Rangeland Journal最新文献

Ivermectin, a commonly used parasiticide, is known to affect dung beetle abundance when present in cattle dung. In this experimental study, we explicitly manipulated ivermectin concentrations in dung pats to examine its effects on dung beetle abundance, soil properties, and plant growth throughout the growing seasons of spring and summer in a western South Dakota grassland. Dung pats containing zero, low (2 mg/kg), and high (10 mg/kg) concentrations of ivermectin were strategically placed in the grassland in summer 2019 and spring 2021. Over a period of 63 days, we monitored changes in the nitrogen content of dung, soil, plants, as well as the abundance of dung beetles, and plant biomass. Our findings indicated that beetle abundance was 50% greater in dung pats without ivermectin, especially when the dung was fresh. However, ivermectin concentrations did not significantly alter the nitrogen content in dung and plants across both seasons, nor was there a discernible effect on plant biomass, despite the pronounced impact on dung beetle abundance.

The paper reports outcomes of surveys conducted between 2012 and 2014 in mulga (Acacia aneura) dominated arid rangelands of the Murchison Bioregion of Western Australia, approximately 470 km north-east of Perth, the State capital. The bioregion covers 281,200 km². The purpose of the surveys was to measure the stocks of above-ground biomass (AGB) and sequestered organic carbon within 140 plots, each 25 m × 25 m. The resulting large database was interrogated to (1) find a relationship between AGB and contained carbon in trees and in shrubs, and (2) find plant metrics to predict AGB. At the plant level, analysis confirmed the finding that tree AGB was composed of a mean 47% carbon, with shrub AGB averaging 46%. This allowed biomass to be used as a surrogate for carbon in our further analysis. Tree canopy area was found to provide the best linear relationship with tree and shrub AGB. The linear relationships held true for individual plants across the survey sites and across the land systems involved. At the plot level, measures of AGB and carbon stocks varied across land systems. Because tree canopy can be measured by remote-sensing, the results of these field-only surveys indicated a potential for AGB and carbon in mulga-dominated rangelands to be assessed remotely.

China is investing heavily in agri-environmental and eco-compensation schemes to address growing environmental problems in rural areas. However, assessments of the schemes often overlook transaction costs. Transaction costs are of particular importance in pastoral areas characterised by remoteness, dispersed populations, diverse agro-ecological conditions and heterogeneous livestock systems. Drawing on principles from institutional economics, this analysis investigated transaction costs associated with China’s current grassland eco-compensation schemes in Inner Mongolia and how they might change under alternative policy scenarios. The analysis examined the magnitude of overall transaction costs, their disaggregation among cost types and the incidence of the transaction costs at different administrative levels. The analysis found that the relative magnitude of transaction costs is substantial for the existing policy, whereas an alternative policy more effective in achieving stocking-rate reductions and improved grassland conditions increases transaction costs more than two-fold. The analysis demonstrated the value in accounting for transaction costs in the design and assessment of eco-compensation schemes.

Savanna fires are a major source of greenhouse gas (GHG) and particulate pollution globally. Since mid-2006, an Australian Government carbon offset program has incentivised Northern Territory land managers to undertake early dry-season savanna burning with the aim of reducing late dry-season wildfires and associated GHG emissions. The focus of this study is addressing concern that savanna burning carbon abatement projects are causing worsening air pollution in the city of Darwin. Reconstructed concentrations of daily particulate matter of <2.5 μm (PM_2.5) since the 1960s showed since 2000s a worsening in PM_2.5 in the early dry season (May, June, July), some improvement in the late dry season (August, September, October) with little overall difference for the whole dry season. Remote-sensing PM_2.5 estimates in Darwin were correlated with region-wide PM_2.5 estimates during the early dry season. Remote-sensing analysis of area burned and intensity of fires since 2002 showed that savanna carbon projects have shifted burning to the early dry season and caused increases in fire intensity compared with non-project areas. Increased fire intensity appears to follow sharply declining fuel moisture, as well as management effects on carbon project areas, which have possibly undermined the efficacy of savanna burning projects in reducing GHG emissions. More thorough evaluation of underlying assumption of savanna burning carbon abatement in Australia and elsewhere in the world is required to avoid maladaptation, such as over-crediting, smoke pollution, and other environmental harms.

Rapid development and uptake in uncrewed aerial vehicles (UAVs) for environmental monitoring, specifically using three-dimensional data from LiDAR and structure from motion (SfM), has enabled improved condition assessment, including fine-scale erosion monitoring. Comparing the precision of LiDAR and SfM for measuring erosion is essential in enabling appropriate method selection. Additionally, knowledge regarding optimal flight heights allows for consideration of the trade-off among survey areas, flight times and precision. We assessed UAV-based LiDAR and SfM for providing high-precision digital surface models (DSM) of substantial gully erosion on a conservation reserve in the southern Australian arid rangelands. The gullies exist in low-slope chenopod shrublands with calcareous soils, and are of significant management concern, with erosion occurring rapidly over short periods following irregular and intense rainfall events. Root mean squared error (RMSE) values for SfM-derived DSMs with resolutions of 2, 4 and 6 cm were lower than comparable LiDAR datasets (SfM = 0.72–1.39 cm; LiDAR = 2.08–3.15 cm). Additionally, 2 cm SfM-derived datasets exhibit notably lower RMSE values than 4 and 6 cm datasets (2 cm = 0.72 cm; 4–6 cm = 2.08–3.15 cm). Change detection over the 1-year study period highlighted erosion in locations of management concern. We propose that, although both methods are of value, SfM is preferred over LiDAR because of its simplicity, reduced cost, and the additional monitoring capabilities of visible-colour imagery, with no notable sacrifice in precision. Visible-colour survey areas and times can be optimised by increasing flight height without dramatic losses in precision. The use of either method will be of great benefit for the monitoring of arid gully erosion and assessing the effectiveness of management interventions, allowing adaptive management and leading to improved condition of arid rangelands into the future.

Land management changes are and will continue to play a substantial role in national and global strategies towards decarbonisation goals. Yet, roles for land managers and their communities to co-create opportunities for just transitions are not well represented or accounted for in policy instruments or markets, including those for carbon offsets. Understanding regional context is critical to identify strategies for land management changes to underpin just transitions. We outline a mixed-methods approach involving an analysis of socio-economic data and a critical review of regional plans to identify the benefit aspirations that communities have articulated, and the drivers of transitions already at play to understand how land sector carbon abatement projects could support regional transitions. This approach is demonstrated using a case study region in Queensland, Australia. The case study region hosts land sector carbon abatement projects under a national policy that incentivises least cost abatement and under a state policy that incentivises land sector carbon abatement with bundled environmental and social co-benefits. The results show that across sectors and locations, communities are seeking economic, cultural, and social outcomes that can be delivered as co-benefits of land management changes for carbon abatement. Our analysis shows that the value of multiple co-benefits is place-specific and dependent on the provenance of land management changes and broader regional conditions. By understanding regional contexts and aspirations, it is possible to identify how and where land sector carbon abatement investments can be negotiated between investors and communities to support just transitions to low-carbon futures.

Although the concepts of carbon and ecosystem service markets gained traction in the literature in the early 1990s, they have only recently (since the early 2000s) become a reality in Australia. The past decade has seen the appearance of markets for carbon sequestration (and avoiding land-clearing), most of which have occurred in rangeland environments. There has been research in recent decades focusing on the barriers and opportunities for the uptake of such carbon and ecosystem service markets at the landholder level. However, there is limited research into how the policy, institutional and governance arrangements may be affecting the effective and efficient development of cohesive carbon and ecosystem service markets in the Australian rangelands that could result in genuine and enduring environmental, social and community outcomes. Using in-depth interviews with 34 diverse stakeholders, we identified many inter-related themes that provided clear insight into aspects of these markets in Australia. Complexity was the most prominent and overarching theme. The markets operate on multiple levels across state, national and international jurisdictions, leading to confusion for landholders and other stakeholders. The type and number of groups and stakeholders in these systems add to the perceived complexity, with convoluted lines of responsibility, jurisdictional appropriateness, regulation, financial investment, and oversight. There is currently a lack of transparency within these markets, resulting in reduced trust and engagement. We deduce that carbon and ecosystem services markets are, in fact, a wicked policy problem, but have not yet been framed as such. We suggest a multi-stakeholder partnership or roundtable approach be used to tackle the symptoms of the wicked problem associated with carbon and eco-system service markets, which may help in reducing some of the complexities, perverse outcomes and stakeholder trust issues identified in this research.

Adaptive multi-paddock (AMP) grazing is hypothesised to improve livestock diet quality by allowing managers to move livestock among paddocks in a manner that tracks phenological variation in forage growth related to variation in plant community composition. We compared yearling steer (Bos taurus) dietary crude protein (CP), digestible organic matter (DOM), and diet composition on a ranch-scale (2600 ha, 10 pairs of 130 ha paddocks) experiment in shortgrass steppe for 6 years (2014–2019) in contrasting grazing treatments: Collaborative Adaptive Rangeland Management (CARM, a type of AMP with a stakeholder group making science-informed management decisions within the grazing season) and season-long, continuous grazing (TRM, traditional rangeland management). These grazing treatments had the same system-level stocking rate annually but differed in stocking density, with CARM being 10-fold higher than TRM because of all steers in the CARM treatment being in a single herd. Mean grazing-season dietary CP was consistently 13–28% higher in TRM than CARM; in contrast, DOM in TRM was similar to CARM or only slightly higher (2.5%). Differences in diet quality between CARM and TRM grazing strategies were largest early in the grazing season, with CP being 14–36% higher for TRM compared to CARM steers during the first 4 weeks; these diet-quality differences between treatments disappeared towards the end of the grazing season. Implementing AMP on the basis of a diverse stakeholder group’s experiential knowledge about plant communities, soils, and ecological sites did alter within-grazing season plant functional group contributions to steer diets. Although we implemented adaptive decision-making within the grazing season, which allowed CARM steers to track the seasonal phenology of C₃ versus C₄ grasses as steers rotated among paddocks varying in plant community composition, these adaptive movements did not offset the detrimental effects on diet quality associated with grazing in a herd with 10-fold higher stocking density. Managers applying AMP in semiarid rangelands should be cognisant that high stocking density can be associated with lower diet quality early in the growing season, which can compromise livestock gain responses.

Objective monitoring methods that reliably identify grazing impact are required for long-term sustainable management in the arid rangelands. In Australia such methods must contend with highly unpredictable rainfall and large paddocks incorporating spatially complex land types with differing grazing preferences. Retrospective analysis of data collected following very dry and very wet periods removes vegetation dynamics generated by lesser rainfall events and should increase our ability to separate grazing effects from seasonal variability. Two remote-sensing methods were tested for their capacity to quantify trends over 30 years in vegetation-cover dynamics on a pastoral lease in central Australia with a history of heavy grazing. Following destocking by 2002, one section became a conservation reserve and another transitioned to a research station. During drought, the Dynamic Reference Cover Method (DRCM) showed that ground-cover deficit was less negative on both areas towards the end of the study. This improvement was attributable to increased ground cover after removal of grazing, followed by a reduced, but variable, grazing intensity on the research station and the spread of an introduced palatable perennial grass. Ground-cover response following rainfall was highest in 2011. Likewise, increased ground cover meant that the percentage Cover Production Loss (%CPL) index, calculated using grazing gradient methods (GGMs), was considerably less than a decade earlier following similar rainfall. Results from an associated recovery index (R) were inconclusive. Landscape heterogeneity potentially affected calculation of cover deficit using DRCM but, because heterogeneity was stable over time, reported change between dry years reliably indicated a trend owing to grazing. Interpreting trend from successive %CPL values in wet periods was complicated on the research station by altered waterpoint locations being superimposed on pre-existing degradation; however, the method should be effective in large paddocks with stable waterpoint locations. Despite their limitations, both methods can assist in objectively judging the long-term sustainability of grazing practices in contrasting seasonal conditions.

Rangeland degradation, with the loss of perennial grasses and shrub encroachment, negatively affects livestock production and reduces the drought resilience of commercial ranchers and pastoralists in drylands. This situation applies in Namibia, where few attempts have been made to investigate rangeland changes and shrub encroachment across the two major land-tenure systems in the country, namely, freehold and communal land. This study aimed to investigate the inter-relationships among rangeland changes, land tenure and management in Namibia within the past 55 years, by combining remote-sensing analysis, literature review, and interviews. Land-cover classification results revealed different trends in the two tenure systems between 1965 and 2020. Both were affected by shrub invasion. At the onset of the observation period, the percentage of grass-dominated savanna was higher on communal land. Whereas a linear increase in shrubland was observed after 1965 on communal land and on freehold land up to 2001, the shrub encroachment trend on freehold land reversed from 2011, mainly because of de-bushing measures. The most important drivers for rangeland changes and shrub encroachment were related to specific land-management practices and the historical and socio-economic contexts in which they occurred, including various policies associated with colonialism, fire suppression and overgrazing, combined with recurrent droughts. Although farmers on freehold land apply various strategies to combat shrub encroachment, the aftermaths of colonial policies and the issues of common-pool resource management have limited the options of those on communal land to implement such measures. The search for sustainable management options, thus, requires a deeper understanding of their potentials and shortcomings in both land-tenure types; such understanding could be acquired by considering local knowledge and past and current land-use practices. Management options that incorporate the numerous benefits of woody plants and the uses of shrubs hold promise for sustaining livelihoods in both land-tenure systems.