• Grazing-Exclusion Effects on Aboveground Biomass and Water-Use Efficiency of Alpine Grasslands on the Northern Tibetan Plateau

      Wu, Jianshuang; Zhang, Xianzhou; Shen, Zhenxi; Shi, Peili; Xu, Xingliang; Li, Xiaojia (Society for Range Management, 2013-07-01)
      The influences of grazing exclusion on plant species composition and intrinsic water use efficiency (Wi) of alpine grasslands on the Northern Tibet Plateau are not well understood. We conducted a multisite transect field survey across the three main alpine ecosystems (meadow, steppe, and desert steppe) with nine pairs of grazing excluded and adjacent open grazed pastures. Short-term grazing exclusion (started in 2006) did not result in significant changes in nutrients or bulk density of the surface soils (0 - 15 cm), but it slightly changed the aboveground biomass (AGB) and coverage at both community and species levels. Community foliar δ13C and Wi differed among alpine grassland types, with values for steppe being similar to those for meadow and with desert steppe values being higher than both of these. Foliar δ13C and inferred Wi differed among the dominant species and varied negatively with precipitation and positively with temperature in 2010. These results confirm that there is an environmentally selective effect on the replacement of dominant species.There was no evident difference in foliar δ13C or Wi between grazing-excluded and open grazed sites, but there was a slight increase of AGB and coverage in grazing excluded sites compared to open grazed ones at the species and community levels. These results indicated that grazing exclusion may have no clear influence on the physiological processes related to foliar water usage at the species level, but may have a cumulative effect on the carbon-water balance at the community level. Slight changes in linear regressions of foliar δ13C and Wi plotted across climatic gradients indicated that grasslands under grazing management might be more sensitive to regional climatic changes.
    • Optimal Placement of Off-Stream Water Sources for Ephemeral Stream Recovery

      Rigge, Matthew; Smart, Alexander; Wylie, Bruce (Society for Range Management, 2013-07-01)
      Uneven and/or inefficient livestock distribution is often a product of an inadequate number and distribution of watering points. Placement of off-stream water practices (OSWP) in pastures is a key consideration in rangeland management plans and is critical to achieving riparian recovery by improving grazing evenness, while improving livestock performance. Effective OSWP placement also minimizes the impacts of livestock use radiating from OSWP, known as the ‘‘piosphere.’’ The objective of this study was to provide land managers with recommendations for the optimum placement of OSWP. Specifically, we aimed to provide minimum offset distances of OSWP to streams and assess the effective range of OSWP using Normalized Difference Vegetation Index (NDVI) values, an indicator of live standing crop. NDVI values were determined from a time-series of Satellite Pour l’Observation de la Terre (SPOT) 20-m images of western South Dakota mixed-grass prairie. The NDVI values in ephemeral stream channels (in-channel) and uplands were extracted from pre- and post-OSWP images taken in 1989 and 2010, respectively. NDVI values were normalized to a reference imagine and subsequently by ecological site to produce nNDVI. Our results demonstrate a significant (P<0.05) increase in the nNDVI values of in-channel vegetation within 1 250 m of OSWP following their implementation. The area of piospheres (n=9) increased with pasture size (R2=0.49, P=0.05) and increased with average distance to OSWP in a pasture (R2=0.43, P=0.07). Piospheric reduction in nNDVI was observed within 200 m of OSWP, occasionally overlapping in-channel areas. The findings of this study suggest placement of OSWP 200 to 1 250 m from streams to achieve optimal results. These results can be used to increase grazing efficiency by effectively placing OSWP and insure that piospheres do not overlap ecologically important in-channel areas.
    • Marmot Disturbance Drives Trait Variations Among Five Dominant Grasses in a Mongolian Grassland

      Sasaki, Takehiro; Kakinuma, Kaoru; Yoshihara, Yu (Society for Range Management, 2013-07-01)
      We examined how disturbances by Siberian marmots (Marmota sibirica) and associated spatial heterogeneity of foraging patterns and soil properties affect trait variations in five dominant perennial grasses (including sedges) in a Mongolian grassland. Using four continuous traits (leaf height, leaf area, leaf mass per area, and root length) of each grass species, we compared species and plot mean trait values and species’ niche breadth (calculated on the basis of species’ traits) between sites with and without marmots. At sites with marmots, investment in leaves was not favored, probably because of the prevalence of foraging, with the result that plot mean values of leaf height and area were smaller than at control sites. Niche breadth values for leaf area and leaf mass per area were greater at marmot sites, probably due to the spatially heterogeneous patterns of foraging. We observed greater values of species and plot mean root length values at marmot sites. We suggest that the modification of soil physicochemical properties by marmot burrowing, defecation, and urination might enhance root growth for ensuring physical stability of plant bodies and increasing the rate of nutrient acquisition. Niche breadth value for root length was greater at marmot sites, probably due to the spatial heterogeneity of soil properties. Quantification of trait distributions among plant species may help to explain the different plant adaptive mechanisms in relation to external drivers, such as disturbance.
    • Winter Resource Selection by Mule Deer on the Wyoming-Colorado Border Prior to Wind Energy Development

      Webb, Stephen L.; Dzialak, Matthew R.; Kosciuch, Karl L.; Winstead, Jeffrey B. (Society for Range Management, 2013-07-01)
      Areas identified as winter range are important seasonal habitats for mule deer (Odocoileus hemionus) because they can moderate overwinter mortality by providing thermal cover and forage. Therefore, identifying seasonally important resources is a conservation priority, especially when sensitive areas are proposed for development. We used data collected from global positioning system (GPS) collars fitted on female mule deer (n=19; one location every 3 h) to identify resources important during winter (23 February 2011-30 April 2011; 1 November 2011-15 January 2012) in a region spanning southern Wyoming and northern Colorado that has been proposed for wind energy development. The study period included portions of two consecutive winters but were pooled for analysis. We used methods to account for GPS biases, fractal analyses to determine perceived spatial scale, and discrete choice models and conditional logistic regression to assess resource selection prior to development (i.e., baseline data). Resource selection by female mule deer revealed similar patterns between active (0600-1800 hours) and nonactive (2100-0300 hours) periods. Deer selected most strongly for proximity to rock outcrops and shrubland and average values of slope. Deer tended to avoid roads and grasslands; all other landscape features had minimal influence on resource selection (hazard ratios near, or overlapping, 1). Using the fixed-effects coefficient estimates, we developed two spatially explicit maps that depicted probability of mule deer occurrence across the landscape. Based on an independent validation sample, each map (active and nonactive) validated well with a greater percentage of locations occurring in the two highest probability of use bins. These maps offer guidance to managing mule deer populations, conserving important seasonal habitats, and mitigating development (e.g., wind energy) in areas identified as important to mule deer.
    • Grazing and Songbird Nest Survival in Southwestern Saskatchewan

      Lusk, Jennifer Suzanne; Koper, Nicola (Society for Range Management, 2013-07-01)
      Grassland songbird populations are declining, and one reason for this might be livestock management practices in native prairies. Although cattle grazing is a common practice in native mixed-grass prairie, little research has been conducted to date to determine its impact on prairie songbird nest survival. During the summers of 2006-2007, we examined the effects of low- to moderate-intensity cattle grazing typical of the region and nest site vegetation structure on nest survival of five species of ground-nesting songbirds in native mixed-grass prairie in southwestern Saskatchewan, Canada. There was no significant effect of grazing (P>0.10) on Sprague’s pipit (Anthus spragueii), Baird’s sparrow (Ammodramus bairdii), vesper sparrow (Pooecetes gramineus), lark bunting (Calamospiza melanocorys), or chestnut-collared longspur (Calcarius ornatus) nest survival. All five species used denser vegetation than was generally available (P <0.001). Sprague’s pipit nest survival was negatively correlated with vegetation density (P=0.055) and litter depth (P=0.033), and vesper sparrow nest survival was positively correlated with increased visibility from above (P=0.056), but nest survival of the other species was independent of vegetation structure. Our results suggest that low- to moderate intensity grazing is consistent with the conservation needs of ground-nesting songbirds in mixed-grass prairies of southwestern Saskatchewan.
    • Seasonal Variation in Habitat Selection by Free-Ranging Feral Horses Within Alberta’s Forest Reserve

      Girard, Tisa L.; Bork, Edward W.; Nielsen, Scott E.; Alexander, Mike J. (Society for Range Management, 2013-07-01)
      Little is known about habitat selection by free-ranging feral horses in Montane environments, including how horse use may vary seasonally throughout the year. We tracked four global positioning system collared horses in four separate harems between November 2008 and October 2010 for a portion of the Rocky Mountain Forest Reserve in southwest Alberta, Canada. We assessed seasonal habitat selection for the study period by combining locational data with landscape data (including vegetation types) in an information theoretic framework. Home ranges for horses varied from 12.4 to 90 km2 and were confined to local watersheds. Horses selected most for lowland grasslands across all seasons, with shrublands increasingly selected in spring and summer. Harvested conifer forests were only selected by horses during winter. Resource selection functions indicated that in addition to vegetation type, horses were selecting for a variety of habitat characteristics (i.e., distance to forest and solar radiation), while water availability, topographic accessibility, and disturbance features (e.g., distance to roads, recreational trails, and seismic lines associated with energy exploration) had little or no influence on horse selection. Overall, horses demonstrated selection for habitats covering 14% of the study area while avoiding 42% of habitats: remaining areas were used in proportion to their availability. Concentration of horse use within sparse vegetation types (grassland and shrubland), particularly during one or more times of the year, help identify critical horse habitat including areas where multiple, overlapping land uses interact on public land.
    • Reduced Sheep Grazing and Biodiversity: A Novel Approach to Selecting and Measuring Biodiversity Indicators

      Pollock, M. L.; Holland, J. P.; Morgan-Davies, C.; Morgan-Davies, J.; Waterhouse, A. (Society for Range Management, 2013-07-01)
      Traditional upland livestock grazing is declining worldwide, leading to concerns about possible impacts on biodiversity. Although monitoring of protected areas often focuses on rare species, management changes also affect currently common species and vegetation structure. ‘‘Biodiversity’’ is a concept rather than a simple variable, and monitoring it requires indicators that are widely applicable and appropriate to context. This paper presents a novel knowledge-driven approach to developing a selection of biodiversity indicators that can then be rapidly and objectively measured within rangeland environments. Stakeholder and professional opinion on likely changes in biodiversity following reductions in sheep grazing was elicited using a workshop-based process. Potential variables suitable for use as biodiversity indicators were developed and professional opinion on their usefulness sought. A number of indicators were then tested in a natural experiment field study on the impact of reduced sheep grazing in Scotland. In the field study, red deer abundance appeared to increase where sheep grazing was reduced. It was therefore necessary to use estimates of both sheep and deer abundance as explanatory variables. In agreement with the professionals’ predictions, dwarf shrub abundance and vegetation height were greater where sheep grazing had been reduced, after taking into account differences in deer. In contrast to the professionals’ predictions, the field results showed rough grasses and dead material were less abundant where sheep had been reduced, with deer also having an impact on dead material. The professionals were unsure of the effects of reduced sheep grazing on vegetation mosaic structure; the field results suggested that reduced sheep grazing leads to a reduction in structural heterogeneity, but that deer had the greater impact in this case. Several other predictions showed nonsignificant differences in relation to reduced sheep grazing. The participatory method and some of the field methods presented are cost effective and widely applicable.
    • Using Range Condition Assessment to Optimize Wildlife Stocking in Tindress Wildlife Sanctuary, Nakuru District, Kenya

      Muya, Shadrack M.; Kamweya, Able M.; Muigai, Anne W. T.; Kariuki, Apollo; Ngene, Shadrack M. (Society for Range Management, 2013-07-01)
      Over 70% of Kenya’s wildlife resources occur outside protected areas, in areas where land use practices do not necessarily conform to wildlife conservation standards. Ensuring that land use practices in these areas accommodate wildlife conservation is vital in effectively conserving wildlife in this country. Tindress Farm in Rift Valley offers a good example of a place where economic activities and wildlife conservation can work harmoniously. The farm has set up a 320-ha wildlife sanctuary in the hilly parts of the property to provide a haven for wildlife displaced by human settlements in the surrounding environs. The Tindress Farm management needed to know the diversity and optimum number of wildlife species that the sanctuary could accommodate. This study set out to 1) outline a set of models for objectively calculating wildlife stocking levels and 2) demonstrate the practical use of these models in estimating optimum stocking levels for a specific wildlife sanctuary. After comparing models using forage inventory methods models and utilization-based methods (UM), we opted to use UM models because of their focus on ecological energetics. This study established that the range condition in Tindress Wildlife Sanctuary varied from poor to good (29-69%) and recommended a total stocking density of 158.9 grazer units and 201.4 browser units shared out by the various herbivore species. These estimates remain a best-case scenario. The effects of rainfall, range condition, and condition of the animals should be monitored continuously to allow for adjustments through active adaptive management.
    • Soil Morphologic Properties and Cattle Stocking Rate Affect Dynamic Soil Properties

      Schmalz, Heidi J.; Taylor, Robert V.; Johnson, Tracey N.; Kennedy, Patricia L.; DeBano, Sandra J.; Newingham, Beth A.; McDaniel, Paul A. (Society for Range Management, 2013-07-01)
      Soil properties that influence the capacity for infiltration and moisture retention are important determinants of rangeland productivity. Monitoring effects of grazing on dynamic soil properties can assist managers with stocking rate decisions, particularly if monitoring takes into account environmental variability associated with inherent soil morphological properties. On a Pacific Northwest Bunchgrass Prairie in northeast Oregon, we applied three cattle stocking rates (0.52, 1.04, and 1.56 animal unit months . ha^-1) and an ungrazed control in a randomized complete block design for two 42-d grazing seasons and measured the change in four dynamic soil properties: soil penetration resistance, soil aggregate stability, bare ground, and herbaceous litter cover. To address apparent environmental heterogeneity within experimental units, we also utilized a categorical soil factor (termed Edaphic Habitat Types or EHT), determined by characterizing soil depth, texture, and rock fragment content at sample sites. Stocking rate did not affect extent of bare ground or soil aggregate stability. Stocking rate had a significant effect on penetration resistance, which was greatest at the high stocking rate (1.6 J . cm^-1 +/- 0.1 SE) and lowest in the control (1.1 J . cm^-1 +/- 0.1 SE). For litter cover, the effects of stocking rate and EHT interacted. In two rocky EHTs, litter cover was highest in the controls (60% +/- 6 SE; 50% +/- 3 SE) and ranged from 27% +/- 3 SE to 33% +/- 6 SE in the stocking ratetreatments. Measures of penetration resistance, aggregate stability, and bare ground were different across EHTs regardless of stocking rate, but did not interact with stocking rate. Our study demonstrates that response of dynamic soil properties to stocking rates should be considered as a useful and accessible approach for monitoring effects of livestock management decisions on rangeland conditions.
    • Restoring the Sagebrush Component in Crested Wheatgrass-Dominated Communities

      Davies, Kirk W.; Boyd, Chad S.; Nafus, Aleta M. (Society for Range Management, 2013-07-01)
      Monotypic stands of crested wheatgrass (Agropyron cristatum [L] Gaertm. and Agropyron desertorum [Fisch.] Schult.), an introduced grass, occupy vast expanses of the sagebrush steppe. Efforts to improve habitat for sagebrush-associated wildlife by establishing a diverse community of native vegetation in crested wheatgrass stands have largely failed. Instead of concentrating on a diversity of species, we evaluated the potential to restore the foundation species, Wyoming big sagebrush (Artemisia tridentata spp. wyomingensis [Beetle A. Young] S. L. Welsh), to these communities. We investigated the establishment of Wyoming big sagebrush into six crested wheatgrass stands (sites) by broadcast seeding and planting seedling sagebrush across varying levels of crested wheatgrass control with glyphosate. Planted sagebrush seedlings survived at high rates (~70% planted sagebrush survival 3 yr postplanting), even without crested wheatgrass control. However, most attempts to establish sagebrush by broadcast seeding failed. Only at high levels of crested wheatgrass control did a few sagebrush plants establish from broadcasted seed. Sagebrush density and cover were greater with planting seedlings than broadcast seeding. Sagebrush cover, height, and canopy area were greater at higher levels of crested wheatgrass control. High levels of crested wheatgrass control also created an opportunity for exotic annuals to increase. Crested wheatgrass rapidly recovered after glyphosate control treatments, which suggests multiple treatments may be needed to effectively control crested wheatgrass. Our results suggest that planting sagebrush seedlings can structurally diversify monotypic crested wheatgrass stands to provide habitat for sagebrushassociated wildlife. Though this is not the full diversity of native functional groups representative of the sagebrush steppe, it is a substantial improvement over other efforts that have largely failed to alter these plant communities. We also hypothesize that planting sagebrush seedlings in patches or strips may provide a relatively inexpensive method to facilitate sagebrush recovery across vast landscapes where sagebrush has been lost.
    • Managing High-Elevation Sagebrush Steppe: Do Conifer Encroachment and Prescribed Fire Affect Habitat for Pygmy Rabbits?

      Woods, Bonnie A.; Rachlow, Janet L.; Bunting, Stephen C.; Johnson, Timothy R.; Bocking, Kelly (Society for Range Management, 2013-07-01)
      Both fire and conifer encroachment can markedly alter big sagebrush communities and thus habitat quality and quantity for wildlife. We investigated how conifer encroachment and spring prescribed burning affected forage and cover resources for a sagebrush specialist, the pygmy rabbit. We studied these dynamics at spring prescribed burns in southwestern Montana and eastern Idaho during the summer of 2011. Within each spring prescribed burn, we established plots that described the habitat conditions for pygmy rabbits (forage plant biomass and habitat components that influence predation risk) in areas that were burned, adjacent areas of conifer encroachment, and areas that were neither burned nor encroached. We analyzed the data for significant differences in habitat conditions between the paired reference and encroachment plots and modeled when the burned areas would approximate the conditions on the paired reference plots. Biomass of forage plants and habitat components that reduce predation risk differed between undisturbed reference plots and areas that were either burned or encroached with >30% conifer canopy. Our models estimated that 13-27 yr were required for a spring prescribed burn to provide levels of cover and forage resources similar to sagebrush steppe reference plots. We documented that vegetation composition was associated with the plot designations (burn, reference, or conifer encroachment), but not with other abiotic factors, such as soil texture, aspect, or study site; this suggested that the documented differences in habitat were related to the treatments, rather than being site-specific characteristics. The information from this study can contribute to habitat management plans for high-elevation mountain big sagebrush sites where conifer encroachment is altering habitat for sagebrush-dependent wildlife species.
    • Temperature and Precipitation Affect Steer Weight Gains Differentially by Stocking Rate in Northern Mixed-Grass Prairie

      Reeves, Justin L.; Derner, Justin D.; Sanderson, Matt A.; Petersen, Mark K.; Vermeire, Lance T.; Hendrickson, John R.; Kronberg, Scott L. (Society for Range Management, 2013-07-01)
      Cattle weight gain responses to seasonal weather variability are difficult to predict for rangelands because few long-term (>20 yr) studies have been conducted. However, an increased understanding of temperature and precipitation influences on cattle weight gains is needed to optimize stocking rates and reduce enterprise risk associated with climatic variability. Yearling steer weight gain data collected at the USDA-ARS High Plains Grasslands Research Station at light, moderate, and heavy stocking rates for 30 years (1982-2011) were used to examine the effects of spring (April-June) and summer (July-September) temperature and precipitation, as well as prior-growing-season (prior April-September) and fall/winter (October-March) precipitation, on beef production (kg ha-1). At heavier stocking rates, steer production was more sensitive to seasonal weather variations. A novel finding was that temperature (relatively cool springs and warm summers) played a large predictive role on beef production. At heavier stocking rates, beef production was highest during years with cool, wet springs and warm, wet summers, corresponding to optimum growth conditions for this mixed C3-C4 plant community. The novelty and utility of these findings may increase the efficacy of stocking rate decision support tools. The parsimonious model structure presented here includes three-month seasonal clusters that are forecasted and freely available from the US National Oceanic and Atmospheric Administration up to a year in advance. These seasonal weather forecasts can provide ranchers with an increased predictive capacity to adjust stocking rates (in advance of the grazing season) according to predicted seasonal weather conditions, thereby reducing enterprise risk.