Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact email@example.com with any questions.
Timber harvesting in riparian zones without leaving a buffer can increase the likelihood of livestock grazing along streams. The wet soil around small streams can accentuate the negative impact of grazing, affecting vegetation, as well as other ecosystem characteristics. In this study, we tested the effectiveness of using coarse woody debris, a readily available barrier method to reduce the effects of livestock grazing after timber harvesting on small stream vegetative and other ecosystem values over two grazing seasons. We placed debris barriers within four recently harvested cutblocks where livestock graze seasonally on extensive, forested rangeland in the Okanagan region of Interior British Columbia, Canada. We sampled cover, species richness, bare soil, litter, biomass, trampling, and manure within 0.25m2 quadrats to determine the effectiveness of the barriers on these variables over two grazing seasons. We used log response ratios to compare the pretreatment and post-treatment values of these variables in control plots and plots with debris barriers. We also used log response ratios to test the effect of debris barriers on biomass utilization within and outside 1-m2 cages. Results varied by site: debris barriers resulted in improved richness and litter in two sites each, reduced trampling in three sites, and reduced bare soil in one site when compared with plots without barriers. Barriers also increased cover in one site but had no influence on manure. Biomass utilization was significantly reduced by debris barriers in uncaged grazed plots compared with caged plots. Debris barriers can be a convenient tool to mitigate the potential negative effects of livestock grazing after timber harvest in and around small headwater streams.
Land management decisions need context about how landscapes will respond to different circumstances or actions. As ecologists' understanding of nonlinear ecological dynamics has evolved into state-and-transition models (STMs), they have put more emphasis on defining and mapping the soil, geomorphological, and climate parameters that mediate these dynamics. The US Department of Agriculture Natural Resources Conservation Service ecological site descriptions (ESDs) have become the foremost system in classifying lands into ecological units based on STMs. However, an exhaustive inventory of ESDs has proved challenging to complete in the United States, and there have been questions about the consistency of detail in areas completed and the ability to objectively support some assertions made in existing ESDs. To address these issues, this study examines ESDs in the diverse Upper Colorado River region, where ESDs are only partially complete, to look at quantitative approaches to generalizing ecological site concepts based on unifying underlying soil, geomorphology, and climate patterns. Using existing ESDs and vegetation monitoring plot data, results show that a simple hierarchical soil geomorphic unit (SGU) framework based on topographic mediation of moisture, soil salinity, soil depth, slope, rock content, and soil texture can represent much of the ecological dynamics cataloged in ESDs. Analyses of reference plant production data, ecological state attribution, and regional monitoring data show that the new SGUs represent more variation than common climate parameters. This study also included predictively mapping SGUs at 30-m resolution (Kappa of 0.53, 74% agreement with top two predictions in validation). An optimized combination of SGUs with climate zones derived from an aridity index and maximum temperature of the hottest month resulted in an ecological site group framework that condensed over 826 unique ecological site records at various stages of completeness in the regional soil survey down to 35 intuitive and mappable ecological site groups.
Biosolids application in semiarid rangelands has been proposed as a viable alternative for the rehabilitation of degraded soils. We analyzed the effect of rate, time, and number of applications of biosolids per year on the growth of herbaceous vegetation. Summer and winter single applications and a dual application (summer + winter) of biosolids were tested in two soils (calcareous and igneous) of the southern Chihuahuan desert at four rates (0, 3.5, 7, and 10.5 Mg/ha). A single period of vegetation growth occurs in the summer in this region. No major net changes in biomass were recorded with one application of biosolids in the summer or winter applications on both soil types. Winter biosolids application increased the annual species cover on igneous soil. However, annual species cover decreased in the second year on both soil types with one application (summer) or two applications (summer + winter) of biosolids. The lack of synchrony between the availability of NO3-N and moisture may have been the reason for the highly variable response of vegetation growth on calcareous soil. The igneous soil had better soil moisture retention, probably allowing for increased uptake of nitrate by plants. The largest increases in both biomass and plant cover were obtained for perennials with the dual strategy of biosolids application on igneous soil at higher rates. The patterns of plant biomass and cover responses to biosolids application were different on each functional group and soil type. Biosolids application rate and timing are important for enhancing plant productivity in semiarid areas; overall biosolids should be considered as a viable amendment for rangeland restoration.
Arbuscular mycorrhizal (AM) fungi play a major role in maintaining ecosystem functions. AM fungi are found in most ecosystems including rangelands currently under increasing pressures from human activities. Southern Patagonia (Argentina) is a semiarid region influenced by extensive livestock production in rangelands. There is a lack of information about the environmental conditions and functionality of AM fungi in plant species of Patagonia ecosystems associated with livestock grazing. We assessed how soil properties, climatic conditions, and grazing intensities influence the response of AM fungi colonization. We studied most palatable and representative plant species (Poa dusenii, Rytidosperma virescens, Festuca gracillima, Nardophylum bryoides, Mulguraea tridens, and Carex argentina) growing in main ecological areas of Southern Patagonia. Most of the studied plant species (except C. argentina) presented AM symbiosis. AM colonization showed a negative relationship with soil organic carbon and nitrogen and a positive relationship with soil bulk density and pH. Results suggest that plants promoted a higher root AM colonization when soil nutrients and water availability (rainfall) are limiting. Sheep stocking rates had a differential impact depending on the ecological areas and plant life forms. High grazing decreased the AM colonization in the ecological areas with palatable plant dominance, suggesting that the impacts of grazing could lead to further negative effects on the ecosystem. Moderate grazing allows to maintain higher AM colonization, which would probably benefit the aboveground production of palatable plant and, consequently, to herbivores, particularly in degraded rangelands like Patagonian steppes. This study improves the knowledge of AM association in Patagonian semiarid rangelands by increasing our understanding of the impacts of grazing on belowground ecology. This information becomes relevant for grazing sustainable management, which may contribute to food security.
On public lands grazing allotments in the western US sagebrush steppe, cattle are generally excluded from burned pastures for 2 yr post fire. If only a portion of a pasture burns, the burned area may be fenced, allowing for cattle grazing to resume in the unburned portion. However, traditional wire-based fencing is often not an option due to expense, conflicts with wildlife management objectives, and extensive procedural logistics. We evaluated the use of a “virtual fence” (VF) for excluding cattle from burned areas within small pastures in the sagebrush steppe of southeast Oregon. VF technology (Vence Corporation, San Francisco, CA) uses satellite-controlled collars that direct animal movement within user-defined polygons using auditory and electrical cues. We fall-burned a 0.6-ha area in each of six adjacent 2.1-ha pastures in a Wyoming big sagebrush plant community in 2019. In June 2020, each pasture was stocked with 3 mature dry cows for 14 d. All cows were fitted with VF collars; collars were programed to create a virtual fence around the burned area within three of the pastures (VF treatment), and remaining pastures had electrical and auditory cues turned off (control treatment). Collars recorded animal location every 5 min. Cows in the control treatment initially spent up to 40% of their time within the burned area, and forage utilization of the burned area was nearly 70%. Cows in the VF treatment spent approximately 4% of their time in the burned area on day 1 and were recorded in the burn only incidentally thereafter; forage utilization in the burn was < 3%. Our trial suggests VF technology is effective in controlling rangeland cattle movements and can severely curtail use of burned areas. Additional work is needed to evaluate VF technology in larger rangeland settings.
In temperate rangelands, the timing of livestock breeding is managed so that most births occur late winter to midspring. Nutrient demands of young livestock increase steadily as they grow, while nutrients supplied by rangelands typically increase in spring and then decline through summer as plant tissues mature and senesce. Timing births in late winter rather than spring can increase weight gain of young livestock by ensuring young are larger and in need of more nutrition when forage quality is greatest, but this risks exposing newborns to lethal cold. We studied effects of calving date on weight gain and exposure risk of beef calves using 82 yr of data from the western United States. Our analysis indicated that, averaged over study years, 180-d-old calves weighed 13% ± 5.0% more (mean, 95% confidence interval) when born at the beginning (early March) compared with the end (early May) of our studied calving interval. Early calving likewise appeared to benefit calf production (weight of 180-d-old surviving calves per calf born), with benefits increasing as climate warming reduced neonatal mortality from cold exposure. Compared with calf production from early May calving, estimated calf production from early March calving was 8% ± 4% greater in the 1940s and 10% ± 4% greater in the 2010s (P < 0.001). Continued late winter and early spring warming would further increase benefits of early calving.
Woody plant encroachment has serious negative consequences for ranchers because of the reduction in herbaceous fodder for domestic livestock. A long-term monitoring of a tree-thinning experiment was established near Magudu (northern KwaZulu-Natal, South Africa) in 1990. The objective of this experiment was to determine the optimal tree density that would maximize grass production while benefiting grasses from nitrogen fixation, hydraulic lift, and/or shade from the leguminous trees. The initial dominant species was the nitrogen-fixing tree, Dichrostachys cinerea. There were 12 plots (6 pairs) with trees removed to approximate 0, 179, 277, 428, and 625 trees ha–1, with 1 pair left as a control (unmanipulated). One plot of each replicate (except the controls) was treated with short-acting herbicide (picloram) once in 1990. We collected data on herbaceous cover and species composition, tree species composition, sizes, and mortality. We also used remote sensing to examine the patterns of herbaceous cover. Herbaceous biomass decreased as tree density increased. After 30 yr, the same dominant tree species (D. cinerea) had reinvaded all the removal plots despite the fact that several encroaching species (Vachellia karroo, V. tortilis, V. nilotica) occurred in these plots. These D. cinerea trees were mostly less dense and contained many more juvenile individuals in the cleared and partially cleared plots than those in the control plots after 30 yr. Should maximizing herbaceous cover be the goal, repeated brush management would be necessary to maintain adequate control of woody plants in these savannas.
There has been a limited understanding of herdsmen's livestock reduction behavior (positive vs. negative) as an evaluation index of the successful implementation of the grassland subsidy and reward policy in Inner Mongolia (IM). In remedy, we investigated herdsmen livestock reduction behavior and the strategies involved based on the survey data obtained from 844 herdsmen in 15 banners (counties) across the grassland types in IM using a sample t-test and Binary Logit model. We found that herdsmen with lower total cash income, fewer livestock resources, lower nonhusbandry income, and those living farther away from the city complied with the policy directive by reducing livestock numbers. More herdsmen in the desert region (38.42%) decline stock size than other grassland types. Herdsmen of Han origin were more inclined to reduce livestock numbers than the Mongolia or Manzu group. There is a need to improve the incentives of the subsidy and reward program, incorporate technical managerial skills to educate herders on the merit of focusing on production per head of animals as collateral for livestock reduction to raise herdsmen income, and foster better grassland ecological environment. In addition, herdsmen who comply with the policy directive should be identified and offered more prosperous support, such as market information and better feeding strategies to promote the sustainability of their livelihood and the grassland ecosystem. It is suggested that the top-down approach of implementing the subsidy and reward policy in IM should be reversed for improved household welfare, compliance with policy directives, and sustainable pastoral development.