• Long-term vegetation change provides evidence for alternate states in silver sagebrush

      Kachergis, E.; Rocca, M. E.; Fernández-Giménez, M. E. (Society for Range Management, 2014-03)
      A key goal in land management is to prevent ecosystem shifts that affect human well-being. Like other types of sagebrush shrublands, large areas dominated by the common but little-studied mountain silver sagebrush may have shifted to a less productive shrub-dominated alternate state under heavy livestock grazing in the 19th century. The goals of this study are to 1) describe long-term vegetation change in a silver sagebrush mountain park and 2) evaluate evidence that these changes constitute alternate states. We examined vegetation change over the last 57 yr in California Park, Colorado, USA, using monitoring data from 15 permanent transects at six sites. We analyzed change in species composition over time and related it to management and climatic drivers using nonmetric multidimensional scaling. We found that management practices influenced species composition. Spraying herbicides resulted in decreases of sagebrush and a dominant, unpalatable forb (Wyethia amplexicaulis), but sagebrush recovered. Spraying also triggered a temporary increase in native palatable grasses and forbs. Native grasses have since decreased again, coinciding with increases in the cattle stocking rate and elk population. The nonnative pasture grass Phleum pratense has increased to become one of the dominant grasses in 2010. Sagebrush and herbaceous understory dynamics were not consistent with a shrub-dominated alternate state: changes were gradual and not persistent. However, historic Wyethia dominance and the widespread increase in the nonnative grass Phleum were persistent and may represent alternate states. We used these findings to update a state-and-transition model of high-elevation silver sagebrush shrubland dynamics for land management decision making. Our analysis differentiated gradual, nonpersistent changes from potentially irreversible changes, as is necessary for identifying alternate states that are important for land management and ecosystem function. The gradual but persistent increase in the nonnative grass Phleum reinforces others' observations that even incremental changes may lead to irreversible shifts. © 2014 The Society for Range Management.
    • Near infrared spectroscopy and fecal chemistry as predictors of the diet composition of white-tailed deer

      Jean, P. -O.; Bradley, R. L.; Giroux, M. -A.; Tremblay, J. -P.; Côté, S. D. (Society for Range Management, 2014-03)
      Overbrowsing by white-tailed deer (Odocoileus virginianus Zimmermann) on Anticosti Island (Canada) created a need to develop efficient methods for estimating their foraging patterns. We tested the ability of near infrared (NIR) spectra of feces and of fecal chemical properties to predict diet composition of different individuals. We first used a principal component-based discriminant analysis to sort the NIR spectra of fecal samples (n-=-102) obtained from two groups of captive deer that had been fed two different diets. The diets differed only in their relative abundance of balsam fir (Abies balsamea "L." P.Mill.) and white spruce (Picea glauca "Moench" Voss.) foliage. The calibrated model allowed us to assign 28 of 30 validation fecal samples (93.3 %) to the correct diet. In a second study, we attempted to estimate the proportion of coniferous, deciduous, herbaceous, and lichenous forages in diets of free-ranging white-tailed deer, as determined by fecal microhistology. Both NIR spectra and chemical properties of feces were used as predictors of diet composition. NIR spectra were analyzed using partial least-squares regression (PLSR), whereas fecal chemical properties were analyzed using mixed-linear regressions (MLRs). The PLSR models were robust (R2-=-0.89; ratio of prediction to deviation-=-3.2) for predicting the amount of coniferous fragments, but not for predicting the relative amounts of balsam fir, white spruce, and deciduous and lichenous fragments within feces. MLR models revealed a positive relationship (47% variance explained) between acid detergent lignin (ADL) and coniferous fragments within feces. ADL and cellulose explained 24% of variance in deciduous fecal fragments, whereas ADL alone explained 22% of variance in balsam fir fecal fragments. These results suggest that NIR spectroscopy and fecal chemical properties have several applications on Anticosti Island, such as measuring the degree of variation in diets within a given home range or determining dietary conifer intake during winter. © 2014 The Society for Range Management.
    • Perception and management of spatio-temporal pasture heterogeneity by hungarian herders

      Molnár Z. (Society for Range Management, 2014-03)
      The goal of our study was to document traditional steppe herders' perception and management of spatial and temporal heterogeneity of forage availability of their seminatural pastures. Ninety-two herders living in the Hortobágy saline steppe, Hungary, Central Europe were interviewed, and participatory observation was used to understand herding and habitat improvement techniques. The herders recognized 47-66 habitat types (mostly grassland types), and listed at least 90 plant species important for grazing. They have a nuanced knowledge of the intra- and interannual variations of forage quality and quantity. They perform very strong and well-planned herding practices. Daily spatial pattern of grazing is, however, often opportunistic and flexible, but has a more-or-less regular year-round cycle, in which marshes and stubbles provide forage in drought periods. Reciprocal learning and continuous communication between the herder and his driving dogs and livestock strongly influence grazing pattern. Herders manage and improve different habitats of their pastures differently by traditional and, less frequently, modern methods. The main method is grazing supplemented by manuring, burning, and removal of spiny weeds. Traditional knowledge of herders could be effectively used in evidence-based conservation and pasture management of European saline steppes; e.g., the reintroduction of some old herding techniques (opportunistic pasture use, grazing of marshes, and burning). Herders' knowledge could also help the fine-tuning and local adaptation of European agri-environmental regulations (e.g., how to balance subsidies for hay-making and grazing in saline steppes). More research is needed, however, on the ecological effects of different traditional grazing techniques, e.g., rotation, manuring, and burning. In general a more complex socio-ecological understanding of the internal and external factors affecting adaptation of the Hortobágy herders to changing environment, society, and European Union policies is needed. © 2014 The Society for Range Management.
    • Root biomass and distribution patterns in a semi-arid mesquite savanna: Responses to long-term rainfall manipulation

      Ansley, R. J.; Boutton, T. W.; Jacoby, P. W. (Society for Range Management, 2014-03)
      Expansion of woody plants in North American grasslands and savannas is facilitated in part by root system adaptation to climatic extremes. Climatic extremes are predicted to become more common with global climate change and, as such, may accelerate woody expansion and/or infilling rates. We quantified root biomass and distribution patterns of the invasive woody legume, honey mesquite (Prosopis glandulosa), and associated grasses following a long-term rainfall manipulation experiment in a mixed grass savanna in the southern Great Plains (United States). Root systems of mature trees were containerized with vertical barriers installed to a depth of 270 cm, and soil moisture was manipulated with irrigation (Irrigated) or rainout shelters (Rainout). Other treatments included containerized, precipitation-only (Control) and noncontainerized, precipitation-only (Natural) trees. After 4 yr of treatment, soil cores to 270 cm depth were obtained, and mesquite root length density (RLD) and root mass, and grass root mass were quantified. Mesquite in the Rainout treatment increased coarse-root (->-2 mm diameter) RLD and root mass at soil depths between 90 cm and 270 cm. In contrast, mesquite in the Irrigated treatment increased fine-root (-<-2 mm diameter) RLD and root mass between 30 cm and 270 cm depths, but did not increase total root mass (fine-+-coarse) compared to the Control. Mesquite root-to-shoot mass ratio was 2.8 to 4.6 times greater in Rainout than the other treatments. Leaf water stress was greatest in the Rainout treatment in the first year, but not in subsequent years, possibly the result of increased root growth. Leaf water use efficiency was lowest in the Irrigated treatment. The increase in coarse root growth during extended drought substantially increased mesquite belowground biomass and suggests an important mechanism by which woody plant encroachment into grasslands may alter below ground carbon stocks under climate change scenarios predicted for this region. © 2014 The Society for Range Management.
    • Vegetation responses to Pinyon-Juniper treatments in Eastern Nevada

      Provencher, L.; Thompson, J. (Society for Range Management, 2014-03)
      Comparisons of tree-removal treatments to reduce the cover of single-leaf pinyon (Pinus monophylla Torr. and Frém.) and Utah juniper (Juniperus osteosperma Torr. Little), and subsequently increase native herbaceous cover in black sagebrush (Artemisia nova A. Nelson), are needed to identify most cost-effective methods. Two adjacent vegetation management experiments were initiated in 2006 and monitored until 2010 in eastern Nevada to compare the costs and efficacy of various tree reduction methods. One Department of Energy (DOE) experiment compared a control to five treatments: bulldozing imitating chaining ($205-·-ha-1), lop-pile-burn ($2-309-·-ha-1), lop-and-scatter ($1-297- ·-ha-1), feller-buncher and chipper ($4-940-·- ha-1), and mastication ($1-136-·-ha-1), whereas a second Bureau of Land Management (BLM) experiment compared one-way chaining ($205-·-ha-1) to a control treatment. Chaining and bulldozing resulted in the least reduction of tree cover among the treatments. In the DOE experiment, forb cover only decreased in the mastication treatment. Litter increased in all methods. Slash cover was lowest in the control and lop-pile-burn treatments, intermediate in the feller-buncher and mastication treatments, and highest in the bulldozing and lop-and-scatter treatments. By 2010, forb cover and the combined cover of dead shrubs and trees were increased and decreased, respectively, by chaining in the BLM experiment. Nonnative annual grass and biotic crust were absent or uncommon before and after treatment implementation. In both experiments, tree removal resulted in a nonsignificant increase in perennial grass cover even 4 yr post-treatment. An ecological return-on-investment (EROI) metric was developed to compare perennial grass cover and tree cover per unit area cost of each active treatment. By 2010, chaining or bulldozing, followed by mastication, showed the highest EROI for improving perennial grass and decreasing tree cover. Mastication is recommended for restoration of smaller tree-encroached areas, whereas land managers should reconsider smooth chaining, despite its negative perceptions, for rapid and cost-efficient restoration of large landscapes obligates. © 2014 The Society for Range Management.