Resilience Of Rangelands Research Articles

Understanding rangeland desertification through pastoralist perspectives using a grounded theory approach

Rangeland desertification risk has significantly increased due to the fragility of these ecosystems and the severity of degradation caused by climate instability and human activities over the last decade. This research focuses on identifying indicators of rangeland desertification risk using a qualitative grounded theory approach based on the perspectives of pastoralists in Kolijah and Qolaq-Borte, Golestan Province, Iran. The study population comprised regional pastoralists, with 15 experts selected through snowball sampling. Data collection was conducted through in-depth, semi-structured interviews, with thematic analysis carried out via open, axial, and selective coding. Results revealed three primary categories of desertification indicators: “vegetation,” “employment and income sources,” and “climate and natural hazards,” scoring 3.08, 3.00, and 2.80, respectively. Meanwhile, “water and water resources,” “animal health and diseases,” and “participation and social capital” were identified as less significant. Key findings emphasize the importance of vegetation decline, with reduced forage quality and increased prevalence of unpalatable plants serving as prominent signs of desertification. Additionally, socio-economic impacts, including increased animal husbandry costs and reduced livelihood resilience, highlight the multifaceted nature of desertification risk. The study underscores the critical need for targeted conservation policies, incorporating local knowledge to enhance restoration and sustainable management practices. By identifying the key indicators and their impacts, this research provides valuable insights for mitigating desertification and promoting the resilience of rangelands and pastoralist communities.

Love your wet grass! Dry season grazing reserves show highest grass regrowth in communal semi-arid rangelands of Tanzania.

Land management by seasonal migratory herding, traditionally implemented by pastoralists, has allowed semi-arid rangeland ecosystems to remain productive and resilient to highly erratic, seasonal rainfall patterns. Changing pastoralist practices and rainfall patterns due to climate change have the potential to negatively influence the resilience of rangelands. To test the impact of different communal rangeland practices and increasing frequency of disturbance on the rangelands' vegetation, we established a clipping experiment in three rangeland management types: rainy season rangeland, dry season rangeland and seasonal exclosures, in the Maasai Steppe, northern Tanzania. Across these rangeland management types, we tested two clipping frequencies monthly vs. once per growing period and either fenced or open to grazing (herbivory) over two consecutive growing periods. We found that rainy season rangeland exhibited lowest regrowth rates and highest proportion of bare ground across herbivory, clipping frequency and growing period. When rainfall was low, seasonal exclosures showed lowest proportion of bare ground across herbivory and clipping frequency and plots that were seasonally clipped and excluded herbivores generated significantly more grass biomass, higher grass regrowth rates and lowest proportion of bare ground compared to all other treatments. Excluding herbivores had little impact on the vegetation biomass and cover but had a positive impact on grass regrowth rates when rainfall was high. Seasonal clipping allowed for lower proportion of bare ground, and in most cases higher regrowth rates and higher biomass compared to monthly clipping. We conclude that traditional seasonal migratory herding is a relevant concept to sustain rangeland productivity and resilience under increasing intensity of disturbance if grazing pressure on rainy season rangelands is adapted to rainfall conditions and sufficient resting time after heavy defoliation is granted. Dry season grazing (including rainy season resting) proved to be the most sustainable concept to maintain regrowth and control erosion.

Fulfilling the promise of digital tools to build rangeland resilience

The world's rangelands and drylands are undergoing rapid change, and consequently are becoming more difficult to manage. Big data and digital technologies (digital tools) provide land managers with a means to understand and adaptively manage change. An assortment of tools—including standardized field ecosystem monitoring databases; web‐accessible maps of vegetation change, production forecasts, and climate risk; sensor networks and virtual fencing; mobile applications to collect and access a variety of data; and new models, interpretive tools, and tool libraries—together provide unprecedented opportunities to detect and direct rangeland change. Accessibility to and manager trust in and knowledge of these tools, however, have failed to keep pace with technological advances. Collaborative adaptive management that involves multiple stakeholders and scientists who learn from management actions is ideally suited to capitalize on an integrated suite of digital tools. Embedding science professionals and experienced technology users in social networks can enhance peer‐to‐peer learning about digital tools and fulfill their considerable promise.

Review: Rangeland management in Tanzania: Opportunities, challenges, and prospects for sustainability

Abstract. Muzzo BI, Maleko DD, Thacker E, Provenza FD. 2023. Review: Rangeland management in Tanzania: Opportunities, challenges, and prospects for sustainability. Intl J Trop Drylands 7: 83-102. Rangelands in Tanzania play a crucial role in supporting local livelihoods and the country's economic development. However, their long-term sustainability is threatened. This review paper identifies challenges and explores opportunities to ensure their continued sustainability. Opportunities include implementing dedicated policies and regulations, using expertise in range science, leveraging technological advancements, investment land for opening private ranches, ample bushes and shrub resources for small ruminants, and high market demand for milk and meat from ruminants. Major challenges include insufficient technology and limited technical know-how, low and erratic rains leading to dry season pasture scarcity, infectious diseases, and the spread of invasive species. Other challenges include conflicting interests from other land users that have led to the massive conversion of communal rangelands to croplands, areas to protect wildlife, and human settlements. These challenges can be addressed by policy enforcement, strengthening pastoral organizations, fostering the growth of experts in climate-adapted forage breeding, and embracing advanced technology. Active involvement of local communities in decision-making processes and facilitating rangeland restoration can ensure the sustainable management of rangelands in Tanzania. Another promising avenue is the strategic use of locally adapted livestock species to control invasive plants, complemented by governmental enforcement of a grading system for meat and establishing a price-based quality meat market. Incorporating these prospects into rangeland management strategies can enhance the ecological sustainability and resilience of rangelands while supporting local livelihoods. Future research should focus on evaluating and implementing these strategies to promote sustainable rangeland management practices in Tanzania and elsewhere with similar environment.

Rangeland resilience to droughts: Changes across an intensification gradient

AbstractAimThe intensification of livestock systems generates structural and functional changes in native grassland, which alter their capacity to respond to disturbances. Our objective was to evaluate the resilience to an extraordinary consecutive‐droughts event, across an intensification gradient of livestock systems. Our prediction was that sites with more intensive management (less diverse) will have lower resilience (as resistance and/or recovery) to drought.LocationSouth‐central region of Uruguay.MethodsWe evaluated the resilience (as resistance and recovery) to consecutive droughts, across an intensification gradient of livestock systems. We analyzed the effect of diversity on resilience at two scales: (1) regional — an observational experiment with real commercial farms, where we compared three systems with an increasing level of intensification that determine changes in diversity, (2) patch — we carried out a manipulative experiment with different grazing management intensities determined by the level of biomass removal and fertilization. In both experiments, resistance and recovery were calculated from the Normalized Difference Vegetation Index.ResultsThe most intensified and less diverse management (sown pastures) had significantly lower resistance than native and overseeded grassland. Also, it showed the lowest recovery rate, and its productivity did not reach previous values after the drought's end. The grazing intensification gradient at the plot scale did not show clear differences among treatments both for resistance and recovery. However, resistance of the individual plots showed a positive significant association not only with species richness and diversity, but also with evenness and diversity of functional groups.ConclusionOur research supports the insurance hypothesis by demonstrating that farms with greater biodiversity (less intensive management) have higher resistance to drought. We found that species richness is not enough to account for the effect of diversity on resilience. Our results emphasize the importance of preserving grassland biodiversity to maintain resilient ecosystems in the face of climate change.

Spatial E-PSR modelling for ecological sensitivity assessment for arid rangeland resilience and management

In semi-arid regions, land vulnerability and food security are crucial challenges for the scientific community, as millions of livestock keepers depend on rangeland ecosystem services. However, the Aravalli range is a fragile ecotonal arid ecosystem of western India, which acts as a barrier against the desertification of the Thar Desert. Besides increasing biotic pressure, land cover change, precipitation variability, and climate water deficits have a high potential to render the exploitation of resources unsustainable. This study is on the urgent basis addressing the sensitivity, fragility, and vulnerability status for rangeland ecosystem conservation management practices. Based on 17 distinct environmental indicators under five themes: topography, geo-climatic, socio-economic, ecological, and edaphic, which measure their susceptibility. Then, they evaluate their characteristics and sensitivity responses, as well as the resilience capabilities of the areas, utilizing the integrative methodology of the E-PSR (Ecosystem – Pressure, Sensitivity, and Resilience) model using a weightage decision matrix geostatistical approach. As a result, the study area is categorised into four eco-sensitive areas: I, II, III, and IV; they have an area of 4.1%, 62.5%, 32.2%, and 1.2%, respectively. As well, vulnerability reasons, i.e., human intervention, regulations, and management strategies for the arid rangeland ecosystem were discussed. To achieve eco-sensitivity and ecosystem stability in this study area, the government and conservationists must manage invasive species dominance and adjust buffer zones in reserve areas. In addition, study suggests using cutting-edge-technology for monitoring. In sum, this study helps governments and ecologists understand arid mountainous environments, their sensitivity and management.

Compost amendment to enhance carbon sequestration in rangelands

Rangelands contain 20% of global soil carbon (C). Past management of rangelands has resulted in significant losses of soil C, threatening the long-term productivity and sustainability of these ecosystems. Compost amendments have been proposed as a means to increase soil C sequestration while providing important cobenefits to rangeland ecosystems and land managers. Here, we review the literature on the effects of compost amendments on soil and plant characteristics and rates of soil C storage. We extracted values related to biological, physical, and chemical responses to compost applications in rangelands in eight countries and on five continents. Studies reported both short (<1 y) and long-term (>12 y) effects with compost types derived from green waste, food waste, manure, and biosolids. Generally, we found that compost amendments improved aboveground production by >40%, and belowground C content by 50%. Further benefits of compost additions included increasing aggregate stability (~42%), water retention (~18%), nutrient availability (~37% and 126% for nitrogen [N] and phosphorus [P], respectively), as well as generally reducing erosion but with high variability. We found little to no effect of compost amendments on plant diversity and very few studies investigated effects on soil microbial community and function. Both field and modeling studies demonstrated that the changes in soil C from compost amendments can result in long-term C storage. Overall, results suggest that compost amendments may contribute to rangeland resilience to climate change with the additional benefit of climate mitigation via soil C sequestration.

Ratcheting up resilience in the northern Great Basin

• Rangeland resilience is influenced by a variety of ecosystem properties that fall into two broad categories, 1) abiotic and 2) biotic. • Although important to consider in land management planning, abiotic properties cannot be directly influenced with management. In contrast, biotic properties of the ecosystem can be readily influenced by management. • The formula for robust biotic resilience to wildfire and resistance to invasive annual grasses in the northern Great Basin sagebrush ecosystem is about maintaining and promoting perennial bunchgrasses. • The management system must be resilient if we hope to promote ecosystem resilience in an ever-changing risk, seedling recruitment, and recovery environment. A successful strategy for promoting ecosystem resilience will require securing a resilient management system, and a shift in paradigm from random acts of opportunistic restoration to a sustained, organized, process-based approach for promoting ecosystem resilience.

Challenges of Brush Management Treatment Effectiveness in Southern Great Plains, United States

Woodland expansion is a global challenge documented under varying degrees of disturbance, climate, and land ownership patterns. In North American rangelands, mechanical and chemical brush management practices and prescribed fire are frequently promoted by agencies and used by private landowners to reduce woody plant cover. We assess the distribution of agency-supported cost sharing of brush management (2000−2017) in the southern Great Plains, United States, and evaluate the longevity of treatment application. We test the general expectation that the current brush management paradigm in the southern Great Plains reduces woody plants and conserves rangeland resources at broad scales. This study represents the most comprehensive assessment of treatment longevity following brush management in the southern Great Plains by linking confidential private lands management data to a national inventory program (US Department of Agriculture Natural Resources Conservation Service National Resources Inventory). We observed regional differences in the types of brush management techniques used in cost-sharing programs throughout the study area. Mechanical brush management was the most common practice cost shared in Texas, while a mixture of mechanical and chemical application was most common in Oklahoma. Prescribed fire was most common in Kansas with some areas receiving chemical treatment. Our analysis showed brush management, as implemented, did not reduce tree cover long term and minimally reduced shrub cover. Evidence to support the current brush management paradigm only existed at local site-level scales of analysis (40- to 50-acre area), but treatment effectiveness was short-lived. At regional scales, observed changes in woody plant cover showed little to no overall net reduction from 2000 to 2017. These findings bring into question the philosophy of the current brush management paradigm, its implementation as the default rangeland conservation practice, and its prioritization over alternative practices that prevent new woody plant establishment and enhance resilience of rangelands in the southern Great Plains region.

Targeted Grazing of an Invasive Grass Improves Outcomes for Native Plant Communities and Wildlife Habitat

Rangelands provide ecosystem services that are economically and ecologically critical for humans. Globally, invasion of exotic grasses drives loss of biodiversity and resilience of rangelands. In South Texas, buffelgrass (Cenchrus ciliaris syn. Pennisetum ciliare [L.] Link), a C4 perennial grass, was brought from Africa for range improvement as early as the 1930s. Buffelgrass generally increases forage biomass for livestock yet reduces habitat suitability for wildlife. Interest in controlling buffelgrass has increased due to its negative impacts on iconic wildlife, such as whitetailed deer (Odocoileus virginianus, Zimmermann 1780) and northern bobwhite (Colinus virginianus, Linnaeus 1758). The objective of this study was to evaluate the effect of a targeted grazing strategy that used buffelgrass and plant community phenology as indicators to determine the timing of cattle movement. On two private ranches in different ecoregions, we tracked targeted grazing versus light grazing in native-dominated and buffelgrass-dominated plant communities across variable precipitation through five growing seasons. We measured the effects of grazing type, plant community type, and precipitation on buffelgrass cover, native plant species richness, foliar cover, and Shannon diversity. Targeted grazing had a strong impact on diversity, increasing 0.37 ± 0.07 from a mean of H = 1.29 under the targeted grazing management. Conversely, buffelgrass cover was negatively correlated with Shannon diversity, decreasing it by 0.075 ± 0.03 for every 10% increase in buffelgrass cover from a mean of H = 1.29. Despite a variability in precipitation across seasons and years (93−455 mm), targeted grazing improved species richness and cover of native plants throughout the study. Our findings suggest that targeted grazing shows promise as an adaptive grazing strategy that reduces the impact of buffelgrass across highly variable precipitation. In unpredictable environments, management techniques that improve the resilience of plant communities through preserving biodiversity are critical.

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.

Contrasting CO2 and water vapour fluxes in dry forest and pasture sites of central Argentina

AbstractThe dry forests of South America are a key player of the global carbon cycle and the regional water cycle, but they are being intensively deforested. We used eddy covariance measurements to compare the temporal patterns of CO2 and water vapour fluxes and their relationships with environmental variables in dry forest and pastures sites of central Argentina. Ecosystem fluxes showed clear contrasts in magnitude, timing and response to environmental controls between ecosystems. The dry forest displayed higher daily gross primary productivity (GPP, 10.6 vs. 7.8 g CO2 m−2 d−1) and ecosystem respiration (Reco, 9.1 vs. 7.0 g CO2 m−2 d−1) and lower net ecosystem exchange (NEE, −1.5 vs. −0.7 g CO2 m−2 d−1) than the pasture. These differences were explained by a lower tolerance of the pasture to cool temperatures and drought. The lowest NEE rates were observed between 26°C and 34°C in the pasture, but below this range, NEE increased sharply, switching to a carbon source with temperatures <20°C. By contrast, the dry forest remained as a strong carbon sink down to 18°C. The pasture also showed a stronger drop of GPP with drought compared with the dry forest, becoming a carbon source with soil wetness <25% of soil available water. Rainfall was strongly coupled with GPP in both ecosystems, but the dry forest responded to longer rainfall integration periods. This study helps to understand how ecosystems can respond to climate change, improve global scale modelling and increase the productivity and resilience of rangelands.

Nutritional evaluation and productivity of supplemented sheep grazing in semiarid rangeland of northeastern Brazil.

Sheep production systems in Brazilian caatinga rangelands require supplementation adapted to changes in floristic and chemical composition as dry seasons progress. Meeting sheep nutritional needs in extensive semiarid systems is challenging because of sheep dietary preferences and habits. The objective of this trial was to evaluate the substitutive effect of concentrate supplementation on grazing sheep in the Brazilian caatinga rangeland and its consequences on performance in different seasons. The trial was conducted from March to August 2013 at Embrapa Goat and Sheep in Sobral, Ceará State, Brazil. Thirty-two Brazilian Somali multiparous ewes were submitted to estrus synchronization and controlled breeding. At the start of the trial, ewes averaged 30.45 + 2.60kg body weight (BW). Ewes were divided into four groups and individually offered 0, 200, 350, or 500g supplement head-1 day-1. Intake prediction and digestibility trials were evaluated at three periods: rainy season (April), transition rainy-dry (June), and dry season (August). Sheep weights were taken every 14days to measure their performance from late gestation until weaning. Ewe BW and body condition score changes were determined too. Lamb BW changes were also measured every 14days from birth through weaning. A completely randomized design with split plot arrangement using eight replications was used for intake and digestibility measurements. The differences between supplement offered (0, 200, 350, and 500g sheep-1) and season (rainy, transition rainy-dry, and dry) were submitted to analyses of variance and multiple means were separated, where differences were detected, using the Tukey's test. During lactation up through weaning, ewes supplemented at 500gday-1 had greater BW than ewes without supplement. Ewes supplemented with 200g concentrate head-1 day-1 had 9.1% greater (P ≤ 0.05) BW at weaning and their lambs had 19.7% greater birth and 16.6% heavier wean BW despite lower dry matter intake compared to unsupplemented animals. Supplementation with 200g concentrate increased carrying capacity by 28.8% during the dry season and by 20.5% during the rainy season. This study confirmed that in the dry season, when quality of rangeland forages decreases, supplementation contributes to greater DMI, improves postpartum and lactation BW recovery of ewes, and contributes to greater lamb birth and wean weights. Moreover, supplementation leads to feed substitution effects that may increase rangeland resilience by mitigating overgrazing. Supplementation with 200g concentrate can also prevent negative energy balance for grazing animals, improving longer postnatal recovery, longer intervals between parturitions, fewer double and is necessary to ensure a better BW at birth to lambs.

Using an integrated social-ecological analysis to detect effects of household herding practices on indicators of rangeland resilience in Mongolia

Temperate grasslands, including those of northern Eurasia, are among the most imperiled ecosystems on Earth. Eighty percent of Mongolia’s land area is rangeland, where interacting climate, land-use and changes in governance threaten the sustainability of Mongolia’s rangelands and pastoral culture. Particularly concerning are the potential ecological impacts of changing pastoral grazing practices—namely declining use of grazing reserves and pastoral mobility. However, like other grazing practices globally, there have been no empirical studies to evaluate the effects of specific Mongolian grazing practices on ecological function at a management scale. We collected data on the grazing practices of 130 pastoral households across four ecological zones and sampled ecological conditions in their winter pastures. We used a novel social-ecological analysis process to (1) develop integrated, holistic indicators of ecological function using exploratory and confirmatory factor analysis, and (2) assess the effects of individual grazing practices on these indicators using statistical matching to control for confounding management and contextual factors. We identified two latent factors related to ecological and pastoral resilience: Factor 1 represents resource retention and soil stability and Factor 2 represents species richness and functional diversity. Using these two factors as response variables, we found that the values of both resilience factors were higher in pastures where households made fall or winter otor migrations or set aside grazing reserves. This study provides the first management-scale empirical test of the ecological response to specific grazing practices in Mongolia, using an approach that can be applied in other rangeland systems. Our findings highlight the importance to ecological and pastoral resilience of supporting traditional pastoral practices of mobility and grazing reserves, while also controlling stocking densities, increasing rangeland monitoring, and ensuring equitable access to state-designated emergency grazing reserves at local, regional, and national levels.

Coping Strategies During Drought: The Case of Rangeland Users in Southwest Iran

On the Ground • This study assesses the drought coping strategies of rangeland users (RUs) in Fars province in southwest Iran. • Our findings reveal that in the RUs' experience, the most effective drought coping strategies include reducing stocking rates and the gradual reduction of inefficient, old, and sick livestock. • The data also indicate that RUs promote rangeland resilience during a drought through range protection/exclosures, seeding, and broadcast seeding. • This study therefore suggests that the indigenous knowledge of RUs could improve existing training and extension programs by providing localized environmental contexts for developing coping strategies before, during, and after drought.

Urbanization and environmental policy effects on the future availability of grazing resources on the Mongolian Plateau: Modeling socio-environmental system dynamics

The rangelands of the Mongolian Plateau are dynamic socio-environmental systems that are influenced by a complex network of drivers, including climate, social institutions, market forces, and national-scale policies affecting land access and management. The sustainability and resilience of rangelands in this region depend on the ability of residents and policy makers to quickly respond by adapting livelihoods and land uses to changes in environmental and socio-economic conditions, but the responses of the system to these changes are often non-linear and difficult to predict. We developed a system dynamics model to understand how the human, natural, and land-use processes in the Mongolian rangeland ecosystem interact to produce dynamic outcomes in both grassland productivity and livestock populations. We developed two separate models based on a common integrative framework for two case study areas: Suhkbaatar Aimag in Mongolia and Xilingol League in Inner Mongolia. We used future scenarios for each region generated with stakeholder input to forecast trends in grassland area, livestock numbers, and biomass under alternative climate, socioeconomic, and land-use futures. By incorporating stakeholder-developed scenarios, we were able to explore future scenarios tailored to the particular questions and concerns relevant to the individual study areas. We find that while there are many similarities in the factors driving system dynamics in the two countries, the trajectories of key grassland resources are quite different, both between the two study regions and across the individual scenarios. Environmental policies play a key role in Xilingol, while economic development is a key driver in Sukhbaatar. Urbanization dynamics will be a major influence on the availability of grassland resources in the future.

Dynamics and Resilience of Rangelands and Pastoral Peoples Around the Globe

Rangelands cover more of Earth's land surface than any other type of land. They have variable and harsh climates, are sparsely populated and remote from markets, produce significant quantities of livestock, and are mostly used and managed in common. Under this already unpredictable and harsh climate, pastoral peoples and rangelands face new and accelerating political, economic, and climatic stresses that challenge their coupled resilience and ability to adapt. In response, pastoralists are creating new ways to manage rangelands through conservancies and community-based institutions on state, common, and private land. In this review, we focus on recent advances in our understanding of rangeland social-ecological systems, as well as on the causes and consequences of change in these systems. We then explore how pastoral peoples, governments, and businesses are responding to these changes to build resilience to sustain both pastoralism and rangelands. We close with a description of unresolved issues, challenges, and questions for the future.

Physical impact of sheep grazing on arid Karoo subshrub/grass rangeland, South Africa

Grazing levels and rotational schemes need to be tailored to each individual farm or pasture, and more studies are needed on the resilience of rangelands and on separating the effects of grazing and climate. The direct short-term impact of three rates of stocking (4, 8 and 16 Small Stock Units-SSU/ha) was quantified in terms of composition and cover of arid Nama Karoo vegetation (subshrub/grass). Mature Merino wethers grazed in one hectare plots during May in 1995 and 1996 (the plots were not subjected to grazing at any other time). The basal cover of the Karoo bushes (shrubs) showed a decrease at the highest stocking rate only, with the species Phymaspermum parvifolium the most sensitive to intensive grazing. An increase in stocking rate caused a significant decrease in both canopy cover and canopy-spread cover. The canopy cover of palatable Karoo bushes such as Felicia muricata, Salsola calluna and Walafrida geniculata decreased most. Light stocking (4 SSU/ha) was apparently the least detrimental to the vegetation composition and cover. Regardless of stocking rate, an 11-month resting period was possibly sufficient for all the vegetation parameters concerned to be fully restored after grazing took place. The rangeland rapidly reacted to rainfall as the ephemeral cover increased temporarily. The higher the stocking rate was, the greater the increase in ephemerals occurring. The ecological sustainability of the Nama Karoo ecosystem, utilised by high stocking densities, is questioned. Keywords: Basal cover; canopy cover; canopy-spread cover; ephemerals; Karoo bushes; stocking rate

Twenty years of rest returns grazing potential, but not palatable plant diversity, to Karoo rangeland, South Africa

Summary 1. Up to 73% of the world’s rangelands are degraded, and increasing demand for meat in developing countries and a growing human population are likely to exert even greater pressures on rangelands in the next 20–50 years. Restoration of rangeland grazing potential and resilience is therefore important, particularly in the face of climate change. 2. We investigated the influence of past stocking rates (from 1910 to 1987), rainfall, and current grazing regimes (from 1988 to 2008) on plant assemblages, grazing potential, and diversity of palatable species in southern Karoo rangelands, South Africa. 3. We used herbivore exclusion experiments to test whether resting rangeland for 20 years enables recovery of plant assemblages (where seed sources are present within 50 m), regardless of previous grazing history. Mean annual rainfall over this period was 15% higher than the mean annual rainfall for the preceding 80 years and included two exceptionally wet years. 4. While rainfall was a primary driver of total vegetation cover, grazing history explained differences in plant species composition: plots with shared historical grazing intensity were more similar than plots with the same grazing regimes between 1988 and 2008. 5. In historically heavily‐grazed exclusion plots, cover of the palatable species Tripteris sinuata (formerly Osteospermum sinuatum) returned to levels comparable to that in both exclusion and lightly‐grazed plots with a moderate grazing history. Five palatable species (Pteronia empetrifolia, Tetragonia spicata, Berkheya spinosa, Hereroa latipetala and Ruschia spinosa) failed to re‐establish, however, despite the presence of seed‐producing plants nearby. Furthermore, only cover of P. empetrifolia increased significantly in historically moderately‐grazed plots. Cover of unpalatable plants (e.g. Pteronia pallens) increased in all plots over time. 6. Synthesis and applications. These findings suggest that present species composition of arid shrublands reflects historical management at time scales greater than 20 years. Despite high rainfall enabling the return of grazing potential through recovery of a single forage species, rest alone did not ensure the return of all palatable species, with implications for rangeland resilience. Restoring the full suite of palatable species over management timeframes will require more complex interventions such as reseeding or selective clearing.

Pitfalls of institutional change: Rain-index insurance may impair rangeland's resilience

This article was submitted without an abstract, please refer to the full-text PDF file.