North American grassland birds have experienced steeper population declines than any other avian guild, yet conservation efforts remain largely reactive and fragmented. We used nearly four decades of North American Breeding Bird Survey data to identify biome-scale spatial patterns (clustering) of grassland bird abundance for the Great Plains. Our results reveal an ecological core in the north-central Plains where community-level abundance is either increasing by >100% or remains high and stable, providing a strategic roadmap for a “Defend the Core” conservation approach. This approach flips the script from reactive triage centered on isolated population fragments to a proactive strategy of maintaining large-scale ecosystem integrity. Conversely, we found that population losses are more spatially clustered than wins, reflecting the relentless, one-way movement of woody encroachment and agricultural conversion. This asymmetry supports prioritizing intact landscapes, as current restoration rates are often outpaced by the scale of habitat loss. Notably, we found that community-level spatial clustering is a more robust indicator of biome condition than trends of individual flagship species, suggesting that managing for ecosystem integrity provides a more effective multi-species umbrella. Given our results, there is an opportunity for operationalizing a Great Plains Conservation Design that is ecosystem-centric and rooted in the sustainability of the private-land cattle production that maintains these open spaces. By leveraging avian abundance as a biological sensor, managers and producers can deploy a shared vision that matches the spatial scale of the threats, moving from reactive triage to proactive defense of core working grasslands in North America.
Restoring fire in fire-adapted ecosystems is necessary to curtail woody plant expansion, enhance biodiversity, and reduce wildfire risks, yet prescribed fire is promoted less by federal agencies than other grassland conservation practices. The U.S. Department of Agriculture Natural Resources Conservation Service (NRCS) is the primary federal agency responsible for the delivery of rangeland conservation incentives to private landowners in the Great Plains. The degree to which NRCS employees choose to offer technical guidance on prescribed fire and whether they encourage landowners to consider financial support is not well-understood and varies among states. Our study explored the extent to which prescribed fire awareness and social interaction factors influence NRCS employees' knowledge and comfort level regarding prescribed fire and the frequency with which they recommend this conservation practice. The results show that while prescribed fire awareness influences knowledge, it was not significantly associated with frequency of prescribed fire recommendations. Rather, social interaction factors were significantly related to recommendation frequency; these included priority of prescribed fire education in their jobs, positive interactions with landowners regarding prescribed fire, and how often they were asked to deal with brush management. An important implication is that while better knowledge about prescribed fire is necessary, it is not sufficient for more frequent prescribed fire recommendation by natural resource professionals. Instead of focusing primarily on technical proficiency, federal agencies tasked with expanding the application of prescribed fire as an ecosystem restoration and wildfire mitigation tool should focus more on building stronger social networks through, for example, providing greater support of existing and new prescribed burning associations. Our findings also have implications for a national unified policy that supports the application of prescribed fire on privately-owned rangelands because negative fire culture at the federal level has an erosive effect on agencies' willingness to assist landowners with prescribed fire applications. (c) 2025 The Authors. Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Accurate monitoring of cropland dynamics in North American grasslands is essential for assessing biodiversity threats, guiding sustainable land management, and ensuring food security amid rapid environmental change. We developed a 30-meter resolution dataset capturing annual 'active' and 'cumulative' cropland (1996 to 2021) across the central grasslands of North America using an Attention U-Net convolutional neural network. Our biascorrected estimates reveal that while active cropland showed no significant change (+3.51 +/- 1.32 million ha, p = 0.17), the cumulative cropland footprint expanded by 17 % (+20.64 +/- 0.93 million ha, p < 0.05) relative to the baseline (1996-2000), reaching 142.21 +/- 4.84 million ha by 2021. This divergence indicates substantial new conversion or recultivation of previously restored grasslands, occurring at a consistent rate of 0.98 +/- 0.04 million ha per year (p < 0.001). Mexico showed the largest relative gain in cumulative cropland area, expanding by nearly half (48 %, 1.69 +/- 0.06 million ha, p < 0.05). By distinguishing between active and cumulative cropland extents, our dataset enables differentiation between short-term, intermittent cultivation and longerterm land-use legacies, allowing for more nuanced assessments of agriculture's cumulative effects on biodiversity and critical ecosystem services at the biome scale. This approach provides critical information for conservation planning and sustainable land management across North American grasslands.
The almost complete eradication of fire from grasslands in North America has led to non-linear hysteretic transitions to shrub- and woodlands that the reintroduction of low-intensity fire is unable to reverse. We explore the ability of the extreme ends of variation in fire behavior to help overcome hysteretic threshold behaviors in huisache (Vachellia farnesiana) encroached grasslands. We contrasted experimental fire treatments with unburned control areas to assess the ability of extreme fires burned during drought to alter the density and structure of huisache. We found that extreme fires reduced the density of huisache by over 30% compared to control plots, both through driving huisache mortality and reducing the number of new recruits following treatments. For instance, extreme fire drove 48% huisache mortality compared to 4% in control treatments. For surviving plants, the number of stems increased but the crown area did not significantly change. Prescribed fire, conducted under the right conditions, can drive high mortality in one of the most notorious encroaching species in the southern U.S. Great Plains. With the fire conditions observed in this study likely to increase under future climate projections, utilizing extreme fire as a management tool for huisache will help scale up management to meet the growing extent of woody encroachment into grasslands.
Woody encroachment has driven drastic declines in grassland biodiversity and productivity. In the U.S. Great Plains, high-intensity prescribed fire is increasingly being used to shift encroaching redcedar woodlands to a grassland state. High-intensity fire treatments drive redcedar mortality and increase herbaceous biomass. However, it is unclear how grassland community composition recovers following stand-consuming fire. We contrast herbaceous community composition, basal cover, and species richness in woodlands treated with stand-consuming high-intensity fire to reference grassland and woodland sites to examine whether high-intensity fires facilitate restoration of grassland communities. To determine the long-term outcomes of high-intensity fire treatments, we use a space-for-time substitute to measure changes to herbaceous community and species richness over a time-since-fire gradient of 17 years. We found that herbaceous cover and species richness increased substantially in woodlands treated with stand-consuming high-intensity fire compared to unburned woodlands, and that these values were similar to those observed in both burned and unburned grasslands. Herbaceous community composition in woodlands treated with high-intensity fire also shifted towards grasslands, though some legacies of woodland communities persisted. Time-since-fire generally did not have a large influence on total herbaceous cover or species richness through time, though grass cover decreased in woodlands treated with high-intensity fire a decade post-treatment. Our findings suggest that a single high-intensity fire can support the restoration of herbaceous plant species richness and cover, and shift community composition to a grassland regime, though additional low-intensity fire treatments may be necessary to erode legacies from the encroached state.
Woody plant encroachment and row-crop agricultural land conversion are existential threats to species that rely on grassland ecosystems. The American Burying Beetle (Nicrophorus americanus) is a threatened species whose largest remnant populations are predominantly located in grassland ecoregions comprised of privately-owned ranching lands. Here, we seek to determine functional scaling patterns and population trends of the American Burying Beetle in the face of conservation threats and grassland restoration. We used 13 years (2007-2019) of American Burying Beetle abundance data collected from permanent sampling locations across the Loess Canyons ecoregion (Nebraska, USA), where a network of ranchers have been restoring large-scale grasslands. To estimate beetle abundance relative to land cover variables, we developed a Bayesian N-mixture model, incorporating the Bayesian latent indicator scale selection (BLISS) method to probabilistically determine at which scales land cover variables best explained beetle abundance. American Burying Beetle abundance exhibited high interannual variation but overall significantly increased across the ecoregion. Increases in beetle abundance were associated with large-scale (1149 ha extent) grassland cover. Decreases in abundance were associated with large-scale crop conversion (590 ha extent) and large-scale increases in woody cover (1149 ha extent). This study provides the first evidence of ecoregion-scale population increases of the American Burying Beetle. These increases are tied to landscape variables that are managed in a large-scale, coordinated private lands grassland restoration effort. Our results suggest that successful grassland restoration will depend on coordinating across property boundaries to implement conservation at scales necessary to conserve species that require large-scale, unfragmented grasslands.
Implementing strategies to navigate large-scale ecological transitions in grasslands is one of this century's greatest conservation challenges. In the US Great Plains, managing areas impacted by woody transitions have been reactive, short-lived, costly, and ineffective. Along with current technological innovation in rangeland monitoring, the promise of early warning science is to provide managers with sufficient time to be better prepared for novel signals of ecological change. Combining the science of early warning signals and frameworks such as the Resist - Accept - Direct (RAD) can provide land managers with guidelines to identify proactive strategies when facing ecological change. Using this approach, we found that opportunities to resist woody transitions decreased from 84 % to 60 % between 1990 and 2020 over the entire biome but remained highest in the northern and western Great Plains, which contributes to large scale conservation targets. These are key areas to prioritize resist opportunities. In contrast, 11 % of the biome exhibited early warning transition signals across all hierarchical scales by 2020, a fourfold increase since 1990. Lastly by 2020, 30 % of the biome exhibited early warning signals across multiple but not all scales. Here, efforts may be more effective when management is directed to conserve fragmented grassland legacies within a woody-dominated matrix and avoid large-scale monocultures of problematic encroaching woody species. Our multi-scale study indicates that 1) anchoring to the last remaining grassland core areas with no early warning of transitions and 2) strategically investing in these intact grasslands may provide the best results for grassland conservation.
Rangelands are extensive ecosystems, providing important ecosystem services while undergoing continuous change. As a result, improved monitoring technologies can help better characterize vegetation change. Satellite remote sensing has proven effective in this regard, tracking vegetation dynamics at broad and fine scales. We leveraged the spatial, spectral, and temporal resolution of Sentinel-2 satellites to estimate fractional cover and canopy gap across rangelands of the western United States. We produced annual, 10 m spatial resolution estimates of fractional cover and canopy gap size class for years 2018 to 2024. Fractional cover estimates include that of common plant functional types (annual forb and grass, bareground, littler, perennial forb and grass, shrub, tree) and select genera (including invasive annual grass species, pinyon-juniper species, and sagebrush species); canopy gap size classes include gap sizes 25 to 50, 51 to 100, 101 to 200, and greater than 200 cm. We make these data available as Cloud Optimized GeoTIFFs, organized as 75 × 75 km tiles covering the 17 western states of the United States.
Rangelands are extensive ecosystems, providing important ecosystem services while undergoing continuous change. As a result, there is a need for improved monitoring technologies that better characterize vegetation changes over space and time. Satellite remote sensing has proven effective in this regard, tracking vegetation dynamics at both broad and fine scales. Advancements in technology provide the opportunity to improve monitoring efforts and to better capture subtle yet ecologically significant changes. We leveraged the enhanced spatial, spectral, and temporal resolution of Sentinel-2 satellites to estimate fractional cover and the size distribution of plant inter-canopy gaps across rangelands of the western United States. We developed a one-dimensional convolutional neural network, trained on extensive field data, to predict cover of plant functional types and select genera, and canopy gap size classes. We produced annual, 10 m resolution estimates from 2018 to 2024, providing an unprecedented resource for monitoring rangeland condition and assessing the effectiveness of management strategies. ### Competing Interest Statement The authors have declared no competing interest.
Aboveground growth and production of native perennial grasses are determined by vegetative reproduction from belowground bud banks. Despite their importance, the phenology and dynamics of these belowground bud banks are poorly researched, even for dominant grass species. This information becomes even more essential for managers considering the potential use of high-energy fires to reduce encroaching woody shrubs because it might impact herbaceous bud bank dynamics and resultant grass productivity and relative abundance. The objectives of this study were to assess long-term bud bank dynamics of two dominant perennial grasses with different growth forms and physiologies, Nassella leucotricha and Hilaria belangeri, in a Texas semiarid savanna and determine the impact of fire energy on the recovery of their bud bank dynamics. Our experimental treatments were applied in the summer and consisted of replicated and randomized no burn (control), low-energy burn, and high-energy burn plots. For both species, the total bud number peaked in the spring and was lowest in the winter, although N. leucotricha had fewer buds in winter than H. belangeri and greater variability in total buds. For both species, dormant buds increased during the winter and active buds decreased. However, N. leucotricha maintained a smaller dormant bud bank through the winter, with larger fluctuations in total buds. In high-energy burned treatments, N. leucotricha had some bud loss but recovered; 8 months postfire, bud counts were comparable to the low-energy and control treatments. However, H. belangeri did not return to pretreatment bud totals in high-energy burned treatments during the study period. This suggests that grass productivity should not be reduced over the long term following restoration of woody-encroached grasslands with high-energy fire but that managers should consider potential shifts in species dominance from differential responses of grass species within the community.
An important question in restoration ecology is whether restored ecological regimes are more vulnerable to transitions back to a degraded state. In woody-invaded grasslands, high-intensity fire can collapse woody plant communities and induce a shift back to a grass-dominated regime. Yet, legacies from woody-dominated regimes often persist and it remains unclear whether restored regimes are at heightened vulnerability to reinvasion. In this study, we utilize a 17-year history of fire-based restoration in Nebraska's Loess Canyons Experimental Landscape to determine whether restored grassland regimes experience faster rates of Juniperus virginiana (eastern redcedar) reinvasion compared to the initial invasion process in adjacent grasslands. In addition, we examine whether reinvasion and invasion patterns are clearly differentiated based on former ecotonal boundaries between grassland and woodland regimes. Our results show that J. virginiana reinvasion of restored grassland regimes outpaced the initial invasion process in adjacent grasslands, providing evidence that restored grassland regimes are more vulnerable to transitions back to woody dominance. J. virginiana seedlings established sooner and increased faster in density and cover during reinvasion compared to the initial invasion process. Seedlings established 1-year post-fire in restored grassland regimes compared to 14-years post-fire in adjacent grasslands that were >40 m from the former grassland-woodland boundary. Reinvasion was initially easy to differentiate from invasion based on former ecotonal boundaries between grassland and woodland; however, reestablished juniper woodlands eventually began to expand into adjacent grasslands. Our findings demonstrate clear differences between reinvasion and invasion and highlight the need for management frameworks that explicitly account for reinvasion.
Abstract Social connections among individuals are essential components of social‐ecological systems (SESs), enabling people to take actions to more effectively adapt or transform in response to widespread social‐ecological change. Although scholars have associated social connections and cognitions with adaptive capacity, measuring actors' social networks may further clarify pathways for bolstering resilience‐enhancing actions. We asked how social networks and socio‐cognitions, as components of adaptive capacity, and SES regime shift severity affect individual landscape management behaviours using a quantitative analysis of ego network survey data from livestock producers and landcover data on regime shift severity (i.e. juniper encroachment) in the North American Great Plains. Producers who experienced severe regime shifts or perceived high risks from such shifts were not more likely to engage in transformative behaviour like prescribed burning. Instead, we found that social network characteristics explained significant variance in transformative behaviours. Policy implications: Our results indicate that social networks enable behaviours that have the potential to transform SESs, suggesting possible leverage points for enabling capacity and coordination toward sustainability. Particularly where private lands dominate and cultural practices condition regime shifts, clarifying how social connections promote resilience may provide much needed insight to bolster adaptive capacities in the face of global change. Read the free Plain Language Summary for this article on the Journal blog.
Conservation is increasingly focused on preventing losses in species' populations before they occur. Tracking changes in demographic parameters that can impact a population's resilience in response to drivers of global change can support early conservation efforts. We assessed trends in population productivity (late summer juveniles per 100 females) relative to drivers of global change in 40 pronghorn (Antilocapra americana) herds across sagebrush (Artemisia spp.) steppe in Wyoming. Pronghorn are an iconic rangeland species that have been exposed to increasing levels of anthropogenic, climatic, and land -use change. Using data collected across the state of Wyoming, we (1) assessed long-term trends in population productivity, (2) identified patterns in large-scale drivers of global change (i.e., climate, land cover change) across pronghorn habitat, and (3) determined the relationship between drivers of global change and population productivity over a 35 -year (1984-2019) period. While Wyoming hosts some of the most abundant populations of pronghorn in North America that have been largely stable in recent years, we found many herds are experiencing long-term declines in productivity. Long-term declines in productivity were associated with increases in oil and gas development and woody encroachment. Although increasing across almost all herd units, woody vegetation cover remains at low levels, suggesting that pre-emptive management may help to prevent losses in pronghorn populations.
Woody encroachment is one of the greatest threats to grasslands globally, depleting a suite of ecosystem services, including forage production and grassland biodiversity. Recent evidence also suggests that woody encroachment increases wildfire danger, particularly in the Great Plains of North America, where highly volatile Juniperus spp. convert grasslands to an alternative woodland state. Spot-fire distances are a critical component of wildfire danger, describing the distance over which embers from one fire can cause a new fire ignition, potentially far away from fire suppression personnel. We assess changes in spot-fire distances as grasslands experience Juniperus encroachment to an alternative woodland state and how spot-fire distances differ under typical prescribed fire conditions compared to conditions observed during wildfire. We use BehavePlus to calculate spot-fire distances for these scenarios within the Loess Canyons Experimental Landscape, Nebraska, U.S.A., a 73,000-ha ecoregion where private-lands fire management is used to reduce woody encroachment and prevent further expansion of Juniperus fuels. We found prescribed fire used to control woody encroachment had lower maximum spot-fire distances compared to wildfires and, correspondingly, a lower amount of land area at risk to spot-fire occurrence. Under more extreme wildfire scenarios, spot-fire distances were 2 times higher in grasslands, and over 3 times higher in encroached grasslands and Juniperus woodlands compared to fires burned under prescribed fire conditions. Maximum spot-fire distance was 450% greater in Juniperus woodlands compared to grasslands and exposed an additional 14,000 ha of receptive fuels, on average, to spot-fire occurrence within the Loess Canyons Experimental Landscape. This study demonstrates that woody encroachment drastically increases risks associated with wildfire, and that spot fire distances associated with woody encroachment are much lower in prescribed fires used to control woody encroachment compared to wildfires.
QuestionsFire regime alterations are pushing open ecosystems worldwide past tipping points where alternative steady states characterized by woody dominance prevail. This reduces the frequency and intensity of surface fires, further limiting their effectiveness for controlling cover of woody plants. In addition, grazing pressure (exotic or native grazers) can reinforce woody encroachment by potentially reducing fine-fuel loads. We investigated the effects of different fire energies on the herbaceous plant community, together with mammalian wildlife herbivory (exotic and native combined) exclusion, to inform best management practices.LocationTexas semi-arid savanna, southern Great Plains, USA.MethodsWe conducted an experiment in which we manipulated fire intensity and herbivore access to herbaceous biomass in a split-plot design. We altered fire energy via fuel addition rather than applying fire under different environmental conditions to control for differences in standing biomass and composition attributable to differential plant physiological status and fire season.ResultsHigh-energy fire did not reduce herbaceous biomass or alter plant community composition, although it did increase among-plot variability in composition and forb biomass relative to low-energy fire and non-burned controls. Grazing pressure from native and non-native mammalian herbivores reduced above-ground herbaceous biomass regardless of fire treatments, but did not alter community composition.ConclusionsManagers seeking to apply high-intensity prescribed fire to reduce woody encroachment will not negatively impact herbaceous plant productivity or alter community composition. However, they should be cognizant that repeated fires necessary for greatly reducing woody plants in heavily invaded areas might be difficult to accomplish due to fine-fuel reduction from wild herbivores. High fencing to restrict access by wildlife herbivores or culling might be necessary to build fuels sufficient to conduct high-intensity burns for woody-plant reduction. We conducted an experiment manipulating fire energy and herbivore access to herbaceous biomass in a well-replicated, split-plot design. Managers seeking to apply high-intensity prescribed fire to reduce woody encroachment will not negatively impact herbaceous plant productivity or alter community compositional trajectories. However, exotic herbivores greatly reduce fine fuels.image
Worldwide, tree or shrub dominated woodlands have encroached into herbaceous dominated grasslands. While very few studies have evaluated the impact of Eastern Redcedar (redcedar) encroachment on the water budget, none have analyzed the impact on water quality. In this study, we evaluated the impact of redcedar encroachment on the water budget in the Nebraska Sand Hills and how the decreased streamflow would increase nitrate and atrazine concentrations in the Platte River. We calibrated a Soil and Water Assessment Tool (SWAT model) for streamflow, recharge, and evapotranspiration. Using a moving window with a dilate morphological filter, encroachment scenarios of 11.9 %, 16.1 %, 28.0 %, 40.6 %, 57.5 %, 72.5 % and 100 % were developed and simulated by the calibrated model. At 11.9 % and 100 % encroachment, streamflow was reduced by 4.6 % and 45.5 %, respectively in the Upper Middle Loup River, a tributary to the Platte River. Percolation and deep aquifer recharge increased by 27 % and 26 % at 100 % encroachment. Streamflow in the Platte River, a major water source for Omaha and Lincoln, would decrease by 2.6 %, 5.5 % and 10.5 % for 28 %, 57.5 %, and 100 % encroachment of the Loup River watershed, respectively. This reduction in streamflow could increase nitrate and atrazine concentrations in the Platte River by 4 to 15 % and 4 to 30 %, respectively. While the density of redcedar is minimal, it is important to manage their encroachment to prevent reductions in streamflow and potential increases in pollutant concentrations.
AbstractFire is a fundamental ecological process in rangeland ecosystems. Fire drives patterns in both abiotic and biotic ecosystem functions that maintain healthy rangelands, making it an essential tool for both rangeland and wildlife management. In North America, humanity’s relationship with fire has rapidly changed and shifted from an era of coexistence to one that attempts to minimize or eliminate its occurrence. Prior to Euro-American settlement, Indigenous people’s coexistence with fire led to regionally distinct fire regimes that differed in terms of their fire frequency, intensity, severity, seasonality, and spatial complexity. As the relative occurrence of prescribed fire and wildfire continue to change in North American rangelands, it is necessary for wildlife managers to understand the complex social-ecological interactions that shape modern fire regimes and their conservation outcomes. In this chapter, we discuss the fire eras of North American rangelands, introduce foundational relationships between fire and wildlife habitat, and discuss potential futures for fire in wildlife management.
Carrick Detweiler合作论文数University of Nebraska-Lincoln
Computer Science and Engineering4