• Classification of Digital Photography for Measuring Productive Ground Cover

      Rotz, J. D.; Abaye, A. O.; Wynne, R. H.; Rayburn, E. B.; Scaglia, G.; Phillips, R. D. (Society for Range Management, 2008-03-01)
      Productive ground cover (PGC) is often used as a measure of sward health and persistence. To measure PGC, a camera stand was constructed to provide diffuse lighting of grass swards for color digital photography; the photographs were classified into productive and nonproductive cover using Mahalanobis distance. The PGC measurement techniques were tested on a grazing experiment that used four forage types: Lakota prairie grass (Bromus catharticus Vahl.), Kentucky 31 endophyte (Neotyphodium coenophialum)-free tall fescue (Lolium arundinaceum [Schreb.] S. J. Darbyshire), Kentucky 31 endophyte- infected tall fescue, and Quantum (novel-endophyte) tall fescue. The accuracy of the PGC maps was assessed using a stratified subsample of 48 images, 12 from each of four productive cover classes (0%-39%, 40%-59%, 60%-79%, and 80%-100%). On each of these 48 images 100 random points were labeled by a single skilled interpreter. The PGC percentages thus derived had an 83.7% agreement with the PGC maps. However, the percentages derived from the PGC maps were not well correlated with the PGC percentages derived from either ocular estimation (r = 0.22) or a simple digital point quadrat method (r = 0.47). This experiment highlights the potential for semiautomated classification of ground-based digital photographs for estimating PGC, though further research (including more direct comparison with established field techniques) is warranted. 
    • Effects of Experience and Lactation on Lupine Consumption by Cattle

      Pfister, James A.; Lee, Stephen T.; Panter, Kip E.; Motteram, Ernie S.; Gay, Clive C. (Society for Range Management, 2008-03-01)
      Lupines (Lupinus spp.) are widespread range plants that are often toxic to livestock. Some reports suggest that naïve, younger animals might consume more lupine than more experienced, older cattle. Further, lactational stress might alter forage selection, and lactating cows might eat more lupine than nonlactating cows. Thus, the objectives of these trials were to examine the influence of experience and lactation on lupine intake. Both study areas were near Ritzville, Washington, on rangeland dominated by cheatgrass or downy brome (Bromus tectorum L.), with abundant velvet lupine (Lupinus leucophyllus Dougl.). During the first trial, six naïve and six experienced Hereford cows were grazed together for 25 d during summer. There was no difference (P > 0.5) in consumption of lupine by naïve and experienced cows. Consumption peaked at 10%-14% of daily bites. During the second trial, six lactating and six nonlactating cows grazed a lupine-infested pasture for 18 d. There was no difference (P > 0.6) in consumption between lactating and dry cows. Lupine consumption gradually increased and peaked at 10%-15% of the diets. Our results suggest that experience and lactation status are probably minor considerations in livestock management schemes to reduce losses to lupine. 
    • Predicting Diet Quality of Donkeys via Fecal-NIRS Calibrations

      Kidane, Negusse F.; Stuth, Jerry W.; Tolleson, Douglas R. (Society for Range Management, 2008-03-01)
      Successful applications of fecal-near infrared reflectance spectroscopy (fecal-NIRS) techniques have been reported for ruminant animals. Information on the ability of fecal-NIRS to characterize diet quality in equines is lacking. The objective of these studies was to determine the potential of fecal-NIRS to predict diet quality of free-grazing equines. Two independent in vivo feeding trials, one in Texas (United States) and one in Kenya, were conducted to generate paired samples of diet chemistry:fecal spectrum (D:F). Using 20 female donkeys (Equus asinus), 14 (10 US, 4 Kenya) in vivo pen feeding trials were conducted to generate 140 (100 US, 40 Kenya) D:F paired samples. Over 25 species of forage and crop residues ranging from 3.3% to 21.4% crude protein (CP) were used to blend unique diets. Three CP predictive equations based on paired samples from US alone, Kenya alone, US + Kenya combined, and one predictive equation for digestible organic matter (DOM) from US alone were developed. The standard errors of calibration (SEC) and R2 values were 0.77 and 0.97, 0.97 and 0.95, and 0.88 and 0.90, respectively, for the US, US+Kenya, and Kenya CP equations. The US DOM equation resulted in an SEC of 2.58 with a corresponding R2 of 0.60. Validation of the US CP equation using an independent dataset resulted in standard error of prediction (SEP) and R2 of 1.79 and 0.82, respectively, indicating acceptable predictive ability. The validation results (SEP = 15.56) for the US DOM equation were not satisfactory. We calibrated and validated fecal-NIRS equations to predict the DOM and CP contents of diets for donkeys. Crude protein content of diets was predicted with acceptable levels of accuracy, but prediction of diet digestibility was less successful. The degree of accuracy obtained for CP equations indicated that fecal-NIRS can be considered as a tool for routine nutritional management of donkeys. 
    • GPS Collar Sampling Frequency: Effects on Measures of Resource Use

      Johnson, Dustin D.; Ganskopp, David C. (Society for Range Management, 2008-03-01)
      A challenge in animal behavior studies using Global Positioning System (GPS) collars is selecting a sampling frequency to accomplish desired goals. High data resolution (i.e., frequent sampling) is appealing, because it maximizes behavioral information garnered. Extended sampling might be needed, however, to describe long term behaviors or seasonal dynamics. Because tradeoffs exist between high data resolution and sampling duration, we evaluated the effects of variable GPS sampling intervals on proportions of pastures used by cattle and distance traveled per day. This was accomplished with GPS collars configured to record cattle positions every 5 min for 15 d in three 829-864-ha pastures. Data were iteratively reduced to simulate increasingly longer GPS recording intervals from once every 10 min up to once daily. Two techniques were used to measure the percentage of pastures accessed by cattle. The first counted only pixels containing GPS coordinates. The second counted pixels containing coordinates and/or traversed by lines between vertices. Expansion of GPS recording intervals decreased (P < 0.01) estimates of the proportion of pastures visited by cattle with rates of decline best fit by exponential decay functions for both line and point techniques (R2 = 0.93 and 0.97, respectively). Spatial errors accompanying less frequent sampling intervals, however, were extremely large with the line technique and misrepresented areas visited by cattle. Expansion of GPS sampling intervals decreased (P < 0.001) distance traveled per day by cattle about 10% with each iteration. If travel corridors or accurate assessments of resources accessed are of critical concern, then longer GPS integration intervals should be avoided because they propagate flawed spatial interpretations. Similarly, if accurate measures of travel distances are critical, we suggest using a relatively frequent GPS recording interval. 
    • Conifer Dispersion on Subalpine Pastures in Northeastern Spain: Characteristics and Implications for Rangeland Management

      Bartolome, Jordi; Boada, Martín; Saurí, David; Sánchez, Sònia; Plaixats, Josefina (Society for Range Management, 2008-03-01)
      Pinus sylvestris L. and Pinus mugo Turra originating from two plantations established during the 1960s are invading subalpine heathlands higher than 1 500 m above sea level in Montseny Natural Park (northeast Spain). Both species are native at a regional scale but may not have been present in the park’s subalpine vegetation previously. In addition, Abies alba P. Mill., which is in regression in many areas in Europe, is also colonizing the area from a neighboring natural forest. This invasion appears to be stimulated by a combination of natural and human factors, including differences between vegetation components, climate (i.e., drought periods), changes in land use due to conservation policies (i.e., suppressing fire or grazing practices), the creation of the plantations, and probably the nurse role played by accompanying dwarf shrubs (Calluna vulgaris [L.] Hull and Juniperus communis subsp. nana [Willd.] Syme). We examined the effects of this process in terms of the spatial dispersion and characteristics of the established conifers and deduce implications for the conservation of isolated subalpine pastures in Mediterranean Basin mountains. P. sylvestris was the most successful invading species in this area. The P. mugo invasion is distributed mainly near the plantation. The only native conifer species, A. alba, appears to be colonizing only the eastern slope. The invasion process is related to the diversity and species richness recorded on each slope. Conserving valuable subalpine heathlands at the latitude of the Montseny mountain range implies suppressing propagule pressures from the plantations. The option of removing conifers that are nonnative, at a local scale, must be considered. However, in the case of the native A. alba this option leads to a management conflict between conserving former pastureland and the dispersion of A. alba. 
    • Crested Wheatgrass Defoliation Intensity and Season on Medusahead Invasion

      Sheley, Roger L.; Bingham, Brett S.; Svejcar, Tony J. (Society for Range Management, 2008-03-01)
      The objective of this study was to determine the effects of crested wheatgrass (Agropyron cristatum [L.] Gaertn.) defoliation intensity and timing on medusahead density and biomass. We hypothesized that crested wheatgrass defoliation greater than 60% during the spring would provide maximum medusahead (Taeniatherum caput-medsae [L.] Nevski subsp. asperum [Simk.] Melderis; taxonomy from US Department of Agriculture) density and biomass. Eighteen treatments (six defoliation levels, three seasons of defoliation) were applied to 2-m2 plots in a randomized complete block design on two sites with varying clay content. Blocks were replicated five times at each site. Plants were clipped in 2004 and 2005. Crested wheatgrass was hand clipped to defoliation levels of 0%, 20%, 40%, 60%, 80%, and 100% in the spring, summer, or fall. Density of crested wheatgrass and medusahead was sampled in June 2005 and 2006, but their biomass was harvested only in 2006. Data were analyzed with least square means analysis of variance. Over the two seasons, site had much more of an impact on medusahead invasion than either defoliation intensity or timing of defoliation. The results support previous suggestions that clayey soils favor medusahead and that perennial grasses with high biomass can resist this invasive species. On the clayey site where medusahead did persist, fall defoliation of crested wheatgrass reduced the density of this invasive species by 50% or more compared to spring defoliation. Given the developmental pattern of medusahead, the goal of any management program should be to maximize resource use by the desirable species during April to late July. 
    • Grazing Systems for Yearling Cattle on Tallgrass Prairie

      Owensby, Clenton E.; Auen, Lisa M.; Berns, Hannah F.; Dhuyvetter, Kevin C. (Society for Range Management, 2008-03-01)
      This 9-yr study tested steer gains, residual aboveground biomass (AGB) in mid-July and early October, and economic returns and risk for tallgrass prairie grazed annually under season-long stocking (SLS) at 1.62 ha steer-1 until early October or intensive early stocking (IES) at 0.81 ha steer-1 until mid-July compared to a composite grazing system. The three-pasture, three-herd ‘‘IES+ System’’ is a 3-yr fixed sequence of SLS, IES, and IES (0.81 ha steer-1) plus late-season grazing (LSG; 1.62 ha steer-1) until early October (IES/LSG). All grazing treatments began in late April. Average gains per steer for SLS and SLS in the IES+ System did not differ, but were significantly less than gains for steers that grazed the entire season under IES/LSG. Gains per steer in mid-July under IES alone or in combination with LSG were similar to the same repeated grazing treatments, but were significantly less than those for steers grazed season-long. Gains per hectare under SLS did not differ, but were significantly less than those for IES treatments and the IES+ System. Gain per hectare in July was similar for IES repeated annually and IES/LSG, but there was greater gain per hectare for IES-treated pastures rotated within the system. Residual grass and total aboveground biomass (AGB) in mid-July did not vary among years and was generally greater on SLS than IES. In early October, grass AGB was similar for all treatments except IES/LSG, which had less residual AGB. When pasture rent was charged per head, the IES+ System increased the 20-yr mean return per hectare by 5.98 compared to repeated use of IES, and 8.52 compared to using only SLS. Measures of economic risk were generally intermediate for the IES+ system compared to IES, which consistently had the highest risk, and SLS. 
    • Grazing Impacts in Vegetated Dune Fields: Predictions From Spatial Pattern Analysis

      Blanco, Paula D.; Rostagno, César M.; del Valle, Héctor F.; Beeskow, Ana M.; Wiegand, Thorsten (Society for Range Management, 2008-03-01)
      This study deals with the changes induced by grazing on soil erosion processes in vegetated dune fields of Península Valdés, in the Patagonia region of Argentina. We performed a spatial analysis to assess erosion features’ patterns. Blowouts, used as main indicators of aeolian erosion processes, as well as dune crests, which are susceptible to erosion, were mapped on aerial photographs and images from Landsat 7 Enhanced Thematic Mapper Plus, in eight paddocks under two grazing conditions: lightly (0.4 sheep ha-1) and heavily grazed (0.8 sheep ha-1). From the mapped locations of water points, crests, and blowouts we calculated a spatial statistic (O-ring statistic), which gives the expected intensity of blowouts within the area covered by crests as function of distance away from water points. Additionally, to explore if the density of crests around water points influences the density of blowouts, we estimated the intensity of dune crests in the neighborhood of water points and compared the densities of blowouts among water points with low, medium, and high densities of crests. For the heavy grazing treatment we found highly significant (P < 0.05) aggregation of blowouts around water points with peak densities threefold higher than expected at random occurring between 90 and 210 m. However, the aggregation was only weakly significant for the light grazing treatment and occurred only at distances of about 30 m away from the water point. We found that the impact of grazing on soil stability contrasted among sites with different sensitivity to accelerated erosion. In sites with a high density of dune crests close to water points, wind erosion becomes more intense and the density of blowouts increases. A more sustainable management of these rangelands depends primarily on the conservation of the soils. Therefore, the location of water points in sites not susceptible to accelerated soil erosion would represent a better management strategy of the dune fields of Península Valdés. 
    • The Response of Thurber’s Needlegrass to Fall Prescribed Burning

      Davies, Kirk W.; Bates, Jonathan D. (Society for Range Management, 2008-03-01)
      Thurber’s needlegrass (Achnatherum thurberianum [Piper] Barkworth) is an important component of many sagebrush communities in the Intermountain West. Prescribed fall burning is often implemented in sagebrush plant communities to mimic historic wildfires, improve wildlife habitat, and increase livestock forage production. Burning is used because it shifts dominance from sagebrush to herbaceous vegetation. The effects of prescribed fall burning on Thurber’s needlegrass are largely unexplored. The purpose of this study was to determine the response of Thurber’s needlegrass to prescribed fall burning. A randomized block design was used, and each block consisted of a fall burned and unburned (control) Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis [Beetle A. Young] S. L. Welsh)-bunchgrass communities. Response variables measured in the first and second years after burns were Thurber’s needlegrass community foliar cover and density, vegetative and reproductive biomass, photosynthetic rates, tissue carbon (C) and nitrogen (N) content, and N (15N:14N) and C (13C:12C) isotope ratios. Density of Thurber’s needlegrass in both postburn years and cover in the second postburn year were not different between treatments (P > 0.05), but cover was less in the burned than control treatment in the first postburn year (P = 0.008). Carbon isotope ratios in Thurber’s needlegrass differed between the burn (225.9 +/- 0.1 SE) and control (226.3 +/- 0.1 SE) treatments in the first postburn year (P = 0.019). Nitrogen isotope ratios indicated nitrogen was more available in the burned than control treatment in both years (P < 0.05). Photosynthetic rates of Thurber’s needlegrass were also generally greater in the burned than control treatment (P = 0.045). Our results suggest burning altered the availability of resources to Thurber’s needlegrass plants. Our results also suggest that prescribed fall burning is not detrimental to Thurber’s needlegrass and, thus, can be used as a method to shift dominance from sagebrush to herbaceous vegetation. 
    • Response of Acacia sieberiana to Repeated Experimental Burning

      Aleper, Daniel; Lye, Kåre A.; Moe, Stein R. (Society for Range Management, 2008-03-01)
      We conducted a study on how Acacia sieberiana respond to repeated burning in the Kidepo National Park in northeastern Uganda. The study was conducted to understand effects of common burning regimes (early dry season, late dry season, and no burn [control]) in the area on Acacia sieberiana. The three treatments were applied for three consecutive years to 14 replicate blocks in a randomized block design. All A. sieberiana trees were number tagged and monitored for height and girth (diameter at breast height) growth. All fires were set as head-fires and attained intensity ranging between 422 and 5693 kW ? m21. Both early and late dry season burning increased the number of small (< 49 cm) A. sieberiana trees after 2 yr. Burning did not affect the growth rates. Although the number of trees < 49 cm increased after 2 yr, the mortality in this height class was also increased by the late dry season burning, and after 3 yr of consecutive burning there were no statistical treatment differences in the height class < 49 cm. Late dry season burning also led to high mortality among trees > 250 cm in the third year. Mortality attributed to elephant browsing was important in all treatments but a substantial portion of mortality could not be attributed to any particular cause. In the late burn, fire was the most important mortality factor. Thus, 2 yr of burning may be used as a tool to stimulate recruitment of A. sieberiana, but additional years of late dry season burning will increase the mortality of older trees. 
    • Prescribed Fire, Soil, and Plants: Burn Effects and Interactions in the Central Great Basin

      Rau, Benjamin M.; Chambers, Jeanne C.; Blank, Robert R.; Johnson, Dale W. (Society for Range Management, 2008-03-01)
      Pinyon and juniper expansion into sagebrush ecosystems results in decreased cover and biomass of perennial grasses and forbs. We examine the effectiveness of spring prescribed fire on restoration of sagebrush ecosystems by documenting burn effects on soil nutrients, herbaceous aboveground biomass, and tissue nutrient concentrations. This study was conducted in a central Nevada woodland and included control and burn treatment plots sampled before and after a prescribed fire. Six native understory plant species (Crepis acuminata, Eriogonum umbellatum, Eriogonum elatum, Poa secunda secunda, Festuca idahoensis, and Lupinus argenteus) important for native sagebrush obligate foragers were chosen to represent the understory plant community. L. argenteus is also important for system nutrient cycling and nitrogen fixation. Plants were collected from three microsites (under tree canopy, under shrub canopy, and interspace) common in transitional woodlands during peak growth the summer before a spring prescribed burn and each of two summers following the burn. Soils were collected from corresponding locations at two depth intervals (0-8 and 8-52 cm) to determine the relationships between soil and plant nutrients following fire. Microsite affected soil nutrients but did not influence plant tissue concentrations with the exception of F. idahoensis. Burning resulted in increases in soil surface NH+4 , NO-3 , inorganic N, Ca2+, Mn2+, and Zn2+. Increases in NO-3 , inorganic N, and Zn2+ were also observed in deeper horizons. Burning did not affect aboveground plant biomass or nutrient concentrations in the first year with the exception of F. idahoensis, which had increased tissue P. By the second year, all species had statistically significant responses to burning. The most common response was for increased aboveground plant weight and tissue N concentrations. Plant response to burning appeared to be related to the burn treatment and the soil variables surface K+, NO-3 , and inorganic N. 
    • Long-Term Effects of a Summer Fire on Desert Grassland Plant Demographics in New Mexico

      Parmenter, Robert R. (Society for Range Management, 2008-03-01)
      Plant demographic responses to an experimental summer fire were monitored for 12 yr on the Sevilleta National Wildlife Refuge, New Mexico, to determine recovery rates of burned plants and evaluate fire effectiveness in preventing shrub invasion of desert grasslands. Fourteen common species of grasses, shrubs, yucca, and cacti were measured for mortality, resprouting, regrowth, herbivory, and reproduction. After the first postfire growing season, black grama (Bouteloua eriopoda [Torr.] Torr.) declined 80% in size, whereas blue grama (Bouteloua gracilis [Willd. ex Kunth] Lag. ex Griffiths) exhibited no decline. Linear regression indicated that B. eriopoda needed 11 yr to recover. Spike dropseed (Sporobolus contractus A.S. Hitchc.) and purple three-awn (Aristida purpurea Nutt.) showed postfire declines in plant sizes, requiring 4- and > 5-yr recovery times, respectively. Sand muhly (Muhlenbergia arenicola Buckl.) exhibited no fire impact. Snakeweed (Gutierrezia sarothrae [Pursh] Britt. Rusby) sustained 61% fire mortality and reduction in regrowth canopy size. Creosotebush (Larrea tridentata [Sesse Moc. ex DC.] Coville) had 12% mortality, but survivors recovered over 12 yr. Fourwing saltbush (Atriplex canescens [Pursh] Nutt.) sustained 62% mortality, but recovered plant size in 5-6 yr. Winterfat (Krascheninnikovia lanata [Pursh] A. D. J. Meeuse Smit) suffered 7% mortality, but required 9+ yr to recover. Pale desert-thorn (Lycium pallidum Miers) survived fire, recovering prefire canopy size in 3 yr. Torrey joint-fir (Ephedra torreyana Watson) exhibited < 1% mortality, and recovered in 2-3 yr. Soapweed yucca (Yucca glauca Nutt.) had < 2% mortality, recovered plant sizes in 2 yr, and increased numbers of rosettes 17%. Chollas (Opuntia imbricata [Haw.] DC. and Opuntia clavata Engelm.) suffered high mortality rates and required > 12 yr recovery times. Results demonstrated that summer fire may counter some shrub and cacti invasion in central New Mexico, but once shrubs mature, fire is less effective in removing woody plants to restore southwestern grasslands. 
    • Knowing the Land: A Review of Local Knowledge Revealed in Ranch Memoirs

      Knapp, Corrine Noel; Fernandez-Giminez, Maria (Society for Range Management, 2008-03-01)
      Lack of long-term ecological monitoring presents a challenge for sustainable rangeland management in many areas of the western United States. Ranchers and other land managers have local knowledge gained from ongoing experience in specific places that could be useful for understanding ecological change and best management practices. Local knowledge is defined as knowledge gained by daily contact with the natural world and ecological processes. Unfortunately, little is known about ranchers’ local knowledge, and few studies have systematically examined the types, depth, and validity of this knowledge. Ranch memoirs offer an unexplored entry into rancher knowledge acquisition, categories, and context. In this study, we coded and analyzed eighteen ranch memoirs from the western United States to investigate the specific types, depth, and quality of local land knowledge. We found that ranchers possess knowledge of both management and ecology, and that these knowledge realms are intertwined and often inseparable. In addition to learning from experience, social interactions are an important part of rancher education and create a shared knowledge culture. In most of the memoirs, ranchers revealed very little knowledge of long-term patterns of vegetation change. In all the memoirs reviewed, ranchers articulated a deep sense of responsibility and connectedness to the landscapes they manage and steward. This review of ranch memoirs provides a framework for future studies of local knowledge by identifying how ranchers gain their knowledge of the landscapes they manage, describing some of the distinctive types of knowledge that ranchers possess, and challenging conventional classifications of rancher knowledge. 
    • Ranching as a Conservation Strategy: Can Old Ranchers Save the New West?

      Brunson, Mark W.; Huntsinger, Lynn (Society for Range Management, 2008-03-01)
      Working ranches are often promoted as means of private rangeland conservation because they can safeguard ecosystem services, protect open space, and maintain traditional ranching culture. To understand the potential for generating broad social benefits from what have come to be called ‘‘working landscapes,’’ one must consider the synergies of people, environment, and institutions needed to accomplish conservation, as well as complicating factors of scale and uncertainty. Focusing on the problem as it has unfolded in the western United States, we review the state of knowledge about the extent of ranchland conversion; reasons why maintaining working ranches may benefit conservation; and the challenges and opportunities of rancher demographics, attitudes, values, and propensities for innovation. Based on this review, we explore whether the supply of traditional, full-time ranch owners is likely to be sufficient to meet conservation demand, and conclude that although demographic trends seem to suggest that it is not, there exist alternative enterprises and ownership forms that could achieve the goals of ranch conservation. We offer suggestions on how potential shortfalls might be addressed.