Understanding the distribution and abundance of habitat and resources is an important issue in wildlife conservation and will advance understanding of wildlife habitat relationships (Morrison 2001). Jones et al. (2005) developed a vital habitat layer, describing the distribution of silver sagebrush (Artemisia cana Pursh) in southeastern Alberta, Canada, and identifying relationships between sagebrush characteristics and physiographic parameters. This paper adds greatly to our understanding of poorly-studied silver sagebrush communities and as Jones et al. (2005) point out, this is an important first step in developing management plans for sage-grouse (Centrocercus spp.) recovery. This product has recently been used to understand sage-grouse habitat relationships, linking habitat to the viability of the endangered Alberta greater sage-grouse (Centrocercus urophasianus) population (Aldridge 2005). 

Western juniper (Juniperus occidentalis spp. occidentalis Hook.) woodlands are rapidly replacing lower elevation (< 2 100 m) quaking aspen (Populus tremuloides Michx.) stands throughout the northern Great Basin. Aspen restoration is important because these communities provide critical habitat for many wildlife species and contain a high diversity of understory shrubs and herbaceous species. We studied two juniper removal treatments to restore aspen woodlands. Treatments included cutting one-third of the juniper trees followed by early fall burning (FALL) or early spring burning (SPRING). Selective cutting of juniper was performed to increase cured surface (0-2 m) fuel levels to carry fire through the woodlands. We tested treatment effectiveness at removing juniper from seedlings to mature trees, measured aspen sucker recruitment, and evaluated the response to treatment of shrub and herbaceous cover and diversity. In the FALL treatment, burning eliminated all remaining juniper trees and seedlings, stimulated a 6-fold increase in aspen suckering (10 000 ha-1), but initially resulted in a significant reduction in herbaceous cover. Spring burning removed 80% of the mature juniper trees that remained after cutting. However, 50% of juniper juveniles survived the SPRING treatment, which will permit juniper to redominate these stands in less than 80 years. Aspen suckering in the SPRING increased only 2.5-fold to 5 300 stems ha-1 by the third year after fire. In the SPRING, herbaceous cover increased 330% and the number of species observed doubled by the third year after fire. If the management objective is to eliminate western juniper with minimal cutting and stimulate greater aspen suckering, we recommend that woodlands be burned in the fall. If the objective is to maintain shrub and herbaceous cover and moderately increase aspen suckering, spring burning is recommended. With spring burning it appears follow-up management will be necessary to remove juniper that are missed in initial treatments. 

Prairie dogs (Cynomys spp.) have been labeled keystone species because of the role they play as disturbance creators and ecosystem engineers in the western grasslands of North America. Most studies have concentrated on the black-tailed species (C. ludovicianus); however, other species of prairie dogs may have different effects on their ecosystems. We measured plant cover and biomass, canopy height, and plant nitrogen concentration on and off 6 Gunnison’s prairie dog (C. gunnisoni) towns and 6 paired areas off prairie dog towns in southern Colorado. Multivariate analysis of variance and analysis of variance showed no significant differences (P > 0.05) in vegetation cover or biomass on and off of Gunnison’s prairie dog towns, contrary to what has been found for black-tailed prairie dog towns. No significant differences were found in canopy height (P > 0.05); however, this may be due to already short vegetation (5-7 cm). Only 1 of 4 focal plants showed a significant difference in nitrogen concentration. No significant differences were found in species diversity on and off prairie dog towns; however, because of drought, these results are inconclusive. This study found few vegetation differences on and off Gunnison’s prairie dog towns. Furthermore, those differences were more subtle than those reported on black-tailed prairie dog towns. While the mechanisms for differences in vegetation on and off Gunnison’s prairie dog towns may be similar to those on black-tailed prairie dog towns, the magnitude of these differences may be different. 

Data describing long-term sediment yield rates on semiarid rangeland watersheds are relatively rare. To augment existing data and gain a better understanding of the controlling variables, sediment yields from 8 subwatersheds within the US Department of Agriculture-Agricultural Research Service Walnut Gulch Experimental Watershed in southeastern Arizona were computed from stock pond sediment accumulation measurements, water level records, and estimates of sediment transported in pond overflows. Sediment accumulation records ranging from 30 to 47 years were evaluated for subwatersheds ranging in size from 35.2 to 159.5 ha. Sediment yield ranged from 0.5 to 3.0 m3 ha-1 y-1, with a mean of 1.4 m3 ha-1 y-1 and a standard deviation of 1.0 m3 ha-1 y-1. As expected, runoff volume was a significant factor (P = 0.005) in explaining the variability in sediment yield, but regression analysis demonstrated other variables are important. For example, the ratio of watershed area to main channel length significantly described (P = 0.06) sediment yield, suggesting that more detailed measurements are needed to characterize channel networks to relate internal watershed sediment transport and deposition processes to sediment delivery at the outlets. To generalize sediment yield rates across rangeland regions, additional research is necessary to determine the relative influence of rainfall and runoff patterns, and watershed physiographic and geomorphic characteristics on sediment transport. 

With the development and commercial availability of submeter spatial resolution satellite imagery, geospatial tools can better accommodate the needs of range professionals than ever before. However, with these new tools comes a new set of challenges. Range managers and range scientists must now 1) better understand and take advantage of the geotechnical tools at their disposal, 2) collect field observations/measurements in ways that act synergistically with these tools, and 3) utilize high-accuracy global positioning system (GPS) receivers. To produce reliable rangeland models it is important to collect field data that correspond with what the satellite ‘‘sees.’’ Further, it is frequently necessary to use high-resolution imagery, which subsequently necessitates the use of high-accuracy GPS receivers to ensure field data are recorded in the correct pixel and properly coregistered. This paper describes the results of research and experimentation that have led to the development of techniques to improve geospatial rangeland applications. For optimal classification accuracy, field data collected for use in remote sensing applications should estimate/measure ground cover using general vegetation community types and must never exceed 100%. Further, the field sample sites used for classification must be located using a GPS receiver with accuracy 50% of the size of satellite imagery pixels (e.g., if Landsat imagery is used—with 28.5-m pixels—the GPS receiver must be able to achieve +/- 14 m accuracy with 95% confidence). Finally, a series of best practices are suggested to help range managers and range scientists better understand and implement geospatial technologies. 

The degree of rangeland degradation in the United States is unknown due to the failure of traditional field-based monitoring to capture the range of variability of ecological indicators and disturbances, including climatic effects and land use practices, at regional to national spatial scales, and temporal scales of decades. Here, a protocol is presented for retrospective monitoring and assessment of rangeland degradation using historical time series of remote sensing data and catastrophe theory as an ecological framework to account for both gradual and rapid changes of state. This protocol 1) justifies the use of time-series satellite imagery in terms of the spatial and temporal scale of data collection; 2) briefly explains how to acquire, process, and transform the data into ecological indicators; 3) discusses the use of time-series analysis as the appropriate procedure for detecting significant change; and 4) explains what reference conditions are appropriate. Landsat data have been collected and archived since 1972, and include complete coverage of US rangelands. Characteristics of land degradation can be retrospectively measured for a nearly 33-year trend using surrogate remote sensing-based indicators that correlate with changes in life-form composition (time series of thematic maps), declines in vegetation productivity (vegetation indices), accelerated soil erosion (soil indices), declines in soil quality (piospheric analysis), and changes in landscape configuration (time series of thematic maps). Aspects of 2 retrospective studies are presented as examples of application of the protocol to considerations of the land use impacts from military training and testing and ranching activities on rangelands. 

Prescribed fire was used in two semiarid grasslands to reduce shrub cover, promote grass production, and reduce erosional loss that represents a potential non-point-source of sediment to degrade water quality. This study measured transported soil sediment, dynamics in soil surface microtopography, cover of the woody shrub, grass, and bare ground cover classes, and soil fertility measured by nitrogen-mineralization potentials for the respective cover classes over a 9-year period during which 2 fires occurred. In general, the effects of two drought periods were equal to or greater than the effects of fire on the measured parameters. Following the second fire at the grama grass-dominated site, the number of live junipers was significantly lowered (P < 0.001). Fire consumed grass and shrub cover, which created the potential for greater transport of sediment and loss in soil surface elevation. Soil fertility under shrubs was significantly higher than soil fertility under grasses in both grassland sites before and after the first fire; however, that highly significant pattern was not present after the second fire for about 2 years at both sites. This suggests that the reestablishment of a natural fire frequency would likely dampen the well-documented pattern of greater soil fertility under shrub islands relative to grass islands. Repeat use of prescribed fire may keep shrub cover in check and promote fundamental changes in soil processes within semiarid grasslands, but its value must be weighed against the increased potential for erosion following fire.