Rangeland Journal最新文献

Practices that improve the quantity, composition, and persistence of ground cover can contribute to a range of ecosystem services that support agricultural production, regulate climate, reduce erosion and support nutrient cycling. In rangeland grazing systems, incorporating periods of rest and matching stocking rates to feed availability is commonly used with the goal of improving land condition and productivity at a property scale. Understanding and quantifying differences in ground cover associated with changes to grazing management can provide livestock producers with greater confidence in the outcomes associated with their management. It can also demonstrate their nature positive activities which may be valued in emerging markets. This study sought to quantify any changes in ground cover resulting from changed grazing management (strategically managing the timing, intensity and duration of grazing events to maintain or improve land condition) across seven mixed grazing (cattle, sheep and/or goats) study sites in the semi-arid rangelands of western New South Wales, Australia. Time-series estimates of ground cover derived from Landsat imagery for each study site were compared with biophysically similar regional benchmark areas as controls. Overall, ground cover was found to have increased significantly (2–7%) following change in grazing management at four of the seven study sites, relative to control benchmark areas. It was apparent different land units varied in their response to the management change, and that the preceding 12 months rainfall (such as wet, intermediate or dry rainfall years) did not have a consistently significant effect on the relative response. Results of this study highlight that improvements in ground cover and land condition may be achieved through changes to grazing management, but also that there are complexities in both achieving and measuring any change. This study demonstrates the practical application of remotely sensed cover data and dynamic regional comparison techniques to document environmental outcomes at the property scale from grazing management in low input, extensive rangeland grazing systems.

Reconciling profitable cattle production with rangeland health and reduced emissions is a key challenge in the southern rangelands of Western Australia (WA). Stocking rate and herd structure selection are crucial decisions to achieve this balance. This study assessed the emission profiles of three contrasting herd structures (weaner production, live export, and slaughter production), and three stocking rates within a herd–carbon accounting modelling framework. The analysis considers the impact of varying drought frequencies on these cattle production systems. Herd models were developed for the semiarid southern WA rangelands. Stocking rates were set at 100%, 80% and 66% of the government recommended rate. Drought events (represented by Decile 2 rainfall years) were introduced at different frequencies within a 30-year simulation period. Slaughter production with a 66% stocking rate exhibited the lowest and most consistent carbon footprint, averaging around 15 kg CO₂ equivalents/kg liveweight sold. Higher stocking rates and weaner production systems generally resulted in increased carbon footprint variability. Selecting a herd structure producing heavy steers and heifers for slaughter, combined with a conservative stocking rate (66% of recommended), offers a combined economic and environmental benefit for cattle production in the southern rangelands of WA. This strategy promotes financial sustainability while minimising emissions and enhancing resilience to drought events.

Globally, there is growing interest and potential for investment in Nature-based Solutions (NbS) to protect, manage or restore ecosystems through incentive schemes including Payment for Ecosystem Services (PES), Nature Repair, Carbon Markets, Common Asset Trusts. Collectively, these NbS markets establish interchangeable mechanisms to help address biodiversity and climate crises, as well as socio-economic issues concerning many Indigenous Peoples and Local Communities (IPLCs). IPLCs manage and/or own almost 32% of the world’s land area through customary and community-based tenure arrangements. Since 2000 several PES schemes have been implemented in Australia. These schemes have been overwhelmingly implemented as public-good expenditure, with governments providing ~90% of total funding. Indigenous people have either the legal right to run or veto a carbon market or nature repair project over 57% of the Australian land mass, increasing to 63% in savanna and 85% in desert regions. Here we critically assess opportunities and challenges for Australia’s Indigenous estate associated with existing and emerging NbS market approaches, especially the Commonwealth’s current Savanna Fire Management (SFM) and Human Induced Regeneration methods, evolving Integrated Farm & Land Management (IFLM) and Blue Carbon methods, and proposed Nature Repair (NR) market. To date, Indigenous NbS interests have focused especially on SFM across northern Australia, with prospective opportunities especially for IFLM and NR markets. Most available schemes focus on remediation of degraded lands and seas, ignoring cost-effective investment opportunities to maintain habitats and ecosystems in less-degraded condition. Government-supported Common Asset Trusts can provide effective models for governance of stewardship schemes relevant to on-going care for relatively intact ecosystems. In Discussion we summarise key methodological, institutional, and policy opportunities and challenges for constructive Indigenous engagement with developing NbS markets. Our purpose is to provide an Indigenous land and sea management context to inform development of rapidly evolving NbS markets in Australia.

Land-use changes through carbon farming in Australia have the potential to deliver significant environmental, economic, social and cultural benefits to regional areas, especially in the rangelands. For this reason, policymakers and carbon market proponents have articulated the notion of ‘co-benefits’, to refer to the desirable impacts of carbon farming beyond emissions abatement. Aboriginal leaders similarly refer to crucial ‘core benefits’ like First Nations’ custodianship of land or Country. In this article, we navigate the complex conceptual and policy terrain that now surrounds carbon farming co-benefits in Australia through a comprehensive review. This is a vital undertaking because carbon farming to date has been dominated by the federal government’s purchasing of Australian Carbon Credit Units (ACCUs) in accordance with a mandate that seeks lowest cost emissions abatement, with no formal recognition or valuation of co-benefits. This has produced an ad hoc policy environment in which some co-benefits are recognised and valued, often with significant price premiums, through a range of federal and state government, nongovernment and private schemes. To interpret this policy domain, we first argue for greater conceptual clarity through using the notion of ‘co-impacts’, which conveys how carbon farming produces an array of potential benefits, costs and risks across space and time, with differential impacts for diverse actors. Second, we review current initiatives related to carbon co-benefits in Australia, identifying over 20 separate schemes with distinct governance arrangements. Our findings point to the significant potential and value of carbon co-benefits in Australia. To achieve this potential, we argue that nationwide policy frameworks must now harmonise approaches, standardise units and measures where possible, and localise carbon farming implementation strategies.

The objective of this study was to analyse the contribution of camel farming to pastoral household livelihood. A survey was conducted among 200 households, 108 in peri-urban N’Djamena and 102 in pastoral Fitri in central Chad. Two types (one per zone) of household livelihood strategies were used to analyse the data. Camel herders’ households are largely specialised, with camels comprising at least 80% of herds (in terms of tropical livestock units, TLU). Such households are livestock farming specialists, with 60% of households not undertaking any cultivation. Camel farming in peri-urban N’Djamena differed from that in pastoral Fitri because of the importance of milk sales that contribute to the monetary income of families. Milk self-consumption as part of the gross product of camel farming represented 45% for pastoral Fitri and 21% for peri-urban N’Djamena. Households also exploited live animals for meat, mainly for sale, and a little for self-consumption in Fitri. The added value of live animals represented 55% (3.6 animals/year) of camel gross product in pastoral Fitri, because of the volume of milk self-consumption, and only 10% (1.6 animals/year) in peri-urban N’Djamena, because of milk sales. The livestock per adult equivalent (AE) was, on average, double for households in Fitri compared to those in peri-urban N’Djamena (14 vs 7 TLU/AE). Livestock composition was more diversified in Fitri, with camels (80% of TLUs), small ruminants and cattle, whereas households in peri-urban N’Djamena were even more specialised towards camels (90% of TLUs), besides keeping small ruminants. At Fitri, 40% of households grew crops, compared with only 24% around N’Djamena. The size of livestock holdings ranged from 7.8 TLU/AE for small-size households (4.8 AE) to 8.2 TLU/AE for very large-sized households (9.3 AE) in peri-urban N’Djamena, whereas at Fitri small households had a very high capital endowment (24.4 TLU/AE), medium-sized households were moderately endowed, with 13.9 TLU/AE, and large households were poorly endowed, with 10.8 TLU/AE. In both areas, camel farming provided a daily gross margin per AE over 663 CFA francs/day for three quarters of households, which corresponds to the national poverty threshold. However, only 16% of households generated a gross margin higher than the guaranteed interprofessional minimum wage, estimated at 2000 CFA francs/day. This specialisation of moving to camel herding allowed herders to get well adapted to arid environments. Additional research work is needed to provide a global vision of the potential of camels as a basis for livelihood strategies.

The agronomic benefits of soil organic matter have been studied for centuries, but contemporary focus has expanded to ask how increasing long-term storage of soil organic carbon (SOC) can contribute to mitigation of climate change. Understanding the potential for SOC sequestration in the vast rangelands is crucial for climate change policy, agricultural land management and carbon market opportunities. In this review, we evaluate the evidence from published field trials and modelling studies for sequestration in Australian rangeland soils managed for livestock grazing. We found few long-term studies with high quality SOC stock change data linked to new management, and our analysis was constrained by data limitations, conflicting results between studies, and highly variable climate, soil and landscape conditions across production systems. Rainfall and soil properties are dominant determinants of variation in SOC stocks in rangelands, and it was difficult to detect management impacts in these environments. However, there was consistent evidence that: (1) Sowing more productive grasses or legumes in existing grass pastures generally increases SOC stocks; (2) Prolonged high stocking is associated with net SOC loss; (3) Destocking or exclusion of grazing results in small SOC increases, especially in degraded soils; (4) Conversion from cropping to permanent pasture results in sequestration, influenced by management history; (5) Rotational grazing strategies show negligible impact on SOC stocks relative to continuous grazing; and (6) Waterponding increased SOC stocks initially but persistence has not been demonstrated. We discuss possible opportunities for SOC sequestration in rangelands in the context of uncertainties and associated benefits and trade-offs for livestock production, and make recommendations to improve the evidence-base for major management strategies.

In drylands, soil inorganic carbon (SIC) represents the largest terrestrial carbon sink, and observational studies indicate a negative relationship and possible trade-off between SIC (e.g. calcium carbonate [CaCO₃]) and soil organic carbon (SOC). Some rangeland managers aim to increase SOC stocks to help decarbonise the atmosphere. Unfortunately, the fate of SIC (and SOC) is uncertain, and grazing-induced SOC accrual may correspond with CaCO₃ dissolution, which can produce CO₂ emissions. An added concern is whether carbon sequestration schemes focused on SOC stocks need to be discounted for putative CO₂ emissions due to CaCO₃ dissolution. We used data from a 5-year grazing experiment in the Northern Great Plains of the US. We tested whether grazing management treatments affect SIC, and whether grazing-induced SOC accrual was potentially offset by SIC loss. The experiment had a randomised complete block design and pretreatment data. Response variables were SOC and SIC stocks (0–60 cm depth). Moderate summer grazing (control) is regionally common and treatments that may alter soil stocks included: no grazing, severe summer grazing, moderate autumn grazing, and severe autumn grazing. We also tested for a negative relationship between SOC and SIC across all soil cores (n = 244). Severe grazing (summer and autumn) increased SOC by 0.83 and 0.88 kg × m⁻² relative to moderate summer grazing, respectively. However, no treatments affected SIC. Conversely, we found an overall weak but significant (r² = 0.04, P = 0.002), near one-to-one negative relationship between SIC and SOC stocks of soil cores. Our findings suggest severe grazing can increase SOC without affecting SIC, at least over the short term (5 years). This finding mirrors results from an observational study elsewhere in the Northern Great Plains that also failed to detect grazing effects on SIC. Long-term grazing experiments (>5 years) with pretreatment data may be required to detect grazing effects on SIC.

Significant and lasting soil carbon change in rangeland ecosystems requires ecological state change. Although within-ecological state, soil carbon dynamics can occur, they are driven primarily by short-term fluctuations in weather, specifically precipitation, and are insufficient to provide reliable estimates of change to support policy and management decisions. Changes in grazing management typically do not result in ecological state change, apart from the vegetation structural change associated with long-term overgrazing. Dominant vegetation attributes such as shrub-to-grass ratios, cool season versus warm season plant production, and annual versus perennial growth habit define ecological state and are detectable accurately and cost-effectively using existing remote-sensing technology. These vegetation attributes, along with stationary soil properties, allow for mapping at scales consistent with a variety of policy and management decisions and provide a logical basis for developing a credible sampling framework for verification. Furthermore, state-transition models of ecological state dynamics are designed to provide information that can be used to support inventories and management decisions for soil carbon and other ecosystem services.

The relationships between the encroachment of Calotropis procera (Apocynaceae) and understorey herbaceous cover and various environmental variables of recipient grasslands were studied in the north-eastern Ruaha National Park in southern Tanzania. Three hypotheses were investigated. (1) C. procera exerts a negative influence on the cover of understorey herbaceous plants. (2) C. procera exerts a negative influence on environmental variables (humidity, light intensity, soil pH, air temperature, and soil temperature). (3) The native shrub canopy exerts a negative influence on understorey herbaceous plant cover and the environmental variables. We identified two sampling areas, one encroached by C. procera, the other with only native tree/shrub species. In each area, 21 5 m × 5 m subplots were established, and within each, two 1 m × 1 m sample plots were established, one 20 cm from the stem of a C. procera or native trees/shrub, the other at 5 m distance, and herbaceous plant cover and environmental variables were measured. Variables were measured on three occasions (December 2022, March, and July 2023) on the 42 subplots in each sampling area. Results demonstrated a negative influence of C. procera on understorey herbaceous cover, with a significantly lower percentage (16 ± 1.7) of herbaceous cover for plots at 20 cm than 5 m (72.4 ± 1.4) from C. procera stems. Moreover, soil pH was significantly lower at 20 cm than at 5 m distance from the stems in the encroached area, whereas in the non-encroached area, there was no recorded difference in the environmental variables. These results emphasised the necessity for a prompt intervention to contain the spread of C. procera in suitable grazing areas. A detailed study to find out the most practical and cost-effective control approaches appears warranted.

Sustainably managing grazing lands is aided by monitoring and responding to simple and reliable indicators of how well the vegetation and soils of these landscapes are functioning to capture scarce resources such as water and nutrients. Indicators are needed because direct measurement of resource capture is time consuming and costly. Our aim was to assess how simple measures of vegetation patch cover and size, and soil surface condition, would apply to patchy (run-on/run-off) semi-arid landscapes being grazed at different intensities. We used the grazing gradient design where distance from water serves as a surrogate for grazing intensity, which is a combination of herbage consumption and trampling. From 0.5 to 8.9 km distance from water, we measured vegetation and soil indicators of landscape function on 12 sites, six along a grazing gradient in a mulga (Acacia aneura) woodland and six in a gidgee (Acacia cambagei) woodland. We found the size of tree groves, at both mulga and gidgee sites, declined near water, indicating a loss in the capacity of these groves to capture mobile resources in run-off. Enhancing this capacity at sites in ‘good’ rangeland condition was the presence of a thick band of grass upslope of tree groves. The number of soil erosion features (rills) was also a reliable indicator of landscape function at both gidgee and mulga sites. Soil surface condition indices of stability, infiltration and nutrient cycling had no detectable trends with distance from water at gidgee and mulga sites, but these three indicator values were always significantly higher within groves than inter-groves, confirming the important role of maintaining healthy groves of trees and upslope bands of grass within these semi-arid rangelands.