Rangeland Ecology & Management最新文献

Deferred grazing regimes are viewed as a grazing management strategy that can aid in the enhancement of rangeland productivity and health. However, there is limited empirical evidence from drylands of East Africa. This study investigated the effects of deferred grazing regime on rangeland productivity and health in northern Tanzania. Aboveground vegetation biomass, plant species composition and diversity, as well as soil organic carbon (SOC) were assessed in 45 rectangular sample plots (20 × 50 m) which were randomly distributed in a rangeland subjected to deferred grazing for 8 years. For control adjacent rangelands subjected to continuous grazing management were evaluated. Statistical analyses were performed using an independent t-test to discern differences in vegetation biomass, SOC, species abundance and diversity between the two grazing regimes. Additionally, Multivariate General Linear Model (MvGLM) were performed to test if grazing system affected vegetation composition. Results revealed that the herbaceous biomass, SOC, and the richness of shrubs (with a diameter at breast height, or DBH ≥5 cm and <10 cm) and trees (DBH ≥10 cm) were higher in rangeland subjected to deferred grazing, in comparison to the rangeland under continuous grazing regime. Moreover, rangeland under continuous grazing was found to be more heavily invaded by non-native plant species, notably the invasive weeds Prosopis juliflora and Calotropis procera. The findings of this study suggest that rangelands in the study area can be both more productive and healthier when managed under a deferred grazing regime, as compared to continuously grazing rangeland.

Rangelands globally face escalating threats from overgrazing, land conversion, and climate change. This study investigates spatio-temporal rangeland degradation patterns in Pakistan's Bhakkar District, a semiarid region dependent on fragile pastoral ecosystems, over the past four decades at 10-yr intervals (1990, 2000, 2010, 2020). Remote sensing offers a valuable tool for monitoring these vast yet understudied dryland environments. We employed Landsat satellite data and machine learning algorithms to map land cover change and analyze vegetation health indicators. The random forest classifier achieved high accuracy (94%) in delineating six land cover categories–water, built-up, forest, cropland, rangeland, and barren land. Classified rangeland area declined by over 25%, largely due to agricultural expansion. Vegetation indices showed mixed trends, with decreases in enhanced vegetation index but marginal improvement in normalized difference vegetation index. Meanwhile, rising land surface temperatures pointed to increased aridity. These concerning changes underscore the urgent need for conservation policies tailored to community needs through participatory engagement. Rangeland degradation threatens the livelihoods and welfare of pastoral communities reliant on these ecosystems. Integrated solutions centered on adaptation and resilience can promote sustainability in Bhakkar's marginal dryland environments. This study demonstrates the power of satellite monitoring coupled with social research for implementing holistic strategies to address the globally prevalent threat of rangeland disruption.

Globally, land use and land cover change (LULCC) is recognized as posing a substantial environmental challenge with lasting and severe consequences. This study quantified LULCC within the Vea catchment area spanning 24 years, from 1998 to 2022. Landsat TM imagery from 1998, ETM+ imagery from 2006, and Landsat 8 OLI imagery from 2014 to 2022 were used. A supervised classification algorithm was employed to classify the LULC classes. The findings reveal a notable transformation in the Vea catchment area from 1998 to 2022, primarily by converting grassland to cropland. Agricultural activities emerged as a significant contributor to the observed LULCC trend. Notably, cropland expanded from 10.9% to 51.98% between 1998 and 2022, while grassland and mixed vegetation/forest areas decreased from 54.8% to 18.14% and 31.7% to 22.73%, respectively. These results, it is argued, underscore the potential implications for achieving the targets set by the UN's Sustainable Development Goals.

The Montezuma quail (Cyrtonyx montezumae) is a game bird that inhabits oak-juniper-pine savannas of Arizona, New Mexico, and Texas, extending its range south into montane grasslands of Mexico. The species occurs within a complex matrix of public and private rangeland in which land management regimes and habitat quality are disparate. Given that food limitation can be a driver of wildlife populations, studies of the Montezuma quail diet can inform the management of its habitat. Our objective was to determine the composition and variation of the Montezuma quail's diet in Arizona, New Mexico, and Texas by macrohistological analysis of crops (n = 175) collected in 2016−2020 during winter in all three states and during spring in Texas. We used Dirichlet regression to determine the effects of ecological factors on diet composition. Winter diet in Arizona was mainly represented by woodsorrel bulbs (Oxalis spp.; 35.22% of dry weight), sedge rhizomes and bulbs (Cyperus spp.; 30.92%), and acorns (Quercus spp.; 7.17%). Winter diet in New Mexico consisted mainly of sedge bulbs (64.13%), bushbean seeds (Macroptilium sp.; 15.82%), and Hall's panicum seeds (Panicum hallii; 10.11%). Winter diet in Texas was composed of sedge rhizomes and bulbs (28.17%), Texas snoutbeans (Rhynchosia senna; 22.49), Hall's panicum seeds (19.54%), and wild onions (Allium spp.; 8.58%). Spring diet in Texas included sedge rhizomes and bulbs (67.90%), woodsorrel bulbs (19.49%), and Texas snoutbeans (5.55%). Geographic variation in diet composition was related to climatic, ecological, and intrinsic factors. For instance, in addition to being consumed by males at a higher rate, woodsorrel bulbs were also consumed at a greater rate in hotter and wetter locations. Along with novel information about the Montezuma quail diet in Texas, our investigation will stimulate questions relevant to rangeland and wildlife management, including determinants of habitat quality and the effects of climate change on wildlife populations.

In light of climate change, ranchers need management tools to restore dry grasslands. To boost productivity and resilience, compost applications have shown promise, but little is known about the effect of composts that differ in initial feedstock and resulting biological and chemical characteristics. Our objective was to compare commonly available composts to evaluate how they affected soil microbial community composition and soil health−related responses in drylands. We added biosolid versus manure composts to 64-m² plots in a rangeland in Socorro County, New Mexico and measured microbial, soil, and plant characteristics after 6 mo and 1 yr. We found that while composts hosted diverse microbial taxa, relative abundance of native soil microbial communities did not shift dramatically from controls at either 6 mo or 1 yr after compost addition. Aggregate stability was 22% lower in manure than biosolid compost and controls (P = 0.048), but aboveground biomass tended to strongly increase depending on exclosure treatment (P = 0.048), and composition shifted to relatively abundant annual forbs with biosolid compost compared with controls. Together, these results suggest that while increased organic matter enhanced vegetation biomass, an important implication for range managers, the dominant microbial community members were not primarily responsible for observed shifts in responses.

This technical note asks what role Canadian Bison ranchers play in conserving North American Bison. Bison are keystone species in grassland ecosystems and pose numerous ecological benefits as wild animals. Unfortunately, most wild Bison have been eradicated through the process of colonization. Today, over 90% of Bison exist in commercial production rather than for conservation; however, the Canadian Bison Association—an organization committed to protecting the industry—wishes to blur the line between the two. Conversations with a few members of the CBA suggest that ranching may support the numerical recovery of Bison but may not support ecological recovery. Although there have been calls for cross-jurisdictional collaboration in the Bison conservation literature, more research is needed to reconcile what appear to be incompatible values between ranchers and ecological conservationists.

Livestock grazing is the most economically important use of rangeland ecosystems in many parts of the world. An extensive body of literature has investigated livestock grazing plans that are economically optimal or ecologically sustainable. This paper's contribution to the literature is development and application of an empirical mathematical programming model for optimizing the economic performance of livestock grazing on rangeland ecosystems for a wide array of vegetation biomes, forage productivity levels, and economic conditions. The model is calibrated to replicate historically observed data for select counties, in which predictions of the income optimization model match available data on county-wide forage, animal performance, grazing pressure, stocking level, and net income. Results show how climate stress and economic conditions affect the economically optimized choice of stocking rates and net income for 18 observed conditions and 126 potential conditions for six counties in the Intermountain West and Mediterranean western US. While findings show optimized outcomes for a large set of conditions in that region, the methods developed here have potential application to rangeland ecosystems internationally wherever data required by the model can be secured. The modeling results provide insight and utility for ranchers, scientists, and policymakers who seek economically optimal rangeland ecosystem outcomes.

Cattle (Bos taurus) grazing is often excluded from restored grasslands due to potential risks to grassland recovery. This restriction has often been applied to the 5.6 million acres of Conservation Reserve Program (CRP) plantings designed to restore native grassland plant communities on former cropland. Because large herbivores historically played a key role in maintaining these grassland systems, excluding such grazers may hamper recovery of plant compositional and structural heterogeneity important to wildlife. We conducted a grazing experiment on 108 CRP sites in Kansas, quantifying the effects of periodic cattle grazing on plant communities restored via two CRP conservation practices (CP2, Establishment of Permanent Native Grasses and CP25, Rare and Declining Habitat) across a broad precipitation gradient. Cattle grazing was implemented during the growing season on 53 of the 108 sites in 2017−2018 with rest from grazing in 2019. Grazing reduced vegetation biomass and increased vegetation structural heterogeneity in 2017 and 2018. Grazing effects on plant community composition, specifically shifts in dominant grass abundances, were observed in 2018 but not 2017 or 2019. These effects were subtle and did not result in consistent changes to plant species richness, non-native abundance, or floristic quality. The effects of conservation practice were independent of grazing but strongly dependent on mean annual precipitation. Plant community composition differed significantly between CP2 and CP25 in the western (drier) and eastern (wetter) regions, but no differences were detected in the central region. Forb cover increased with precipitation at a greater rate on CP25 than CP2, indicating greater forb establishment in the eastern region. These results indicate that moderate, short-term grazing can enhance habitat structural heterogeneity that may be beneficial for wildlife while causing minimal plant community changes.

Black greasewood (Sarcobatus vermiculatus Hook., Torr) is a native halophytic, resprouting shrub found on saline rangeland soils in the western United States, including the western Great Plains grasslands. Stands can become dense, with limited native herbaceous biomass, and are prone to invasion by exotic species. We tested fall and spring prescribed fire compared with nonburned controls in a degraded rangeland site near Miles City, Montana, and a healthy rangeland site near Laramie, Wyoming to determine effects on greasewood shrub survival, density, and canopy structure. We additionally tested fuel load, time since fire, fire seasonality and prefire measurement effects on postfire greasewood canopy structure. In a second experiment at the Montana site only, nontreated controls, fall fire, 2,4-D, and 2,4-D preceded by fire were tested for effects on herbaceous biomass and greasewood survival, density, and canopy structure. Fire did not affect greasewood survival, but fire in either season reduced canopy volume by 52% across two growing seasons and models projected four or five growing seasons for structural recovery. Fine fuel load was negatively related to greasewood density and canopy structure. Herbicide reduced greasewood survival by 55%, and fire plus herbicide reduced survival by 30%. No treatment effects were detected for herbaceous biomass at the degraded site. Prescribed fire can reduce greasewood canopy structure for multiple years without killing the shrubs. Herbicide is more effective than fire if the objective is to reduce greasewood density, but multiple applications may be required. While 2,4-D herbicide was less effective when applied to resprouts after fire, results may improve with later postfire application. Although 2,4-D provided the greatest reduction of greasewood, skeletons of dead shrubs remained. Following herbicide treatment with fire could be a treatment combination to strategically reduce greasewood influence because fire would remove skeletons and further reduce canopy structure.