Carissa L. Wonkka

Carissa L. Wonkka
United States Department of Agriculture | USDA · Agricultural Research Service (ARS)

About

71
Publications
8,852
Reads
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837
Citations
Introduction
Carissa L. Wonkka currently works at the Northern Plains Agricultural Research Laboratory, USDA, ARS. She studies ecological approaches to rangeland restoration.
Additional affiliations
April 2020 - present
USDA Agricultural Research Service
Position
  • Research ecologist
September 2014 - present
University of Nebraska at Lincoln
Position
  • PostDoc Position
August 2008 - December 2015
Texas A&M University
Position
  • Graduate Research Associate

Publications

Publications (71)
Article
Fire is widely understood to be an important ecological process in grasslands around the world, but little research has been done on soil heating and nutrient and microbe responses to prescribed fire in the northern Great Plains of North America. We investigated plant-available nitrogen responses to soil heating in semi-arid grassland in southweste...
Article
Full-text available
This is the second paper of a two-part series on the barriers to prescribed fire use in the Great Plains of the USA. While the first part presented a systematic review of published papers on the barriers to prescribed fire use, specifically regarding perceptions and attitudes of land managers, this second part reviews the solutions that are employe...
Article
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Prescribed fire is increasingly being considered as a viable management tool by public and private land managers. Fully expanding prescribed fire use in a land management context, where it is an ecologically effective but not commonly applied tool, requires a comprehensive understanding of barriers that limit prescribed fire, especially in working...
Article
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Wildland fire literacy is the capacity for wildland fire professionals to understand and communicate fundamentals of fuel and fire behavior within the socio-ecological elements of the fire regime. While wildland fire literacy is best developed through education, training, and experience in wildland fire science and management, too often, developmen...
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Invasive annual grasses alter fire regime in steppe ecosystems, and subsequent trends toward larger, more frequent wildfires impacts iconic biodiversity. A common solution is to disrupt novel fuel beds comprising continuous swaths of invasive annual grasses with greenstrips—linear, human-maintained stands of less-flammable vegetation. But selecting...
Article
Fire has transformative effects on soil biological, chemical, and physical properties in terrestrial ecosystems around the world. While methods for estimating fire characteristics and associated effects aboveground have progressed in recent decades, there remain major challenges in characterizing soil heating and associated effects belowground. Ove...
Article
Human alteration of fire regimes is a hallmark of the Anthropocene; yet few studies have fully explored the implications of utilizing high-intensity fires in grasslands and savannas to manage shrub encroachment. Decades of fire research in South Africa inspired a unique convergence of high-intensity fire experiments in the USA. In the Great Plains...
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Rangelands worldwide have experienced significant shifts from grass-dominated to woody-plant dominated states over the past century. In North America, these shifts are largely driven by overgrazing and landscape-scale fire suppression. Such shifts reduce productivity for livestock, can have broad-scale impacts to biodiversity, and are often difficu...
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Woody plant encroachment in North American rangelands has led to calls for greater use of prescribed fire to reduce fuel loads and restore grazing productivity and grassland biodiversity. However, the use of prescribed fire during periods when woody plant mortality is maximized has often been limited by temporary restrictions on outdoor burning ena...
Article
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The identity of an ecological regime is central to modern resilience theory and our understanding of how systems collapse and reorganize following disturbance. However, resilience-based models used in ecosystem management have been criticized for their failure to integrate disturbance outcomes into regime identity. Assessments are needed to underst...
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Increasingly, land managers have attempted to use extreme prescribed fire as a method to address woody plant encroachment in savanna ecosystems. The effect that these fires have on herbaceous vegetation is poorly understood. We experimentally examined immediate (<24 hr) bud response of two dominant graminoids, a C3 caespitose grass, Nassella leucot...
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Suppression of historical fire regimes has changed the composition and structure of many fire-dependent ecosystems, frequently resulting in decreased grazing productivity and biodiversity in grasslands and savannas. Land managers have attempted to reverse these trends through the application of prescribed fire, but regulations and liability concern...
Article
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Grassland environments face a number of threats including land use change, changing climate and encroachment of woody plants. In the Southern Plains of the United States, woody plant encroachment threatens traditional agricultural grazing economies in addition to grassland dependent wildlife species. Numerous studies have examined the physical driv...
Article
Documented increases in woody plant abundance worldwide can reduce land value and grazing capacity. Throughout many grasslands and savannas in South Africa, Seriphium plumosum, an encroaching woody plant, has been rapidly displacing desirable native species. Cost-effective management techniques are required, in order to prevent encroachment. Howeve...
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Wildfire activity has surged in North America's temperate grassland biome. Like many biomes, this system has undergone drastic land-use change over the last century; however, how various land-use types contribute to wildfire patterns in grassland systems is unclear. We determine if certain land-use types have a greater propensity for large wildfire...
Article
Species conservation requires monitoring and management that extends beyond the local population, yet studies evaluating population trends and management outcomes across the spatial range of a species remain rare. We conducted the first range-wide assessment of population trends for the iconic Rocky Mountain bighorn sheep (Ovis canadensis canadensi...
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Heterogeneity has emerged as a fundamental principle for grassland management and the importance of environmental heterogeneity for biological diversity has raised questions about the appropriateness of grassland practices that seek to promote uniform grassland structure and composition. Principles of uniformity in grassland management reflect a ut...
Article
Suppression of fire in the Southern Plains has led to proliferation of woody plants and fuel load accumulation that spurs wildfires. These effects have led to calls for widespread application of prescribed fire to reduce fuel loads, but there is substantial landowner resistance to the use of this land management tool. Here we explore factors that a...
Article
Mechanisms underlying the loss of ecological resilience and a shift to an alternate regime with lower ecosystem service provisioning continues to be a leading debate in ecology, particularly in cases where evidence points to human actions and decision-making as the primary drivers of resilience loss and regime change. In this paper, we introduce th...
Article
Mechanisms underlying the loss of ecological resilience and a shift to an alternate regime with lower ecosystem service provisioning continues to be a leading debate in ecology, particularly in cases where evidence points to human actions and decision-making as the primary drivers of resilience loss and regime change. In this paper, we introduce th...
Article
Changing climate and fuel accumulation are increasing wildfire risks across the western United States. This has led to calls for fire management reform, including the systematic use of prescribed fire. Although use of prescribed fire by private landowners in the southern Great Plains has increased during the past 30 yr, studies have determined that...
Article
Understanding the capacity of ecosystems to adapt and to cope (i.e. adaptive capacity) with change is crucial to their management. However, definitions of adaptive capacity are often unclear and confusing, making application of this concept difficult. In this paper, we revisit definitions of adaptive capacity and operationalize the concept. We defi...
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Increasing wildfires in western North American conifer forests have led to debates surrounding the application of post-fire management practices. There is a lack of consensus on whether (and to what extent) post-fire management assists or hinders managers in achieving goals, particularly in under-studied regions like eastern ponderosa pine forests....
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The rapid pace of global climate change necessitates tools for prioritizing limited climate-adaptation resources in the face of imperfect knowledge regarding plant community responses to changing climate. In addition, global climate change often leads to novel shifts in plant communities which are difficult to anticipate with detailed models based...
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Disturbance legacies structure communities and ecological memory, but due to increasing changes in disturbance regimes, it is becoming more difficult to characterize disturbance legacies or determine how long they persist. We sought to quantify the characteristics and persistence of material legacies (e.g., biotic residuals of disturbance) that ari...
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The conservation of rare species is typically challenging because of incomplete knowledge about their biology and distributions. Species distribution models (SDMs) have emerged as an important tool for improving the efficiency of rare species conservation. However, these models must include biologically relevant predictor variables at scales approp...
Article
Historically, eastern ponderosa pine (Pinus ponderosa) forests were described as sparse patches of old-growth trees maintained by frequent, low-severity fires; however, in recent decades, there have been a number of large mixed-severity wildfires throughout the range of these forests. Wildlife responses to severe fire disturbance in eastern pondero...
Article
Full-text available
Wildland fire science literacy is the capacity for wildland fire professionals to understand and communicate three aspects of wildland fire: (1) the fundamentals of fuels and fire behavior, (2) the concept of fire as an ecological regime, and (3) multiple human dimensions of wildland fire and the socio-ecological elements of fire regimes. Critical...
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Context Plant invasions of native ecosystems are one of the main causes of declines in biodiversity via system-simplification. Restoring native biodiversity can be particularly challenging in landscapes where invasive species have become dominant and where a new set of feedbacks reinforce an invaded state and preclude restoration actions. We lack a...
Presentation
Full-text available
Navasota ladies'-tresses (Spiranthes parksii) is a federally listed endangered species which is endemic to east-central Texas. It occurs in thirteen Texas counties with ninety-three percent of known population sites in Brazos and Grimes counties, two counties in the Brazos River Valley of east-central Texas. This percentage is considered to be infl...
Article
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New concepts have emerged in theoretical ecology with the intent to quantify complexities in ecological change that are unaccounted for in state-and-transition models and to provide applied ecologists with statistical early warning metrics able to predict and prevent state transitions. With its rich history of furthering ecological theory and its r...
Article
Understanding how extreme drought alters spatial patterns and temporal stability in grassland biomass will become increasingly important by the end of the century when climate model forecasts suggest drought events will occur more frequently. In grassland landscapes where grazing is driven by fire (termed pyric herbivory), temporal stability in abo...
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A modern challenge for conservation biology is to assess the consequences of policies that adhere to assumptions of stationarity (e.g., historic norms) in an era of global environmental change. Such policies may result in unexpected and surprising levels of mitigation given future climate-change trajectories, especially as agriculture looks to prot...
Article
In the Nebraska Sandhills, one of the largest contiguous grassland ecoregions remaining in North America, sandy textured soils are stabilized by fine root biomass from predominantly warm-season grasses. Concerns over destabilization have led to management that aims to avoid an undesirable state change toward mobile sand dunes. In 2012, the Sandhill...
Article
Populus deltoides is considered to be a weak resprouter and highly susceptible to wildfire, but few post-wildfire studies have tracked P. deltoides response and resprouting within the Great Plains of North America. Following a wildfire in southwestern Kansas, U.S.A., we surveyed burned and unburned areas of a cottonwood riparian forest along the Ci...
Article
Rapid changes in wildfire patterns are documented globally, increasing pressure to identify regions that may experience increases in wildfire in future decades. Temperate grassland and savanna biomes were some of the most frequently burned regions on Earth; however, large wildfires have been largely absent from the Great Plains of North America over t...
Article
In rangelands, management interventions have sought to minimize disturbances that decrease survival of perennial grasses to avoid compositional shifts toward less desirable species. However, the effects of rangeland management techniques on perennial grass survival and turnover are not known for individual species because the discipline has largely...
Article
On the Ground • Rangeland managers actively focus on the potential to induce a shift in a site to an alternative state, but predicted changes in climate, particularly the likelihood of more extreme drought, necessitate reevaluating risks for alternative states. • Rangelands will differ in their susceptibility to undergo state changes due to climate...
Article
Increases in precipitation variability, coupled with higher temperatures, will lead to greater frequencies of severe, prolonged droughts for many regions with the expectation of attendant increases in woody plant die-off events. We took advantage of a 2-yr extension of a severe drought following an initial study of woody plant dieback in a woody-en...
Article
Summary 1. Management intervention in ecosystems with degraded environmental services requires innovative resource management strategies that go beyond conventional restoration and conservation practices. We established a unique study that experimentally targeted extreme fire conditions during drought in humid subtropical and semi-arid ecoregions....
Article
Full-text available
•Due to woody plant encroachment and seeing the need for fire on their lands, private landowners throughout the southern Great Plains have started forming prescribed burn associations (PBA) to assist each other with conducting prescribed fires.•Members of PBAs work together by pooling equipment and other resources, organizing training opportunities...
Article
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Non-native plant invasions and changing management activities have dramatically altered the structure and composition of forests worldwide. Invasive shrubs and fire suppression have led to increased densification and biomass accumulation in forest ecosystems of the southeastern USA. Notably, Chinese and European privets are rapid growing, shade-tol...
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In ecosystems with alternative stable states, restoration success can be thought of as overcoming the resilience of an undesirable state to promote an alternative state that yields greater ecosystem services. Since greater resilience of undesirable states translates into reduced restoration potential, quantifying differences in resilience can enhan...
Article
In ecosystems with alternative stable states, restoration success can be thought of as overcoming the resilience of an undesirable state to promote an alternative state that yields greater ecosystem services. Since greater resilience of undesirable states translates into reduced restoration potential, quantifying differences in resilience can enhan...
Article
Full-text available
Fire is widely recognized as a critical ecological and evolutionary driver that needs to be at the forefront of land management actions if conservation targets are to be met. However, the prevailing view is that prescribed fire is riskier than other land management techniques. Perceived risks associated with the application of fire limits its use a...
Article
Resistance to the use of prescribed fire is strong among many private land managers despite the advantages it offers for maintaining fire-adapted ecosystems. Even managers who are aware of the benefits of using prescribed fire as a management tool avoid using it, citing potential liability as a major reason for their aversion. Recognizing the impor...
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Full-text available
Concerns regarding the long-term viability of threatened and endangered plant species are increasingly warranted given the potential impacts of climate change and habitat fragmentation on unstable and isolated populations. Orchidaceae is the largest and most diverse family of flowering plants, but it is currently facing unprecedented risks of extin...
Conference Paper
Background/Question/Methods Developing effective restoration techniques for coastal prairies degraded by woody encroachment and invasive introduced grasses requires an understanding of two fundamental ecological processes: fire and grazing. Prescribed fire and grazing are recommended for suppressing non-native species that are functionally distin...
Conference Paper
Background/Question/Methods Fire and herbivory are widely recognized as important in savanna ecosystems, however, little is known about their effects on Spiranthes parksii, an endangered terrestrial orchid endemic to Texas post oak savannas. We designed a full-factorial, completely randomized field experiment to assess fire and vertebrate herbivo...
Conference Paper
Background/Question/Methods Woody plant expansion (WPE) is a phenomenon that is occurring in many fire adapted grassland and savanna ecosystems. Fire suppression policies during the last 100 to 200 years have been a primary driver of WPE and elevated atmospheric CO2 concentrations appears to be accelerating this trend. To maintain open grasslands...
Article
Questions: How do recent patterns of drought-induced woody plant mortality in Texas semi-arid savanna compare to the extended drought of the 1950s? Does the relative composition of the woody plant community shift ubiquitously across the landscape following woody plant mortality and dieback or are shifts dependent on differences among species, soils...
Article
Despite years of accumulating scientific evidence that fire is critical for maintaining the structure and function of grassland ecosystems in the US Great Plains, fire has not been restored as a fundamental grassland process across broad landscapes. The result has been widespread juniper encroachment and the degradation of the multiple valuable eco...
Conference Paper
Background/Question/Methods Ecosystems with diminished environmental services require innovative resource management strategies. Conventional restoration and conservation practices have been historically ineffective and/or economically cost prohibitive at repairing degraded rangelands in the southern Great Plains. Landowners throughout this region...
Conference Paper
Background/Question/Methods Recent severe droughts in Texas have resulted in high levels of woody plant dieback in areas that have experienced decades of woody encroachment. These were the most severe droughts on record since the 1950s. Following an exceptional drought from 1951-1957, a study was conducted to quantify rates of dieback for various...
Article
Full-text available
Japanese honeysuckle is one of the most aggressive invasive vines in forestlands of the southern United States. We analyzed field data collected by the U.S. Forest Service to identify potential determinants of invasion and to predict likelihood of further invasion under a variety of possible management strategies. Results of logistic regression, wh...
Article
Full-text available
Navasota ladies' tresses (Spiranthes parksii Correll [Orchidaceae]) is a federally and state-listed endangered orchid of east-central Texas. Habitat loss and degradation related to urban and industrial development are major threats to S. parksii populations. To ensure recovery, a complete understanding of the population dynamics, ecology, and biolo...
Conference Paper
Background/Question/Methods The effects of herbivory on plant populations are not well known for many species despite a large body of literature related to plant-herbivore interactions. This is likely related to difficulty in translating herbivore damage of individual plants to herbivore effects on population dynamics. In order to investigate pop...
Conference Paper
Background/Question/Methods Fire and herbivory are known to strongly influence the structure and dynamics of numerous plant populations in savanna ecosystems. While other terrestrial orchid species have demonstrated a wide variety of responses to fire and herbivory, little is known about the effects of these disturbances on Spiranthes parksii, a...
Article
Differences in life history strategy influence the ecological roles of plant species, including their susceptibility to disturbance events. According to Grime's CSR model, plants exhibit three primary strategies, which reflect tradeoffs between stress and disturbance. Here we classify eastern North American tree species into life history strategies...
Conference Paper
Background/Question/Methods Spiranthes parksii Correll is an endangered orchid endemic to the post oak savanna of east central Texas. Fire suppression in the post oak savanna has altered the structure and composition of these communities and may be a factor driving the decline of S. parksii through mechanisms such as heightened interspecific comp...