Grazing Land Management Research Articles

Mapping Seasonal Variations of Grazing Land Above-ground Biomass with Sentinel 2A Satellite Data

Seasonal variations have brought about significant changes in vegetation cover and spatial distribution in the past decade. Globally, grazing lands are experiencing a significant warming and drying process more especially the grazing lands in the Savannah and Sahel regions. This paper reports the study undertaken for mapping changes on the grass above ground biomass (GAB) due to these seasonal changes using Sentinel 2A Multispectral Instrument (MSI) data. Emphasising on the GAB, the main objective of this study is to map and model monthly GAB variations to their corresponding meteorological data. A set of selected widely used vegetation indices were applied to satellite data, and later were further regressed against corresponding in-situ GAB samples and weather data, hence, producing a predictor of GAB from satellite data. Sentinel 2A MSI data were acquired monthly from January to December 2018. Combined with precipitation and temperature data, the GAB variations on monthly scales were analysed. The results indicated that GAB determined and its seasonal variations shown good agreement (r = 0.8, p < 0.001) with corresponding in-situ verifications. Temperature was found inversely proportionally to GAB for the whole grazing calendar. Therefore, it was concluded that mapping GAB seasonal variations is achievable with Sentinel2 MSI, vast potential for input to grazing land management.

The influence of grazing and cultivation on runoff, soil erosion, and soil nutrient export in the central highlands of Ethiopia

BackgroundGrazing by livestock and cultivation have been considered as two important causes of soil erosion and nutrient export. However, there has been limited evidence that grazing or cultivation matters to soil erosion and nutrient export in Ethiopia. Hence, this study was conducted in the Galesa watershed in Ethiopia to examine the effects of grazing and cultivation on runoff, soil loss, and nutrient export. Daily values of runoff, soil erosion, and nutrient outflow were measured for three consecutive years following standard procedures. Independent t test was performed to check if the means of runoff, soil loss, and nutrient loss from grazing and cultivated lands were significantly different. Moreover, repeated analysis of variance (ANOVA) was used to test if mean values of runoff, soil loss, and nutrient export varied significantly over the study years.ResultsAlthough the average annual runoff depth was 7.8% higher in grazing land (GL), soil erosion was significantly lower (39%) in GL as compared to cultivated land (CL). Similarly, sediment and runoff-associated annual losses of total nitrogen (N), available phosphorus (P), exchangeable potassium (K), and organic carbon (OC) were low in the GL treatments. Lowest losses of total N (9.30 kg ha−1 year−1), available P (0.83 kg ha−1 year−1), and exchangeable K (1.84 kg ha−1 year−1) were recorded in GL treatment. Likewise, lowest losses of sediment-associated total N (32.8 kg ha−1 year−1), available P (0.39 kg ha−1 year−1), exchangeable K (0.23 kg ha−1 year−1), and soil organic carbon (630 kg ha−1 year−1) were recorded from GL over the 3 years of experimentation.ConclusionOur results indicate that cultivation increased soil erosion as compared to grazing. Although there were significant reductions in soil erosion and nutrient export from grazing lands compared with cultivated lands, the absolute losses were still high. This implies the need for grazing land management using appropriate physical and biological erosion control measures to increase productivity and reduce soil erosion as well as nutrient export.

Intensification enhances litter carbon and nitrogen decomposition dynamics in subtropical grazinglands

AbstractIncreased grazing land management intensification through the selection of productive species and the use of N affects the amount and quality of C and N inputs to the soil. This study evaluated the short‐term impacts of litter quality on litter decomposition and C and N distribution among soil size–density fractions. A 168‐d litter bag mesocosm experiment and a 120‐d incubation study evaluated the decomposition of three perennial species [rhizoma peanut (Arachis glabrata Benth., RP), bahiagrass (Paspalum notatum Flügge; BG), and saw‐palmetto (Serenoa repens Bartr., SP)] on grazing land soils with contrasting C concentrations (3.4 and 18 g C kg−1; Buck Island Ranch and Ona, respectively). Soil did not affect litter decomposition. There was less remaining biomass at the end of incubation for RP and BG (58%) than SP (79%). Nitrogen immobilization occurred on SP litter, probably because of its high initial lignin/N and fiber‐bound N/N ratios (43 and 384 g kg−1 organic matter, respectively). Litter had no effect on soil C and N concentrations in size–density fractions; however, greater proportions of C and N (∼47 and 59%, respectively) were found in the light‐free fraction. Nitrogen addition promoted C and N accumulation in the mineral fraction. These results suggest plant litter chemical characteristics played a more important role on litter decomposition than soil C and N concentrations. Management intensification through changes in plant species and N fertilization had positive effects on C and N dynamics in coarse‐textured soils, with enhanced decomposability of cultivated forage species relative to native vegetation.

Response of Grazing Land Soil Health to Management Strategies: A Summary Review

Grazing land ecosystem services including food provision and climate regulation are greatly influenced by soil health. This paper provides a condensed review of studies on the response of three important soil properties related to soil health to grazing land management: water infiltration, carbon (C) sequestration, and nitrogen use efficiency (NUE). Impacts of management strategies that are often used in grazing lands are discussed in this review including vegetation composition, grazing methods, and other factors such as fertilizer use and climatic conditions. In general, proper grazing management such as continuous moderate grazing and rotational/deferred-rotational grazing with low or moderate stocking rates tends to benefit all three soil properties. Water infiltration can usually be increased with full vegetation cover, increased soil C, and aggregate stability, or be decreased with greater soil bulk density. Adoption of highly productive plant species with faster turnover rates can promote soil C sequestration by increasing C input. However, excessive C removal from ecosystems due to overgrazing or improper soil fertilization management results in higher C loss, which can have detrimental effects on soil C sequestration. Proper stocking rate and a balanced manure/fertilizer management was found to be critical for enhancing NUE. Grazing land management sometimes simultaneously influence the three soil properties. Techniques that can increase soil C such as introduction of high productive plant species can often promote water infiltration and soil nitrogen (N). Some other practices such as adoption of N fertilizer may enhance C sequestration while being detrimental to NUE. An integrated management plan for a specific location or farm should be considered carefully to improve soil health as well as ecosystem production. This review provides farmers and policy makers the current state of general knowledge on how health-related soil processes are affected by grazing land management.

Soil Health as a Transformational Change Agent for US Grazing Lands Management

There is rapidly growing national interest in grazing lands’ soil health, which has been motivated by the current soil health renaissance in cropland agriculture. In contrast to intensively managed croplands, soil health for grazing lands, especially rangelands, is tempered by limited scientific evidence clearly illustrating positive feedbacks between soil health and grazing land resilience, or sustainability. Opportunities exist for improving soil health on grazing lands with intensively managed plant communities (e.g., pasture systems) and formerly cultivated or degraded lands. Therefore, the goal of this paper is to provide direction and recommendations for incorporating soil health into grazing management considerations on grazing lands. We argue that the current soil health renaissance should not focus on improvement of soil health on grazing lands where potential is limited but rather forward science-based management for improving grazing lands’ resilience to environmental change via 1) refocusing grazing management on fundamental ecological processes (water and nutrient cycling and energy flow) rather than maximum short-term profit or livestock production; 2) emphasizing goal-based management with adaptive decision making informed by specific objectives incorporating maintenance of soil health at a minimum and directly relevant monitoring attributes; 3) advancing holistic and integrated approaches for soil health that highlight social-ecological-economic interdependencies of these systems, with particular emphasis on human dimensions; 4) building cross-institutional partnerships on grazing lands’ soil health to enhance technical capacities of students, land managers, and natural resource professionals; and 5) creating a cross-region, living laboratory network of case studies involving producers using soil health as part of their grazing land management. Collectively, these efforts could foster transformational changes by strengthening the link between natural resources stewardship and sustainable grazing lands management through management-science partnerships in a social-ecological systems framework.

MANAGEMENT EFFECTS ON GROUND COVER CLUMPINESS: SCALING FROM FIELD TO SENTINEL-2 COVER ESTIMATES

Abstract. Significant progress has been made in the development of cover data and derived products based on remotely sensed fractional cover information and field data across Australia, and these cover data sets are now used for quantifying and monitoring grazing land condition. The availability of a dense time-series of nearly 30 years of cover data to describe the spatial and temporal patterns in landscape changes over time can help with monitoring the effectiveness of grazing land management practice change. With the advent of higher spatial resolution data, such as that provided by the Copernicus Sentinel 2 series of satellites, we can look beyond reporting purely on cover amount and more closely at the operational monitoring and reporting on spatial arrangement of cover and its links with land condition. We collected high spatial resolution cover transects at 20 cm intervals over the Wambiana grazing trials in the Burdekin catchment in Queensland, Australia. Spatial variance analysis was used to determine the cover autocorrelation at various support intervals. Coincident Sentinel-2 imagery was collected and processed over all the sites providing imagery to link with the field data. We show that the spatial arrangement and temporal dynamics of cover are important indicators of grazing land condition for both productivity and water quality outcomes. The metrics and products derived from this research will assist land managers to prioritize investment and practice change strategies for long term sustainability and improved water quality, particularly in the Great Barrier Reef catchments.

Willingness and Participation of Local Communities to Manage Communal Grazing Lands in the Lake Tana Biosphere, Ethiopia

ABSTRACTSustainable management of communal grazing lands in Ethiopia is crucial to sustain livestock productivity and reduce land degradation. This study was conducted in Dera district, Ethiopia, to assess local communities’ perceptions of the degradation and their attitudes on the management of communal grazing lands. Household surveys, group discussions, and the contingent valuation method were used to gather data. Results indicated that local communities are aware of the degradation and are willing to participate in the management of communal grazing lands by contributing labor and cash. Labor contribution is positively and significantly correlated to total livestock units (TLU) and credit, and negatively correlated with household size and extension service. Significant correlation between the willingness to contribute cash and TLU was also detected. Community participation and discussions, demarcation of boundaries, equity in benefit sharing, and engaging both formal and informal institutions are crucial to sustain and enhance the effectiveness of grazing land management.

Risk Behaviours and Grazing Land Management: A Framed Field Experiment and Linkages to Range Land Condition

We use a framed field experiment considering hypothetical stocking rate decisions made by grazing enterprise managers and estimate non-linear multinomial logit models for a range of nested non-expected utility and expected utility models. The risk and decision-bias parameters for five models estimated for individual responses are shown to be significantly related to land condition but in ways which suggest behavioural aspects of decision making are critical in understanding land management and stocking rate decisions. Our results show that individual heterogeneity in decision making amongst farming groups is likely to be a significant source of variation in farming intensity and technology adoption decisions. This heterogeneity does not appear to be a reflection of socio-demographic characteristics. Furthermore, decision functions appear to be biased toward selection of simpler representative functions (e.g. Expected Utility) for sample averages. This suggests that experimental findings that Expected Utility is representative for actual decisions may be due to sample averaging rather than reflect actual behaviour.

Tracking changes in the land use, management and drainage status of organic soils as indicators of the effectiveness of mitigation strategies for climate change

The tracking of land use since 1990 presents a major challenge in greenhouse gas (GHG) reporting under the United Nations Framework Convention on Climate Change (UNFCCC) and the Kyoto Protocol because there is often limited availability of data, especially for the base year of 1990. There is even less land management and soil moisture data, which are needed to track climate change mitigation activities since soil moisture is one of the main drivers of GHG emissions of organic soils. Information is also needed for the reporting of land-based activities such as grazing land management or wetland drainage and rewetting of organic soils. Different spatial and thematic resolutions of land-use data produce inconsistent time series with a strong overestimation of land-use change (LUC) if not adequately accounted for. Our aim was to create a consistent time series of land use since 1990 that is in line with GHG reporting under the UNFCCC and the Kyoto Protocol by combining official cadastral data with colour-infrared aerial photography used for biodiversity monitoring in six federal states in northern and eastern Germany. We developed a generic hierarchical classification by land use, management and drainage status, and a translation key for data harmonisation into a consistent time series. This time series enabled the quantification of LUC on organic soils between 1992 and 2013 in a spatially explicit manner. Furthermore we used this time series to develop indicators for changes in land management and drainage to evaluate the success of protection statuses on peatland restoration.The study area encompassed one million hectares, half of which had some type of legal nature protection status. Areas with no protection status tended to become more intensively farmed and drier, while highly protected areas (e.g. Natura 2000) showed the opposite trend. Land-use trends also differed greatly between federal states. In Schleswig-Holstein organic soils tended to become drier during the study period, while in Mecklenburg-Western Pomerania they tended to become wetter overall. The trends and differences in LUC between federal states were linked to German reunification, changes in the European Common Agricultural Policy (CAP) and Germany's Renewable Energy Act (EEG). A large-scale peatland protection programme also had major impact.In conclusion, our study demonstrates how data derived for biodiversity monitoring and other highly detailed land-use data can be used to track changes in land use, management and drainage status in accordance with the reporting requirements under the UNFCCC and the Kyoto Protocol.

Conflicts, security and marginalisation: institutional change of the pastoral commons in a 'glocal' world.

This paper argues that pastoral commons are under increasing pressure not just from overuse by pastoralists themselves, but from land management policies. Since colonial times, these have been based on a persistent misconception of the nature of pastoral economies and combined with increasing land alienation and fragmentation through government policies and covert privatisation of pastures. The paper focuses especially on pastoral populations in African drylands and is based on long-term research by independent researchers summarising some of their experiences in western, eastern and southern Africa. Most of them are organised in the African Drylands Dialogue, trying to shed some light on the developments in these areas. Before discussing the actual situation of African pastoralists, the authors focus on basic institutional features of the political and economic management of common grazing lands. This is followed by an overview of land alienation processes in colonial times, which serves as a basis for understanding the current land alienation constellations. The paper then moves on to explain how and why pastoralists are framed by the national discourses as the 'other' and the 'troublemaker', even being labelled as terrorists in nation state contexts. This goes hand in hand with a new wave of land alienation in the form of large-scale land acquisitions or 'land grabbing' (including water grabbing and 'green grabbing' processes). The paper then outlines different coping and adaptation strategies adopted by pastoral groups in a context in which a range of different global and local political, economic and ecological situations interrelate ('glocal'). Finally, the paper discusses the way in which pastoralism could be reframed in a participatory way in the future.

Fine-grained detection of land use and water table changes on organic soils over the period 1992⿿2012 using multiple data sources in the Drömling nature park, Germany

The construction of consistent time series of land use presents a key challenge when accounting for elective land use-based activities under the Kyoto Protocol (wetland drainage and rewetting (WDR), cropland management (CM) and grazing land management (GM)), in which current land use-driven greenhouse gas emissions are compared to a reference situation in 1990.This case study is the first to demonstrate the feasibility of using high-resolution land-use proxies from different datasets for Kyoto accounting in a data-rich case study region in Germany. The study region is characterised by organic soils and has been subject to significant nature conservation measures, including land-use changes, reductions in land-use intensity and changes in groundwater table depth.A consistent time series of 20 years of land use with a spatial resolution of 0.01ha was created from various fine-grained spatial datasets for organic soils in the Drömling nature park by applying a newly developed ⿿translation key⿿. The translation key accounted for systematic differences in legends and thematic resolution. We also tested whether the land-use datasets served as trustworthy proxies for groundwater table depth.Land use in the Drömling nature park became less intensive during the study period of 1992⿿2012. The greatest land-use change (142hayear⿿1, 1.14% year⿿1) occurred between 2000 and 2008. This was in line with management measures undertaken in the nature park. The centre of the nature park became wetter and there was an increase in the share of grassland and more natural vegetation types.The groundwater table correlated with land use and land-use intensity on organic soils in the study area throughout the entire period. Land-use changes were accompanied by altered groundwater tables, except for the conversion from cropland to grassland.Our study indicates that detailed land-use time series can serve as a semi-quantitative proxy for groundwater depth, but that any robust quantitative assessment of water table changes requires in situ data, e.g. from a network of dipwells. Therefore, the combination of land-use and dipwell data provided an accurate basis for estimating GHG emission reductions from drained organic soils since 1990, which is the centre of the Kyoto activity WDR, but also part of afforestation/reforestation (AR) and deforestation (D), forest management (FM), CM and GM. Even the detailed land-use time series on its own would fulfil the requirements for WDR accounting, although with considerable uncertainty about the drainage status of the organic soils. We present the study area of organic soils as a showcase for combining the difficult issues of monitoring changes in land-use intensity as well as in soil wetness, the latter being most relevant for organic soils. The methodology is equally applicable to and relevant for mineral soils.

Degraded Land Restoration in Reinstating CH4 Sink.

Methane (CH4), a potent greenhouse gas, contributes about one third to the global green house gas emissions. CH4-assimilating microbes (mostly methanotrophs) in upland soils play very crucial role in mitigating the CH4 release into the atmosphere. Agricultural, environmental, and climatic shifts can alter CH4 sink profiles of soils, likely through shifts in CH4-assimilating microbial community structure and function. Landuse change, as forest and grassland ecosystems altered to agro-ecosystems, has already attenuated the soil CH4 sink potential, and are expected to be continued in the future. We hypothesized that variations in CH4 uptake rates in soils under different landuse practices could be an indicative of alterations in the abundance and/or type of methanotrophic communities in such soils. However, only a few studies have addressed to number and methanotrophs diversity and their correlation with the CH4 sink potential in soils of rehabilitated/restored lands. We focus on landuse practices that can potentially mitigate CH4 gas emissions, the most prominent of which are improved cropland, grazing land management, use of bio-fertilizers, and restoration of degraded lands. In this perspective paper, it is proposed that restoration of degraded lands can contribute considerably to improved soil CH4 sink strength by retrieving/conserving abundance and assortment of efficient methanotrophic communities. We believe that this report can assist in identifying future experimental directions to the relationships between landuse changes, methane-assimilating microbial communities and soil CH4 sinks. The exploitation of microbial communities other than methanotrophs can contribute significantly to the global CH4 sink potential and can add value in mitigating the CH4 problems.

Using experiments to improve understanding of limits to decision making in Grazing Land Management

Modern farming is characterised by complexity, dynamics, and in many cases, heterogeneity in farming methods. Increasing use of dynamic investment theories, such as the Real Options Analysis method, allow integration of dynamic aspects but retain untenable assumptions in the face of widely acknowledged complexity and uncertainty in management of grazing systems. Relaxation of the requirement for rationality in decision making may provide economic models with a better ‘fit’ to observed behaviour of managers of rangelands grazing enterprises whilst allowing exploration of the reasons for and costs of particular patterns of decision making on farms. The economic analysis of decision making using explicitly dynamic choice functions and dynamic choice experiments framed in a grazing land management scenario is considered in this paper. Results indicate that models of bounded rationality, relaxing the assumptions of perfect knowledge and cognitive abilities, will have improved explanatory power for farm decision making whilst risk preferences appear to contribute little by way of variation in observed decision making. These insights suggest the need to broaden economic models of decision making to incorporate limits on rationality which will allow analyse of the costs of these limits and provide the framework to assist farm managers achieve higher enterprise and environmental efficiency.

Use of business analysis in beef businesses to direct management practice change for climate adaptation outcomes

Beef businesses in northern Australia are facing increased pressure to be productive and profitable with challenges such as climate variability and poor financial performance over the past decade. Declining terms of trade, limited recent gains in on-farm productivity, low profit margins under current management systems and current climatic conditions will leave little capacity for businesses to absorb climate change-induced losses. In order to generate a whole-of-business focus towards management change, the Climate Clever Beef project in the Maranoa-Balonne region of Queensland trialled the use of business analysis with beef producers to improve financial literacy, provide a greater understanding of current business performance and initiate changes to current management practices. Demonstration properties were engaged and a systematic approach was used to assess current business performance, evaluate impacts of management changes on the business and to trial practices and promote successful outcomes to the wider industry. Focus was concentrated on improving financial literacy skills, understanding the business’ key performance indicators and modifying practices to improve both business productivity and profitability. To best achieve the desired outcomes, several extension models were employed: the ‘group facilitation/empowerment model’, the ‘individual consultant/mentor model’ and the ‘technology development model’. Providing producers with a whole-of-business approach and using business analysis in conjunction with on-farm trials and various extension methods proved to be a successful way to encourage producers in the region to adopt new practices into their business, in the areas of greatest impact. The areas targeted for development within businesses generally led to improvements in animal performance and grazing land management further improving the prospects for climate resilience.

Grazing impacts on the susceptibility of rangelands to wind erosion: The effects of stocking rate, stocking strategy and land condition

Abstract An estimated 110 Mt of dust is eroded by wind from the Australian land surface each year, most of which originates from the arid and semi-arid rangelands. Livestock production is thought to increase the susceptibility of the rangelands to wind erosion by reducing vegetation cover and modifying surface soil stability. However, research is yet to quantify the impacts of grazing land management on the erodibility of the Australian rangelands, or determine how these impacts vary among land types and over time. We present a simulation analysis that links a pasture growth and animal production model (GRASP) to the Australian Land Erodibility Model (AUSLEM) to evaluate the impacts of stocking rate, stocking strategy and land condition on the erodibility of four land types in western Queensland, Australia. Our results show that declining land condition, over stocking, and using inflexible stocking strategies have potential to increase land erodibility and amplify accelerated soil erosion. However, land erodibility responses to grazing are complex and influenced by land type sensitivities to different grazing strategies and local climate characteristics. Our simulations show that land types which are more resilient to livestock grazing tend to be least susceptible to accelerated wind erosion. Increases in land erodibility are found to occur most often during climatic transitions when vegetation cover is most sensitive to grazing pressure. However, grazing effects are limited during extreme wet and dry periods when the influence of climate on vegetation cover is strongest. Our research provides the opportunity to estimate the effects of different land management practices across a range of land types, and provides a better understanding of the mechanisms of accelerated erosion resulting from pastoral activities. The approach could help further assessment of land erodibility at a broader scale notably if combined with wind erosion models.

Land use intensification effects on soil C dynamics in subtropical grazing land ecosystems

The impacts of land intensification on carbon (C) responses are important components of soil organic carbon (SOC) management. Grazing land intensification typically involves the use of highly productive plant species that can support greater grazing pressure, removal of higher proportions of site biomass and nutrients during mechanical harvest or grazing, and increased use of fertilizers, particularly N. Current improved grazing land management strategies are aimed at increasing above-ground biomass yield, with less regard for below-ground C dynamics. Since intensive management affects aboveand belowground C inputs (Schuman et al. 1999; Liu et al. 2011a, 2011b), it can have important implications for the amount and characteristics of SOC stored in grazing lands (Franzluebbers and Stuedemann 2003; Dubeux et al. 2006; Silveira et al. 2013). The objective of this study was to investigate the long-term impacts on SOC dynamics in subtropical ecosystems of converting native rangeland ecosystems into intensively managed systems.

Collective management on communal grazing lands: Its impact on vegetation attributes and soil erosion in the upper Blue Nile basin, northwestern Ethiopia

Collective action, on communal grazing land, has evolved in the highlands of northwestern Ethiopia to mitigate the problems of feed shortage and land degradation due to overgrazing. The exercise is liked by farmers for improving the availability of natural pasture during the long dry season when other feed sources get depleted. However, large portions of the communal grazing lands are still managed under free grazing throughout the year. This study was undertaken in Maynet village in the upper Blue Nile basin, northwestern Ethiopia, to assess the impacts of three different types of grazing land management (GLM) and two slope gradients (<10%; 15–25%) on aboveground herbaceous biomass yield, ground cover, species richness, runoff, soil loss and soil bulk density of grazing lands. The GLMs include (a) freely open communal GLM, (b) restricted communal GLM – collective management of communal grazing land locally named as ‘yebere sar’ and (c) private holding GLM. Stocking density was more than carrying capacity of grazing lands across all GLMs. However, the extent of overstocking problem was exceptionally severe in freely open communal GLM. The interaction between GLM and slope was significant (P<0.05) for runoff, soil loss and runoff coefficient. The average runoff coefficient was close to 50% in freely open communal GLM on steeper slopes (15–25%). Freely open communal GLM on steeper slopes resulted in consistently highest cumulative runoff and soil loss amounting to 491mm and 32t/ha per year, respectively. Polynomial regression analysis showed that quadratic relationship (r2=0.87) existed between soil loss and runoff. But, soil loss was close to nil when runoff did not exceed 2mm per rainfall event. As expected, restricted communal GLM appeared to reduce surface runoff by more than 40% and curb the rate of soil erosion by more than 50% compared to freely open communal GLM. Its vegetation cover persisted above 70% throughout the year, meeting the threshold level recommended to keep surface runoff and soil loss to minimum. Reducing the problem of overstocking and pasture resting in August–November are important components to improve ground cover and aboveground herbaceous biomass yield, which in turn reduce land degradation on grazing lands.

The role of grasslands in food security and climate change

Grasslands are a major part of the global ecosystem, covering 37 % of the earth's terrestrial area. For a variety of reasons, mostly related to overgrazing and the resulting problems of soil erosion and weed encroachment, many of the world's natural grasslands are in poor condition and showing signs of degradation. This review examines their contribution to global food supply and to combating climate change. Grasslands make a significant contribution to food security through providing part of the feed requirements of ruminants used for meat and milk production. Globally, this is more important in food energy terms than pig meat and poultry meat. Grasslands are considered to have the potential to play a key role in greenhouse gas mitigation, particularly in terms of global carbon storage and further carbon sequestration. It is estimated that grazing land management and pasture improvement (e.g. through managing grazing intensity, improved productivity, etc) have a global technical mitigation potential of almost 1·5 Gt CO(2) equivalent in 2030, with additional mitigation possible from restoration of degraded lands. Milk and meat production from grassland systems in temperate regions has similar emissions of carbon dioxide per kilogram of product as mixed farming systems in temperate regions, and, if carbon sinks in grasslands are taken into account, grassland-based production systems can be as efficient as high-input systems from a greenhouse gas perspective. Grasslands are important for global food supply, contributing to ruminant milk and meat production. Extra food will need to come from the world's existing agricultural land base (including grasslands) as the total area of agricultural land has remained static since 1991. Ruminants are efficient converters of grass into humanly edible energy and protein and grassland-based food production can produce food with a comparable carbon footprint as mixed systems. Grasslands are a very important store of carbon, and they are continuing to sequester carbon with considerable potential to increase this further. Grassland adaptation to climate change will be variable, with possible increases or decreases in productivity and increases or decreases in soil carbon stores.

Relationships between Plant Biomass and Species Richness under Different Farming Systems and Grazing Land Management in Montane Grasslands of Kokosa District, Southern Ethiopia

The study was conducted in a montane grassland of Kokosa District, West Arsi Zone of Oromia Region, southern Ethiopia. The objective of the study was to investigate the relationships between aboveground plant biomass and species richness in three farming systems and four grazing management systems. A total of 180 quadrats (each 1 m x 1 m) were sampled in the three farming systems (dominant livestock-enset, enset-livestock and enset-livestock-cereal) and four grazing management systems (communal, enclosure, stream bank and benchmark). All the farming system and grazing management have different management practices. Plant species composition and aboveground plant biomass at different sites were quantified. Altogether 50 plant species (34 grasses, 4 legumes, 3 sedges and 9 forbs) were recorded in the montane grassland of Kokosa District. Even though the majority of the plant species share the different farming systems and grazing management practices, the highest number of species (39) was recorded in the enset-livestock farming system, whereas the lowest (33) species were recorded in the enset- livestock-cereal farming system when all the grazing management and farming systems were combined. Significantly, the highest species richness (4.9 species m-2) was recorded in the enclosure grazing management site whereas the lowest (3.4 species m-2) was recorded in the benchmark grazing site when all grazing sites and farming systems were combined. The relationship between species richness and biomass was detected in the montane grassland. There was significant difference (P &le; 0.05) in species richness for a combination analysis of farming system by grazing management system of the montane grassland. The highest biomass was recorded in the benchmark grazing management sites while the lowest was recorded in the communal grazing sites. On the contrary, maximum species richness was found in the enclosure grazing management sites which had intermediate biomass yield and the lowest species richness was recorded in the benchmark grazing areas with the maximum biomass records. Thus, species richness was observed first to ascend along with biomass increment up to 1932 kg ha-1 and then declined at constant increase of biomass. An increase in biomass in the benchmark grazing sites was not accompanied by an increase in species richness suggesting the dominance of few species in these sites. The rationale behind this might be due to the competitive exclusion of the less competent species from the community at peak biomass production.Keywords: Biomass; Farming System; Grazing Management; Montane Grassland; Species Richness

Informal institutions as mechanisms to address challenges in communal grazing land management in Tigray, Ethiopia

The role of institutions providing rules, norms and regulations, in addressing challenges in communal resources management has been debated for several decades. This article analyses the role of informal institutions for addressing shortage of grazing land, conflicts among users of communal grazing land and resistance among users to shift from free grazing to zero grazing in Tigray, Ethiopia. We used in depth interviews and focus group discussions for data collection. We argue that informal institutions are important mechanisms for addressing the challenges in communal grazing land management. The contributions of informal institutions for addressing challenges in communal grazing lands varied with type of challenge and were influenced by distances from markets and Wereda towns. Although the informal institutions were crucial in reversing the shortage of grazing land by regulating access to communal grazing land and enhancing controlled use of grass, they did not contribute to resolving conflicts that arose from unequal allocation of benefits in the village far from a market and Wereda town. Incorporating zero-grazing practices in informal institutions was hindered by disagreements among users and the top-down approach used by development agents when introducing zero grazing. To enhance effectiveness of informal institutions, the increasing grazing pressure should be addressed using more efficient schemes for harvesting grass. Moreover, creating awareness of the need for fewer but more productive cattle breeds is crucial. Consideration of well-performing informal institutions in policy and development interventions is essential to maximise the benefits of communal grazing lands to improve livelihoods of users.