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Society’s struggle with unwanted species: What centuries of history reveal about species bounty programs

Species bounty programs, much like bounty hunters charged to bring fugitives to justice, enlist the public to locate and remove unwanted species through financial incentives. With the goal of reducing population sizes, these programs address perceived ecological and economic damage caused by target species. In this study, we provide the first global assessment of species bounty programs, drawing on evidence from both historical and contemporary efforts across diverse regions and cultural contexts over the past eight centuries. We uncovered a long history of bounty programs involving at least 283 species—mammals, birds, fish, plants, reptiles, mollusks, insects, amphibians, and crustaceans—across 449 programs in 60 countries. Using this collective knowledge, we offer five perspectives on species bounty programs. First, bounty programs are launched for a variety of reasons, including economic (livestock, crops, fisheries, infrastructure), ecological (species, ecosystems), and social (human health) considerations related to unwanted species. Second, bounty programs vary in their design and implementation, ranging from well-planned operations with clear management and conservation objectives to ad hoc operations with limited articulation and investigation of project outcomes. Third, evidence points to unintended consequences, in which bounty programs result in the incidental removal of non-target species or in effects that may inadvertently benefit target species. Fourth, while not always the case, fraudulent activities have been reported, compromising the management outcomes of some programs. Fifth, public perception of bounty programs is highly dynamic and ensuring program engagement remains a persistent challenge. By reviewing the scattered narratives of past and present bounty programs globally, this review seeks to inform the evolving role of this management strategy.

npj Biodiversity↗

Plant effects on and response to soil microbes in native and non-native Phragmites australis

Plant–soil feedbacks (PSFs) mediate plant community dynamics and may plausibly facilitate plant invasions. Microbially mediated PSFs are defined by plant effects on soil microbes and subsequent changes in plant performance (responses), both positive and negative. For microbial interactions to benefit invasive plants disproportionately, native and invasive plants must either (1) have different effects on and responses to soil microbial communities or (2) only respond differently to similar microbial communities. In other words, invasive plants do not need to cultivate different microbial communities than natives if they respond differently to them. However, effects and responses are not often explored separately, making it difficult to determine the underlying causes of performance differences. We performed a reciprocal-transplant PSF experiment with multiple microbial inhibition treatments to determine how native and non-native lineages of Phragmites australis affect and respond to soil bacteria, fungi, and oomycetes. Non-native Phragmites is a large, fast-growing, cosmopolitan invasive plant, whereas the North American native variety is comparatively smaller, slower growing, and typically considered a desirable wetland plant. We identified the effects of each plant lineage on soil microbes using DNA meta-barcoding and linked plant responses to microbial communities. Both Phragmites lineages displayed equally weak, insignificant PSFs. We found evidence of slight differential effects on microbial community composition, but no significant differential plant responses. Soils conditioned by each lineage differed only slightly in bacterial community composition, but not in fungal composition. Additionally, native and non-native Phragmites lineages did not significantly differ in their response to similar soil microbial communities. Neither lineage appreciably differed when plant biomass was compared between those grown in sterile and live soils. Targeted microbial inhibitor treatments revealed both lineages were negatively impacted by soil bacteria, but the negative response was stronger in non-native Phragmites . These observations were opposite of expectations from invasion theory and imply that the success of non-native Phragmites , relative to the native lineage, does not result from its interaction with soil microorganisms. More broadly, quantifying plant effects on, and responses to soil microbes separately provides detailed and nuanced insight into plant-microbial interactions and their role in invasions, which could inform management outcomes for invasive plants.

Ecological Applications↗

Greenup and evapotranspiration following the Minute 319 pulse flow to Mexico: An analysis using Landsat 8 Normalized Difference Vegetation Index (NDVI) data

In the southwestern U.S., many riparian ecosystems have been altered by dams, water diversions, and other anthropogenic activities. This is particularly true of the Colorado River, where numerous dams and agricultural diversions have affected this water course, especially south of the U.S.–Mexico border. In the spring of 2014, 130 million cubic meters of water was released to the lower Colorado River Delta in Mexico. To understand the impact of this pulse flow release on vegetation in the delta’s riparian corridor, we analyzed a modified form of Landsat 8 Operational Land Imager (OLI) Normalized Difference Vegetation Index (NDVI*) data. We assessed greenup during the growing period and estimated actual evapotranspiration (ET a ) for the period prior to (yr. 2013) and following (i.e., yr. 2014 and 2015) the pulse flow. We found a significant increase in NDVI* from 2013 to 2014 (P < 0.05) and a decrease from 2014 to 2015; however, 2015 levels were still significantly higher than in 2013. ET a was also higher in 2014 vs. 2013, with an estimated 74.5 million cubic meters in 2013 and 88.9 in 2014. The most intense greening occurred in the zone of inundation but also extended into the non-flooded part of the riparian zone, indicating replenishment of groundwater. These findings suggest the peak response by vegetation to the flow lasted about one year, followed by a decrease in NDVI*. As a long term solution to the declining condition of vegetation, additional pulse releases are likely needed for restoration and survival of riparian plant communities in the Colorado River Delta.

Ecological Engineering↗

An overview of the NASA Adaptation and Response in Drylands field experiment scoping study

Drylands cover 41% of Earth’s land surface, support 36% of the global population, and contribute 60% of global food production. Despite these ecosystems’ importance and high vulnerability to droughts and heatwaves, drylands remain some of the most understudied systems on Earth. Monitoring drylands is challenging due to their complex ecosystem structure of visible soil mixed with diverse plant species that respond rapidly to weather and climate. In 2023 and 2024, a NASA scoping study was conducted for a proposed dryland terrestrial ecology field campaign called Adaptation and Response in Drylands (ARID). Thereafter, the NASA ARID scoping team submitted their campaign proposal to NASA Headquarters, providing a study design for how field, aircraft, and satellite measurements, as well as modeling, would address the most critical fundamental and applied science questions in drylands. The extensive study plan was created by and for the drylands research community – including remote sensors, modelers, experimentalists, and ecologists from across the world – and the overall approach can be further utilized and changed for different uses and data information needs. Here, we summarize the ARID research road map, including its main objectives, field campaign strategy, data end-user support strategy, and U.S. and global community engagement.

Drylands↗

Macroclimatic change expected to transform coastal wetland ecosystems this century

Coastal wetlands, existing at the interface between land and sea, are highly vulnerable to climate change. Macroclimate (for example, temperature and precipitation regimes) greatly influences coastal wetland ecosystem structure and function. However, research on climate change impacts in coastal wetlands has concentrated primarily on sea-level rise and largely ignored macroclimatic drivers, despite their power to transform plant community structure and modify ecosystem goods and services. Here, we model wetland plant community structure based on macroclimate using field data collected across broad temperature and precipitation gradients along the northern Gulf of Mexico coast. Our analyses quantify strongly nonlinear temperature thresholds regulating the potential for marsh-to-mangrove conversion. We also identify precipitation thresholds for dominance by various functional groups, including succulent plants and unvegetated mudflats. Macroclimate-driven shifts in foundation plant species abundance will have large effects on certain ecosystem goods and services. Based on current and projected climatic conditions, we project that transformative ecological changes are probable throughout the region this century, even under conservative climate scenarios. Coastal wetland ecosystems are functionally similar worldwide, so changes in this region are indicative of potential future changes in climatically similar regions globally.

Nature Climate Change↗

Early post-fire succession in California chaparral: Changes in diversity, density, cover and biomass

For four consecutive years, following the fires in November 1993, temporal variations in species richness, cover and biomass of component plant groups in early post-fire chaparral succession were monitored on different aspects at the Stunt Ranch Santa Monica Mountains Reserve, southern California. Plant groups were categorized based on growth form, life form, ability to fix nitrogen, geographic origin and regeneration strategies. North-facing slopes exhibited higher species richness, higher species turnover rate over time and faster vegetation recovery in terms of biomass accumulation and return to pre-fire species composition. This was probably due to higher species richness and biomass of nitrogen-fixing species found on north-facing slopes in comparison to south-facing slopes. On both north- and south-facing slopes, annuals had the highest species turnover rate, followed by herbaceous perennials and shrubs. In the first four post-fire years, annual species were the largest floristic group, but herbaceous perennials and shrubs were the major contributors to community biomass. Nitrogen-fixing species and exotics contributed significantly to early post-fire community structure. Although the general trends in post-fire succession are clear in terms of temporal changes in the relative proportions of different plant groups, environmental variation and the nature of plant life histories of component species, especially dominant species, could alter such trends significantly.

Ecological Research↗

Beyond just sea-level rise: Considering macroclimatic drivers within coastal wetland vulnerability assessments to climate change

Due to their position at the land-sea interface, coastal wetlands are vulnerable to many aspects of climate change. However, climate change vulnerability assessments for coastal wetlands generally focus solely on sea-level rise without considering the effects of other facets of climate change. Across the globe and in all ecosystems, macroclimatic drivers (e.g., temperature and rainfall regimes) greatly influence ecosystem structure and function. Macroclimatic drivers have been the focus of climate-change related threat evaluations for terrestrial ecosystems, but largely ignored for coastal wetlands. In some coastal wetlands, changing macroclimatic conditions are expected to result in foundation plant species replacement, which would affect the supply of certain ecosystem goods and services and could affect ecosystem resilience. As examples, we highlight several ecological transition zones where small changes in macroclimatic conditions would result in comparatively large changes in coastal wetland ecosystem structure and function. Our intent in this communication is not to minimize the importance of sea-level rise. Rather, our overarching aim is to illustrate the need to also consider macroclimatic drivers within vulnerability assessments for coastal wetlands.

Global Change Biology↗

Drought in the Delta: Socio-ecological impacts, responses, and tools

Droughts are frequent events in the western United States, and can disrupt water supply and degrade water quality, challenging water management in the Sacramento–San Joaquin Delta (Delta). This chapter for the State of Bay–Delta Science report describes what drought means for the Delta, how drought is managed in the Delta, and how drought management has changed over time. Projections of future climate indicate the possibility of increased frequency and severity of droughts which would have increasing effects on California’s water system, society, and ecological functions within and beyond the Delta. California has experienced several major droughts in the 20th and 21st centuries, each of which has caused significant social and ecological impacts and motivated improvements in water management. Droughts decrease native fish populations, increase harmful algal blooms, and promote the spread of many invasive plant and animal species. For people living within the Delta and those that rely on Delta water exports, droughts increase drinking water costs and decrease agricultural production, negatively affecting agricultural economies and labor markets. Tools developed in response to droughts include actions that increase supply, such as building water infrastructure, actions to reduce demand, such as water conservation campaigns, and mitigation actions, such as monetary relief for drought-impacted communities. Improving drought resilience requires development of additional drought responses, increased forecasting accuracy, and increased awareness of impacts on vulnerable communities and ecosystems. Even with development of additional management actions, strategies, and regulations, there will likely be difficulties meeting the current levels of demand for water. Drought conditions already cause conflict between human and environmental uses, and with more extreme droughts possible in the future and projected increases in demand, it will be challenging to provide for all users’ needs even with major changes to water management in the Delta.

California↗

Patterns of plant species richness, rarity, endemism, and uniqueness in an arid landscape

Most current conservation literature focuses on the preservation of hotspots of species diversity and endemism, as if the two were geographically synonymous. At landscape scales this may not be the case. We collected data from 367 1000-m 2 plots in the Grand Staircase–Escalante National Monument, Utah, USA, to show that: (1) the vast majority of plant species are locally rare; (2) species-rich areas are generally in rare, mesic, or high-elevation habitats such as aspen stands or riparian zones high in soil N and P; (3) endemic species (to the Colorado Plateau and the Monument) were generally found in relatively species-rich, but low-elevation, xeric vegetation type areas low in soil P; (4) unique species assemblages were found in areas moderately high in endemism and species richness; and (5) nonnative plant species were widely distributed, but more prevalent in species-rich, mesic sites high in soil fertility or disturbed sites, and significantly less prevalent in plots with endemic species. We show that primary hotspots of species richness, high endemism, and unique species assemblages are not co-located on the landscape. Hence, conservation strategies may have to consider a much broader concept of “hotspots” to adequately preserve native plant species and the processes that foster persistence.

Ecological Applications↗

Continuous water-quality and suspended-sediment transport monitoring in the San Francisco Bay, California, water years 2014–15

The U.S. Geological Survey (USGS) monitors water quality and suspended-sediment transport in the San Francisco Bay (bay) as part of a multi-agency effort to address management, water supply, and ecological concerns. The San Francisco Bay area is home to millions of people, and the bay teems both with resident and with migratory wildlife, plants, and fish. Freshwater mixes with salt water in the bay, which is subject both to riverine influences (floods, droughts, managed reservoir releases and freshwater diversions) and to marine influences (tides, waves, effects of salt water). To understand this environment, the USGS, along with its partners (see “Acknowledgements”), has been monitoring the bay’s waters continuously since 1988. Several water-quality variables are of particular importance to State and Federal resource managers and are monitored at key locations throughout the bay (fig. 1). Salinity, which indicates the relative mixing of fresh and ocean waters in the bay, is derived from specific conductance measurements. Water temperature, along with salinity, affects the density of water, which controls gravity-driven circulation patterns and stratification in the water column. Turbidity, a measure of light scattered from suspended particles in the water, is used to estimate suspended-sediment concentration (SSC). Suspended sediment affects the bay in multiple ways: attenuation of sunlight in the water column, affecting phytoplankton growth; deposition on tidal marsh and intertidal mudflats, which can help sustain these habitats as sea level rises; deposition in ports and shipping channels, which can necessitate dredging; and often, adsorption of contaminants, affecting their distribution and concentrations in the environment. Dissolved oxygen concentration, essential to a healthy ecosystem and a fundamental indicator of water quality, is affected by water temperature, salinity, ecosystem metabolism, tidal currents, and wind. Tidal currents in the bay reverse four times a day, and wind direction and intensity typically vary on a daily cycle. Consequently, salinity, water temperature, SSC, and dissolved-oxygen concentration vary spatially and temporally throughout the bay. Therefore, continuous measurements are needed to observe these changes. The purpose of this fact sheet is to provide information about these variables, as well as internet links to access these continuous water-quality data collected by the USGS.

California↗

Effects of climate change on nutrition and genetics of White-tailed Ptarmigan

White-tailed Ptarmigan ( Lagopus leucura ) are well suited as a focal species for the study of climate change because they are adapted to cool, alpine environments that are expected to undergo unusually rapid climate change. We compared samples collected in the late 1930s, the late 1960s, and the late 2000s using molecular genetic and stable isotope methods in an effort to determine whether White-tailed Ptarmigan on Mt. Evans, Colorado, have experiences recent environmental changes resulting in shifts in genetic diversity, gene frequency, and nutritional ecology. We genotyped 115 individuals spanning the three time periods, using nine polymorphic microsatellite loci in our genetic analysis. These samples were also analyzed for stable carbon and nitrogen isotopic composition. We found a slight trend of lower heterozygosity through time, and allelic richness values were significantly lower in more recent times, but not significantly using an alpha of 0.05 ( P < 0.1). We found no changes in allele frequencies across time periods, suggesting that population sizes have not changed dramatically. Feather δ 13 C and δ 15 N values decreased significantly across time periods, whereas the range in isotope values increased consistently from the late 1930s to the late time periods. Inferred changes in the nutritional ecology of White-tailed Ptarmigan on Mt. Evans relate primarily to increased atmospheric deposition of nutrients that likely influenced foraging habits and tundra plant composition and nutritional quality. Future work seeks to integrate genetic and isotopic data with long-term demographics to develop a detailed understanding of the interaction among environmental stressors on the long-term viability of ptarmigan populations.

Studies in Avian Biology↗

Quantifying and predicting fuels and the effects of reduction treatments along successional and invasion gradients in sagebrush habitats

Sagebrush shrubland ecosystems in the Great Basin are prime examples of how altered successional trajectories can create dynamic fuel conditions and, thus, increase uncertainty about fire risk and behavior. Although fire is a natural disturbance in sagebrush, post-fire environments are highly susceptible to conversion to an invasive grass-fire regime (often referred to as a “grass-fire cycle”). After fire, native shrub-steppe plants are often slow to regenerate, whereas nonnative annuals, especially cheatgrass (Bromus tectorum) and medusahead (Taeniatherum caput-medusae), can establish quickly and outcompete native species. Once fire-prone annuals become established, fire occurrences increase, further promoting dominance of nonnative species. The invasive grass-fire regime also alters nutrient and hydrologic cycles, pushing ecosystems beyond ecological thresholds toward steady-state, fire-prone, nonnative communities. These changes affect millions of hectares in the Great Basin and increase fire risk, decrease habitat quality and biodiversity, accelerate soil erosion, and degrade rangeland resources for livestock production. In many sagebrush landscapes, constantly changing plant communities and fuel conditions hinder attempts by land managers to predict and control fire behavior, restore native communities, and provide ecosystem services (e.g., forage production for livestock). We investigated successional and nonnative plant invasion states and associated fuel loads in degraded sagebrush habitat in a focal study area, the Morley Nelson Snake River Birds of Prey National Conservation Area (hereafter the NCA), in the Snake River Plain Ecoregion of southern Idaho. We expanded our inference by comparing our findings to similar data collected throughout seven major land resource areas (MLRAs) across the Great Basin (JFSP Project “Fire Rehabilitation Effectiveness: A Chronosequence Approach for the Great Basin” [09-S-02-1]). 4 We used a combination of field-sampling, experimental treatments, and remotely sensed data to address the following questions: (1) How do fuel loads change along gradients of succession and invasion in sagebrush ecological sites? (2) How do fuel reduction treatments influence fuels in invaded areas formerly dominated by sagebrush? (3) How do fuel loads vary across landscapes and which remote sensing techniques are effective for characterizing them?

Idaho↗

Northern Prairie Wildlife Research Center

The Northern Prairie Wildlife Research Center (NPWRC) conducts integrated research to fulfill the Department of the Interior's responsibilities to the Nation's natural resources. Located on 600 acres along the James River Valley near Jamestown, North Dakota, the NPWRC develops and disseminates scientific information needed to understand, conserve, and wisely manage the Nation's biological resources. Research emphasis is primarily on midcontinental plant and animal species and ecosystems of the United States. During the center's 40-year history, its scientists have earned an international reputation for leadership and expertise on the biology of waterfowl and grassland birds, wetland ecology and classification, mammalian behavior and ecology, grassland ecosystems, and application of statistics and geographic information systems. To address current science challenges, NPWRC scientists collaborate with researchers from other U.S. Geological Survey centers and disciplines (Biology, Geography, Geology, and Water) and with biologists and managers in the Department of the Interior (DOI), other Federal agencies, State agencies, universities, and nongovernmental organizations. Expanding upon its scientific expertise and leadership, the NPWRC is moving in new directions, including invasive plant species, restoration of native habitats, carbon sequestration and marketing, and ungulate management on DOI lands.

Fact Sheet↗

Ecological acclimation: A framework to integrate fast and slow responses to climate change

Ecological responses to climate change occur across vastly different time-scales, from minutes for physiological plasticity to decades or centuries for community turnover and evolutionary adaptation. Accurately predicting the range of ecosystem trajectories will require models that incorporate both fast processes that may keep pace with climate change and slower ones likely to lag behind and generate disequilibrium dynamics. However, the knowledge necessary for this integration is currently fragmented across disciplines. We develop ‘ecological acclimation’ as a unifying framework to emphasize the similarity of dynamics driven by processes operating on dramatically different time-scales and levels of biological organization. The framework focuses on ecoclimate sensitivities, measured as the change in an ecological response variable per unit of climate change. Acclimation processes acting at different time-scales cause these sensitivities to shift in magnitude and even direction over time. We highlight shifting ecoclimate sensitivities in case studies from diverse ecosystems, including terrestrial plant communities, coral reefs and soil microbiomes. Models predicting future ecosystem states inevitably make assumptions about acclimation processes; these assumptions must be explicit for users to evaluate whether a model is appropriate for a given forecast horizon. Similarly, decision frameworks that clearly account for multiple acclimation processes and their distinct time-scales will help natural resource managers plan for ecological impacts of climate change from years to many decades into the future. We outline a synthetic research programme focused on the time-scales of ecological acclimation to reduce uncertainty in ecological forecasts.

Functional Ecology↗

Of elephants and blind men: Deer management in the U.S. National Parks

Overabundant populations of white-tailed deer ( Odocoileus virginianus ) are becoming common in the eastern United States. Faced with burgeoning deer populations in eastern parks, the National Park Service (NPS) formulated policy based on its long experience with ungulate management in western parks. That the NPS failed to find a management solution acceptable to its many constituencies was inevitable. Like blind men touching different parts of an elephant and disagreeing about its form, those engaged in the debate about deer management in parks are viewing different parts of the ecological system. None has seen the entire system, and consequently, there is neither common agreement on the nature of the problem nor on the solutions. We explore the quandary of deer management in eastern parks by addressing three questions: (1) Can the National Park Service reconcile its management goals with those of its neighbors? (2) Can thresholds be identified for determining when to intervene in natural processes? (3) Is there a scientific foundation for proceeding with effective management of deer? We argue that reconciling the NPS management with that of state conservation agencies is not possible because management policy guides these agencies in opposite directions: the NPS is charged with limiting human impact on ecological processes, and state agencies are charged with exerting human control over population abundance. Questions about thresholds and a scientific basis for management arise from concern that irrupting deer populations are a manifestation of disrupted natural processes. Several population growth paradigms are at the heart of this ecological question. The science provides no consensus about which of these paradigms are appropriate to deer in eastern ecosystems. Thus, it is premature to expect science to identify if or when natural processes have been disrupted. While the NPS cannot effectively achieve its goals without better science, neither can it wait for science to fully understand the dynamics of plant–herbivore interactions. The best hope for resolving both the biological and political dilemmas surrounding deer management is through an adaptive management approach.

Ecological Applications↗

Hydrological regime and climate interactively shape riparian vegetation composition along the Colorado River, Grand Canyon

Question How closely do riparian plant communities track hydrological and climatic variation in space, and how do interactions among hydrological and climatic filters influence success of flow management strategies? Location Grand Canyon, Arizona, USA. Methods Multi‐year vegetation surveys were conducted across three hydrological zones – active channel, active floodplain and inactive floodplain – within each of 42 sandbars that vary geographically in temperature and precipitation along a 400‐km river segment. Ecological niche models were used to estimate locally optimal conditions of maximum inundation duration, elevation above daily peak flow, mean annual precipitation, and mean maximum and minimum temperature for 16 of the most abundant woody and 58 most abundant herbaceous plant species. These estimates were used to calculate community‐weighted mean (CWM) environmental preferences, which were used to determine how closely vegetation preferences tracked local variation in environmental factors, and to assess interactive responses of species and communities to variation in hydrology and climate. Results Communities closely tracked hydrological variation across zones, but less so within zones. Communities tracked variation in minimum temperature more closely than maximum temperature or precipitation. At the species level, woody plants that were more abundant in wetter hydrological conditions were also more abundant in wetter climatic conditions, and vice versa. This relationship was even stronger at the community level, where there were significant negative relationships between CWM preferences of inundation duration and temperature for both woody and herbaceous vegetation. Conclusions The climate‐hydrology linkages found in this system suggest that increasing temperatures and drought are likely to reduce the inundation tolerance of riparian vegetation within the Grand Canyon. Increasing the duration of high flow events would likely reduce the abundance of encroaching woody vegetation, but could also reduce the resilience of remaining vegetation to heat waves and drought. The reinforcing effects of climatic and hydrological filters are likely to generally result in greater sensitivity of species composition to environmental change than if those environmental filters acted independently. These results have implications for predicting resource responses to environmental change, as well as prescriptions for direct vegetation management to enhance resilience.

Colorado River, Grand Canyon↗

Response of Schoenoplectus acutus and Schoenoplectus californicus at different life-history stages to hydrologic regime

For wetland restoration success to be maximized, restoration managers need better information regarding how the frequency, depth, and duration of flooding affect soil chemistry and the survival, growth, and morphology of targeted plant species. In a greenhouse study we investigated the impact of four different flooding durations (0 %, 40 %, 60 %, and 100 %) on soil physicochemistry and the responses of seedlings and adults of two species of emergent wetland macrophytes commonly used in restoration efforts ( Schoenoplectus acutus and Schoenoplectus californicus ). The longest flooding duration, which created more reducing soil conditions, resulted in significantly reduced survival of S. acutus adults (34 &plusmn; 21 % survival) and complete mortality of seedlings of both species. Schoenoplectus californicus adults exhibited higher flooding tolerance, showing little impact of flooding on morphology and physiology. A companion field study indicated that S. californicus maintained stem strength regardless of flooding duration or depth, supporting the greenhouse study results. This information serves to improve our understanding of the ecological differences between these species as well as provide restoration managers with better guidelines for targeted elevation and hydrologic regimes for these species in order to enhance the success of restoration plantings and better predict restoration site development.

Wetlands↗

Trends, impacts, and cost of catastrophic and frequent wildfires in the sagebrush biome

Fire regimes in sagebrush ( Artemisia spp.) ecosystems have been greatly altered across the western United States. Broad-scale invasion of non-native annual grasses, climate change, and human activities have accelerated wildfire cycles, increased fire size and severity, and lengthened fire seasons in many sagebrush ecosystems to the point that current wildfire-management practices and postfire restoration efforts cannot keep pace to ameliorate the ecological consequences of sagebrush ecosystem loss. The greatest impact of uncharacteristically frequent fire is the transition from native sagebrush-perennial grass communities to invasive, non-native, annual grasslands that are highly flammable. These community transitions are often permanent, owing to the low probability of reestablishing native perennial plants in non-native annual grass−dominated communities. Moreover, these grasses can form extensive and continuous fine fuel loads that promote more frequent fire and the continued expansion of invasive, non-native annuals. More frequent, larger, and severe wildfires necessitate greater resources for fire-prevention, fire-suppression, and postfire restoration activities, while decreasing critical ecosystem services, economic and recreational opportunities, and cultural traditions. Increased flexibility and better prioritization of management activities based on ecological needs, including commitment to long-term prefire and postfire management, are needed to achieve notable reductions in uncharacteristic wildfire activity and associated negative impacts. Collaboration and partnerships across jurisdictional boundaries, agencies, and disciplines can improve consistency in sagebrush-management approaches and thereby contribute to this effort. Here, we provide a synthesis on sagebrush wildfire trends and the impacts of uncharacteristic fire regimes on sagebrush plant communities, dependent wildlife species, fire-suppression costs, and ecosystem services. We also provide an overview of wildland fire coordination efforts among federal, state, and tribal entities.

Rangeland Ecology and Management↗