Rangeland Ecology & Management最新文献

In savanna ecosystems, fire is common, yet little is known on the direct and long-term effects of prescribed burns on arthropod abundance, richness, diversity, and composition. To understand the impact of fire on arthropods at Kruger National Park (KNP), standardized pitfall traps and active searches were used to collect arthropods at unburnt, annually burnt, and triennially burnt plots of the long-term experimental burnt plots (EBPs). Abundance, richness, diversity, and assemblage composition of arthropods were compared across EBPs. Results showed that arthropods from the order Hymenoptera, particularly those in the family Formicidae, were the most abundant (76.4%), followed by Coleoptera (18.6%), Araneae (3%), Orthoptera (1%), and other small/less dominant orders (1%). However, the species richness of arthropods from Coleoptera was high (30.2%) compared with Formicidae (24.6%), Araneae (24.6%), and Orthoptera (4%). Abundance, richness, diversity, and assemblage composition of multitaxon and Formicidae were significantly different among EBPs. Although the abundance of multitaxon and Formicidae was significantly high at unburnt plot, species richness and diversity were low while the assemblage composition was unique at this plot compared with the annually and triennially burnt. Furthermore, the assemblage of arthropods in annually burnt EBP differed compared with those collected at unburnt and triennially burnt EBPs. We conclude that the frequency of prescribed fires improves the richness, diversity, and assemblage composition of arthropods with a significant reduction of abundances. Thus, fire can be used as a conservation tool for arthropods in the protected savanna of KNP.

Land use and land cover change (LULC) play a critical role in influencing ecosystem processes, biodiversity, hydrology, and climate. In recent years, human activities have greatly influenced changes in LULC more than ever before. The Yayo Coffee Forest Biosphere Reserve (YCFBR) is currently experiencing major effects from human activities, such as the spread of forest fires and the expansion of coffee plantations. The objective of this study is to quantify changes in LULC and their effects on ecological preservation within the YCFBR from 1992 to 2022. Landsat images from 1992, 2002, 2012, and 2022 were used for the study after the application of common image preprocessing techniques such as geometric and radiometric correction algorithms. A supervised image classification method using maximum likelihood algorithms was used to create LC maps consisting of six different LULC types in ERDAS Imagine software. The results revealed that throughout the study period, there was a consistent 80.81% of open forests that remained unchanged, while 79.08% of high forests stayed high forests. Similarly, the percentage of agricultural land that remained unchanged was 72.77%, while the percentage of built-up areas that remained the same was 62.84%. Grazing land experienced a conversion of about 58%, followed by high forest with (13.65%) conversion into open forest, whereas 22% of the agricultural land was converted to built-up area. About 62% of the YCFBR landscape persisted during the study period, while the total net change accounted for 59% of the total change in the area. The study's results can be used as valuable input for planning biodiversity management in the region, helping policymakers improve management strategies for LU, and potentially reducing pressure on high forest areas.

Domestic livestock grazing is the primary land use across the planet, but the relationship between grazing and rangeland productivity is difficult to determine because it is influenced by a variety of ecological and management factors. Fine-scale environmental data available through remote sensing are increasingly used to understand land use changes, such as grazing. In this study, we assessed the relationship between a variety of grazing and rangeland productivity metrics while accounting for environmental complexity within the sagebrush steppe ecosystem of Montana. We created mixed-effect generalized linear models using remotely sensed productivity as response variables. Explanatory variables included management and field-based grazing data combined with remotely sensed abiotic and biotic environmental factors. We found point-level field measures of grazing (e.g., cow patties, percentage of dung in Daubenmire plots, and number of plants grazed) showed positive effects, especially on perennial forbs and grasses. Grazing measures at the pasture-level showed a small negative effect on annual forbs and grasses. Grazing metrics tended to have smaller covariate effects on rangeland productivity compared to environmental factors, and interaction effects between grazing and environmental factors were common. This study provides insight into the relationship between grazing and plant productivity in the sagebrush steppe rangeland of Montana and highlights the importance of assessing the effects of grazing using multiple scales while accounting for environmental complexity.

High-density short-duration grazing (SDG) is widely suggested to increase productivity. Among various SDG practices, the most widespread and popular, “holistic grazing,” claims to mimic the movement patterns of wild African ungulate herds to improve rangeland health and promote biodiversity. However, this claim has rarely been empirically tested. Focusing on Karoo Escarpment Grasslands in the eastern Karoo, South Africa, we compared patch use patterns of black wildebeest (Connochaetes gnou) in a continuously grazed wildlife system with cattle paddock use on farms implementing SDG management in the same landscape. Camera trap data revealed heterogeneous wildebeest patch use over the 26-mo sampling period, with wildebeest consistently using some patches more intensely than others. Mean intensity of patch use by wildebeest varied with a factor of 10, from 0.05 LSU · ha⁻¹ · day⁻¹ to 0.51 LSU · ha⁻¹ · day⁻¹ across patches. The relative difference in mean intensity of paddock use among farms ranged across a similar magnitude from < 0.01 to 0.18 LSU · ha⁻¹ · day⁻¹ for least to most intensely grazed paddocks, respectively. Grazing durations in wildebeest patches ranged from 3-15 d (mean = 8 d), compared to the range of 3-60 d (mean = 18 d) for cattle. Intense grazing periods in wildebeest patches ranged from 0 to 2 d (mean = 1 d) and from 1 to 30 d (mean = 7 d) across cattle farms. The greatest difference was between rest intervals, lasting from 1 to 5 d on average across wildebeest patches, compared to 60–365 d across cattle farms. Our findings suggest that SDG systems prevalent in Karoo Escarpment Grasslands differ from the patch use patterns of black wildebeest in most aspects. These findings add to growing literature on grazing behavior of wild herbivores, and effectively contrasts these patterns with SDG cattle farming practices in the same landscape.

Although several strategies can be used for pasture recovery, pasture degradation remains an issue in Brazilian cattle raising. The use of shrub legumes can change the environment (microclimate and water consumption) and productive potential of the pasture. Therefore, the objective of this study was to evaluate the effect of two pasture recovery strategies on the microclimate, soil water dynamics, and forage accumulation of tropical pastures. The research was conducted between 2020 and 2022 in signalgrass (Urochloa [syn. Brachiaria] decumbens Stapf cv. Basilisk) pastures managed under continuous and variable stocking rate throughout the experimental period in São Carlos, SP, Brazil. Three production systems were assessed: 1) degraded pasture without N fertilization (DEG); 2) recovered pasture with application of 200 kg N-urea ha⁻¹ yr⁻¹ (REC); and 3) recovered pasture by intercropping with pigeon pea (Cajanus cajan L. Millsp. cv. BRS Mandarim) (MIX). Soil moisture in the 0–60 cm layer and microclimate, which included photosynthetically active radiation and the animal thermal comfort index, were assessed. The vegetative and productive characteristics of pastures, as well as the total mass production of the production systems, were also evaluated. Overall, intercropping pigeon pea plants with tropical pasture did not significantly affect the soil water content or the animal thermal comfort index. However, it did alter the transmission of photosynthetically active solar radiation to the pasture (0%‒65%) and decreased wind speed (0%‒60%). During the 2 yr, the pigeon pea exhibited a great forage accumulation potential (12 615 kg·ha⁻¹·yr⁻¹). Additionally, pigeon pea provided high-quality forage available during the dry season. Forage accumulation increased in both pasture recovery strategies (REC and MIX), with a significantly greater amount of crude protein (CP) content in the MIX. Intercropping tropical pastures with pigeon pea can be used as a strategy for pasture recovery and dry season forage supplementation.

Tallgrass prairie is one of the major ecosystems in the Southern Great Plains of the United States of America (USA). We investigated the impact of diverse weather conditions on the vegetation dynamics obtained through satellite remote sensing and the dynamics of carbon dioxide (CO₂) fluxes, evapotranspiration (ET), and ecosystem water use efficiency (EWUE) obtained through eddy covariance (EC) in a native tallgrass prairie pasture in central Oklahoma, USA. The study was conducted from 2019 to 2022, considering varying growing conditions. Daily peak net ecosystem CO₂ exchange (NEE), gross primary production (GPP), and ET were −8.7 g C m⁻², 15.1 g C m⁻², and 5.9 mm, respectively. Dynamics of eddy fluxes aligned with the dynamics of vegetation, indicating the accuracy and reliability of satellite-based vegetation indices in tallgrass prairie. Both CO₂ fluxes and ET rates showed little variation over the years during the non-growing season (November to March). However, eddy fluxes exhibited diverse patterns during growing seasons. During the regrowth phase after the hay harvest, the differences in eddy fluxes were particularly substantial due to large variations in late-season rainfall. Consequently, the strength and duration of carbon gain during growing seasons varied substantially by year (i.e., carbon sink for 6 mo in 2019 vs. 2 mo in 2022). The highly variable magnitude of EWUE over the years illustrates that EWUE is not a constant property of this prairie ecosystem. A greater reduction in GPP than ET during dry years led to reduced EWUE. Strong relationships between eddy fluxes and vegetation indices suggest that CO₂ fluxes and ET can be estimated from satellite imagery alone for tallgrass prairie across large spatial scales. Overall, this study provides valuable insights into the carbon and water cycles of tallgrass prairie and the impacts of environmental drivers and disturbances on their function.

Virtual fence (VF) is the use of a global positioning system (GPS) to dictate where on the landscape livestock can graze without relying on traditional physical fence such as barbed wire. The recent acceleration in the development and adoption of VF technology for grazing management has been characterized by the evolution of divergent terminology. Different research and commercial entities have adopted terms and definitions independently. Some terms and definitions are inherently problematic, while others are more aligned, and the simple fact that differences exist contributes to confusion in communication among scientists, producers, land managers, manufacturers, government agencies, and the public. In this paper, we propose a standard terminology determined during a 2-d in-service workshop at the annual meeting of the Society of Rangeland Management in February 2023. Standard terminology will aid in efficient and effective communication among all entities and interested parties.