Leafy spurge is an exotic, noxious, perennial weed which is widely established in the north central United States and is an especially serious problem in the northern Great Plains. In 1997, the Agricultural Research Service and Animal and Plant Health Inspection Service, US Department of Agriculture, initiated a major Integrated Pest Management (IPM) research and demonstration project, The Ecological Area-wide Management (TEAM) Leafy Spurge (TLS), to develop and demonstrate ecologically based IPM strategies that can produce effective, affordable leafy spurge control. A key component of the TLS project was expanding the use of biological control agents. To assess the level of insect utilization and implementation and the level of current and perceived future control of leafy spurge as a result of biological control agents, a mail survey of 468 individuals that obtained biological control agents (insects) at TLS-sponsored events and of all the county weed boards in North Dakota, South Dakota, Montana, and Wyoming was conducted. Forty-six percent of the landowner/land managers and 70% of the county weed boards responded to the questionnaire. Respondents reported basic information about the number and characteristics of release sites, and characteristics of the leafy spurge stands, as well as the level of control to date and perceived level of eventual control.

Black (Aphthona lacertosa and Aphthona czwalinae) and brown (Aphthona nigriscutis) flea beetles are among the more successful biological control agents used in the control and management of leafy spurge on a relatively large scale in the Northern Great Plains. The objectives of this study were to document leafy spurge population dynamics in response to control by black and brown flea beetles, determine the role of selected site characteristics on establishment and persistence of the beetles, and evaluate the general response of the resident vegetation to control of leafy spurge. In late June 1998, about 3 000 insects of each species were released into permanently marked plots in northwestern South Dakota and southeastern Montana. Beetle abundance, density and foliar cover of leafy spurge, and foliar cover of the resident vegetation were evaluated each year from 1998 through 2004. Black beetles increased rapidly and peaked at 65% of their measurable potential abundance within 2 years (P < 0.05) following release and dominated all release plots throughout the study. Although population growth characteristics of black flea beetles were highly variable, the successful patterns in reducing the dominance of leafy spurge were fairly consistent. By 2004, foliar cover of leafy spurge on both release and nonrelease plots was significantly reduced compared to prerelease values. Foliar cover of grass and grasslike plants increased concomitantly with the reduction in leafy spurge dominance while cover of forbs on release and nonrelease plots remained consistently below noninfested values.

Leafy spurge has invaded the habitat of the western prairie fringed orchid, a federally listed threatened species. Imazapic ([±]-2-[4,5-dihydro-4-methyl-4-{1-methylethyl}-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid) and quinclorac (3,7-dichloroquinoline-8-carboxylic acid) are relatively new herbicides that control leafy spurge and can be used in the mesic areas where the orchid is found. Research was initiated to evaluate the effects of imazapic and quinclorac on the survival and fecundity of the western prairie fringed orchid. Herbicides were applied at the commonly used and maximum labeled rates in mid-September. This timing is optimum for leafy spurge control with quinclorac and imazapic and the orchid generally has senesced by mid-September, making injury less likely. Quinclorac applied at 840 and 1 120 g·ha⁻¹ did not affect regrowth or fecundity of the western prairie fringed orchid 1 or 2 years after treatment. Orchids treated with quinclorac at 840 or 1 120 g·ha⁻¹ generally were as tall, had racemes as long as, and produced as many flowers and seed capsules as untreated orchids. In contrast, orchids treated with imazapic at 140 or 210 g·ha⁻¹ tended to regrow as vegetative plants and were shorter, had shorter racemes, and produced fewer flowers and seed capsules than untreated orchids. Orchids treated with imazapic averaged 21 cm in height and produced an average of 1 flower per plant 10 months after treatment, whereas untreated orchids and orchids treated with quinclorac were approximately 36 cm in height and produced 5 flowers per plant. Quinclorac could be a valuable tool to control leafy spurge in the habitat of the orchid because orchids treated with quinclorac regrew as vigorously and were as fecund as untreated orchids. However, the current quinclorac label prohibits grazing or haying for 309 days after application.

Flea beetles (Aphthona spp.) are biological control agents introduced from Eurasia to reduce the cover and density of leafy spurge (Euphorbia esula L.). The potential for the introduced beetles to use alternate hosts for feeding and development in North America is slight; however, it is possible. Species at highest risk are native species closely related, ecologically and taxonomically, to leafy spurge. A native spurge, Euphorbia brachycera Engelm. is consubgeneric and sympatric with leafy spurge throughout the northern Great Plains of the United States, and was not included in prerelease host-specificity testing for Aphthona nigriscutis or Aphthona lacertosa. The objective of this study was to evaluate the actual and potential ecological overlap among leafy spurge, flea beetles, and E. brachycera. Wide-ranging and intensive field surveys indicate that E. brachycera is found well within the range of leafy spurge and flea beetles. E. brachycera occurs infrequently, in low densities, in areas with a high percentage of bare ground, and with a root system dissimilar to leafy spurge. Flea beetles released directly into populations of E. brachycera failed to persist beyond a single field season and plants showed no evidence of feeding by beetles. Our results suggest that the potential for flea beetles to host-shift is low due to differences in growth habit and root morphology between E. brachycera and leafy spurge.

Leafy spurge is an invasive Eurasian weed on pastures and rangeland in North America where it reduces grass forage production. Our objective was to determine the effects of multispecies grazing combined with Aphthona flea beetles on leafy spurge-infested rangeland. On two western North Dakota sites divided into four 25- to 79-ha pastures, two grazing duration treatments were applied: season-long with 7 to 10 cow calf pairs and 20 to 25 sheep from late May through mid-September, and rotation with 18 to 21 cow calf pairs and 45 to 50 sheep for 3 weeks twice per year. Grazing treatments started in 1998 and continued through 2002. Aphthona spp. were released beginning in 1991 and were widespread in both pastures by 1998. Four grazing exclosures were randomly located in each pasture in the spring of 1998. Cover of leafy spurge, grass, and forbs, as well as density of vegetative and flowering leafy spurge stems were measured in July 1998 through 2002. Aphthona densities were counted July 1999 through 2002. Grazing initially increased leafy spurge vegetative stem density, but grazing decreased vegetative stem density from 104 in 1999 to 20 stems · m⁻² in 2002. Season-long grazing reduced vegetative stem density by over 30 stems · m⁻² compared to rotation grazing. Leafy spurge flowering stems decreased from 80 stems · m⁻² in 1998 to 4 stems · m⁻² in 2002 in all treatments. The decrease was more rapid when grazing was combined with Aphthona. Initially, Aphthona densities were greater in the grazed areas than the exclosures, but by 2002 more Aphthona were found in the exclosures than the grazed areas. Grazing reduced grass cover and increased forb cover. Results suggest combining multispecies grazing and Aphthona when restoring spurge-infested grasslands produces a synergistic effect.

Leafy spurge (Euphorbia esula L.) is an exotic, noxious, perennial weed which is widely established in the north central United States and is an especially serious problem in the northern Great Plains. In 1997, the Agricultural Research Service and Animal and Plant Health Inspection Service, U.S. Department of Agriculture, initiated a major Integrated Pest Management (IPM) research and demonstration project to develop and demonstrate ecologically based IPM strategies that can produce effective, affordable leafy spurge control. In 1998 and 1999, a survey of ranchers, local decision makers, and public land managers was conducted to evaluate managerial, institutional, and social factors that might affect the rate and extent of implementation of various control strategies. In 2001, a second survey of the same ranchers, local decision makers, and public land managers was conducted to 1) assess any changes in land managers' perceptions of weed problems, control alternatives, and related issues and 2) evaluate the impact of The Ecological Area-wide Management (TEAM) Leafy Spurge (TLS) project on the respondents' weed control practices. Findings from the first survey identified a number of constraints limiting land managers' ability to utilize available control techniques to manage leafy spurge infestations. The TLS project used a variety of tools and communication strategies, such as presentations at local meetings, demonstration plots, and field days, to communicate and demonstrate weed control strategies and address the impediments to leafy spurge control identified in the first survey. Findings from the second survey indicated TLS efforts had effectively addressed many of the constraints to leafy spurge control previously reported by landowners and land managers.

The distribution and abundance of flowering leafy spurge (Euphorbia esula L.) can be determined with hyperspectral remote sensing, but the availability of hyperspectral sensors is limited. Hence, the Landsat 7 Enhanced Thematic Mapper Plus (ETM ) and System Pour d'Observation de la Terre (SPOT) 4 imagery were acquired to test the ability of these sensors to detect leafy spurge. The green:red band ratio was the vegetation index with the highest correlations to flowering leafy spurge cover, but the correlations were weak and not useful for predictions. With Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data, the green:red band ratio was also weakly correlated to flowering leafy spurge cover, although the output from a hyperspectral unmixing algorithm was highly correlated with cover using the same data, indicating simple indices have limited power for detecting leafy spurge. Canopy reflectance modeling using the Scattering by Arbitrarily Inclined Leaves (SAIL) model suggests the weak correlations were caused by variations in leaf area index. It is important to develop spectral libraries in order to use canopy reflectance simulation models that can reduce the time and effort of remote sensing analysis for detecting leafy spurge and other invasive weeds.

Euphorbia esula L. (leafy spurge) is an invasive weed that is a major problem in much of the Upper Great Plains region, including parts of Montana, South Dakota, North Dakota, Nebraska, and Wyoming. Infestations in North Dakota alone have had a serious economic impact, estimated at $87 million annually in 1991, to the state's wildlife, tourism, and agricultural economy. Leafy spurge degrades prairie and badland ecosystems by displacing native grasses and forbs. It is a major threat to protected ecosystems in many national parks, national wild lands, and state recreational areas in the region. This study explores the use of Landsat 7 Enhanced Thematic Mapper Plus (Landsat) imagery and derived products as a management tool for mapping leafy spurge in Theodore Roosevelt National Park, in southwestern North Dakota. An unsupervised clustering approach was used to map leafy spurge classes and resulted in overall classification accuracies of approximately 63%. The uses of Landsat imagery did not provide the accuracy required for detailed mapping of small patches of the weed. However, it demonstrated the potential for mapping broad-scale (regional) leafy spurge occurrence. This paper offers recommendations on the suitability of Landsat imagery as a tool for use by resource managers to map and monitor leafy spurge populations over large areas.

Leafy spurge (Euphorbia esula L.) is an invasive exotic plant that can completely displace native plant communities. Automated techniques for monitoring the location and extent of leafy spurge, especially if available on a seasonal basis, could add greatly to the effectiveness of control measures. As part of a larger study including multiple sensors, this study examines the utility of mapping the location and extent of leafy spurge in Theodore Roosevelt National Park using Earth Observing-1 satellite Advanced Land Imager (ALI) scanner data. An unsupervised classification methodology was used producing accuracies in the range of 59% to 66%. Existing field studies, with their associated limitations, were used for identifying class membership and accuracy assessment. This sensor could be useful for broad landscape scale mapping of leafy spurge, from which control measures could be based.

In late summer, in a semi-arid mountain range in Nepal, we compared 3 field methods for determining the botanical composition of herbivore diets. Data were collected from the same animals belonging to 1 herd of domestic yak (Bos grunniens) and 2 herds of mixed smallstock, consisting of domestic goats (Capra hircus) and sheep (Ovis aries). Bite count, feeding site examination, and microhistological analysis of feces gave different estimates of forage categories and plant species in both animal groups. Because yaks grazed in other vegetation communities when not observed for bite-counts and feeding signs, the results from the latter methods could not be compared directly with that from fecal analysis. In smallstock, feeding site examination gave higher estimates of graminoids and lower estimates of shrubs than the other 2 methods, probably because all feeding signs on shrubs were not detected. Bite-counts and fecal analysis gave comparable results, except that forbs were underestimated by fecal analysis, presumably due to their more complete digestion. Owing to the difficulty in collecting samples that are representative of the entire grazing period and the problem of recording feeding signs correctly, both feeding site examination and bite-counts are unsuitable methods for studying the food habits of free ranging domestic and wild herbivores. Microhistological analysis of feces appears to be the most appropriate method, but correction factors are needed to adjust for differential digestion. The systematic use of photomicrographs improves the speed and accuracy of the fecal analysis.

Biological soil crusts are a diverse soil surface community, prevalent in semiarid regions, which function as ecosystem engineers and perform numerous important ecosystem services. Loss of crusts has been implicated as a factor leading to accelerated soil erosion and other forms of land degradation. To support assessment and monitoring efforts aimed at ensuring the sustainability of rangeland ecosystems, managers require spatially explicit information concerning potential cover and composition of biological soil crusts. We sampled low disturbance sites in Grand Staircase–Escalante National Monument (Utah, USA) to determine the feasibility of modeling the potential cover and composition of biological soil crusts in a large area. We used classification and regression trees to model cover of four crust types (light cyanobacterial, dark cyanobacterial, moss, lichen) and 1 cyanobacterial biomass proxy (chlorophyll a), based upon a parsimonious set of GIS (Geographic Information Systems) data layers (soil types, precipitation, and elevation). Soil type was consistently the best predictor, although elevation and precipitation were both invoked in the various models. Predicted and observed values for the dark cyanobacterial, moss, and lichen models corresponded moderately well (R² = 0.49, 0.64, 0.55, respectively). Cover of late successional crust elements (moss  lichen   dark cyanobacterial) was also successfully modeled (R² = 0.64). We were less successful with models of light cyanobacterial cover (R² = 0.22) and chlorophyll a (R² = 0.09). We believe that our difficulty modeling chlorophyll a concentration is related to a severe drought and subsequent cyanobacterial mortality during the course of the study. These models provide the necessary reference conditions to facilitate the comparison between the actual cover and composition of biological soil crusts at a given site and their potential cover and composition condition so that sites in poor condition can be identified and management actions can be taken.

We surveyed a group of rangeland managers in the Southwest about vegetation monitoring needs on grassland. Based on their responses, the objective of the RANGES (Rangeland Analysis Utilizing Geospatial Information Science) project was defined to be the accurate conversion of remotely sensed data (satellite imagery) to quantitative estimates of total (green and senescent) standing cover and biomass on grasslands and semidesert grasslands. Although remote sensing has been used to estimate green vegetation cover, in arid grasslands herbaceous vegetation is senescent much of the year and is not detected by current remote sensing techniques. We developed a ground truth protocol compatible with both range management requirements and Landsat's 30 m resolution imagery. The resulting ground-truth data were then used to develop image processing algorithms that quantified total herbaceous vegetation cover, height, and biomass. Cover was calculated based on a newly developed Soil Adjusted Total Vegetation Index (SATVI), and height and biomass were estimated based on reflectance in the near infrared (NIR) band. Comparison of the remotely sensed estimates with independent ground measurements produced r² values of 0.80, 0.85, and 0.77 and Nash Sutcliffe values of 0.78, 0.70, and 0.77 for the cover, plant height, and biomass, respectively. The approach for estimating plant height and biomass did not work for sites where forbs comprised more than 30% of total vegetative cover. The ground reconnaissance protocol and image processing techniques together offer land managers accurate and timely methods for monitoring extensive grasslands. The time-consuming requirement to collect concurrent data in the field for each image implies a need to share the high fixed costs of processing an image across multiple users to reduce the costs for individual rangeland managers.

Although remote sensing has many potential applications for range management, its use by range managers thus far has been limited. To investigate the factors that encourage use of remote sensing and to examine its influence on decision making by individuals who manage privately owned rangeland, we evaluated the decision-making processes of 3 ranch owners and 1 professional ranch manager who were introduced to remote sensing while collaborating with us in a rangeland stewardship program in California. Two of the participants had extensive ranching experience (11 to > 20 years) and managed large cattle ranches (1 000 to > 2 000 ha), and 2 had less experience and managed smaller sheep ranches (< 200 ha). During the 5-year program, the participants implemented a series of new management practices, including prescribed burning, rotational grazing, and seeding of native grasses, with the aim of reducing noxious weeds and increasing productivity. We used remote sensing to quantify the effect of these practices and provided ranch-wide remote sensing analyses to each manager on a password-protected Web site. Using case study methodologies, we found that managers of larger, commercially active ranches found the experimental use of remote sensing to be a highly positive experience that convinced them that this technology could help address difficult management situations and increase ranch profitability. This suggests that the broad use of remote sensing by managers of privately held, commercial rangelands may be limited in part by the simple lack of opportunity to test these technologies. Programs that assist ranchers in obtaining appropriate remote sensing products thus may be a cost-effective way to enhance conservation on private rangelands. Our findings suggest that voluntary self-analysis by ranchers of the landscape dynamics of their own properties is likely to lead to more engaged conservation efforts than will top-down prescriptions.

Migration of sand dunes damages range improvements in the Texas Coastal Sand Plain. We determined effects of mulching with native prairie hay and an open weave geotextile fabric, seeding, fertilization, and transplanting on plant species canopy cover on inland sand dunes. We compared applying native hay vs. a synthetic geotextile material to inhibit wind erosion, seeding ‘Alamo’ switchgrass (Panicum virgatum L.), ‘Mason’ sandhill lovegrass (Eragrostis trichodes [Nutt.] Wood), and partridge pea (Chamaecrista fasciculata [Michx.] Greene) vs. no seeding, and fertilization with 468 kg·ha⁻¹ of 45:45:90 (N:P:K) vs. no fertilization. The same treatments were compared in a second experiment except that switchgrass, sandhill lovegrass, vetiver (Vetiveria zizanoides [L.] Nash ex Small), and giant reed (Arundo donax L.) were transplanted rather than seeded. Treatments were applied during March and April 1994 and canopy cover of vegetation in each experimental unit was estimated in October 1994, 1995, and 2004. Livestock were excluded from the study sites. The geotextile fabric degraded within 4 months and was replaced with coastal Bermuda (Cynodon dactylon [L.] Pers.) hay. Fertilization plus native hay mulch resulted in greater (P < 0.05) canopy cover of purple sandgrass (Triplasis purpurea [Walt.] Chapm.), sandbur (Cenchrus incertus M. A. Curtis and C. echinatus L.), and snakecotton (Froelichia spp.) than other treatments in 1994. In 1994 and 1995, canopy cover of switchgrass and sandhill lovegrass was greater (P < 0.05) with a combination of geotextile fabric and commercial hay, seeding, and fertilization than in other treatments. Vegetation composition and canopy cover were similar (P > 0.05) across treatments in 2004 in both experiments. Fertilization, seeding, and transplanting appear unnecessary to establish vegetation on dunes protected from livestock grazing when mulch is applied to inhibit sand movement.

A rapid and reproducible method to determine botanical composition of forage is an ecological and economic goal for range animal ecologists. Multidimensional fluorometry previously demonstrated the possibility of a unique optical approach for accurately determining species composition of clipped and digested plant materials. Fluorometry may be used to detect toxic plants in standing crop as well as diets by using electronic transitions in chemical structures at wavelengths between 370 and 580 nm. Grass hay (genus Pleuraphis) and 6 clipped forbs (4 species of Astragalus and 2 species of Oxytropis) were examined. The resulting spectral signatures were evaluated for differences in the blue and green regions of the visible spectrum using Principal Component Analysis (PCA). This represents the first published data using chemometrics to differentiate among fluorophores from these plant extracts. It was possible to distinguish between the grass and forbs and among forbs. Further research will be required to evaluate these same plant species in mixed diets and fecal samples.