Rangeland Ecosystems Research Articles

Threats and challenges related to grazing paddocks: Recovery of extremely overgrazed grassland after grazing exclusion

Overgrazing causes serious problems for rangeland ecosystems and human livelihoods globally. Sheep grazing paddocks with fixed fences have become increasingly widespread in Europe; however, their effects on biodiversity have rarely been discussed. Our aim was to measure the degradation of grassland vegetation in an experimental sheep paddock in Central-Hungary, and evaluate recovery of alkali grasslands after the exclusion of grazing. We compared the vegetation of heavily overgrazed parcels to parcels excluded from overgrazing, treated with three doses of manure (0, 20 and 40t/ha), in the first three years of grassland recovery. The overgrazed parcels were dominated by nutrient-demanding ruderal plant species and the cover of target grassland species was only 19.8% in the third year. After grazing exclusion, the cover of target grassland species increased to 81.0% for Year 3. The dominant grass Festuca pseudovina became more abundant in the excluded parcels (51.1%) than in the overgrazed ones (8.9%). At the end of the experiment, the rate of degradation (0.2 vs. 3.7) and the cover-weighted ecological indicator values for nutrients (3.8 vs. 5.1) were significantly lower in the exclosures than in the overgrazed parcels. Manuring did not have a significant effect on grassland recovery; thus, it is not necessary in the studied ecosystem. We recommend avoiding grazing paddocks with fixed fence especially in areas harboring habitats of high conservation value. Besides resulting in the degradation of grasslands, grazing paddocks also act as landscape scars and propagule sources of problem species that might negatively affect the surrounding landscape.

Assessing the burning of household dung-cake as an energy source in different rangeland regions of Inner Mongolia

Abstract Burning of livestock dung as a fuel by herdsman households, representing one of the most critical determinants of biogeochemical cycle, has been a tradition for thousands of years in most rangeland regions worldwide. It has been suggested that returning livestock dung to pasture instead of burning them as fuel would benefit ecosystem health and carbon sequestration in rangelands. However, evidence-based studies on the driving factors of household dung-cake collection and burning in various rangeland regions are limited. Using a stratified random sampling approach, we did a household survey on the herders’ behaviors of dung-cake collection and burning, and investigated their relations with climate, availability of other energy sources, and household socioeconomic conditions, across the five rangeland regions in Inner Mongolia on August–November 2015. We found that the energy from dung-cake burning accounted for 34.90% of the total household energy consumption for cooking and heating, and it varied considerably across rangeland regions. The amount of dung-cake energy use in a household mainly depends on the length of cold period in a year (defined as the number of days with mean daily temperature below 5 °C), indicating dung-cake burning is a major and contingent way of heating in the long winter period in Inner Mongolia. Moreover, the reduction in the cold period but not availability of other energy sources can reduce the proportion of dung-cake energy in total household energy consumption. Reducing the quantity of dung collected and burnt by herders is promoted for both enhancing carbon sink capacity of rangeland ecosystems and improving indoor environmental quality of pastoral households. Our findings have important implications for understanding how ecological and socioeconomic factors affect household dung-cake use as fuel, and for developing low-carbon energy infrastructures and novel energy policies to facilitate the use of low-carbon energy sources for the benefit of carbon sequestration and environment.

Animal movement in a pastoralist population in the Maasai Mara Ecosystem in Kenya and implications for pathogen spread and control

Livestock movements are important drivers for infectious disease transmission. However, paucity of such data in pastoralist communities in rangeland ecosystems limits our understanding of their dynamics and hampers disease surveillance and control. The aim of this study was to investigate animal movement networks in a pastoralist community in Kenya, and assess network-based strategies for disease control. We used network analysis to characterize five types of between-village animal movement networks. We then evaluated implications of these networks for disease spread and control by quantifying topological changes in the network associated with targeted and random removal of nodes. To construct these networks, data were collected using standardized questionnaires (N = 165 households) from communities living within the Maasai Mara Ecosystem in southwestern Kenya. Our analyses show that the Maasai Mara National Reserve (MMNR), a protected wildlife area, was critical for maintaining village connectivity in the agistment network (dry season grazing), with MMNR-adjacent villages being highly utilized during the dry season. In terms of disease dynamics, the network-based basic reproduction number, R0, was sufficient to allow disease invasion in all the five networks, and removal of villages based on degree or betweenness was not efficient in reducing R0. However, we show that villages with high degree or betweenness may play an important role in maintaining network connectivity, which may not be captured by assessment of R0 alone. Such villages may function as potential “firebreaks.” For example, targeted removal of highly connected village nodes was more effective at fragmenting each network than random removal of nodes, indicating that network-based targeting of interventions such as vaccination could potentially disrupt transmission pathways in the ecosystem. In conclusion, this work shows that animal movements have the potential to shape patterns of disease transmission in this ecosystem, with targeted interventions being a practical and efficient measure for disease control.

Balancing Bees and Livestock: Pastoralist Knowledge, Perceptions and Implications for Pollinator Conservation in Rangelands, Northern Tanzania

Insect pollinators provide numerous ecosystem services that support other living organisms. While pollinators play a large role in cropping systems, little is known about their presence and function in rangeland ecosystems, which have recently become fragmented and overexploited at an extraordinary rate. We assessed local Maasai knowledge on insect pollinators and how pollinators affect livelihood diversification in Simanjiro rangelands, Tanzania. Through questionnaires, key informant interviews, focus group discussions, and field observations, we found varied insect knowledge among Maasai herders. Lasioglossum of sub genus Ipomalictus and Syriphidae were the least commonly recognized pollinators as only 24%, and 7% of participants could identify them, respectively. Responses varied significantly between men and women (F = 7.397, p = .007). Commiphora africana, Acacia mellifera and Albizia anthelmintica were noted as most important bee forage plants while observations showed Aspilia mossambicensis, Justicia debile and Acacia tortilis. Most (77%) of Maasai herders showed limited ability to link pollinators and rangeland wellbeing. Beekeeping contributed to livelihood diversification for 61% of respondents, with women participating more frequently than men (χ2 = 46.962, p = .0001). Beekeeping was positively influenced by education level ( R = .421, p < .0001) and occupation ( R = .194, p = .009). Pollinator declines were attributed to climate change (47%), agriculture (37%), and habitat destruction (8%). We conclude that Maasai have limited knowledge of common pollinator groups and their roles. Community outreach and training should bridge the knowledge gap in pastoralist communities to fully realize pollinator benefits and highlight the importance of rangeland health.

Dynamics and influence of environmental components on greenhouse gas emissions in sub-Saharan African rangelands: a review

Sub-Saharan African (SSA) countries consist of ~200 million livestock owners who utilise marginal rangelands as a feed resource base for their animals. These rangelands offer various resources to the communities and are in-turn vulnerable to climate change related challenges. Currently, information on greenhouse gases (GHG) emission from SSA rangelands is heavily dependent on the generic values generated by the Intergovernmental Panel on Climate Change (IPCC) Tier I trajectories on various aspects of the environment. There is, therefore, a need to identify research gaps between the dynamics and influences of environmental components, highlight their magnitude and potential aggregate contribution towards GHG emission in an SSA context. Rangeland sustainability, weather patterns, soils, plant biodiversity, and current methods used to measure GHG emission from rangelands are influenced by institutional, community, and national policy frameworks. Various intertwined environmental components exist within the SSA rangeland ecosystems and research has not extensively covered such interactions. It is crucial to generate a database that includes information of in-situ trajectories on GHG emission from soil properties, vegetation image maps using remote sensing and geographic information system, plant biodiversity indices, climatology, and animal husbandry aspects.

Investigating net primary production in climate regions of central Zagros, Iran, using MODIS and meteorological data

Rangeland production is sensitive to climate conditions. In this study, we monitored actual and potential production in the climate zones of Chaharmahal and Bakhtiari province in central Zagros, Iran, from 2000-2016. Net primary production (NPP), light use efficiency (LUE) and rain use efficiency (RUE) were extracted from climatic and MODIS satellite data using the Carnegie-Ames-Stanford approach (CASA) and Miami models. The accuracy of the modeled NPP maps was assessed using regression analysis, based on field data collected at 750 sites under different rangeland conditions. The spatial distribution of NPP and RUE indicated that annual production and photosynthetic efficiency in degraded rangelands with poor and very poor conditions have decreased compared to those of moderate-good classes. The highest relationship between the field and modeled NPP was associated with the Astragalus spp.-Ferula spp. (R2 = 0.865, p < 0.001) in the humid and cold climate zone with good rangeland conditions while the lowest was observed in the annual grasses-annual forbs (R2 = 0.198, p < 0.001) vegetation type with very poor rangeland conditions within the semi-arid and cold climate zone. Furthermore, the highest and lowest NPP values were observed in the Daphne mucronata-Prangos ferulacea (48.38 g C m-2 yr-1) and annual grasses-annual forbs (3.42 g C m-2yr-1) vegetation types with LUE values of 0.13 and 0.02 g C MJ-1 within the humid and cold and the semi-humid and cold climate zones, respectively. According to these findings, remote sensing-based differences between actual and potential NPP can be used as a valuable tool for identification of human impacts on broad rangeland ecosystems.

Can Collaborative Adaptive Management Improve Cattle Production in Multipaddock Grazing Systems?

Collaborative adaptive management (CAM) is hypothesized to benefit management of rangeland ecosystems, but the presumed benefits have seldom been quantified, and never in a multipaddock rotational grazing system. Here, we evaluated average daily weight gain (ADG) of livestock (kg steer−1 d−1) in four grazing management treatments during the summers of 2016−2018 in a semiarid shortgrass steppe. These four treatments had the same stocking rate but differed in stocking densities. The three lowest stocking densities were implemented using nonadaptive grazing management, while the highest stocking density was implemented using CAM by an 11-member Stakeholder Group. Three of the four treatments used multipaddock rotational grazing. Growing season precipitation varied from drought in 2016 to near average in 2017 and dry in 2018. During nondrought years, ADG under nonadaptive grazing declined linearly as stocking density increased from low to high. This relationship was not significant during drought (2016). CAM increased absolute livestock production by 0.13 to 0.19 kg steer−1 d−1 in nondrought years, or a 23−25% relative increase in ADG. This benefit of CAM arose from the Stakeholder Group's ability to rotate cattle in response to spatiotemporal heterogeneity across the landscape—i.e., the ability to graze the “right pastures at the right time.” Multiplying the additional grazing season livestock gains achieved through CAM by the monetary value of gains ($ kg−1) resulted in an estimated additional gross revenue return from CAM of $48.16 to $55.54 per steer annually, as compared with revenues from nonadaptive multipaddock rotational grazing under nondrought conditions. These results indicate that CAM, supported with substantial and timely monitoring data, can minimize decreases in livestock production associated with high stocking densities used in multipaddock rotation systems. However, in this experimental context, the economic benefits of increased livestock production associated with CAM were likely insufficient to offset the substantial cost of this approach.

Big landscapes meet big data: Informing grazing management in a variable and changing world

On the Ground • Rangeland-based livestock raising is the only agricultural production system that maintains native plant communities, providing ecosystem services in the same space as food and fiber production. • Annual aboveground net primary productivity (ANPP) underlies forage production and multiple ecosystem services. ANPP is highly variable in rangelands in the western United States, across the landscape, from year to year, and within a growing season. Variability is also increasing as the climate changes. • Grazing management decisions that determine when, where, and how much of ANPP is consumed by livestock, including stocking rate decisions, can ultimately determine rangeland health and the future sustainability of livestock production and provision of ecosystem services. • Yet managers' access to data on available forage and its variability is limited, and existing field methods to quantify forage production accurately require extensive sampling and are prone to errors or bias. • A variety of remotely sensed data sources exist to help characterize forage availability and how it has varied spatially and temporally over the last 30 or more years, as well as other datasets that can estimate available forage and inaccessible terrain for livestock. • We discuss the need for a state-of-the-art decision support tool that integrates available remote-sensing data on forage availability with land managers’ knowledge of local needs and information for managers to access to the depth and breadth of information they need to sustainably manage grazing under variable and changing conditions. • Such a decision support tool could help land managers better manage rangeland ecosystems with flexible stocking rates and adaptive grazing management opportunities that adjust to variations in ANPP, leading to increased regional and site-specific rangeland resilience.

Effect of grazing exclusion on soil and vegetation characteristics in desert steppe rangelands: a case study from north-western Iran

This case study examined the effect of grazing exclusion on the soil and vegetation characteristics to provide support for the restoration of the degraded desert steppe rangelands of the Arshagh ecoregion. Six sampling sites were selected (three overgrazed and three not grazed sites) from the ecoregion. Vegetation sampling (1 m2 area at 10 intervals) was carried out along 18 pieces of 90 m long transects. Soil samples were collected from the plots at the beginning, middle, and end of each transect from 0–15 cm depths and then combined to get one sample per transect. Differences between vegetation and soil properties of the grazing exclusion and overgrazed sites were analyzed using the t-test statistic. Species richness index (2.32), the diversity index (1.87), and plant cover (69.46%) were maximum at sites after 20-years of grazing exclusion. All species of plant functional types at the exclusion sites were significantly (p < 0.05) different from those at the overgrazed site. Total aboveground net primary production was greater at the exclusion sites (56.50 g/m2) than at the overgrazed sites. Soil pH was significantly (p < 0.05) higher at the exclusion site than at the overgrazed sites. Electrical conductivity was significantly higher at the overgrazed sites than at the exclusion sites. These results imply that livestock exclusion plays an important role in such vegetation parameters as the diversity, cover and soil properties of degraded rangeland ecosystems. Moreover, grazing exclusion in Arshagh rangelands may be a promising management option for the restoration of such rangelands.

A climate change indicator framework for rangelands and pastures of the USA

Rangelands and pastures include grasslands, savannas, shrublands, and woodlands and are often maintained to support grazing animals. Rangelands and pastures cover more than one-third of the land area in the USA and a similar extent globally. The ecosystem goods and services associated with rangeland and pastureland include critical wildlife habitat, forage for livestock, amenities related to water conservation, sustainable soil functions, and soil stabilization and support a diversity of biota and livelihoods. This paper provides a framework for development of a socio-ecological system (SES)–oriented set of indicators for rangeland and pasture systems to support evaluation of impacts of climate and land use changes. These indicators will also serve to inform adaptive management practices. We present a rationale for using an SES approach to evaluate trends and vulnerabilities of rangeland and pasture systems and provide an example of a set of system indicators arising from the SES approach. The indicators include evaporative demand, land cover extent, aboveground plant biomass, human demographics (population age distribution), cattle numbers, and economic value of cattle products relative to total agricultural value. These indicators are not meant to be comprehensive but are offered to illustrate how they might be used in a SES approach to plan for, assess, and mitigate climate change impacts. The conceptual framework provides a systems perspective on the impact of climate change on the socio-ecological dynamics of rangeland and pasture systems including measures of the resilience and vulnerability of ecosystem services with respect to the six indicators. The article focusses on livestock production in rangeland ecosystems, recognizing that additional work is needed to address pastures and other ecosystem services. Examples of the types of regional information associated with the indicators are provided. Guidance for future efforts in indicator development is offered. This framework will serve to guide future development of indicators for rangeland and pasture components of a larger national effort of indicators.

A learning network approach to resolve conservation challenges in the Ngorongoro Conservation Area

The Ngorongoro Conservation Area (NCA) is a protected area and UNESCO World Heritage Site and part of the Serengeti‐Ngorongoro Biosphere reserve in northern Tanzania. It is famous for its large volcanic caldera, unique cultural heritage, early hominid fossils and significant wildlife populations. NCA has been managed as a multiple land‐use area since 1959, a designation intended to foster a harmonious coexistence between indigenous residents and wildlife (Goldstein, 2004).

Local adaptation to precipitation in the perennial grass Elymus elymoides: Trade-offs between growth and drought resistance traits.

Understanding local adaptation to climate is critical for managing ecosystems in the face of climate change. While there have been many provenance studies in trees, less is known about local adaptation in herbaceous species, including the perennial grasses that dominate arid and semiarid rangeland ecosystems. We used a common garden study to quantify variation in growth and drought resistance traits in 99 populations of Elymus elymoides from a broad geographic and climatic range in the western United States. Ecotypes from drier sites produced less biomass and smaller seeds, and had traits associated with greater drought resistance: small leaves with low osmotic potential and high integrated water use efficiency (δ13C). Seasonality also influenced plant traits. Plants from regions with relatively warm, wet summers had large seeds, large leaves, and low δ13C. Irrespective of climate, we also observed trade‐offs between biomass production and drought resistance traits. Together, these results suggest that much of the phenotypic variation among E. elymoides ecotypes represents local adaptation to differences in the amount and timing of water availability. In addition, ecotypes that grow rapidly may be less able to persist under dry conditions. Land managers may be able to use this variation to improve restoration success by seeding ecotypes with multiple drought resistance traits in areas with lower precipitation. The future success of this common rangeland species will likely depend on the use of tools such as seed transfer zones to match local variation in growth and drought resistance to predicted climatic conditions.

Assessment of the nutritional value of Gundelia tournefortii during its growth stages as a key element in the Senowbar rangeland ecosystem, Northeast of Iran

To achieve sustainability and land degradation neutrality in rangeland ecosystems, understanding the growth stages of key plants to develop land management and conservation plans is vital. This study was conducted to determine the nutritional value of Gundelia tournefortii and its changes during different growth stages as one of the most dominant rangeland plants in Khorasan Razavi province, NE of Iran. The plants were randomly sampled in three stages of growth (vegetative, flowering and seeding) in the Senowbar rangeland and eventually moved to the laboratory for chemical analysis. Results showed that crude fiber and acid-detergent fiber and neutral-detergent fiber increased and dry matter, crude protein, ether extract decreased. Ash, Ca, P, K and Na decreased during plant matured; furthermore, these changes were statistically significant (Duncan’s test, 99% and 95%). Dry matter intake, digestible dry matter and relative feed value decreased during growth, which was statistically significant (p < 0.01). The metabolizable energy of Gundelia tournefortii during growth periods reached values of 11.77, 11.58 and 10.46 Mj/Kg, respectively. Also, organic matter digestibility showed a similar decreasing trend. It is concluded that the best time to harvest Gundelia tournefortii from rangelands and to feed is the vegetative period dated from March to April, so harvesting during this period does not prevent seeding.

Mapping the spatial distribution of Lantana camara using high-resolution SPOT 6 data, in Mpumalanga communal areas, South Africa

Agroecosystems play a critical role in rural economics and contribute to the national economy. However, these areas are currently threatened by invasive species. Timely information on potential hotspots and affected areas is required for management purposes. We assess the spatial distribution patterns of Lantana camara invasion in savanna rangeland ecosystems before and after clearing (2014, 2016 and 2018), using high-resolution SPOT 6 data, in Agincourt, South Africa. A maximum likelihood classification algorithm was applied to SPOT 6 data to detect and map areas affected by this invasive species. Furthermore, different accuracy assessment measures (e.g. producer accuracy (PA), user accuracy (UA) and overall accuracy (OA)) were used to assess the validity of the classification results, namely built-up areas, bare areas, uninvaded areas and invaded areas. The results demonstrate that Lantana camara occurrence in rangelands ecosystems can be mapped with high accuracy. An overall accuracy of 81.29% was attained for 2014, 86.85% for 2016 and 88.69% for 2018. It was further observed that in 2016 Lantana camara occurrence was minimal when compared to 2014, but the results indicate regeneration in 2018 in previously cleared areas. Approximately 40.84% of the area was covered by Lantana camara in 2014, 25.19% in 2016 and 27.02% in 2018. Overall, the findings in this study underscore the need for continuous monitoring of affected areas, especially after clearing, to continuously advise on areas that are at risk for potential re-establishment of invasive weeds.

Impacts of Climatic Factors on Vegetation Species Diversity, Herbaceous Biomass in Borana, Southern Ethiopia

The study was conducted in three districts of Borana Zone, with the objective to determining the impacts of climatic factors on vegetation species diversity, herbaceous biomass yield of Borana rangelands under commonial grazing rangeland types during end of growing season. The most types rangeland of communial properties are traditional enclosure and continuous grazing rangeland from in where our different data were collected. Within both rangeland types of each districts 20 m × 20 m plots that placed at 200 m distances intervals with three replication was used to collect woody vegetation. The data of herbaceous plant community was collected from seventeen quadrants (1 m ×1 m) that layout in the main plot. The collected data was analyzed by linear regression to determine the impact of climate factors. The herbaceous species richness, diversity and biomass study sites had highly significantly difference (P < 0.001) and positive linear with mean annual precipitation. There is significantly difference (P < 0.05) and negative linear in woody species richness and diversity. Both herbaceous and woody plant species richness and diversity of study areas had a negative linear with mean annual temperature. Climate factors specieally rianfall have a great impact on semi-arid rangeland ecosystems of study areas. Therefore, semi-arid rangeland user should be considering climatic factors to improve productivity of rangeland at semi-arid enviroments.

Long-Term Effectiveness of Tree Removal to Re-Establish Sagebrush Steppe Vegetation and Associated Spatial Patterns in Surface Conditions and Soil Hydrologic Properties

Pinyon (Pinus spp.) and juniper (Juniperus spp.) woodland encroachment into sagebrush (Artemisia spp.) steppe communities throughout western North America has substantially altered the vegetation structure and hydrologic function of one of the most ecologically important rangeland ecosystems in the world. Various pinyon and juniper tree removal practices are employed to re-establish sagebrush steppe vegetation and an associated resource-conserving ecohydrologic function. The effectiveness of these practices is highly variable owing to the vast domain in which woodland encroachment occurs, climate fluctuations, differences in treatment applications, and myriads of pre-treatment conditions and post-treatment land uses. This study evaluated the long-term (13 years post-treatment) effectiveness of prescribed fire and mechanical tree removal to re-establish sagebrush steppe vegetation and associated spatial patterns in ground surface conditions and soil hydrologic properties of two woodland-encroached sites. Specifically, we assessed the effects of tree removal on: (1) vegetation and ground cover at the hillslope scale (990 m2 plots) and (2) associated spatial patterns in point-scale ground surface conditions and soil hydrologic properties along transects extending from tree bases and into the intercanopy areas between trees. Both sites were in mid to late stages of woodland encroachment with extensive bare conditions (~60–80% bare ground) throughout a degraded intercanopy area (~75% of the domain) surrounding tree islands (~25% of domain, subcanopy areas). All treatments effectively removed mature tree cover and increased hillslope vegetation. Enhanced herbaceous cover (4–15-fold increases) in burned areas reduced bare interspace (bare area between plants) by at least 4-fold and improved intercanopy hydraulic conductivity (&gt; than 2-fold) and overall ecohydrologic function. Mechanical treatments retained or increased sagebrush and generally increased the intercanopy herbaceous vegetation. Intercanopy ground surface conditions and soil hydrologic properties in mechanical treatments were generally similar to those in burned areas but were also statistically similar to the same measures in untreated areas in most cases. This suggests that vegetation and ground surface conditions in mechanical treatments are trending toward a significantly improved hydrologic function over time. Treatments had limited impact on soil hydrologic properties within subcanopy areas; however, burning did reduce the soil water repellency strength and the occurrence of strong soil water repellency underneath trees by three- to four-fold. Overall, the treatments over a 13-year period enhanced the vegetation, ground surface conditions, and soil hydrologic properties that promote infiltration and limit runoff generation for intercanopy areas representing ~75% of the area at the sites. However, ecological tradeoffs in treatment alternatives were evident. The variations in woodland responses across sites, treatments, and measurement scales in this long-term study illustrate the complexity in predicting vegetation and hydrologic responses to tree removal on woodland-encroached sagebrush sites and underpin the need and value of multi-scale long-term studies.

Expert understandings on rangeland ecosystem services and their sustainable management (Atrak River Basin, NE Iran)

Over the last three centuries, worldwide improper utilization of rangelands has led to degradation of ecosystem services. Rangelands, like other natural resources used by humans, are embedded in complex socio-ecological systems. To determine how to better manage this important resource, we developed a rangeland ecosystem services model using the Driver-Pressure-State-Impacts–Response (DPSIR) conceptual model. The model was tested in a river basin in north-east of Iran. We asked 56 experts and 42 local land users on their perceptions of rangeland changes, causes of change, and possible actions to mitigate impacts using Delphi method, workshops, and questionnaires. A Multi-Criteria Decision Making method was used to evaluate the perceived interactions among the components of the DPSIR framework. Climate change and rangeland degradation were the most important pressures, leading to a decline in rangeland production, decreased vegetation cover, and land-use change. Experts and locals argued that forage and herbal species production, erosion control, and flood control were the most affected ecosystem services. They suggested the use of resistant plants, local training, and rangeland rest to manage these problems. The DPSIR framework was useful in developing a comprehensive insight for local people and managers on the social and ecological complexity of rangelands and the potential responses for coping with pressures

Efecto del pastoreo de llamas y vacunos en la función hidrológica de pastizales altoandinos

Se evaluó el impacto del pastoreo de vacunos versus llamas en la función hidrológica del suelo en sitios ecológicos altoandinos de condición pobre y regular, pastoreados bajo un esquema diferido. Se utilizó un diseño completamente al azar con arreglo factorial 2x2 con covariancia, donde los factores fueron especie animal y condición del pastizal, con medidas repetidas. Los parámetros hidrológicos fueron biomasa, mantillo, densidad del suelo, tasa de infiltración, y humedad del suelo. Los resultados mostraron que luego del pastoreo diferido, hubo mayor acumulación de biomasa y mantillo en potreros de condición regular, donde la respuesta hídrica fue mejor. Potreros pastoreados con llamas tuvieron mayor biomasa y mantillo y menor compactación del suelo resultando en una mayor tasa de infiltración. Se recomienda evaluar el rol pastoreo diferido y pastoreo con camélidos para mantener y mejorar de la función hidrológica del pastizal.

Impacts of cattle, hunting, and natural gas development in a rangeland ecosystem

This paper investigates the impacts from natural gas development, hunting, and cattle grazing on a typical Western U.S. rangeland ecosystem using a general equilibrium model that describes ecosystem dynamics. The study area is located in the region surrounding the Atlantic Rim Natural Gas project in southern-central Wyoming and analyzes the population densities of various species, net hunting benefits, cattle profits, and existence value of sage grouse. The general equilibrium model analyzes the responses of six animal species, two plant species, and accounts for differences in prey scarcity inside and outside the disturbed areas around the wells. The differences in scarcity arise from sage grouse, mule deer, and elk experiencing stress in the disturbed areas and the changes in foraging behavior from the rest of the species. The simulations highlight the advantage of a general equilibrium ecosystem model because it is capable of capturing the complex changes that occur between plant and animal species when natural gas development reduces the habitat of vulnerable species. For the study area, the present-value loss in ecosystem services is $58.40 million (or $2,796 per ha), but could vary between -$0.12 and $81.67 million depending on the size of the disturbed area and coordination of government agencies.

Climate Change, Rangelands, and Sustainability of Ranching in the Western United States

Accelerated climate change is a global challenge that is increasingly putting pressure on the sustainability of livestock production systems that heavily depend on rangeland ecosystems. Rangeland management practices have low potential to sequester greenhouse gases. However, mismanagement of rangelands and their conversion into ex-urban, urban, and industrial landscapes can significantly exacerbate the climate change process. Under conditions of more droughts, heat waves, and other extreme weather events, management of risks (climate, biological, financial, political) will probably be more important to the sustainability of ranching than capability to expand output of livestock products in response to rising demand due to population growth. Replacing traditional domestic livestock with a combination of highly adapted livestock and game animals valued for both hunting and meat may be the best strategy on many arid rangelands. Eventually, traditional ranching could become financially unsound across large areas if climate change is not adequately addressed. Rangeland policy, management, and research will need to be heavily focused on the climate change problem.