• Biomass and Defoliation Tolerance of 12 Populations of Pseudoroegneria spicata at Two Densities

      Mukherjee, Jayanti Ray; Jones, Thomas A.; Monaco, Thomas A. (Society for Range Management, 2013-11-01)
      Pseudoroegneria spicata (Pursh.) A. Löve is an important native grass of the rangelands of the Intermountain West, USA and is widely used in this region for restoration applications. High grazing preference, together with high grazing sensitivity, has reduced the abundance of this species, indicating the need for the development of grazing-tolerant plant materials. While a genotype may be defoliation tolerant at low density, e.g., in an experimental setting, an effective grazing-tolerant genotype must also display this trait at higher densities resembling those found in natural and restoration settings. We compared 12 restoration plant materials for response to spring-defoliation at high (25 plants m-2) and low (8 plants m-2) plant densities in a field experiment. Two consecutive years of spring-defoliation reduced shoot biomass 19% compared to the nonspring-defoliated control, and this reduction was similar for the two densities examined. Two populations, P-3 and Acc:238, were able to compensate for shoot biomass after 2 yr of spring-defoliation, while the remaining 10 populations undercompensated, as is commonly reported for cool-season grasses in arid and semiarid regions. While the association between control and springdefoliated shoot biomass was marginally positive (R2=0.26; P<0.10), we found a stronger negative association (R2=0.36; P<0.05) between spring-defoliation tolerance and control shoot-biomass production. This suggests a possible trade-off between growth and defoliation tolerance (calculated as percentage of control biomass) among populations. Of the four commercially available plant materials in our study, the more recent prevariety germplasm, P-7, exhibited higher control shoot biomass and higher spring-defoliation tolerance than the older cultivars, Whitmar and Goldar. Anatone germplasm was intermediate but not statistically different from these other plant materials for these two traits.
    • Bison Versus Cattle: Are They Ecologically Synonymous?

      Kohl, Michel T.; Krausman, Paul R.; Kunkel, Kyran; Williams, David M. (Society for Range Management, 2013-11-01)
      Historically, the plains bison (Bison bison Linnaeus) was the most numerous and influential grazer on the Great Plains. Today 500 000 bison occupy North America among more than 100 000 000 cattle. In an attempt to restore their historical ecological role, bison are translocated onto landscapes previously manipulated for cattle use through water and fence development. We hypothesized that bison would use these landscapes similarly to cattle, thus maintaining homogenous grazing and reducing the restoration potential of bison at a landscape scale. We quantified differences between bison populations at different locations and spatial scales (American Prairie Reserve, Malta, Montana, USA, and Grasslands National Park, Val Marie, Saskatchewan, Canada, 2010-2011) and bison and cattle at similar locations and spatial scales using behavioral observations, movement analyses, and resource selection functions. Bison and cattle differed in all behaviors (grazing, standing, bedded, moving, other); however, landscape attributes resulted in behavior differences within species. Cattle spent a higher proportion of time grazing (45-49%) than bison (26-28%) and increased time at water. Bison moved at a 50-99% faster rate than cattle, and first passage time movement analyses identified selection of bison foraging patches (11 690 ha) larger than cattle foraging patches (48-615 ha). Similar to cattle, bison avoided most vegetation communities in relation to riparian communities and selected areas closer to water. Cattle selected for high plant biomass, whereas bison selected for intermediate plant biomass. This study has implications when bison and cattle are used to meet prairie restoration objectives. For bison, large landscapes that include variation in topography and vegetation communities are required. Furthermore, limiting manmade water sources may facilitate bison grazing patterns that more closely approximate historical bison use. For livestock, reduced movement and increased time spent grazing encourage grazing practices that increase heterogeneous grazing at a pasture scale.
    • Comparison of Season-Long Grazing Applied Annually and a 2-Year Rotation of Intensive Early Stocking Plus Late-Season Grazing and Season-Long Grazing

      Owensby, Clenton E.; Auen, Lisa M. (Society for Range Management, 2013-11-01)
      This research measured steer gains, aboveground biomass remaining at the end of the growing season, and economic returns of tallgrass prairie grazed under season long stocking (SLS-C) and a grazing system that included a 2-yr rotation of SLS rotated (SLS-R) and intensive early stocking (IES; 2X normal stocking rate) + late season grazing at the normal stocking rate (IES + LSG-R). We hypothesized that even though the stocking rate on the IES + LSG-R pasture was above the recommended rate, the greater regrowth availability in the late season would result in steers gaining as well as or better than those stocked SLS at the normal rate. By rotating the IES + LSG treatment with SLS over 2 yr, we anticipated that the aboveground biomass productive capacity of the IES + LSG pasture would be restored in one growing season. Further, we hypothesized that the increased stocking rate with IES + LSG would increase net profit. Comparing traditional season-long stocking to the system, which was a combination of SLS and IES + LSG rotated sequentially over a 2 yr period, the system increased steer gains by 7 kg . hd-1 and by 30 kg ha-1, had a consistent reduction of 429 kg ha-1 biomass productivity, and increased net profit by 55.19 per steer and 34.28 per hectare.
    • Conservation Program Participation and Adaptive Rangeland Decision-Making

      Lubell, M. N.; Cutts, B. B.; Roche, L. M.; Hamilton, M.; Derner, J. D.; Kachergis, E.; Tate, K. W. (Society for Range Management, 2013-11-01)
      This paper analyzes rancher participation in conservation programs in the context of a social-ecological framework for adaptive rangeland decision-making. We argue that conservation programs are best understood as one of many strategies of adaptively managing rangelands in ways that sustain livelihoods and ecosystem services. The framework hypothesizes four categories of variables affecting conservation program participation: operation/operator characteristics, time horizon, social network connections, and social values. Based on a mail survey of California ranchers, multinomial logit models are used to estimate the impact of these variables on different levels of rancher involvement in conservation programs. The findings suggest that ranchers with larger amounts of land, an orientation towards the future, and who are opinion leaders with access to conservation information, are more likely to participate in conservation programs.
    • Grazing and Grazing Exclusion Along a Resource Gradient in Magellanic Meadows of Tierra del Fuego

      Collantes, Marta B.; Escartín, Celina; Braun, Karen; Cingolani, Ana; Anchorena, Juan (Society for Range Management, 2013-11-01)
      Although Magellanic meadows have been subject to ungulate herbivory for a long time; they have suffered severe grazing by domestic sheep since the end of the 19th century. We hypothesized that, if protected from grazing, the present dominant dwarf forms would be replaced by taller competitive forms, mainly grasses. We then monitored floristic composition along a gradient of soils over periods of 5 to 16 yr on seven meadow sites under grazing and, in five, also on exclosures. Initial and final floristic samples were classified with TWINSPAN and ordinated with Detrended Correspondence Analysis (DCA). We also tracked cover changes in life-forms (grasses, dwarf sedges/rushes, rhizomatous helophytes, and cushion shrubs). At the end of the study, we assessed floristic similarity between paired grazed and exclosed treatments, and compared their life-form cover, diversity, biomass, and soil compaction with Student’s t and Mann-Whitney’s tests. Temporal displacements of composition in ordination space showed the effect of a long drought (DCA axis 1) and of grazing removal (DCA axis 2). Grazing exclusion had a much greater impact in wet meadows–where grasses became the dominant life-form–than in dry meadows. The effect of drought was shown in 1) the expansion of the cushion shrub Azorella trifurcata (Gaertn.) Pers. in both grazed and nongrazed treatments of the drier wetlands; 2) the decrease in Caltha sagittata Cav. in riparian meadows, and its encroachment under grazing in the wettest spring meadow; and 3) the large increase in Poa pratensis L. in exclosed wet meadows. Despite this strong response to environmental conditions, overall results supported the idea that these wetlands are equilibrium systems. Although the drier meadows have crossed an irreversible threshold, the Caltha-encroached wet meadows returned to a grass state in about 4 yr when protected from grazing. Their resilience suggests that they could be partly restored with rest-rotation grazing.
    • Influence of Wildland Fire Along a Successional Gradient in Sagebrush Steppe and Western Juniper Woodlands

      Strand, Eva K.; Bunting, Stephen C.; Keefe, Robert F. (Society for Range Management, 2013-11-01)
      Western juniper (Juniperus occidentalis Hook. var. occidentalis) has been expanding into sagebrush (Artemisia L. spp.) steppe over the past 130 yr in Idaho, Oregon, and California. Fuel characteristics and expected fire behavior and effects change as sagebrush steppe transitions into juniper woodlands. Little is currently known about how wildfire influences burn severity and ecosystem response in steppe altered by woodland conversion. In 2007, the Tongue-Crutcher Wildland Fire burned 18 890 ha along a successional gradient ranging from sagebrush steppe to mature juniper woodlands, providing a unique opportunity to evaluate the effects of prefire vegetation on burn severity and ecosystem response across spatial scales. Plot-scale burn severity was evaluated with the composite burn index (CBI) in locations where prefire vegetation data were available, and landscape-scale burn severity was estimated via remotely sensed indices (differenced normalized burn ratio [dNBR] and relative differenced normalized burn ratio [RdNBR]). Strong positive relationships exist between CBI and remotely sensed burn severity indices in woodlands, whereas the relationships are weaker in steppe vegetation. Woodlands in late structural development phases, and sagebrush patches near developed woodlands, incurred higher burn severity than steppe and young woodlands. The results support the idea that a threshold exists for when juniper-encroached sagebrush steppe becomes difficult to restore. Implications for fire management in sagebrush/juniper ecosystems are discussed.
    • Legumes in Chinese Natural Grasslands: Species, Biomass, and Distribution

      Jin, Dongmei; Ma, Jianjing; Ma, Wenhong; Liang, Cunzhu; Shi, Yue; He, Jin-Sheng (Society for Range Management, 2013-11-01)
      The composition and abundance of legumes affect the economic value and ecological sustainability of natural grasslands. We collected data on species richness and aboveground biomass of legumes and their percentages of the total community at 78 field sites in Chinese natural grasslands on the Tibetan Plateau (alpine steppe and alpine meadow) and in Inner Mongolia (meadow steppe, typical steppe, and desert steppe), and analyzed the association between these attributes with community, climate, and soil factors. At least one legume species occurred in 89.7% of the sites studied; the genera Astragalus, Oxytropis, and Medicago were dominant among the 12 legume genera recorded. Generally, within 1 m2 of grassland, only one legume species was present with an aboveground biomass of 1.1 g; this accounted for 9.1% of community species richness and 1.7% of total aboveground biomass. In comparison with many other types of grassland around the world, both the legume aboveground biomass and its percentage of the total were low in Chinese grasslands, especially in Inner Mongolia. The low biomass of legumes in grassland might be attributable to the low growing-season temperature on the Tibetan Plateau, while in Inner Mongolia, low precipitation combined with high temperatures during the growing season may be the main reason. Although legumes in Chinese grasslands have substantial potential for nitrogen fixation and contain a variety of forage species, their ecological and economic value has been limited by their low biomass. Suggestions to enhance legume biomass in Chinese grasslands are provided.
    • Outplanting Wyoming Big Sagebrush Following Wildfire: Stock Performance and Economics

      Dettweiler-Robinson, Eva; Bakker, Jonathan D.; Evans, James R.; Newsome, Heidi; Davies, G. Matt; Wirth, Troy A.; Pyke, David A.; Easterly, Richard T.; Salstrom, Debra; Dunwiddie, Peter W. (Society for Range Management, 2013-11-01)
      Finding ecologically and economically effective ways to establish matrix species is often critical for restoration success. Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) historically dominated large areas of western North America, but has been extirpated from many areas by large wildfires; its re-establishment in these areas often requires active management. We evaluated the performance (survival, health) and economic costs of container and bare-root stock based on operational plantings of more than 1.5 million seedlings across 2 200 ha, and compared our plantings with 30 other plantings in which sagebrush survival was tracked for up to 5 yr. Plantings occurred between 2001 and 2007, and included 12 combinations of stock type, planting amendment, and planting year. We monitored 10 500 plants for up to 8 yr after planting. Survival to Year 3 averaged 21% and was higher for container stock (30%) than bare-root stock (17%). Survival did not differ among containerstock plantings, whereas survival of bare-root stock was sometimes enhanced by a hydrogel dip before planting, but not by mycorrhizal amendments. Most mortality occurred during the first year after planting; this period is the greatest barrier to establishment of sagebrush stock. The proportion of healthy stock in Year 1 was positively related to subsequent survival to Year 3. Costs were minimized, and survival maximized, by planting container stock or bare-root stock with a hydrogel dip. Our results indicate that outplanting is an ecologically and economically effective way of establishing Wyoming big sagebrush. However, statistical analyses were limited by the fact that data about initial variables (stock quality, site conditions, weather) were often unrecorded and by the lack of a replicated experimental design. Sharing consistent data and using an experimental approach would help land managers and restoration practitioners maximize the success of outplanting efforts.
    • Performance of Quantitative Vegetation Sampling Methods Across Gradients of Cover in Great Basin Plant Communities

      Pilliod, David S.; Arkle, Robert S. (Society for Range Management, 2013-11-01)
      Resource managers and scientists need efficient, reliable methods for quantifying vegetation to conduct basic research, evaluate land management actions, and monitor trends in habitat conditions. We examined three methods for quantifying vegetation in 1-ha plots among different plant communities in the northern Great Basin: photography-based grid-point intercept (GPI), linepoint intercept (LPI), and point-quarter (PQ). We also evaluated each method for within-plot subsampling adequacy and effort requirements relative to information gain. We found that, for most functional groups, percent cover measurements collected with the use of LPI, GPI, and PQ methods were strongly correlated. These correlations were even stronger when we used data from the upper canopy only (i.e., top “hit” of pin flags) in LPI to estimate cover. PQ was best at quantifying cover of sparse plants such as shrubs in early successional habitats. As cover of a given functional group decreased within plots, the variance of the cover estimate increased substantially, which required more subsamples per plot (i.e., transect lines, quadrats) to achieve reliable precision. For GPI, we found that that six-nine quadrats per hectare were sufficient to characterize the vegetation in most of the plant communities sampled. All three methods reasonably characterized the vegetation in our plots, and each has advantages depending on characteristics of the vegetation, such as cover or heterogeneity, study goals, precision of measurements required, and efficiency needed.
    • Spring Clipping, Fire, and Simulated Increased Atmospheric Nitrogen Deposition Effects on Tallgrass Prairie Vegetation

      Smart, Alexander J.; Scott, Tabithia K.; Clay, Sharon A.; Clay, David E.; Ohrtman, Michelle; Mousel, Eric M. (Society for Range Management, 2013-11-01)
      Defoliation aimed at introduced cool-season grasses, which uses similar resources of native grasses, could substantially reduce their competitiveness and improve the quality of the northern tallgrass prairie. The objective was to evaluate the use of early season clipping and fire in conjunction with simulated increased levels of atmospheric nitrogen deposition on foliar canopy cover of tallgrass prairie vegetation. This study was conducted from 2009 to 2012 at two locations in eastern South Dakota. Small plots arranged in a split-plot treatment design were randomized in four complete blocks on a warm-season grass interseeded and a native prairie site in east-central South Dakota. The whole plot consisted of seven treatments: annual clip, biennial clip, triennial clip, annual fire, biennial fire, triennial fire, and undefoliated control. The clip plots consisted of weekly clipping in May to simulate heavy grazing. Fire was applied in late April or early May. The subplot consisted of nitrogen applied at 0 or 15 kg N ha-1 in early June. All treatments were initially applied in 2009. Biennial and triennial treatments were reapplied in 2011 and 2012, respectively. Canopy cover of species/major plant functional groups was estimated in late August/early September. Annual clipping was just as effective as annual fire in increasing native warm-season grass and decreasing introduced cool-season grass cover. Annual defoliation resulted in greater native warm-season grass cover, less introduced coolseason grass cover, and less native cool-season grass cover than biennial or triennial defoliation applications. Low levels of nitrogen did not affect native warm-season grass or introduced cool-season cover for any of the defoliation treatments, but it increased introduced cool-season grass cover in the undefoliated control at the native prairie site. This study supports the hypothesis that appropriately applied management results in consistent desired outcomes regardless of increased simulated atmospheric nitrogen depositions.
    • Stocking Rate and Fuels Reduction Effects on Beef Cattle Diet Composition and Quality

      Clark, Abe; DelCurto, Tim; Vavra, Martin; Dick, Brian L. (Society for Range Management, 2013-11-01)
      An experiment was conducted to evaluate the influence of forest fuels reduction on diet quality, botanical composition, relative preference, and foraging efficiency of beef cattle grazing at different stocking rates. A split plot factorial design was used, with whole plots (3 ha) being fuel reduced or no treatment (control), and split plots (1 ha) within whole plots were grazed to three levels of forage utilization; (low) 3 heifers .  ha-1, (moderate) 6 heifers ha-1, (high) 9 heifers ha-1, with a 48-h grazing duration. Grazing treatments were applied in August of 2005 and 2006. Cattle diet composition and masticate samples were collected during 20-min grazing bouts using six ruminally cannulated cows in each experimental unit. Relative preference indices indicated a strong preference for grass regardless of treatment and stocking rate. Grass consumption was lower in control pastures (P<0.05) and tended (P<0.095) to decrease with increased stocking rates. Shrub use was higher in control pastures displaying a quadratic effect (P<0.05) due to stocking, whereas shrub use increased with stocking rate across all treatments. Cattle grazing control pastures consumed diets higher in crude protein compared to cattle grazing treated pastures (P<0.05). In vitro dry matter digestibility values were lower (P<0.05) in control sites and tended (P=0.10) to decrease with increased stocking rates. In both control and treated pastures, bites per minute and grams consumed per minute declined (P=0.003) with increased stocking, indicating foraging efficiency of cattle decreases with increased stocking rates. Our data indicated cattle grazing late season grand fir habitat types have a strong preference for grasses regardless of treatment or stocking rate. However, as stocking rate increased in both control and treated pastures, grass consumption decreased, shrub consumption increased, and foraging efficiency decreased.
    • Woody Cover and Grass Production in a Mesquite Savanna: Geospatial Relationships and Precipitation

      Ansley, R. J.; Mirik, M.; Heaton, C. B.; Wu, X. B. (Society for Range Management, 2013-11-01)
      Woody plant effects on grass production at specific points in some rangeland savannas may be a function of numerous surrounding woody plants with lateral roots that extend into those patches of grass. This study determined the effects of increasing zones of honey mesquite (Prosopis glandulosa Torr.) influence on the production of three perennial grass types (C4 shortgrasses, C3 midgrasses, and C4 midgrasses) at specific points in gaps between mesquite trees in each of five years. Mesquite canopy cover was determined by geospatial analysis of aerial images for progressively increasing zones (0-5, 0-10, 0-15, and 0-20 m radius) surrounding each grass production point. The woody cover/grass production relationships were mostly linear for C4 shortgrasses and C3 midgrasses, and mostly a declining exponential curve for C4 midgrasses in all canopy zones, indicating that C4 midgrasses were most sensitive to increasing mesquite cover, especially at covers >30%. The relationship between mesquite cover and C4 shortgrass production was strongest (i.e., highest r2) when the smallest woody cover zones (0-5 and 0-10 m) were included. In contrast, the relationship between cover and C4 midgrass production was strongest when the largest zones (0-15 and 0-20 m) were included. These differences were attributed to an inability of C4 midgrasses to persist in smaller intercanopy gaps resulting from increases in mesquite density and infilling. Annual precipitation and C3 annual grass invasions played a large role in determining the woody cover/grass production relationship for each grass type. This study illustrates the complexity involved in quantifying woody cover/grass production relationships in savanna ecosystems. Maintaining productive stands of C4 midgrasses may be facilitated by maintaining woody cover below 30% threshold levels and possibly by limiting grazing during episodic high rainfall events in midsummer when this grass type becomes somewhat decoupled from woody cover effects.