to the plant as compared to plant uptake. 5000
2006 Rew, L Montana State University MT Predicting occurrence of nonindigenous plant species in the Greater Yellowstone ecosystem: A comparison of two models The results of a GLM model were compared with a more regional-scale ecological niche model (ENM) called Maxent, which utilizes presence-only data, to determine which model would be the most appropriate tool for GYE land managers concerned about invasive NIS. We were specifically looking at how model accuracy for the two approaches was affected by data quality, spatial scale, and the inclusion of climate variables. We sought to determine the extent of agreement between models, identify when and where one model out-performeed the other, and make recommendations on how each tool could be used by land managers in the GYE. In general, we found that data quality did not have a strong effect on model accuracy, although addition of stratified random data often improved the model accuracy. We found that climate variables were important for predicting the occurrence of three of the NIS. 4992
2006 Yeakley, A Portland State University OR Superior adaptation to drought in Rubus armeniacus(Himalayan blackberry) in northwest Oregon

The role of water relations in the invasive success of R. armeniacus was studied. The objectives were to determine if R. armeniacus is better adapted to the Pacific Northwest's water regime than congeneric natives; and to determine if and how the water relations of R. armeniacus help it to outgrow native Pacific Northwest competitors. The results suggest that R. armeniacus can access water that other native congener shrubs cannot. R. armeniacus is capable of both rapid water use when water is widely available, and effective water acquisition when it is in short supply.

2006 Aslan, C University of California - Davis CA Noninvasiveness in woody, ornamental species: The roles of abiotic factors and bird dispersal We have initiated a three-year study of bird dispersal of fleshy-fruited trees that have been introduced to central California without strong invasiveness, although they are problematic invasives in similar climates. Our objective is to assess the relative contributions of bird behavior and summer drought to regional noninvasiveness of our three study species. Throat probes showed that the following species can disperse at least small olives: cedar waxwing, American robin, mourning dove, western scrub-jay, western bluebird, Stellar's jay, Brewer's blackbird, Swainson's thrush, hermit thrush, house sparrow, varied thrush, European starling, northern flicker, and yellow-billed magpie. Further survey data analysis will examine the percentage of reported interactions that are known from the literature vs. unknown, and whether certain plant guilds are more likely to be utilized for so-called "habitat interactions" (nesting, roosting, and other benign uses by birds) than for so-called "dispersal opportunity interactions" (fruit feeding with potential for dispersal of nonnatives). 4524
2006 Radosevich, S
Wells, J
Anzinger, D 
Oregon State University, Corvallis, OR CIPM Database for Invasive Plant Species in the Western United States The objectives of the project were to create a database of biological information on the 109 known invasive plant species
in the Northwest United States, make the database available to land managers, and identify information gaps to further expand and verify the database. Significant data gaps were revealed through the course of this project since the majority of noxious plant species in the Northwest have not received much scientific attention. At this point, the Database for Invasive Plant Species in the Western United States is primarily a data organization and storage system designed for data entry rather than for data retrieval. Before the database can achieve its intended purpose—to make demographic and biological information on noxious plant species available to land managers—a data retrieval page must be constructed.
2005 Endress, B Oregon State University OR Animal-mediated seed dispersal and germination of native and invasive plants in western North America The objective of this study was to provide information on seed characteristics which predispose invasive plants to long-distance seed dispersal by native and introduced ruminants to better inform invasive plant management and restoration activities. Results indicate that cattle disperse nearly 100 times as many exotic seeds across the landscape as native ungulates and are an important vector in spreading invasive seeds. 5000
2005 Rew, L
Lehnhoff, E
Montana State University MT Assessing the effect of the scale of soil disturbance on the colonization potential of yellow toadflax ( Linaria vulgaris) and native vegetation Two experiments tested the hypotheses that yellow toadflax seedling establishment and survival would (1) increase with increasing area of soil disturbance, (2) increase with greater seed density and (3) that yellow toadflax colonization success would vary with site, being more successful in sites with less available water and nutrients and lower native plant dominance. 5000
2005 Gold, W University of Washington WA Changes to native forest soils due to English ivy infestation This study examined a selected subset of the soil environmental characteristics associated with English ivy infestation. Analyses of the soil environment from seven English ivy-infested locations were compared to comparable sites nearby that lacked English ivy. Soil nitrogen, carbon, and organic matter content did not differ between ivy and non-ivy sites in soils sampled during 2005. Overall, soils were significantly more acidic (pH of 5.6 vs. 6.0) and had greater quantities of litter (by 10 - 20 tons / ha) in non-ivy locations. These studies show that the soil chemistry of sites infested with English ivy differs in some ways from that of native forest sites without English ivy. 3641
2005 Brown, R Eastern Washington University WA Effects of hydrologic alteration on Polygonumcuspidatuminvasion in riparian ecosystems The goal was to assess the effect of hydrologic alteration by dams on exotic species invasion in riparian plant communities in watersheds in two regions of the US. Research was focused on Japanese knotweed(Polygonum cuspidatum), a predominant invasive plant in riparian systems throughout large parts of the US, which forms large monocultures threatening native plant diversity. The intermediate objectives was to determine the degree to which patterns of Japanese knotweed invasion correspond to hydrologic alteration across a flooding gradient. Results from a t-test showed that knotweed was found at a higher average vertical distance from the river on the Sauk compared to the Skagit River. There were smaller, more frequent patches of knotweed on the undammed Beaverkill and upper reaches of the east and west branches of the Delaware, whereas there were fewer, larger patches on the west branch and main stem of the Upper Delaware. This suggests that the natural flow regimes may affect the dispersal of knotweed, and its ability to grow to a large size. 5000
2005 Wiernasz, D University of Houston TX Granivore activity on the invasive grass Bromustectorum: A factor in establishment or exclusion? The short-term goal was to test the preference of the harvester ant, Pogonomyrmex occidentalis, for seeds of the introduced cheatgrass, Bromus tectorum, relative to those of other species. Our results suggest that the interaction between harvester ants and cheatgrass is not reciprocal. Harvester ant colonies in areas in/near dense cheatgrass stands have a less diverse food supply, and must search for food through a more complicated environment than colonies in low density areas. As cheatgrass increases in density, the number of potential new colonies may decline as a consequence of habitat avoidance by foundress queens. Cheatgrass thus reduces plant community diversity directly, through the exclusion of other species, and indirectly by reducing the density of ant colonies. 3361
2005 Bolger, D Dartmouth College NH The impact of invasive plants on detrital food webs We hypothesized that coastal sage scrub's shift from shrub to grass domination would produce changes in the soil food web. Specifically we predicted that detritivorous arthropods would respond negatively to increasing non-native grass litter. We expected the microbial community would show an overall positive response to increasing non-native grass litter, driven by bacteria. As expected, many detritivorous arthropods showed a decline in areas of higher grass. However, two proxies for microbial abundance, soil respiration and microbial biomass showed no relationship with grass. Analyses on soil organic matter, moisture and microbial biomass carbon show trends towards some of the predicted results. 4939
2005 Renz, M
Steinmaus, S
New Mexico State University NM Impacts of exotic phreatophyte management on the invasiveness of perennial pepperweed and Russian knapweed

The objectives of the study were to determine the ranges of light levels under canopies of large stands of phreatophytes that are currently managed; survey populations of perennial pepperweed and Russian knapweed under phreatophyte canopies and the light and canopy conditions under which they survive; assess the responses of those species to a variety of light levels; and to evaluate the effects of herbicide treatments on them under various light conditions. The light levels just above the canopies for the two species were probably well above and below those levels under uncontrolled tamarisk canopies, respectively. Therefore, light conditions under uncontrolled tamarisk probably would not be conducive for pepperweed or knapweed establishment. The data that was used to generate light response curves of plants grown under shaded and unshaded conditions indicated that perennial pepperweed had a greater ability to acclimate when grown under full sun conditions with a higher light-saturated photosynthetic capacity than Russian knapweed. However, knapweed maintained 81% of its photosynthetic capacity when grown in shaded conditions compared to the 62% of Pmax maintained by pepperweed. The growth analysis revealed patterns of growth among perennial pepperweed plants grown at different shade levels that are consistent with plants that can acclimate well to shaded conditions. Plants in higher shade areas suffered the most from herbicide treatments.

2005 Reichard, S University of Washington WA Invasion by Buddleja davidii: the impact on riparian forests in King County, WA This exploratory study investigated the potential impacts of invasion by Buddleja on the geomorphology of channel landforms by describing the distribution of Buddleja within the active riparian zone, and comparing the contribution to channel roughness and soil shear strength among species. Differences in the distribution of persistent Buddleja, Populus, and Salix plants are most likely the result of species-specific differences in the ability to tolerate different hydrogeomorphological disturbance regimes once established. It is likely that compared to Populus and Salix, Buddleja appears to be less tolerant of conditions present at low elevations such as frequent and/or high intensity inundation; and that Buddleja plants lack mechanisms for tolerating long periods of inundation, and are susceptible to breakage in areas subject to high shear stress due to weak and brittle wood. 4871
2005 Chambers, J
Goergen, E
USDA Forest Service Rocky Mountain Research Station CO The role of fire and nitrogen on plant invasions into the Northeastern Sierra Nevada The goal of the research was to investigate relationships among fire, nitrogen- fixing species, and invasive species to determine if fire and or the presence of nitrogen-fixing species facilitate invasion by exotic species in the sagebrush steppe. Within the sagebrush steppe, density of lupines was greater on burned sites as compared to unburned sites. Prior work in other systems has found similar positive responses of legumes to fire. Although not directly measured, observations also suggest that there is a difference in the proportion of seedlings to resprouts on the different treatments. Plant cover was influenced by treatment. Cover of all functional groups, with the exception of shrubs, tended to be greater on older burned sites. Our results suggest that both fire and lupine presence are associated with not only greater productivity, but also with greater amounts of available soil N. 4987
2005 Hufbauer, R
Blair, A
Colorado State University CO The role of hybridization in biological invasions: A study with Centaurea maculosaand C.diffusa Our goal was to initiate research to evaluate the ecological consequences of hybridization between the noxious weeds spotted and diffuse knapweed (Centaurea maculosa and C. diffusa) for their invasion and biological control. Immediate research objectives were to conduct a combination of phenotypic surveys of hybrid populations and biological control agents; long-term research objectives include molecular surveys and field and greenhouse experiments. From survey date from 47 populations, and using recent work from collaborators in Europe that suggests spotted knapweed in North America is completely tetraploid, we are fairly certain that the diffuse is diploid. Thus, we believe that introgression is not ongoing, but instead diffuse knapweed was introduced as some type of a hybrid swarm. 4884
2005 Schmitz, D
Jacobs, J
Montana State University MT Multiscale impacts of invasive plants on watershed hydrology and riparian ecology: A synthesis The scope of our project included a survey of watershed hydrology, riparian ecology and invasive plant species in the focus area of central and northern parts of North America; developing a database of all published and unpublished documents regarding these components information; conducting a workshop of researchers, managers and consultants about these topics; and drafting a synthesis with the current state of knowledge regarding the aforementioned subjects. Our review showed that there is substantial scientific basis to expect that invasive plants would impact watershed hydrology and riparian ecology. However, it also shows a great amount of variability in hydrologic and ecologic response to invasives due to the interdependence of environmental factors in any given location. 20000
2005 Sher, A University of Denver and Denver Botanical Gardens CO Predictive models for restoration success in Tamarixand Elaeagnusinfested watersheds The goal of the study was to determine which site characteristics are correlated with restoration success, defined in terms of reductions of undesirable species such as Tamarix and establishment of desirable, native species. Vegetative and environmental data were collected at 28 sites in the southwestern US where active revegetation was completed after Tamarix removal. Results suggest that there are easily measurable site characteristics associated with greater native cover and richness, planting success, and Tamarix control. Close proximity to perennial water, sufficient precipitation, recent flooding, and good drainage as well as coarser soil texture and lower soil pH all favored native species. Overall, those site characteristics associated with native species success were the same as those related to lower Tamarix cover. 19800
2004 Enloe, S
Collier, T
University of Wyoming WY Impacts of integrated pest management strategies for sustainable Canada thistle control The primary objective of this research was to develop integrated management strategies that target Canada thistle directly following maximum stem weevil damage before the plants are able to compensate. The central hypothesis was that herbicide treatment timed directly following maximum biocontrol damage would result in improved control of Canada thistle. Due to the problems associated with the asynchronous emergence of the biocontrol agent and the Canada thistle and the subsequent dispersion of the bioagent across all of the plots, it was impossible to meet our first specific objective, to determine the impacts of integrating the Canada thistle stem mining weevil and clopyralid treatment on Canada thistle shoot dynamics. For Objective 2, to determine the impact of clopyralid application timing on non-target desirable vegetation, our data concludes that clopyralid had neither a positive nor a negative impact on non-target desirable native grasses and forbs within the season of application. For Objective 3, to determine the role of clopyralid application timing on the establishment and survival of the Canada thistle stem mining weevil, our data showed no negative impact on infestation levels or on mining length within infested stems. 5000
2004 Differdorfer, J Duggan, J San Diego State University CA The role of small mammals in post-fire establishment of invasive plant species in coastal sage scrub habitat We investigated the role of small mammals in post-fire establishment of invasive plant species in costal sage scrub by experimentally excluding small mammals from burned habitat spanning a gradient of pre-fire invasion by non-native grasses and forbs. We predicted greater cover of non-native grasses inside exclosures, where small mammal granivory is removed, relative to control areas where small mammals are present on study grids. Abundant rainfall during winter of 2004-2005 produced generally high levels of vegetation cover, but cover and richness were highly variable across all grids. Across grids we did find a significant negative influence of heteromyid activity on the average exotic cover seen on controls and pseudo-exclosures. The influence of heteromyid activity was moderated by pre-fire invasion. In particular, heteromyids showed a greater negative influence on exotic cover on grids with lower levels of pre-fire invasion than grids with high pre-fire invasion. 5000
2004 Reichman, O 
Orrock, J
University of California-Santa Barbara CA Do native consumers and patch shape affect the dominance of invasive plants? The goal of the research was to collect baseline documentation about rodent consumers and how they impact the invasion of California grasslands. We have conducted preliminary trapping of rodent populations in habitats dominated either by native perennial and invasive annual plants. During 4288 trap-nights of effort, we obtained 356 captures of 9 small-mammal species. Experiments revealed that consumers reduce the efficacy of different levels of seeding: when all consumers have access to seeds and seedlings, and that the average density of surviving plants is independent of seeding density. Experimental enclosures have also been built for further, long term research of the impacts of rodents an native and non-native grasses. 5000
2004 Barbier, E 
Knowler, D 
Reichard, S
University of Wyoming; Simon Fraser University, BC; University of Washington WY, BC, WA The ecology and economics of commercialization when plants carry a risk of becoming invasive The research team was able to identify the key tasks required for interdisciplinary research into the problem of the risk of accidental invasive plant species introductions due to the commercial operations of the North American horticultural industry as well as find funding sources to apply with for future grants. The team was successful in being awarded a Program of Research on the Economics of Invasive Species (PREISM) of the Economic Research Service of the US Department of Agriculture grant. 4950
2004 Reichard, S University of Washington WA The temporal effects of Ulex europaeus on the soil ecosystem and how they relate to modeling impact of invasive species This research examined the ability of gorse to alter the soil ecosystem and biochemistry over time, including pH, organic matter content, nutrient mineralization/immobilization and soil and water chemistry. This study lays the groundwork for further research into the alteration and impact of invasives to both above and below ground ecosystems over time. 4703
2004 Brown, C
Rowe, H
Colorado State University CO Cheatgrass control and community restoration in Rocky Mountain National Park We tested the facilitation, tolerance and inhibition models of succession when applied to the restoration of cheatgrass- dominated montane plant communities. The models explain different interactions among early- and late-successional species that ultimately allow late-successional species to dominate, as is our goal for restoration. This field experiment was conducted to evaluate the models through the performance of late-successional species when grown alone, planted simultaneously with early-successional species, and planted one year after early-successional species. Because there were no differences between seeded and unseeded treatments, it appears that ambient seed rain is as effective as the seeding treatments for establishing late-successional species. The cheatgrass control treatment appeared to result in a release from competition and consequent increase in diversity and cover of existing late successional species. Early successional diversity appears to follow the same trend, though early-successional cover did not increase over time. 4972
2004 Ramakrishnan, A Portland State University OR Evolution and migration of invasive species: Molecular marker development The research goal was to sequence about 1000 clones, for a total of about 10 sequences, and screen 100 samples for each locus. About 350 clones from two genomic libraries were sequenced, each was enriched for different microsatellite motifs (i.e., CA vs CAG), and two libraries of the results were created. The first library has about 15% redundancy and the second about 25% redundancy.The central populations have more diversity than the peripheral populations, as expected when migration rates are low to moderate. The peripheral populations differ remarkably from each other, with the eastern-most population being quite different than the western-most population. 4895
2004 Maxwell, B Montana State University MT Yellow toadflax population dynamics in different environments We believe that yellow toadflax (L. vulgaris) may only rarely accomplish new colonization through seed production and dispersal, and patch spread is by vegetative reproduction. We have developed an invasiveness index that we hope will be valuable to land managers who want to know which populations are increasing most rapidly or determine how well management practices are reducing a population. Through this research we intend to discover the conditions required for this species to invade or become a source for new colonization. We have established considerable variability in the invasiveness of L. vulgaris populations under different environmental conditions. We plan to correlate these invasiveness values with our probability of occurrence maps and test the hypothesis that population invasiveness increases along the probability of occurrence gradient. 4989
2004 Goodwin, K Montana State University MT Early detection of spotted knapweed (Centaurea maculosa Lam.) using canine olfaction Scientifically valid studies support the usefulness of canines as an effective detection technology for a variety of targets based on advantages in sampling efficiency, sensitivity, target noise discrimination, and gradient detection. Domestic dogs may be effective in sampling plant communities to detect early invasions of spotted knapweed (Centaurea biebersteinii DC.) based on these advantages and their ability to cover more area over human searches. This study has successfully established proof of concept, demonstrating the ability of a specially trained canine to reliably detect spotted knapweed with high accuracy. The efficacy of the canine to discriminate spotted knapweed (n = 41) in a controlled environment was calculated as 96.5%. The mean accuracy of the canine to detect naturally occurring spotted knapweed (n = 91) in field trials across two testing sets was calculated as 90.1% (SE 3.4%). 20000
2004 Hardin, P Brigham Young University UT Invasive plant detection through low-altitude digital aerial photography This research began with the working hypothesis that imagery acquired from inexpensive RPVs could be used to detect and map patches of squarrose knapweed along invasion corridors such as roads, paths, and riparian areas. The three research objectives were to determine whether digital imagery acquired from inexpensive RPVs contain sufficient information to detect squarrose knapweed, to determine the factors which maximize the chances of detecting and mapping squarrose knapweed from digital RPV imagery, and to compare the effectiveness of an RPV squarrose knapweed survey against a traditional windshield survey. Results showed that a significant proportion of squarrose knapweed patches can be accurately detected on photography acquired from low flying RPVs. Although the system can be used to detect knapweed patches and might be cost effective, we do not consider the digital RPV aircraft used in this research to be a practical solution to detecting invasive weeds in remote areas. The research team is currently designing an improved RPV system hat should ameliorate these problems, but more development and testing will be required to increase the feasibility of its use by range technicians who must fly it on a regular basis. 17661
2003 Renz, M New Mexico State University NM Managing establishing infestations of camelthorn in riparian and floodplain habitats along the Virgin River in Nevada The objectives of this project were to quantify the effectiveness of various herbicide treatments on eradicating camelthorn and document the response of resident plant populations to these treatments along riparian areas of the Virgin River. None of the treatments eliminated camelthorn, but significant reductions in its density occurred in the floodplain/riparian site. Arsenal (Imazapyr) and Veteran 720 (2,4-D & Dicamba) reduced stem density 87 and 82% respectively, while all other treatments (Garlon, Weedar 64, Rodeo) did not differ from the untreated control. Repeated applications of herbicides registered for use in water in the spring and fall to camelthorn had no impact on camelthorn invasion. One year after applications ONLY camelthorn cover differed between spot treatments. 4802
2003 Corn, J Western Agricultural Research Center, Montana State University MT Impacts of Cyphocleonusachates in natural systems For this research, we monitored the impacts of the root weevil, Cyphocleonus achates, on knapweed density and vigor and on plant community characteristics. Releases of C. achates in 2002 were successful in establishing populations on all four sites in 2003, based on larval counts of the species from a sample of knapweed plants. Knapweed density was lower in 2003 than 2002, but not due to weevil presence, because knapweed density declined in control plots as well as in areas exposed to weevils. We hypothesize that flooding and/or drought affected both spotted knapweed and biocontrol agent populations in 2003. Nonetheless C. achates became established on all release sites, and their effects on spotted knapweed should be detectable within a few years. 5000
2003 Larson, L Eastern Oregon University OR Russian knapweed grazing/herbicide trials Russian knapweed and perennial pepperweed are invasive to meadow and riparian habitats in the semiarid intermountain west. Seed germination was tested to determine favored seedbed characteristics. Germination was inhibited in both species when water stress was imposed using polyethylene glycol. Knapweed achieved 60% germination after 40 days in dark and alternating light/dark environments. Pepperweed germination was greatest in light and alternating light/dark environments. Both species showed that germination declines when exposed to salt stress but continued to germinate under some salt stress. 5000
2003 Rice, P University of Montana MT Planning for Utah and Nevada coverage by INVADERS database The minimal goal was to expand the INVADERS Database System to include Utah and Nevada. The second level of effort is to add nine western states and provinces: Utah, Nevada, Colorado, Arizona, New Mexico, British Columbia, Alberta, Yukon Territory, and Alaska. The third level of effort is to include California. The final report is a cost analysis of the intended expansion and an investigation into the probability of success and logistical operations. 5000
2003 Rew, L
Maxwell, B
Montana State University MT Determining non-native indigenous plant propagule pressure with distance from roads In this study we measured available soil moisture and emergence of surrogate weed seeds at set distances from a road. In addition propagule pressure, in terms of seed bank and seed rain, of non-native invasive species (NIS) smooth brome (Bromus inermis) and Canada thistle (Cirsium arvense) was recorded at the same distances from the road. The results showed that the soil was at field capacity at all distances in the spring, after which the levels declined but more rapidly further from the road; thus, the sites adjacent to the road retained soil moisture for a longer period in the spring and after precipitation events. Surrogate weed seeds emergence did not differ with distance in the spring but was higher closer to the road in the fall. More Canada thistle seed were recorded at distances of more than 1 m from the parent plant (28%) than smooth brome, which could be attributed to the wind-dispersed attributes of the seed. These data begin to improve our understanding how propagule pressure is influenced by distance from roads, which will benefit our understanding of non-native species colonization. 5000
2003 Anderson, V Brigham Young University, Provo UT Environmentally induced dormancy in cheatgrass seed and seed-banking dynamics Given that all ripened cheatgrass seed readily germinates under adequate moisture, and that after-ripening occurs universally under natural conditions in the wild, the existence of ecologically meaningful dormancy must refer to something else. At each habitat site, the seed bank was collected at five random locations. Separation of seed from respective litter horizons was conducted in the laboratory. Cheatgrass seed from the canopy layer was hand separated from total vegetation. Seed was then classified according to its age. Seed samples were subjected to germination testing following a sufficient after-ripening period to ensure sufficient germination. The presence of cheatgrass seed was most abundant in the sub-litter layer in both the cheatgrass monoculture site and in the sagebrush understory. The contribution of old seed to the seed bank in these two groups is greater than the annual contribution of new seed. Overall, the cheatgrass monoculture site produced the greatest quantity of new seed, followed by the sagebrush interspace. The induction of a state of secondary dormancy in cheatgrass does not appear to occur as a result of seed position in the litter layer, or lateral placement in shrub understory or interspace, nor was there an affect associated with burn history and slope. Secondary dormancy may yet be a phenomenon at other sites where different environmental factor exist or where diverse genotypes exist. 4950
2003 Cottrell, T Central Washington University, Ellensburg WA Weed colonization of fire-disturbed dry forests in eastern Washington The long-term goal of our work is to determine the roles of fire intensity, weed seed dispersal, seed bank composition, and seed predation, in weed invasion of forest stands. During the summers of 2003 and 2004 we sampled vegetation and seed rain at paired sites in 10 different locations in the Tyee fire complex. Specific objectives were to compare current weed species composition of paired stands in the Douglas-Fir Cool Dry Grass Plant Association Group; draw inferences about weed colonization in relation to fire intensity; determine if overall species richness differs between these paired stands; build seed reference collections for this plant association group; perfect seed rain and seed bank collection methods, and seed identification abilities; and develop hypotheses to explain weed species differences between paired stands. Our preliminary conclusions from plant community composition data are that burn intensity does significantly impact species composition, even nine years after the fire disturbance. Relative to low intensity burn sites, sites that were subject to intense, canopy removing fires not only have greater total plant species richness, but also have a greater proportion of non-native species. 4993
2003 Rew, L
Maxwell, B
Montana State University MT Knowledge synthesis of the effect of wildfire on the occurrence and expansion of non-native, invasive species distribution in natural areas Our objective was to review the scientific literature on the response of nonnative plant species to wildfire, focusing on an objective assessment of responses based on quantitative data. We held the null hypothesis that there would be no response by nonnative species following wildfire, and looked for evidence that would allow one to reject this null hypothesis. Thus, we may have erred on the side of conservatism with regard to integrating nondata-based knowledge that often finds its way into conclusions. However, one can be certain that our assessment was as objective as possible. 59876
2003 DiTomaso, J University of California, Davis CA The role of fire as a management tool to contain invasive plant species or rehabilitate natural resource areas where invasive plants dominate The goals of this project were to evaluate the current state of knowledge on prescribed burning as an invasive weed management tool, to identify knowledge gaps prohibiting its effective use, and to describe potential solutions to these limitations. We first developed a thorough literature review. and then designed a workshop with researchers and practitioners from throughout the western states to discuss topics related to prescribed burning as a tool for invasive plant management. Working with lead individuals for each topic, we brought together the information from both researchers and practitioners on each topic discussed at the workshop and produced a 50-page report. The proceedings have been distributed, and posted on the Cal-IPC website. After professional design, the report will be printed in larger quantities for broader distribution. 37180
2003 Rice, P University of Montana MT Fire as a tool for controlling non-native invasive plants This review focuses on the intentional use of fire, alone or integrated with other methods, to control exotic plants in North America. The literature search was intended to retrieve all published articles and abstracts where fire was used to suppress exotic plants. Precise knowledge of invasive plant morphology, phenology, and life history is required to select a suppressive burn prescription. Life history determines the direct susceptibility of weeds to fire. Optimizing longer-term control would include consideration of a burning regime that promotes desirable plants as well as injuring the target weeds. The potential to utilize prescribed burning for weed control varies by environment and habitat type. Fuel quality and quantity, fire behavior, and competing vegetation will influence the target weed response. 42020
2003 Kimberling, D USDA-ARS, Reno NV Prescribed fire and invasive plants in the western United States: A meta-analysis approach to evaluating successes and failures This work is the third component of a research project funded by the Center for Invasive Plant Management that examines the use of fire as a tool to control invasive plants. Our goal here is to quantitatively examine and compare data available on fire effects on invasive species to determine if there are overall patterns that can be used to develop a decision tool for using prescribed burning to control invasive plants. We asked the following questions: 1) What is the overall effect size of fire on different life forms of invasive plants in the western USA and how much does that effect vary? 2) How do season of burn, number of burns, and plant life form influence effect size and its variation? 3) What are the magnitudes of effect sizes based on geographic location? And, 4) Can we develop a practical and useful decision tool for using prescribed burning to control invasive plants? The complete data set for the meta-analysis contained only 21 studies from which effect sizes could be calculated, with 73 comparisons between control and treatment means. Our meta-analysis indicates that prescribed fire has a generally large negative effect on invasive plants, and that this is a true estimate of the measured effect because the confidence interval does not overlap zero. The most important predictor variable in this meta-analysis was the season of burn. Among the life form groups we evaluated, fire had the greatest effect on woody species. 35318
2002 Allen, E University of California-Riverside CA Restoration of Native Vegetation Invaded by Exotic Grasses in Southern California We used the model species Erodium macrophyllum (Geraniaceae), a rare native annual grassland forb, to test the hypotheses that (1) native and exotic grassland species would have differential competitive effects on a native forb and (2) prescribed spring burns will reduce the cover of exotic grasses and promote native species. We found that weeding increased fecundity regardless of the matrix species treatment, although plants growing in the weeded Bromus plots had the greatest fecundity. According to the periodic stage-structured model we developed for E. macrophyllum, populations of E. macrophyllum had a positive growth rate when growing in the weeded plots and in the non-weeded Bromus plots. Exotic grasses such Avena spp. and Bromus spp. were severely decreased in burned plots; burning decreased grass cover from approximately 43% to 5%. However, burning had an opposite affect on exotic forbs; their cover increased from 15% to 45%. Native grass cover was decreased following burning, but increased from the weeding treatment. Our results indicate that different exotic species have differential effects on the rare native forb E. macrophyllum; also noted are some of the specific impacts of invasive species on its different life-history stages. Similarly, prescribed burns in California grasslands, while they may decrease invasive grasses, will likely increase the abundance of E. brachycarpum. 7558
2002 Read, B US Forest Service, LaGrande OR Multi-scale detection of Potentillarecta using remote sensing technologies and geographic information systems in Northeast Oregon We evaluated the effectiveness of natural color aerial photography as a tool to improve detection, monitoring, and mapping of sulfur cinquefoil (Potentilla recta L.) infestations. Potentilla recta is a non-native invasive perennial that is increasing in interior Pacific Northwest rangelands. Our results indicate that aerial photography can be used to detect P. recta infestations in ponderosa pine and grassland plant communities in the intermountain West. We suggest that aerial photographs may be useful to detect P. recta in open forests and rangelands, particularly in areas such as wilderness where field access is restricted. 8000
2002 McPherson, G University of Arizona AZ Fire-Based Restoration of Biodiversity in Ecosystems Dominated by Nonnative Grasses We assessed the influence of nonnative species on biological diversity in the southwestern United States in grasslands and savannas prone to fire. Our specific objectives were to (1) determine effects of fire season on responses of biotic communities, and (2) quantify relationships between biological guilds before and after burning and through post-fire recovery. A slight negative relationship was evident between biomass of Eragrostis lehmanniana, the dominant nonnative grass, and diversity and richness of native plant species. Richness appears to be influenced to a greater extent by seasonal and interannual variation in precipitation than by fire treatments. In general, species richness and relative abundance of small mammals decreased in the first year following fire. From a community perspective, species richness and density of individual birds and their nests were relatively constant between burned and unburned areas and were consistent across the gradient of nonnative grass. Nest species richness and density of nests (at three spatial scales) were positively associated with increasing nonnative grass dominance. 8000
2002 Geiger, E University of Arizona AZ Razing Arizona: Introduced "Wonder Grass" Plagues the American Southwest: The Potential for Modeling Spread of a Nonnative Species A "wonder grass" introduced to the American Southwest has spread far beyond its expected range to the apparent detriment of native organisms. An assessment of current distribution and abundance related to environmental factors will allow land managers to target key areas for reclamation and preservation. We compiled a spatial database of 1,400 locations monitored for presence/absence of E. lehmanniana. From a subset of these locations, in association with environmental data, we developed a logistic regression model to predict probability of presence of E. lehmanniana. Based on our 90% probability model, we found that E. lehmanniana occurs on over 400,000 hectares, more than double the area covered only 20 years ago. We developed maps of potential future distribution of E. lehmanniana by integrating our logistic regression model with global climate scenarios. These models predicted the distribution of E. lehmanniana within Arizona will decrease substantially by 2030. 7777
2002 Johnson, D California Exotic Pest Plant Council, Berkeley CA Weed Ranking System and Inventory Project Funding was used to creat a ranking system and comprehensive inventory project. The ranking system has been developed in collaboration with representatives from Arizona and Nevada. This aided in their process of developing a weed list similar to CaIEPPC's. The system has been designed to be applicable to any of the three states, and it can easily be adapted for use by other states. 8000
2002 Beatty, S University of Colorado CO Treefall Disturbance and Exotic Plant Invasion in Forested Ecosystems of the U.S.: A Comparative Study Several hypotheses about exotic species colonization, edge-effects, disturbance effects, and potential migration into forested wilderness ecosystems of the U.S were tested. Where the forest ecosystems are richest in native species, there is also a greater abundance of exotic species in treefall gaps in those forests. The gap disturbance provides an opportunity for exotic species to invade the most diverse ecosystems successfully. There was no significant trend for gap or canopy plots, which showed a constant exotic species abundance along the trail segment. For trail plots however, there were always more exotic species present than for gaps or canopy at any point along the trail, but the abundance of exotics along the trail declined after the first kilometer. Finally, the richness of exotic species in the source region (trailhead/parking area) was positively correlated with the total number of exotics found in a wilderness area. 5000
2002 Radosevich, S Oregon State University OR Biology of Potentilla recta

The objectives of this study were to: (1) determine germination responses of P. recta, C. solstitialis and C. maculosa to temperature, light and moisture, and (2) compare the early growth characteristics of P. rectawith C. solstitialis and C. maculosa under controlled temperature, light, and moisture regimes. Results suggest that yellow starthistle has a higher temperature tolerance for seed germination than the other species and that maximum percent germination of yellow starthistle occurs within a broader temperature range than the other two species. All three species germinated when light conditions were constant. Water potential below -6 bars precluded germination of P. recta while germination of C. solstitialis and C. maculosa germinated at that water potential. Maximum root and shoot growth generally occurred near 20 degrees C for all species, but resource allocation to root development was much less for P. recta than the other species. Complete phenology and growth analysis was also completed for the three species.

2002 Knops, J University of Nebraska NE Interaction between photosynthetic plasticity and nutrient levels as a factor driving wetland plant invasions We measured morphological and physiological photosynthetic traits of several invasive (Phalaris arundinacea, Phragmites australis, Lythrum salicaria) and comparable non-invasive (Calamagrostis canadensis, Carex lasiocarpa, Carex stricta, Carex sp., Typha angustifolia, Decodon verticillatus) wetland species. We found no inherent difference between invasive and native species in the maximum photosynthetic rates of the light-adapted leaves. Leaves in the lower canopy of native species, however, are shade-adapted. In contrast, the lowest 50 cm of leaves of the invasive species have similar maximum photosynthetic rates as the top leaves of the canopy, indicating that these lower leaves are not shade-adapted. This indicates that the invasive species should have a higher rate of canopy photosynthesis, because they have more leaf tissue and light-adapted leaves higher in the canopy in higher light environments. 5000
2002 Littlefied, J
Wilson, L
Grosskipf, kGK
Montana State University, University of Idaho, CABI Bioscience
(Switzerland )
MT, ID, Biological Control of Invasive Hawkweeds: Determining Risk to Non-Target Plants Biological control of invasive meadow and orange hawkweed is a relatively new biocontrol program in the United States. The primary objective of the research was to conduct a risk assessment of the possible effects of introducing potential biological control agents into North America. We created a list of plant species that may be at risk to attack by hawkweed biocontrol agents and collected and propagated those plants. Galls or larvae of the wasp Aulacidea subterminalis have been observed only on orange hawkweed, H. floribundum and mouse-ear hawkweed. Galls were not observed on any other test plant. H. floribundum appears to be possible host for the wasp as well as H. pilosella. 4994
2001 Heideman, J
Walker, R
Mesa State College, Grand Junction CO Development/demonstration of a long-term management approach to tamarisk control The funding was used to support a conference titled Strategies for Long-Term Management of Tamarisk.  5000
2001 Maxwell, B MSU-Bozeman MT Methods to inventory weed populations in remote areas. We collaborated with YNP personnel using their previous data to identify, through simulation, a range of sampling techniques that may most efficiently inventory weeds away from trails and roads. We found that 2 km, continuously observed transects, perpendicular to roads, trails or other human disturbance, extending out into the wilderness were the most effective technique for discovering isolated weed patches under a wide range of possible distributions. We found that all of the weed species declined in frequency (best quantified as a diffusion gradient) with distance from roads and trails. In addition, vegetation dominated by Idaho fescue and big sagebrush had a significantly higher frequency of weed species. 4940
2001 Maxwell, B MSU-Bozeman MT Identifying the factors that determine the invasion of a weed into native plant communities. We mapped three existing metapopulations (patches) of yellow toadflax at two different sites, measured weed and native plant frequency and abundance, and quantified the intensity and extent of natural disturbance in and adjacent to the invaded areas. We quantified the spatial and temporal dynamics of these invaded communities by repeating the measurements each year in the exact same place in a permanently established grid. After one year of observations, we found that the patch edges were very distinct at site one, but not at the other site, indicating that spread of the patches at site one may be restricted to vegetative reproduction which would coincide with the heavy infestation of seed feeding weevils found at site one. 4929
2001 Rillig, M
Lutgen, E
U Montana, Missoula MT Effects of spotted knapweed (Centaurea maculosa) and leafy spurge (Euphorbia esula) invasion on key soil functions This study examined seasonal dynamics of several soil parameters with a specific interest in the seasonality of external hyphae and glomalin, a glycoprotein produced by AMF fungi (which is correlated with soil aggregate stability). We measured glomalin concentrations and external AMF and non-AMF hyphal length as well as soil moisture, percent fungal colonization (AMF and non-AMF), and root length in soil in an intermountain grassland in western Montana over one growing season. Of the glomalin pools and hyphal lengths measured, significant seasonal changes occurred for total glomalin, immunoreactive easily extractable glomalin, and AM hyphal length. The seasonality of glomalin values observed in this study highlights the importance of implementing a sampling regime that will capture this seasonal variation. 4730
2001 Alaback, P
Pauchard, A
U Montana, Missoula MT Linaria vulgaris Mill. invading the West Yellowstone area: A multi-scale ecological assessment We propose that a multi-scale research approach is needed to capture both patterns and potential mechanisms of the invasion process in protected areas. To illustrate the utility and viability of a multi-scale approach in protected areas invasions, we assessed and monitored L. vulgaris in the West Yellowstone area at multiple scares. Our results show that the species occurs over a broad range of sites at the landscape level, apparently coming from two historical sources. Landscape results show heavily-infested areas that can act as sources of propagules for non-infested areas. At the stand scale, data suggests that once a new patch is established it grows both by clonal advance and by creating new satellite patches. At the micro-scale of clonal patch,L. vulgaris may displace natural vegetation by maintaining vigor even in large and old clonal patches. Three-year observations and analysis show that the reproductive effort of L. vulgaris appears correlated to annual climactic variable. This practical application and example shows that a multi-scale method can provide advantages over single scale approaches to better understand patterns of invasion and prioritize management activities. 5000
2001 Zabinski, C
Stringer, L
MSU-Bozeman MT Revegetation strategies to minimize weed re-colonization following herbicide application The overall goal of this research was to test revegetation methods that may reduce recolonization of invasive species after herbicide application. Our results showed that spot spray herbicide application reduced C. maculosa cover without significantly reducing existing native forbs. However, a repeat-herbicide application increased exotic graminoid cover. Tillage reduced the density of C. maculosaseedlings, but resulted in an increase in C. maculosa percent cover and an overall decline in native forbs. Revegetation methods had limited success at increasing native species, and reducing C. maculosa. We also measured the composition and density of the seed bank in C. maculosa dominated sites using the seedling emergence method. C. maculosa density was 3,900 and 6,714 seeds / m2 at the two sites, which was 2 and 3 times higher than the sum of all other species. 8000
2001 Lane, E Western Weed Coordinating Committee (WWCC) CO Developing a regional approach to noxious weed management The goal of the project was to refine two maps developed in 2001 by western state weed coordinators that depicted the relative abundance and distribution of leafy spurge (Euphorbia esula) and yellow starthistle (Centaurea solstitialis) by county. The WWCC proposed to refine each map by further defining the distribution of each species, particularly in newly invaded areas where incipient infestations are isolated and distinct. WWCC developed two maps depicting the distribution and abundance of leafy spurge and yellow starthistle by surveying county weed supervisors and state weed coordinators in 15 western states. We determined the number of acres infested per quarterquad (one fourth of a USGS topographic quadrangle) for approximately 90% of the West, representing about 90% of the western counties. 7800
2001 Morrison, P Pacific Biodiversity Institute, Winthrop WA Alien plant demographics in the Chewuch watershed.

This study was undertaken to determine the demographic and habitat characteristics of invasive plants in the Chewuch Watershed of North-central Washington. Research regarded the distribution of six target species in 634 roadspots on the watershed. Factors studied include species. range limits, habitat preferences, disturbance response, and population trends over time, whether advancing or retreating. Detailed maps and graphs depict illustrate the habitat and change in cover of various invasive plants. Overall, Centaurea diffusa decreased its coverage in the 3-m plots by about 50% in two years, from 4.8% to 1.2%. Centaurea maculosa also decreased by about half, although it was initially present at lower coverage.

2001 Holt, JS UC-Riverside CA Ecological approaches for prevention and management of artichoke thistle (Cynara cardunculus) invasion by seed

Specific objective were to: 1) construct a phenological model to predict the timing of seed emergence and seedling development and validate the model over one growing season in coastal grasslands; 2) Conduct experiments on seedling mortality following burning, mulching, mechanical control, and chemical control in order to develop effective management techniques; and 3) Combine ecological data from Objectives I and 2 to initiate practical experiments to prevent and manage artichoke thistle seedlings, which will continue to be monitored. Reliable models were obtained for seedling emergence, two leaves, and three leaves; further analysis is underway to model bolting and flowering. A degree-day model with a 6C low temperature threshold and 22C upper vertical cutoff predicted emergence within 5 days of actual emergence, regardless of the calendar date of emergence. With regard to objective 2 regardless of planting depth, both thatch treatments resulted in extension of artichoke thistle shoot apices above the soil line, while buried seeds with no thatch covering had shoot apices below soil. These results suggest that disturbing or burning thatch could provide seedling control by promoting germination to exhaust the seed bank and elevating the shoot apex, leaving it exposed and vulnerable to removal.

2001 Radosevich, S OSU-Corvallis OR Restoration of native plant communities inhabited by Himalayan blackberry Biomass accumulation and control of Himalayan blackberry on previously invaded sites were studied. The specific hypothesis was that if existing Himalayan blackberry populations are subjected to stresses of plant competition and common treatments, spread of the blackberry patches may slow. In Year 1, three types of vetch (Vicia sativa, V. americana, and V. villosa) comprised the first flush of vegetation and grew to >5 ft tall in places; limited blackberry growth was also detected under the vetch. In Year 2, vetch began to grow, but did not reach Year 1 height. Other plant species germinated from the seedbank and were more prominent than in the first year. Patches of teasel (Dipsacus sp.), Shasta daisy (Chrysanthemum sp.), and a strong sward of grasses that had been planted the previous year covered most of the area. Himalayan blackberry covered less than 25% of the plots. When comparing only primary treatments without considering the effects of "shade levels," significant differences wer never found. Plots receiving no treatment produced the most biomass, followed by herbicide "plowed" or "plowed and raked,"  respectively. Data suggest that primary stress (site disturbance) plus shade interact to reduce the rate of production of Himalayan blackberry and indicate that such approaches should be tried on larger areas.