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Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis [Beetle & A. Young] S. L. Welsh) has decreased from its historic prevalence across the sagebrush steppe in part because of its interaction with invasive annual grasses and the increased wildfire frequency. Restoration of this species is vital to the ecosystem; however, traditional seeding methods such as broadcast or drill seeding have low success rates. Seedling mortality is associated with harsh weather conditions such as freezing temperatures in the winter and extreme temperature and soil moisture conditions during the summer drought. Transplanting sagebrush has greater success by overcoming the bottleneck of early seedling mortality. We tested how sagebrush transplant survival and size (canopy volume) are affected by age at the time of planting (10 classes, 6–24 wk), planting season (fall versus spring), and invasive annual grass competition (low/high) with a randomized factorial design over 2 yr. Survival was lower for age classes under 10 or 12 wk (in yr 1 and 2, respectively) but relatively similar from 12 to 24 wk. Fall-planted transplants had lower survival but increased canopy volume compared with spring-planted transplants. Survival and canopy volume decreased with competition with annual grasses. Our results suggest that land managers should consider planting younger transplants than previously thought and controlling invasive annual grasses before planting sagebrush transplants to increase long-term survival and canopy volume.
Wild free-roaming (WFR) horses (Equus ferus caballus) occur on lands administered by the Bureau of Land Management and US Forest Service in 10 western US states. Little is known about public knowledge concerning management of WFR horse populations. In 2020, we conducted a survey to assess public knowledge with the intent of establishing baseline information that may be used to shape horse management programs and policies on the nation's public lands. We obtained responses from 1 124 residents of the western United States. Our survey asked eight knowledge-based questions of WFR horse ecology and management in the western United States. We conducted chi-square analyses to determine the influence of age, gender, region of residence, and income on respondents' ability to answer these questions appropriately. Our results indicate that these demographic characteristics had little predictive ability to explain the level of the western US public's knowledge of WFR horse ecology and management (for all comparisons, λ < 0.10). Furthermore, our respondents had little knowledge of WFR ecology and management. Approximately 30% of respondents correctly identified WFR horse origins, 8% correctly indicated WFR horse population size, and 37.5% indicated that they were unaware of legal management options. The lack of basic understanding of WFR horse ecology and management may influence the public's ability to support management efforts or determine fact from propaganda. Approximately 60% of the respondents indicated they primarily used government, university, and organization websites when seeking information. Efforts to increase dissemination of facts on multiple venues, such as social media, websites, and newspapers that link back to government and university websites, could increase public support of future management actions. Additionally, the announcement of management actions, such as round-ups, should consistently include basic background information regarding WFR horse ecology and populations to ensure that the public can make informed conclusions.
Invasion of non-native annual grasses is a significant threat to the sustainability of sagebrush steppe ecosystems. Ecological resilience, the ability to bounce back after a disturbance, and resistance, the ability to withstand invasion, are influenced by both abiotic factors, such as soil temperature, moisture, elevation, and aspect, and biotic factors, such as plant community composition. We quantified the effects of moss biocrusts, native shrubs, and native perennial grasses on invasion resistance in a greenhouse experiment containing dominant sagebrush ecosystem plants and invasive grasses. We saw greatest suppression of invasive annual grass biomass in treatment replicates containing native bunchgrass species (P < 0.01). Final invasive grass biomass was 4.79 g on average when perennial grasses were not present and was reduced to 1.59 g with perennial grass competition (P < 0.01). Presence of shrubs and moss biocrusts did not decrease annual grass biomass (P= 0.38 and P= 0.25, respectively). We saw complex interactions between native plants grown in these ideal greenhouse conditions such that native perennial grass seedlings grown with sagebrush seedlings had a mean of 4.50 g more biomass (P < 0.001) relative to pots grown with bitterbrush or without shrubs, but shrubs were an average of 7.9 cm (P < 0.001) shorter and had biomass 4.75 g lower (P < 0.001) in pots grown with perennial grasses compared with shrubs grown without perennial grasses. Our results demonstrate that with increased treatment complexity, we see greater invasion resistance, but that nuanced relationships between plant community members should also be considered in managing and restoring these imperiled ecosystems.
Stable isotope analysis of 13C and 15N has been widely used to provide information regarding short- or long-term animal dietary composition as affected by changes in land or ecological system use. In complex mixed-crop–livestock systems, rangeland biomass, crop residues, and feedstuff contribute to livestock diets with high seasonal variations. Particularly in the Limpopo province, South Africa, livestock feed supply varies considerably throughout the year leading to regular feed gaps. Hence, to estimate livestock diet composition in relation to these variations, we analyzed the stable isotopes of C and N of tail hair and feces samples across free-ranging beef cattle in distinct agroecological zones (AEZs) and farm types. Here, farm types were structured according to mixed-crop–livestock farms and livestock-only farms. We found that farm types did not influence the δ13C of feces and hair (P > 0.05), but AEZ had a strong effect on δ13C patterns (P < 0.01). The contribution of C3-C4 plants in the diet varied considerably across farm types and AEZ (P < 0.01). The δ15N values indicated nutritional stress, probably due to low protein concentrations in feed (e.g., rangeland biomass, crop residues) irrespective of AEZ and farm types. In general, cattle exposed to arid conditions (drier AEZ) had significantly decreased δ13C values and increased δ15N values that could potentially be linked to feed gaps. Moreover, the results from the present study indicate that δ13C of feces and hair samples are more meaningful predictors of cattle diet than δ15N as affected by different farm practices. Therefore, stable isotope analyses potentially have an important role in helping improve the understanding of seasonal shifts in livestock diet intake in diverse production systems.
The hypothesis that transformation of rangelands by domestic herbivores follows state-and-transition models predicts that vegetation communities will cross ecological thresholds when shifting from one state to another. We test this hypothesis by identifying threshold responses of soil function in Gamka Thicket, a variation of Arid Thicket in South Africa. We relate indices of soil water infiltration, nutrient cycling, and soil retention (reflecting ecosystem function) to distance from artificial watering points in four piosphere treatments differing in rangeland management history. Furthermore, we compare the pattern, extent, and variation in transformation at the end regions of our piosphere treatments to each other and to a transformed and untransformed reference site. The changes to all the indices of ecosystem function support the hypothesis that functional thresholds have been crossed. We propose a conceptual model that suggests that Arid Thicket transformation due to herbivory transcends three vegetation states. We contend that during the process of transformation the crossing of structural thresholds lead to the crossing of functional thresholds that ultimately drive the formation of new vegetation states.
In dry climates, livestock farming contributes to waterhole creation and maintenance, thereby contributing to biodiversity conservation. However, these lentic water bodies also represent a critical environmental connection between microorganisms and their vertebrate hosts since the water can facilitate pathogen persistence and transmission. Therefore, interventions for tuberculosis (TB) risk mitigation at the wildlife-livestock interface often focus on segregating host species at water points. We hypothesized that waterhole characteristics modulate their use by vertebrates and subsequent pathogen exposure risk. We visited 298 waterholes on 80 TB-positive and 40 TB-negative cattle farms in Spain to assess differences in waterhole characteristics and identify possible management implications. There was an average of 2.7 waterholes per farm. This represents 0.02 waterholes per km2 of farmland and 3.5 m2 of lentic waterbodies per km2 of farmland. Among the studied waterholes, 95% were man-made. Waterholes on TB-positive farms were 42% closer to covering vegetation than waterholes located on TB-negative ones. Farms with man-made waterholes showed a higher risk of TB than those with natural ones. The density of waterholes per surface unit was negatively associated with the farm TB risk. Waterholes placed on TB-positive farms were more intensively trampled by livestock. The best model explained farm positivity to TB as a function of the distance from the waterholes to the nearest cover vegetation, the aquatic vegetation richness found in the waterhole, the intensity of livestock use (trampling), the surrounding waterhole density, and the interaction between waterhole perimeter and the total number of signs of potential wildlife TB hosts per waterhole. Identifying the key waterhole features related to infection risk might allow designing One Health–inspired biosecurity measures such as increasing the number of waterholes, placing new waterholes farther away from cover, or fencing-out cattle from wildlife-rich waterholes to balance biodiversity conservation and animal health needs in extensive grazing systems.
Invasive annual grasses, such as medusahead (Taeniatherum caput-medusae [L.] Nevski), have invaded tens of millions of hectares of the sagebrush ecosystem. These invasions severely reduce ecosystem goods and services provided, as well as increase the probability of frequent, large wildfires. Revegetation of invasive annual grass–invaded rangeland with perennial bunchgrasses is critical to reversing these negative consequences. Short-term evaluations of revegetation efforts have shown promising results. However, long-term evaluations of revegetation efforts in medusahead-invaded rangelands are lacking, so it remains unknown if revegetation attempts in these invaded rangelands have persistent effects. We evaluated the effects of controlling medusahead with prescribed burning and imazapic application followed 1 yr later with drill-seeding large perennial bunchgrasses at two seeding rates (medium and high) for more than a decade post seeding. Large perennial bunchgrass cover and density was > 16- and > 4-fold greater in revegetation treatments compared with the untreated control 11 yr after seeding, respectively. Invasive annual grass abundance was ∼twofold greater in the untreated control compared with the revegetation treatments. These results suggest that revegetation efforts in medusahead-invaded rangelands can have persistent ecological benefits (increased perennials and decreased invasive annuals). The high seeding rate resulted in more perennial bunchgrass and less invasive annual grass compared with the medium seeding rate over the duration of the study, suggesting that high seeding rates may be needed to maximize benefits. Revegetation of medusahead-invaded rangelands can have long-lasting effects, though high establishment of perennial bunchgrasses is likely necessary for success.
Adequate numbers of replicated, dispersed, and random samples are the basis for reliable sampling inference on resources of concern, particularly vegetation cover across large and heterogenous areas such as rangelands. Tools are needed to predict and assess data precision, specifically the sampling effort required to attain acceptable levels of precision, before and after sampling. We describe and evaluate a flexible and scalable process for assessing the sampling effort requirement for a common monitoring context (responses of rangeland vegetation cover to post-fire restoration treatments), using a custom R script called “SampleRange.” In SampleRange, vegetation cover is estimated from available digital-gridded or field data (e.g., using the satellite-derived cover from the Rangeland Assessment Platform). Next, the sampling effort required to estimate cover with 20% relative standard error (RSE) or to saturate sampling effort is determined using simulations across the environmental gradients in areas of interest to estimate the number of needed plots (“SampleRange quota”). Finally, the SampleRange quota are randomly identified for actual sampling. A 2022 full-cycle trial of SampleRange using the best available digital and prior field data for areas treated after a 2017 wildfire in sagebrush-steppe rangelands revealed that differences in the predicted compared with realized RSEs are inevitable. Future efforts to account for uncertainty in remotely sensed–based vegetative products will enhance tool utility.
Seed dispersal plays a pivotal role in plant ecology, impacting various aspects such as dispersal, reproduction, and population dynamics. In this study, we investigated the endozoochoric seed dispersal by the onager or Persian wild ass (Equus hemionus onager) in Qatrouiyeh National Park, located in south-central Iran. Fecal samples were collected from three plains within the park over three seed production seasons. A subsequent greenhouse experiment was conducted to identify and quantify the germinated seedlings. We discovered a total of 63 plant species across 45 genera and 21 families, with the majority of species categorized as annual or perennial forbs. Seasonal variations were observed for seedling count, species richness, and species diversity, with peak values observed during autumn. The seedlings consisted primarily of forbs (86%), followed by grasses (10%) and other plant types (4%). Astragalus podolobus, Lepidium vesicarium, and Chenopodium album emerged as the most abundant species from the fecal samples. Our findings shed light on the critical role played by the onager in the dispersal of numerous plant species and emphasized the potential cascading effects of herbivore-mediated seed dispersal. This highlights the significance of conserving and restoring the remaining populations of this threatened subspecies in arid habitats, where seed dispersal by abiotic factors is limited.
Rangelands are among the important natural resources that are being degraded all around the world. One of the effective ways to control rangeland degradation is to take the advantage of the pastoralists' participation in the implementation of rangeland management projects, especially restoration practices. Therefore, this study was conducted to reveal the consequences of participatory behavior of Turkmen pastoralists on rangeland restoration practices in Aqqala County, Golestan Province, Iran, assuming that the participatory behaviors of pastoralists on restoration practices have positive consequences on the rangeland status. This is descriptive research that was conducted with a survey technique. Stratified random sampling was used to sample pastoralists' population. The statistical population was 120 pastoralists from 8 pastoral units, of which 92 were selected as a sample size. Random samples were taken from pastoral units, in proportion to the population. The data-gathering tool was a researcher-made questionnaire. Its validity and reliability were respectively assessed by expert opinions and Cronbach's alpha coefficient. The results showed that pastoral age, annual income, number of animals, and animal husbandry experience have positive and significant relationships with the participatory behavior of pastoralists. Pastoralists who were members of rangeland management cooperatives and participated in training courses had better participatory behavior in the implementation of rangeland restoration practices. On the basis of the path analysis, participatory behavior of pastoralists had positive effects on livelihood and employment (β = 0.371), social knowledge and awareness (β = 0.408), social capital and participation (β = 0.625), differences and strengthening of cultural contexts (β = 0.422), environmental and wildlife status (β = 0.339), organizational support (β = 0.111), and land use change prevention and ecosystem conservation (β = 0.347). In conclusion, barriers to pastoralists' participation in restoration practices can be removed through identifying the consequences of participatory behavior of pastoralists, and rangeland ecosystems degradation can be controlled.
Introduced annual grasses (IAGs) have invaded tens of millions of hectares of western US rangelands, displacing native vegetation and altering ecosystem functions and services. Our main goal was to assess the influence of introduced annual grasses by 1) exploring the relationships among IAG cover, species richness, diversity, and cover of other plant functional groups; and 2) identifying biotic and abiotic indicators of IAG cover. Using data from 64 sites and 420 plots from rangelands of the northwestern United States, we explored linear correlations between IAG cover and species richness, Shannon index, and plant functional group cover. We also used Least Absolute Shrinkage and Selection Operator (LASSO) regression and nonmetric multidimensional scaling to select environmental variables and plant functional groups that were associated with IAG cover. Our findings revealed a negative correlation among IAG cover and species richness, Shannon index, native perennial grass cover, and other perennial species cover and a positive correlation with other annual species cover. Our results identified several indicators: cover of native perennial grass; other perennial species (forbs and shrubs); litter; bare ground/rock; soil attributes (pH, bulk density, clay, and nitrogen); and mean annual temperatures. Our results showed that perennial vegetation, especially native perennial grasses, have a negative correlation with IAG. Warmer mean annual temperatures, but not higher daily extreme temperatures, and higher bulk density were important indicators for IAG preferred sites, while lower soil nitrogen may denote soil changes due to invasion. Given the fundamental role of disturbance in determining the magnitude and scale of IAG invasion, our results provide important insights for scientists and managers.
Many perennial plants in semiarid rangelands have experienced population declines, and understanding the ecological and demographic processes behind these declines is important to slowing or reversing them. Although anthropogenic disturbances drive many declines, other sorts of environmental variability, such as the differences in solar radiation with aspect, may impact population success locally. We experimentally assessed the role of solar radiation in driving an apparent decline in a common perennial bunchgrass, bluebunch wheatgrass (Pseudoroegneria spicata), on south-facing slopes at a site in the Columbia Basin of North America. Across three separate experiments on south-facing slopes, we observed dramatically (5–36 ×) higher seedling success in plots shaded to approximate the solar radiation of north-facing slopes relative to adjacent open (unshaded) plots. When we applied the rates of seedling success from these experiments to demographic models from this site, we found that seedling success in unshaded plots was often too low to allow a stable population on south-facing slopes, but that seedling success in shaded plots was often high enough to allow a stable or increasing population on north-facing slopes. We originally hypothesized that the primary mechanism driving this effect was water stress caused by greater evaporation from hotter open plots. However, despite soils in open plots being consistently hotter than soils in shaded plots, we did not observe a clear pattern of greater soil moisture in shaded plots. Therefore, it appears that higher solar radiation or higher temperatures on south-facing slopes may be sufficient to dramatically reduce seedling survival, and that the higher density of bluebunch wheatgrass on north-facing slopes relative to south-facings slopes may be driven primarily by this low survival of seedlings. As climate warms, the reduced seedling survival that threatens our bluebunch wheatgrass population may be expected to threaten many other species of perennials in similar rangelands.
Success in conserving biodiversity in rangelands depends on effectively managing the systems to achieve positive economic outcomes while preserving biodiversity. In the native grasslands of the Río de la Plata region, livestock production often falls below its potential due to low forage availability. Cattle management strategies that promote taller grass height can increase forage mass without replacing native vegetation, enhancing cattle dry matter intake and potentially boosting production. Nonetheless, the impact of such changes on grassland bird populations remains unclear. In this study, we implemented management changes to increase grass height across six ranches and evaluated the responses of grassland bird specialists. Initially, the average grass height was 6 cm, but after the management changes, it increased to an average of 12 cm. This also increased grass heterogeneity, which is desirable for supporting a higher richness of grassland birds. We found that both the abundances of individual grassland bird species and richness did not vary after the management changes. Moreover, threatened grassland bird species that rely strictly on taller grasses did not colonize the paddocks following the alterations. Therefore, we conclude that maintaining the abundance of seven grassland bird specialists and potentially increasing livestock production is feasible, as the attained grass height coincided with levels known to maximize cattle dry matter intake rate. However, achieved average grass height was not sufficiently tall to support endangered tall grass specialists. It is possible that longer time frames allow tussocks to grow taller and provide such habitat conditions. Most previous research on rangelands biodiversity has focused on assessing faunal responses in either ungrazed or heavily grazed areas. Therefore, our findings contribute to a better understanding of faunal responses within this spectrum and align with a win-win production-conservation approach, which can aid in safeguarding biodiversity across large geographic scales.
Plant diversity has long been linked to an increase in ecosystem productivity and function, but concrete examples in which ecosystem services are linked to diversity at the scale at which management decisions are taken are rare. We specifically tested for a correlation between plant diversity and provisioning ecosystem services estimated via the potential to produce meat and wool. We also tested whether higher levels of plant diversity conferred higher levels of ecosystem resistance to global change drivers, measured as the ability to sustain productivity across time. This was achieved by analyzing the interactive effects of a range of environmental variables on annual net primary production in a network of long-term biodiversity plots in Southern Patagonia. We found evidence of a positive correlation between plant diversity and plant productivity, which we relate to the ability to produce wool and meat from livestock. We also found evidence of a link between ecosystem resistance and diversity, though the effect was modest. The instrumental (economic) valuation presented doesn't account for the full range of values that rangeland in southern Patagonia generates. Nevertheless, these calculations do provide a starting point for broadening the discussion around the importance and value of natural capital in southern Patagonia. The results are consistent with theory and suggest that plant diversity has instrumental and monetary value as well as insurance value that may increase the resistance of rangeland ecosystems to global change drivers.
Google Earth Engine (GEE) is presently the most innovative international open-source platform for the advanced-level analysis of geospatial big data. In this study, we used three machine learning algorithms to apply this cloud platform for Land Use Land Cover (LULC) research in the Mardan, Pakistan. The machine learning algorithm in GEE is the most advanced technique to generate reliable and informative LULC maps from various satellite data to present reliable results. The primary goal of the present study is to compare the performance of various machine learning models (i.e., classification and regression trees [CART], support vector machine [SVM], and random forest [RF]) in GEE for the reliable four classes LULC maps using the Sentinel-2 imageries of 2022. In the current study, three satellite indices like the Normalized Difference Vegetation Index, Modified Normalized Difference Water Index, and Normalized Difference Built Index were applied to detect the features (i.e., vegetation, built, barren land, and water bodies in the study area). The performance of all three models was evaluated by validation and accuracy assessments. The Kappa coefficients of CART, SVM, and RF for Sentinel-2 images were 94%, 95%, and 97%, while the average overall accuracy is 96.25%, 97%, and 98.68%, respectively. The present study illustates that in this classification and comparison, RF performed better than SVM and CART. The current research study revealed that GEE has speedily processed the satellite imageries to develop the four classes of reliable LULC maps of the study area with the best accuracy results and deliver excellent support for further analysis.
Nonfee grazing costs on both federal and privately leased land have been a topic of research since the 1960s. A nonfee cost difference of $1.23 animal unit mo (AUM)–1, later adjusted to $1.35 AUM–1, was found between grazing on federal and privately leased land. This value became the base for the federal land forage value in the current federal grazing fee. In 1992, a task force group was formed to further research the value of federal forage and update the range for the federal grazing fee and recommended keeping the fee between $3 and $5, which would be $6.60 and $11.01 in 2018 US dollars. This study aims to update the 1992 nonfee costs of federal and privately leased grazing. Packets containing information on costs of grazing were gathered from randomly selected sheep and cattle producers in Wyoming, Idaho, and California for the yr 2018. The current study found an observed difference of $3.09 AUM–1 between public and privately leased grazing in the three states but found the overall costs to have no statistically significant difference. This research can be used in the future for observing the nonfee cost changes of federally and privately leased land in the western United States.
Fire is a naturally occurring process in the Great Plains and was anthropologically applied first by Native Americans and now by a diverse group of landholder types. Fire is a critical tool to help restore historical fire regimes in the region and maintain and grow benefits for agricultural outputs, risk reduction, and ecosystem maintenance. With the Great Plains dominated by private landholdings, lowering barriers to adoption of prescribed burning is important for increasing its use. Costs are a crucial decision element in adoption and regular use of prescribed burning. Using the responses from an Internet-based survey of prescribed burn professionals in the Great Plains, multivariate regression analysis based on cost can identify critical factors and behaviors. The average cost for a prescribed burn in this study is $11.37 per acre, which is comparatively less expensive than numbers reported elsewhere. Seven significant associated variables emerged including number of burns and acreage, firebreak type, and fuel characteristics. The results suggest that economies of scale play an important role in the cost of prescribed burning. Through the identification of the cost of prescribed burning and the factors that influence it, landowners, environmental managers, prescribed burn professionals, and government agencies in the Great Plains will be able to better understand and implement prescribed burns as part of their land management plans.
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