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In the absence of technology-driven monitoring platforms, US rangeland policies, management practices, and outcome assessments have been primarily informed by the extrapolation of local information from national-scale rangeland inventories. A persistent monitoring gap between plot-level inventories and the scale at which rangeland assessments are conducted has required decision makers to fill data gaps with statistical extrapolations or assumptions of homogeneity and equilibrium. This gap is now being bridged with spatially comprehensive, annual, rangeland monitoring data across all western US rangelands to assess vegetation conditions at a resolution appropriate to inform cross-scale assessments and decisions. In this paper, 20-yr trends in plant functional type cover are presented, confirming two widespread national rangeland resource concerns: widespread increases in annual grass cover and tree cover. Rangeland vegetation monitoring is now available to inform national to regional policies and provide essential data at the scales at which decisions are made and implemented.
Geomorphic reclamation creates variable topography and surface architecture, including rolling hillslopes and drainages. In contrast, traditional methods of reclamation result in landscapes susceptible to erosion due to steep, linear gradients. Geomorphic approaches to surface mine reclamation are relatively new, and hypotheses suggest the use of geomorphic principles in reclamation will improve vegetation outcomes relative to traditional methods. Topographic variability created by geomorphic reclamation likely results in more environmental heterogeneity, which should correlate with greater plant diversity. We examined revegetation outcomes of traditional and geomorphic reclamation on two reclaimed surface mines in Wyoming using nadir image sampling. Functional group diversity and measures of cover were compared between reclamation methods and undisturbed rangeland. Geomorphic reclamation supported greater total richness and greater native functional group richness relative to traditional reclamation. Native species cover on geomorphic reclamation, particularly for native perennial grasses, was either similar to undisturbed rangeland or greater than undisturbed rangeland and traditional reclamation. Reclamation shrub cover differed significantly from undisturbed sites, but was greater in geomorphic treatments. Results of nadir image analysis are compared to line-point intercept data from the same locations and outcomes are discussed in light of different reclamation techniques and sampling methods. Significant differences in cover categories were observed between nadir image and line-point intercept methods, however both methods revealed similar patterns between study sites.
The current degradation crisis in arid and semiarid lands is creating severe economic and social difficulties, aggravating the food situation and greatly affecting the least developed countries and small farmers around the world. However, little attention has been given to the wealth of knowledge held by rural livestock farmers on this phenomenon, particularly those linked to environmental indicators. The objective of this work was to investigate plant attributes used by smallholders as ethnoindicators of short- and long-term environmental change. Using an ethnoecological approach, the study was carried out along with rural livestock smallholders who inhabit the central-northern Patagonian plateau. Open and semistructured interviews were carried out with 35 informants who were strongly associated with subsistence livestock farming. A total of 23 plant species were registered as being involved in detection of environmental change. The types of environmental change recorded were short term (such as droughts) and long term (such as desertification). These plants presented 14 different indicators, involving various life forms: gramineous or graminoid plants (65%), woody species (30%), and plants that are not gramineous or graminoid (5%). The plant community attributes that functioned as indicators were presence/absence of species, species abundance, and visible plant characteristics such as exposed roots, changes in plant architecture, and/or changes in phenology. The traits used as indicators provide complex information that is essential to the understanding of plant development and the structure and functioning of the managed ecosystem. Key lessons from this work include the following: The integration of plant ethnoindicators is important for the successful diagnosis and permanent monitoring of arid lands; and development plans incorporating indicators constructed with the involvement of the local people, as well as the rangeland professionals, must help to mobilize knowledge and practice on an equal basis.
Exotic winter annual grasses (Bromus spp.) are a problem in North American rangelands. Defoliation, litter, and mosses are thought to regulate invasive annual Bromus species. We conducted a field experiment that tested effects of mechanical mowing and fungicide applications on Bromus arvensis, other and total graminoids, forbs, litter, and moss. Treatments caused litter biomass and moss cover to vary, which enabled testing whether litter and mosses explain variation in B. arvensis biomass. Two yr after cessation of experimental treatments, mowing treatments caused persistent reductions in B. arvensis, total graminoid, and litter biomasses but had no effect on other graminoid and forb biomasses. We detected a positive relationship between litter and B. arvensis. Fungicide applications increased moss cover and other and total graminoid biomasses, thereby suggesting mosses and several graminoids were released from the suppressive effects of biota (e.g., lichen, pathogenic fungi) susceptible to the fungicide. We found no relationship, however, between moss cover and B. arvensis. In temperate and semiarid ecosystems, mowing during flowering and before seed drop coupled with removal of clippings is likely to help control invasive bromes and fungicide additions may increase grass production.
Terrain can influence vegetation composition, diversity, and biogeochemical cycling in grassland ecosystems. Solar radiation, soil temperature, and moisture distribution are dependent on terrain, which, in turn, can affect plant community structure, rate of litter mass decomposition, and carbon, nitrogen, and phosphorus release. A litter decomposition experiment was conducted over 12 mo at a site representing typical steppe grasslands to better understand the effects of terrain on biogeochemical cycling. The study site had both northeast (shaded) and southwest (sunny) facing aspects with each aspect having three slopes: 15°, 30°, 45°. Litterbags were used for collection of plant community litter from each location. The results indicated that slope and aspect both have significant effects on decomposition rate of litter mass and release rate of C, N, and P. The most rapid decomposition rate of litter mass was on 45° sunny slopes (k value 1.82 × 10–3 d–1). The most rapid release of C was on 30° shaded slopes with release rate of 4.54 g C yr–1. The release rate of N decreased with increasing slope steepness but was more rapid on shaded compared with sunny slopes. The most rapid release of P (10.51 mg P yr–1) occurred on 45° shaded slopes. The total effects of solar radiation and soil temperature on litter mass decomposition were larger, with 0.91 and 0.93, respectively. Soil temperature, litter functional diversity, and initial C/N had positive effects on the litter C release. The release of litter N was mainly promoted by soil temperature. Soil moisture appeared to promote the release of litter P. Overall, terrain influenced litter mass decomposition and C, N, and P release by its effect on the distribution of solar radiation, soil temperature and moisture, and through modification of functional diversity, initial C/N ratios, and water content of litter in typical steppe.
Agricultural practices have historically dominated disturbance on North American grasslands. Disturbances from oil and gas have become increasingly common and problematic for grassland conservation. With growing demand for oil and gas, industry is actively implementing minimal disturbance techniques during construction to reduce impacts on grasslands. This study aimed to determine impacts of a large-diameter pipeline right of way (ROW) on dry mixed-grass prairie to determine if and how far these impacts extended beyond the ROW and the effect of time on grassland recovery on and off ROW. Soil and vegetation on the ROW and on transects extending 300 m on either side of the ROW were assessed over a 10-yr period, starting the yr of construction, at six sites along a pipeline route in southern Alberta, Canada. There were significant impacts to soil and vegetation on the ROW and within 5 m of the ROW in the first yr. The trench was most impacted, followed by work and storage areas. Within 2 yr, soil and plant communities were on a trajectory toward reference prairie conditions. Ten yr following construction, only soil pH and bare ground were greater, and litter was less, on the trench than on work and storage areas, and relative to reference prairie. While native grass richness, dominance, and cover were similar on and off ROW, abundance of some native forb species was less on ROW. Non-native species cover was < 2% in all yr and locations. Although ruderal weed species were abundant on ROW the yr following construction, they disappeared by the following yr. Use of minimal-disturbance construction techniques reduced the size and intensity of the disturbance footprint, allowing for even sensitive arid habitat to recover within a short period of time. Similar approaches to other grassland disturbances can increase ecosystem resiliency.
Restoration of non-sprouting shrubs after wildfire is increasingly becoming a management priority. In the western U.S., Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young) restoration is a high priority, but sagebrush establishment from seed is sporadic. In contrast, planting seedlings often successfully restores sagebrush, but is expensive and time consuming. After planting, hence, there is a need to protect the investment from disturbances such as fire that will erase gains in sagebrush recovery. Grazing is likely the only tool that can be applied feasibly across the landscape to decrease wildfire probability, but there are concerns that grazing and associated activities (e.g. trampling) may negatively impact sagebrush seedlings. We investigated effects of grazing by cattle, applied as a fine fuel management strategy, on planted sagebrush seedlings at five blocks for five years. Grazing substantial reduced exotic annual grasses, large perennial bunchgrasses, and total herbaceous cover, thus achieving fuel management goals. Sagebrush cover and reproductive efforts were almost 2-fold greater in grazed compared to non-grazed areas in the final year of the study. This suggests that grazing favored sagebrush, a generally unpalatable shrub, recovery, likely by reducing competition from highly palatable herbaceous vegetation. Density of sagebrush, however, was similar between grazed and non-grazed areas. This research demonstrates that grazing can be strategically applied to reduce the probability of wildfire in areas with planted sagebrush seedlings; thereby, protecting the investment in sagebrush recovery. With more refinement, it also appears that grazing can be utilized to accelerate the recovery of sagebrush and potentially other woody vegetation habitat by modifying the competitive relationship between herbaceous and woody vegetation.
Human activities have dramatically altered the distribution and density of large herbivores worldwide, particularly on islands. For example, thousands of goats were abandoned to the mountains on Majorca Island, Spain, during the tourism boom in the 1960s. Though this mammal is common throughout the Majorcan mountain range, the impact of goats on the main mountain plant communities has not yet been evaluated. To fill this gap, we recorded goat fecal pellet accumulation and assessed the degree of browsing of 9 363 shrubs and trees located within 231 25-m2 strips systematically distributed in two mountain regions of Majorca. We also recorded the degree of regeneration of woody plants inside the same strips. The environmental factors that significantly influenced pellet accumulation were altitude, rock cover, distance to roads and paths, distance to water, and slope. The correlations between the pellet index and degree of browsing depended on species palatability and abundance. Finally, the natural regeneration of plants was heterogeneously distributed and negatively correlated with pellet accumulation. This study indicates that high levels of browsing of unpalatable species in less preferred areas are a clear indicator of strong herbivore pressure, whereas the presence of nonbrowsed palatable species could indicate low herbivore presence. Moreover, this work demonstrates that the relative abundance of fecal pellets is a good indicator of the pressure exerted by feral goats on vegetation at a fine scale. The simple pellet index used in this work correlates strongly with vegetation damage; thus, it could represent a valuable innovative tool to inform sustainable management of feral goat populations in not only Majorca but probably also other Mediterranean islands.
Managed grazing is the most extensive land use worldwide. Information about the spatio-temporal distribution of livestock is critical for grassland ecosystem management. However, no direct and cost-effective method exists to monitor livestock distribution under natural conditions. We proposed a practical method that uses unmanned aerial vehicles (UAVs), and tested it at a typical household pasture on the Qinghai-Tibetan Plateau. We monitored and analyzed the hourly spatial distribution of each yak (Bos mutus). We found that (1) yak information extracted by our independently developed software was sufficiently accurate (P>0.05); (2) yak density (frequency/area/period) decreased with increasing distance from campsites in the early growing season, while the pattern reversed in the late growing season; (3) dispersion index (DI, m2/yak) of the yak herd exhibited a tendency to decrease in the morning and then to increase in the afternoon within a day; from June to September DI decreased in both the morning and afternoon, but was similar at noon. The monitoring method we developed in this study characterized the spatial distribution of the whole yak herd dynamically with high frequency, resolution, and efficiency. We conclude that this method is suitable for long-term monitoring of animal behavior, and for studying relationship between the distribution of pastoral livestock and resource availability, which will be beneficial for grassland sustainable management.
Aboveground Net Primary Production (ANPP), an indicator of ecosystems' ability to capture and convert solar energy, is critical to evaluate and manage ecosystem carbon balance index including rangelands. Measuring ANPP over a large area is difficult at it varies with different factors including climate and anthropogenic, while satellite-based information shows strong opportunity. The aim of this study was to estimate the ANPP of Plant Functional Types (PFTs) using Landsat-8 imagery over the rangelands of Hir-Neur from Ardabil Province, Iran as a case study area. Landsat-8 Operational Land Imager (OLI) satellite images were collected on 9th June 2017 aligning with the field sampling of PFTs ANPP. Eleven sampling sites with 10 plots at each site (locations recorded with a Global Positioning System, GPS) were selected along a transect with elevation gradient and the ANPP of PFTs were recorded. Twenty-two vegetation indices were calculated from the Landsat-8 imagery and the index values were extracted for the sampling plots. Correlation between derived indices and field collected ANPP data were calculated. Predictive relationships between PFTs and total ANPP and satellite indices were developed using a 3rd-order polynomial model and the model was used to map the whole study area. The best estimation of PFTs and total ANPP was obtained using the Vegetation Index (VI3) for grasses (R2=0.47), Iron Oxide (IO) for forbs (R2=0.51), and Renormalized Difference Vegetation Index (RDVI) for shrubs (R2=0.50). The Difference Vegetation Index (DVI) was the best estimator for the total ANPP (R2=0.49). The overall accuracies of the maps were acceptable (MAE, MDE, RMSE <0.5). Results showed a difference when using PFTs for ANPP estimation in comparison with direct ANPP estimation. Thus, direct estimation of ANPP from the satellite based indices would be more accurate. This study also showed promising capabilities of the indices based on PFTs and total ANPP for estimating aboveground biomass, supply-demand balance and carbon balance at the study area and elsewhere with similar ecological conditions. This study also showed opportunity to select the most appropriate vegetation indices for the estimation of PFTs and the total ANPP.
In Texas, mesquite and yellow-bluestem invasions are widespread. Identifying and monitoring juvenile and adult plants using high-resolution imagery from airborne sensors while they colonize new areas across the landscape can help land managers prioritize locations for treatment and eradication. In this study, we evaluated how data collection design using an unmanned aerial system (UAS) can affect plant detection and mapping. We used a Phantom 3 Professional unmanned aerial vehicle with a Parrot Sequoia multispectral camera for detecting and mapping native honey mesquite (Prosopis glandulosa) and non-native yellow bluestem (Bothriochloa ischaemum) at a rangeland site in northwest Texas. Flights were conducted seasonally during the period from summer 2017 to fall 2018 to test the seasonal impact of detecting plant species. Flights were conducted at altitudes of 30, 60, and 100 m, and four image classification techniques were tested to determine their viability of detecting distinct plant species. Results suggest that flights at 100-m aircraft altitude during the spring season are more effective (>80% user accuracies) for mapping mesquite canopies based on reflectance values and image segmentation information. Yellow bluestem mapping accuracies were low (< 20% user accuracies). Lower spatial resolution (100-m altitude flights, 12-cm pixel resolution) provided less noise and more generalization capabilities for the image classification methods. Overall, random forests and Support Vector Machine classification algorithms outperformed probability-based image classifiers. Land owners and rangeland ecologists using their own UAS in rangeland management can use this information to plan their data collection campaigns before the application of chemical treatments or manual eradication.
Honey mesquite (Prosopis glandulosa Torr.) may maintain apical dominance after a treatment that causes partial top-kill (PTK) and leaves canopies with “stem flagging.” In contrast, top-killing treatments stimulate multistemmed regrowth (i.e., basal sprouting; BSP). Because this difference may impact competition with grasses, a better understanding of physiology associated with PTK and BSP canopies compared with untreated canopies is needed. We quantified predawn leaf water potential (ΨPD), leaf-level gas exchange rates (photosynthesis [A] and stomatal conductance [gs]), and whole-tree stomatal conductance (Gs) of untreated, PTK, and BSP mesquites 2–11 yr after aerial herbicide application in a north Texas savanna. Total leaf area was nearly 4 × greater in untreated and BSP compared with PTK trees. In a few situations where soil moisture stress was greatest, untreated mesquites exhibited more negative ΨPD and lower leaf-level gas exchange than did PTK mesquites. BSP mesquites occasionally had greater ΨPD and leaf-level gas exchange than untreated mesquites. Since imbalances in root-to-shoot ratios caused by PTK were largely not manifested at the leaf-physiology level, PTK mesquites likely adjusted rapidly to herbicide disturbance. When gs was scaled to the whole canopy, Gs estimates were 3–4 × greater in untreated and BSP than PTK trees. Thus, canopy leaf area was the primary driver of differences in whole-canopy Gs. It is LIKELY that transpiration would be lower in a stand of untreated mesquites compared with PTK mesquites of similar stand density and basal areas before treatment, as results from comparing untreated and PTK mesquites indicate. Partially top-killed trees that maintain apical dominance and do not resprout should compete less with grasses for water and light and facilitate species diversity and heterogeneity.
Revegetation of exotic annual grass–invaded rangelands is a primary objective of land managers following wildfires. Controlling invasive annual grasses is essential to increasing revegetation success; however, preemergent herbicides used to control annual grasses prohibit immediate seeding due to nontarget herbicide damage. Thus, seeding is often delayed 1 yr following herbicide application. This delay frequently allows for reinvasion of annual grasses, decreasing the success of revegetation efforts. Incorporating seeds into herbicide protection pods (HPPs) containing activated carbon (AC) permits concurrent high preemergent herbicide application and seeding because AC adsorbs and renders herbicides inactive. While HPPs have, largely in greenhouse studies, facilitated perennial bunchgrass emergence and early growth, their effectiveness in improving establishment of multiple species and functional groups in the field has not been assessed. Five bunchgrass species and two shrub species were seeded at two field sites with high imazapic application rates as bare seed and seed incorporated into HPPs. HPPs significantly improved establishment of sagebrush (Artemesia tridentata Nutt. Spp. wyomingensis Beetle & Young) and crested wheatgrass (Agropyron cristatum [L.] Gaertn.) over the 2-yr study. Three native perennial grass species were protected from herbicide damage by HPPs but had low establishment in both treatments. The two remaining shrub and grass species did not establish sufficiently to determine treatment effects. While establishment of native perennial bunchgrasses was low, this study demonstrates that HPPs can be used to protect seeded bunchgrasses and sagebrush from imazapic, prolonging establishment time in the absence of competition with annual grasses.
Asiatic elephants are facing numerous direct and indirect anthropogenic threats throughout their geographical distributional range. Consequent to the land use and land cover change, habitat loss, fragmentation, and deterioration of the corridor status are the prime threats for the species. The current study aimed to delineate the routes and migratory corridors of elephants in the Indo-Bangla forest along the Patharia Hills Reserve Forest and characterizing existing threats on the corridor for long-term conservation of the elephants using field survey and geospatial techniques. The study identified and mapped the elephant corridor for the first time in the area and named it the “Juri-Patharia-Tilbhum elephant corridor.” Land use and land cover changes in the corridor were markedly observed for over 4 decades (between 1972 and 2018). Forest-covered areas in the corridor were 32.06% in 1972, which has been reduced to only 2.98% in 2018, whereas human development types have all increased, grasslands by 127.18%, plantations by 146.56%, agriculture by 279.63%, and settlements by 147.17% between 1972 and 2018. The study concluded that the corridor area is at risk because of the lack of sustainable development in the area, which deliberately undermines conservation. Human settlement, road construction, and electrification in and around habitats and the corridor are vital threats faced by elephants in the Patharia Hills Reserve Forest. Conservation of habitat and corridor through both adoption of legal measures and community participation might be a better proposition for their long-term conservation in the habitat. The study appeals to the government to take conservation initiative in the area and suggest legal protection of the corridor and provide subsidies to the local private landowner to restrict the land-use change on the corridor.
The feral pig is an exotic species in the Sierra La Laguna Biosphere Reserve, Baja California Sur, Mexico, and is considered harmful to the woodlands and tropical deciduous forest because of its foraging habits. To determine the taxonomic, nutrient, and energy content of the feral pig diet in this area, stomach contents of forty feral pigs were analyzed during the dry and rainy seasons in the woodlands and the tropical deciduous forest. Results indicate that feral pigs are frugivore-herbivore and stenophagous, feeding on a high percentage of fruits and seeds (77–87%) that provide high metabolizable energy (8293–11,585 kJ kg–1 dry matter) and moderate crude protein (94.1–151.6 g kg–1 dry matter) year round in the woodland and during the dry season in the tropical deciduous forest, or high percentage of leaves, stems, and tubers (44%) that provide low metabolizable energy (4740 kJ kg–1 dry matter) and moderate crude protein (107.5 g kg–1 dry matter) in the rainy season in the tropical deciduous forest. Therefore, diets based on fruits and seeds favor a lower quantity of food to meet the energy for maintenance of feral pigs than those based on other plant tissues: pine nuts < acorns ≈ wild figs < leaves, stems, and tubers. The observed diet based on acorns, along with estimates of acorn production results in a carrying capacity estimate of 0.031 adult feral pig ha–1 yr–1 during years of low acorn production. Thus, feral pigs in the area use fruits and seeds in both woodlands and tropical deciduous forest because of their quality as food resources. The availability of the food resources preferred by pigs (pine nuts, acorns, fan-palm fruits, and wild figs) during the year can be used to inform potentially sustainable feral pig carrying capacities and establish hunting programs.
The past decade has seen a rapid rise in beaver-related stream restoration (BRR) using beavers and beaver dams (real or artificial) as a tool. Potential benefits of this low-cost, nature-based restoration approach include restoring aquatic and riparian habitat and recovering of threatened species dependent on it, improving water availability and stream flow regulation, reducing erosion and stream incision, and supporting climate change adaptation. Although the ecological restoration literature acknowledges the importance of addressing the human dimensions of restoration, there is a gap regarding the human dimensions of BRR. To help fill this gap we examined six projects involving riparian revegetation or artificial beaver dams to identify central elements of a supportive social environment for BRR on western rangelands. Our research questions examined how beavers, beaver dams, and BRR affect ranching operations and how ranchers view them; the policy context for BRR; and how BRR practitioners, regulatory agencies, ranchers, and partners work together for successful BRR. We synthesized our findings across cases and identified six social factors important for BRR: 1) ranchers who perceive the benefits of beavers, beaver dams, and BRR to outweigh the drawbacks; 2) education and assistance to help landowners adopt nonlethal mitigation techniques for nuisance beavers; 3) grazing practices compatible with BRR; 4) low harvest pressure on beavers; 5) a regulatory environment that enables experimentation, flexibility, and adaptive management; and 6) proponents, ranchers, and partners willing to take risks, innovate, be flexible, and stay committed.
Livestock guardian dogs (LGDs) are an effective tool for limiting livestock depredation by wild and feral predators. Unfortunately, LGDs have bitten hikers, joggers, and mountain bikers. Strategies are needed to mitigate LGD-human conflicts, especially in landscapes inhabited by large, aggressive predators where the threat of livestock depredation is greatest. One recommendation is to keep groups of sheep protected by LGDs at least 400 m from high-use recreational sites, but few data exist to support or refute this strategy. We monitored sheep and LGDs with Global Positioning System collars at seven ranches during a 3-yr period to evaluate how far, and under what circumstances, LGDs roamed from their sheep. One band of sheep (i.e., flock) was studied per ranch, with a typical band composed of 600–800 mature ewes with 900–1 200 lambs. Sheep were herded in extensive grazing systems within their traditional summer or fall grazing areas in foothill and mountain landscapes of southwestern and west-central Montana. Three bands of sheep inhabited landscapes with a greater threat of depredation by gray wolves and grizzly bears, and 4 bands of sheep inhabited landscapes where the threat of depredation was mostly from coyotes. The mean and median LGD-sheep distance across all LGDs and time periods was 164 m and 86 m, respectively. LGDs roamed farther from their sheep during nighttime and crepuscular periods than during daytime; farther when the moon was more fully illuminated; farther during fall than summer; and farther in landscapes without gray wolves and grizzly bears. Female LGDs roamed farther than males. Juvenile LGDs did not roam farther than adult LGDs. Overall, our results from extensive domestic sheep grazing systems suggest that keeping range sheep 400 m away from recreation sites and rural residences will likely prevent > 90% of agonistic LGD encounters with humans.
Larsen et al. (2019) found stubble heights measured at a systematic interval resulted in higher variability and lower stubble heights than samples collected at random. As the authors do not suggest an environmental mechanism for these outcomes, their conclusions likely reflect differences in the number of plants evaluated at each plot and the low number of independent observers rather than the sample design.
Roper (2020) conducted a critique of the Larson et al. (2019) study of the accuracy and confidence of data collected using systematic and random sampling designs. Roper (2020) did not provide a data set but speculated that the Larson et al. (2019) conclusions likely reflected differences in the number of plants evaluated at each plot and the low number of independent observers rather than the sample design. Our random sampling design employed multiple randomly located quadrat locations and measured multiple plants (> 5) that were averaged within the plot to represent plot characteristics. Data collected in this fashion fulfilled assumptions intrinsic to and necessary for statistical analysis using plot data as observations. Thus, the statistical observations reported in the original paper are valid.
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