• A Landscape Similarity Index: Multitemporal Remote Sensing to Track Changes in Big Sagebrush Ecological Sites

      Hernandez, Alexander J.; Ramsey, R. Douglas (Society for Range Management, 2013-01-01)
      A similarity index for big sagebrush ecological sites was developed in northern Utah. In contrast to field measurements used to calculate similarity to reference states, our approach relies on the utilization of historic archives of satellite imagery to measure the ecological distance to benchmarks of undesired conditions such as invasion by exotic annuals and woodland encroachment. Our benchmarks consisted of locations for which there are field data collected for monitoring and evaluation purposes for several time periods. We utilized a temporal series of Landsat thematic mapper (TM) imagery that spanned 1984 to 2008 from which the soil-adjusted vegetation index (SAVI) and other transformations were extracted. Topographic and climatic variables were also included as ancillary data. Multidimensional scaling (MDS) was used to obtain scores in reduced ordination space for two periods of interest: 1984-1996 and 1997-2008. Interannual SAVI mean-variance plots provided evidence that the benchmarks and ecological sites have a distinct temporal response that allows an objective comparison. Our MDS results also show that natural clusters can be identified in the reduced statistical space for ecological sites that are a dominant component of a soil map unit. The two MDS solutions allowed the ordination of ecological sites in two gradients of productivity and bare ground. Interpretations of the transitions and trajectories of mountain, Wyoming, and basin big sagebrush sites correlated well with the ecological expectation. We anticipate that range conservationists and others actively working in rangeland evaluation can use this application to develop and update ecological site descriptions and state-and-transition models from a remotely sensed perspective.
    • Detecting Channel Riparian Vegetation Response to Best-Management-Practices Implementation in Ephemeral Streams With the Use of Spot High-Resolution Visible Imagery

      Vande Kamp, Kendall; Rigge, Matthew; Troelstrup, Nels H.; Smart, Alexander J.; Wylie, Bruce (Society for Range Management, 2013-01-01)
      Heavily grazed riparian areas are commonly subject to channel incision, a lower water table, and reduced vegetation, resulting in sediment delivery above normal regimes. Riparian and in-channel vegetation functions as a roughness element and dissipates flow energy, maintaining stable channel geometry. Ash Creek, a tributary of the Bad River in western South Dakota contains a high proportion of incised channels, remnants of historically high grazing pressure. Best management practices (BMP), including off-stream watering sources and cross fencing, were implemented throughout the Bad River watershed during an Environmental Protection Agency (EPA) 319 effort to address high sediment loads. We monitored prairie cordgrass (Spartina pectinata Link) establishment within stream channels for 16 yr following BMP implementation. Photos were used to group stream reaches (n=103) subjectively into three classes; absent (estimated <5% cover; n=64), present (estimated 5-40% cover; n=23), and dense (estimated >40% cover; n=16) based on the relative amount of prairie cordgrass during 2010 assessments of ephemeral channels. Reaches containing drainage areas of 0.54 to 692 ha were delineated with the use of 2010 National Agriculture Imagery Program (NAIP) imagery. Normalized difference vegetation index (NDVI) values were extracted from 5 to 39 sample points proportional to reach length using a series of Satellite Pour l’Observation de la Terre (SPOT) satellite imagery. Normalized NDVI (nNDVI) of 2 152 sample points were determined from pre- and post-BMP images. Mean nNDVI values for each reach ranged from 0.33 to 1.77. ANOVA revealed significant increase in nNDVI in locations classified as present prairie cordgrass cover following BMP implementation. Establishment of prairie cordgrass following BMP implementation was successfully detected remotely. Riparian vegetation such as prairie cordgrass adds channel roughness that reduces the flow energy responsible for channel degradation.
    • Spatial Redistribution of Nitrogen by Cattle in Semiarid Rangeland

      Augustine, David J.; Milchunas, Daniel G.; Derner, Justin D. (Society for Range Management, 2013-01-01)
      Nitrogen (N) availability can strongly influence forage quality and the capacity for semiarid rangelands to respond to increasing atmospheric CO2. Although many pathways of nitrogen input and loss from rangelands have been carefully quantified, cattle-mediated N losses are often poorly understood. We used measurements of cattle N consumption rate, weight gains, and spatial distribution in shortgrass rangeland of northeastern Colorado to evaluate the influence of cattle on rangeland N balance. Specifically, we estimated annual rates of N loss via cattle weight gains and spatial redistribution of N into pasture corners and areas near water tanks, and used previous studies to calculate ammonia volatilization from urine patches. Using measurements of plant biomass and N content inside and outside grazing cages over 13 yr, we estimate that cattle stocked at 0.65 animal unit months (AUM) ha-1 consumed 3.34 kg N ha-1 yr-1. Using an independent animal-based method, we estimate that cattle consumed 3.58 kg N ha-1 yr-1 for the same stocking rate and years. A global positioning system tracking study revealed that cattle spent an average of 27% of their time in pasture corners or adjacent to water tanks, even though these areas represented only 2.5% of pasture area. Based on these measurements, we estimate that cattle stocked at 0.65 AUM ha-1 during the summer can remove 0.60 kg N ha-1 in cattle biomass gain and spatially redistribute 0.73 kg N ha-1 to areas near corners and watertanks. An additional 0.17 kg N ha-1 can be lost as NH3 volatilization from urine patches. Cumulatively, these cattle-mediated pathways (1.50 kg N ha-1) may explain the imbalance between current estimates of atmospheric inputs and trace gas losses. While NOx emission remains the largest pathway of N loss, spatial N redistribution by cattle and N removed in cattle biomass are the second and third largest losses, respectively. Management of cattle-mediated N fluxes should be recognized as one means to influence long-term sustainability of semiarid rangelands.
    • Understanding Variability in Adaptive Capacity on Rangelands

      Marshall, Nadine A.; Smajgl, Alex (Society for Range Management, 2013-01-01)
      The art and science of developing effective policies and practices to enhance sustainability and adapt to new climate conditions on rangelands and savannas are typically founded on addressing the ‘‘average’’ or ‘‘typical’’ resource user. However, this assumption is flawed since it does not appreciate the extent of diversity among resource users; it risks that strategies will be irrelevant for many people and ignored, and that the grazing resource itself will remain unprotected. Understanding social heterogeneity is vital for effective natural resource management. Our aim was to understand the extent to which graziers in the northern Australian rangelands varied in their capacity to adapt to climate variability and recommended practices. Adaptive capacity was assessed according to four dimensions: 1) the perception of risk, 2) skills in planning, learning and reorganising, 3) financial and emotional flexibility, and 4) interest in adapting. We conducted 100 face-to-face interviews with graziers in their homes obtaining a 97% response rate. Of the 16 possible combinations that the four dimensions represent, we observed that all combinations were present in the Burdekin. Any single initiative to address grazing land management practices in the region is unlikely to address the needs of all graziers. Rather, policies could be tailored to type-specific needs based on adaptive capacity.Efforts to shift graziers from very low, low, or moderate levels of adaptive capacity are urgently needed. We suggest some strategies.
    • Comparing Two Ground-Cover Measurement Methodologies for Semiarid Rangelands

      Weber, Keith T.; Chen, Fang; Booth, D. Terrance; Raza, Mansoor; Serr, Kindra; Gokhale, Bhushan (Society for Range Management, 2013-01-01)
      The limited field of view (FOV) associated with single-resolution very-large-scale aerial (VLSA) imagery requires users to balance FOV and resolution needs. This balance varies by the specific questions being asked of the data. Here, we tested a FOV resolution question by comparing ground cover measured in the field with the use of point-intercept transects with similar data measured from 50-mm-per-pixel (mmpp) VLSA imagery of the same locations. Particular care was given to spatial control of ground and aerial sample points from which observations were made, yet percent cover estimates were very different between methods. An error budget was used to calculate error of location and error of quantification. These results indicated location error (43.5%) played a substantial role with significant quantification error (21.6%) also present. We conclude that 1) although the georectification accuracy achieved in this project was actually quite good, the level of accuracy required to match ground and aerial sample points represents an unrealistic expectation with currently available positioning technologies, 2) 50-mmpp VLSA imagery is not adequate for accurate species identification or cover assessments of plant functional groups, and 3) the balance between resolution and FOV needs is best addressed by using multiple cameras to acquire nested imagery at multiple VLSA resolutions simultaneously. We recommend ground cover be measured from 1-mmpp imagery and that the imagery be nested in lower-resolution, larger FOV images simultaneously acquired.
    • Collective Action, Innovation, and Wealth Generation Among Settled Pastoral Women in Northern Kenya

      Coppock, D. Layne; Desta, Solomon (Society for Range Management, 2013-01-01)
      Collective action occurs when people join together to tackle problems of common interest. Collective action can be an effective means of group problem solving, especially among poorer residents of densely populated urban areas or farming systems. Few examples have been documented, however, for the lightly populated rangelands, where pastoralists are better known for their social independence and opportunistic behavior. We were therefore surprised to encounter dynamic women’s collective-action groups in small settlements throughout north-central Kenya, a pastoral region characterized by high rates of poverty, few public services, recurrent drought, and ethnic conflict. We wanted to understand why groups were created and how they functioned. We used a semistructured questionnaire to interview representatives from 16 groups in February 2006. Results indicated that most groups had formed since the 1990s. They emerged either spontaneously or after encouragement from local development agency staff. Founding members were exclusively women who were often illiterate and poor. Groups have elected leaders and are governed under constitutional frameworks with extensive bylaws. Groups form to improve living standards for members, and numerous success stories were noted. Groups undertake activities including microfinance, livelihood diversification, and mitigation of drought effects; they also spearhead and fund community education and health initiatives. A tally of 63 groups created over the previous 25 yr indicated that 2 had collapsed, 47 were thriving, and 14 were failing. Group failure was most attributed to poor leadership and negative interpersonal dynamics among members, but important external threats included drought, poverty, political incitement, illiteracy, and agitation by men. In a region beset by large challenges it is notable that such grassroots innovation can help fortify social, human, and financial capital and this, in turn, can improve risk management and human well-being. Collective action should be recognized as a vital development process in Kenya’s rangelands that deserves more policy-level attention.
    • Comparison of Bite-Count and Rumen Evacuation Techniques to Estimate Cattle Diet Quality

      Damiran, Daalkhaijav; DelCurto, Timothy; Findholt, Scott L.; Johnson, Bruce K.; Vavra, Martin (Society for Range Management, 2013-01-01)
      We conducted a study to compare the bite-count technique (BC) of estimating forage intake and synthesized diet quality to direct estimates of diet quantity and quality with the use of the rumen evacuation technique (RE). We used four rumen-fistulated steers to evaluate both techniques. Four enclosures in a mixed-conifer rangeland were used. Each enclosure contained two 0.25-ha paddocks that were either nonstocked or stocked by cattle to remove 32+/-4% of standing crop. We recorded bite-count data during foraging bouts for each steer in each paddock, and then evacuated each rumen following each foraging bout during summer (August). Paddocks stocked prior to each 20-min trial had a reduced (P<0.05) quantity offorage consumed regardless of technique. BC and RE gave similar (P>0.10) results on diet quantity and digestibility. However, BC-derived estimates were lower (P<0.05) for crude protein (CP), acid detergent fiber (ADF), ash, and neutraldetergent fiber (NDF). In summary, although BC has the advantage of not requiring rumen-fistulated animals, it did not yield comparable results to RE under range conditions with dense and diverse vegetation. Therefore, investigators should calibrate bite-count technique against fistula technique to solve any accuracy problem in their specific experimental conditions whenever possible.
    • Heat Dosage and Oviposition Depth Influence Egg Mortality of Two Common Rangeland Grasshopper Species

      Branson, David H.; Vermeire, Lance T. (Society for Range Management, 2013-01-01)
      Rangeland fire is a common naturally occurring event and management tool, with the amount and structure of biomass controlling transfer of heat belowground. Temperatures that grasshopper eggs are exposed to during rangeland fires are mediated by species-specific oviposition traits. This experiment examined egg mortality in two slant-faced grasshopper species with differing oviposition traits, namely Aulocara elliotti (Thomas) and Opeia obscura (Thomas). We hypothesized that A. elliotti egg mortality would increase with fire intensity because the shallow egg location below the soil surface would result in exposure to higher temperatures, and that the deeper O. obscura eggs would not be affected by fire intensity. Fire intensity did not significantly affect the mortality of O. obscura eggs, with very low mortality in all treatments. Fire intensity significantly affected mortality of A. elliotti eggs, which are laid in shallow egg pods with the midpoint of the egg clutch at a depth of ~0.825 cm. Aulocara elliotti egg mortality increased with higher levels of heat application, with 79% egg mortality in the 4 500 kg ha-1 heat treatment. Heat effects on A. elliotti egg mortality were similar to those previously observed for another shallow-egg-layingspecies. Limited research has examined if rangeland fires reduce population densities of specific economically important grasshopper species. The results from this experiment indicate that grasshopper species with the midpoint of the egg pod less than 1 cm below the surface are likely in general to be vulnerable to fire-induced egg mortality during rangeland fires.
    • Influence of Livestock Grazing Strategies on Riparian Response to Wildfire in Northern Nevada

      Dalldorf, K. N.; Swanson, S. R.; Kozlowski, D. F.; Schmidt, K. M.; Shane, R. S.; Fernandez, G. (Society for Range Management, 2013-01-01)
      In 1999-2001 wildfires burned 1.13 million ha across northern Nevada, burning through many grazed riparian areas. With increases in wildfire frequency and extent predicted throughout the Great Basin, an understanding of the interactive effects of wildfire, livestock grazing, and natural hydrologic characteristics is critical. A comparison of pre- and postfire stream surveys provided a unique opportunity to statistically assess changes in stream survey attributes at 43 burned and 38 unburned streams. Livestock grazing variables derived from an extensive federal grazing allotment inventory were used to identify interactive effects of grazing strategies, fire, and natural stressors across 81 independent riparian areas. Differences between baseline and‘‘postfire’’ stream survey attributes were evaluated for significance using the nonparametric Mann-Whitney test for paired data. Binary logistic regression models evaluated the influence of fire, grazing, and hydrologic characteristics on observed stream survey attribute changes. Grazing attributes contributed most significantly to the bankfull width increase and bank stability rating decrease models. The odds of bankfull width degradation (increase in bankfull width) decreased where there had been rest is some recent years compared to continuous grazing. As the number of days grazed during the growing season increased, the odds of bank stability degradation also increased. The occurrence of fire was not significant in any model. Variation in the riparian width model was attributed primarily to hydrologic characteristics, not grazing. For the models in which grazing variables played a role, stream survey attributes were more likely to improve over time when coupled with a history of rotational grazing and limited duration of use during the growing season. This supports long-term riparian functional recovery through application of riparian complementary grazing strategies.
    • Saw Palmetto (Serenoa repens) Flowering and Fruiting Response to Time Since Fire

      Carrington, Mary E.; Mullahey, J. Jeffrey (Society for Range Management, 2013-01-01)
      Saw palmetto (Serenoa repens [Bartr.] Small) is a shrubby palm common in southeastern US pine flatwoods ecosystems. Demand recently has increased for fruits for the herbal remedies market. Because only wild saw palmettos are harvested, management strategies are needed to promote flowering and fruiting. This study investigated effects of time since growing season (April-July) fires on flowering and fruiting of saw palmetto ramets 54 cm in height, in 18 pine flatwoods or dry prairie sites (six sites in three locations, burned in 1996, 1995, 1994, 1993, 1992, or before 1991) in central and southwest Florida from 1996 to 1999. We used repeated measures, linear mixed models to test for time since fire effects on proportion of ramets flowering, proportionof ramets fruiting, and fruit yield. Ranges of means among sites over all years of the study for proportion of ramets flowering, proportion of ramets fruiting, and fruit yield were 0 to 0.78, 0 to 0.72, and 0 kg ha-1 to 2 869 kg ha-1, respectively. Time since fire strongly influenced flowering; highest probability of flowering occurred 1 yr after burning, followed by an abrupt decrease 2 yr after burning, then a gradual increase from 3 to 5 yr after fires (polynomial regression, P<0.0001 for fixed effects). Probability of fruiting increased with increasing time since fire (quadratic regression, P<0.001 for fixed effects), but fruit yields showed no pattern in response to time since fire (P=0.916). The decrease in influence of fire from flowering through fruit maturity presumably was caused by mortality from factors such as caterpillar predation and fungal infection. To promote increased flowering and fruit yields, we recommend that growing season burns be conducted approximately every 5 yr. We suggest, however, that management strategy be modified as necessary to maintain ecosystem diversity and function.
    • Are Droppings, Distance From Pastoralist Camps, and Pika Burrows Good Proxies for Local Grazing Pressure?

      Dorji, Tsechoe; Totland, Ørjan; Moe, Stein R. (Society for Range Management, 2013-01-01)
      Grazing is regarded as one of the most important factors influencing rangeland ecosystems. Many previous studies have used indirect measures (proxies) of grazing intensity, such as the distance from congregation areas and the number of herbivore excreta, to estimate effects of grazing on vegetation parameters in rangeland ecosystems. However, little is known about how such proxies reflect the true grazing intensity, and if their suitability is consistent across landscape conditions. We measured grazing intensity based on the amount of plant ramets being grazed in 75 plots positioned across a rangeland landscape in central Tibet. Several grazing intensity proxies (distance from pastoral camp sites, number of yak dung patches (old and fresh), sheep and goat dropping piles, and pika (Ochotona curzoniae) burrows (active and abandoned)) were also measured in each plot. Regression models were used to examine the suitability of these proxies in predicting our measure of real grazing intensity. None of the examined proxies satisfactorily predicted real grazing intensity in our study system. The distance from camp sites was the best proxy for grazing intensity (P<0.001), but it explained only 30% of its variation. Fresh yak dung and active pika burrows explained only 10% and 3% of the variation in grazing intensity, respectively. The suitability of using proxies for grazing intensity did not significantly differ along landscape parameters (elevation, aspect directions, and slope angle) (P>0.05), except that the number of animal excreta and pika burrows functioned better as proxies at low, compared to high, elevation (P<0.05). Our results should be of concern since many studies use proxies to estimate effects of grazing on vegetation dynamics and ecosystem properties. We recommend awareness of potential limitations and suitability of proxies, when real grazing intensity is not measured.
    • Plant and Small Vertebrate Composition and Diversity 36-39 Years After Root Plowing

      Fulbright, Timothy E.; Lozano-Cavazos, E. Alejandro; Ruthven, Donald C.; Litt, Andrea R. (Society for Range Management, 2013-01-01)
      Root plowing is a common management practice to reduce woody vegetation and increase herbaceous forage for livestock on rangelands. Our objective was to test the hypotheses that four decades after sites are root plowed they have 1) lower plant species diversity, less heterogeneity, greater percent canopy cover of exotic grasses; and 2) lower abundance and diversity of amphibians, reptiles, and small mammals, compared to sites that were not disturbed by root plowing. Pairs of 4-ha sites were selected for sampling: in each pair of sites, one was root plowed in 1965 and another was not disturbed by root plowing (untreated). We estimated canopy cover of woody and herbaceous vegetation during summer 2003 and canopy cover of herbaceous vegetation during spring 2004. We trapped small mammals and herpetofauna in pitfall traps during late spring and summer 2001-2004. Species diversity and richness of woody plants were less on root-plowed than on untreated sites; however, herbaceous plant and animal species did not differ greatly between treatments. Evenness of woody vegetation was less on root-plowed sites, in part because woody legumes were more abundant. Abundance of small mammals and herpetofauna varied with annual rainfall more than it varied with root plowing. Although structural differences existed between vegetation communities, secondary succession of vegetation reestablishing after root plowing appears to be leading to convergence in plant and small animal species composition with untreated sites.
    • Recovery and Viability of Sulfur Cinquefoil Seeds From the Feces of Sheep and Goats

      Frost, Rachel A.; Mosley, Jeffrey C.; Roeder, Brent L. (Society for Range Management, 2013-01-01)
      Targeted grazing by sheep or goats is a potentially useful tool for suppressing the noxious weed sulfur cinquefoil (Potentilla recta L.). However, possible transmission of weed seeds by grazing livestock is a serious ecological concern that must be addressed in any targeted grazing prescription. We investigated the effect of sheep and goat digestion on the viability of sulfur cinquefoil seeds collected from live plants growing on a foothill rangeland site in southwestern Montana. Eight sheep and eight goats (all wethers) were each gavaged with 5 000 sulfur cinquefoil seeds. Four animals of each species received immature seeds, and four animals received mature seeds. All animals were fed ground grass hay in excess daily, and intake averaged 2.0% body weight d-1. Total fecal collection began immediately after gavaging and continued for 7 consecutive days. Once each day, all identifiable sulfur cinquefoil seeds were recovered and counted from fecal subsamples. Seed viability before gavaging averaged 36% for immature seeds and 76% for mature seeds. Sheep and goats excreted similar numbers of viable seeds. Almost all (98%) of the viable seeds recovered from sheep and goats were excreted during Day 1 and Day 2 after gavaging. No viable seeds were recovered from either sheep or goats after Day 3. Our estimates of sulfur cinquefoil seed excretion and viability in sheep and goat feces are likely inflated compared with targeted grazing animals because gavaging with seeds bypassed mastication. Grazing livestock that consume sulfur cinquefoil seeds should be kept in a corral for at least 3 d to prevent transferring viable seeds to uninfested areas.
    • Greater Sage-Grouse and Severe Winter Conditions: Identifying Habitat for Conservation

      Dzialak, Matthew R.; Webb, Stephen L.; Harju, Seth M.; Olson, Chad V.; Winstead, Jeffrey B.; Hayden-Wing, Larry D. (Society for Range Management, 2013-01-01)
      Developing sustainable rangeland management strategies requires solution-driven research that addresses ecological issues within the context of regionally important socioeconomic concerns. A key sustainability issue in many regions of the world is conserving habitat that buffers animal populations from climatic variability, including seasonal deviation from long-term precipitation or temperature averages, and that can establish an ecological bottleneck by which the landscape-level availability of critical resources becomes limited. We integrated methods to collect landscape-level animal occurrence data during severe winter conditions with estimation and validation of a resource selection function, with the larger goal of developing spatially explicit guidance for rangeland habitat conservation. The investigation involved greater sage-grouse (Centrocercusurophasianus) that occupy a landscape that is undergoing human modification for development of energy resources. We refined spatial predictions by exploring how reductions in the availability of sagebrush (as a consequence of increasing snow depth) may affect patterns of predicted occurrence. Occurrence of sage-grouse reflected landscape-level selection for big sagebrush, taller shrubs, and favorable thermal conditions and avoidance of bare ground and anthropogenic features. Refinement of spatial predictions showed that important severe winter habitat was distributed patchily and was constrained in spatial extent (7-18% of the landscape). The mapping tools we developed offer spatially explicit guidance for planning human activity in ways that are compatible with sustaining habitat that functions disproportionately in population persistence relative to its spatial extent or frequency of use. Increasingly, place-based, quantitative investigations that aim to develop solutions to landscape sustainability issues will be needed to keep pace with human-modification of rangeland and uncertainty associated with global climate change and its effects on animal populations.
    • Impact of Land Subdivision and Sedentarization on Wildlife in Kenya’s Southern Rangelands

      Groom, Rosemary J.; Western, David (Society for Range Management, 2013-01-01)
      Subdivision and sedentarization of pastoral communities is accelerating rapidly across the African rangelands, posing a severe threat to wildlife populations, but few studies have looked quantitatively at the ecological impact of sedentarization. Here we look at the impact of sedentarization on wildlife by comparing ecologically matched subdivided and unsubdivided Maasai pastoral lands (ranches) in semiarid southern Kenya. We found no significant difference in livestock densities on the two ranches but there was a significantly higher wildlife density on the unsubdivided ranch, in both dry and wet seasons. Nonetheless, the unsubdivided ranch still had a higher percentage of grass biomass and ground cover and lower grazing pressure than the subdivided ranch. Distribution of homesteads (bomas) was mostly random on the subdivided ranch, with little area unaffected by human settlement. On the contrary, the unsubdivided ranch had a highly clumped boma distribution pattern, resulting in much of the land being relatively far from permanent human settlement. We show that the regular distribution and permanence of settlements following subdivision and sedentarization greatly reduces wildlife populations both through direct displacement and a reduction of forage. Relative to mobile pastoralism on open rangelands, sedentarization leads to reduced seasonal movements of livestock, lowered grass biomass, and slower grass recovery after very dry periods. This study points to the need to maintain mobile, large-scale herd movements to avoid the heavy impact on grasslands associated with sedentarization of pastoral settlement and herds.