David B McWethy

David B McWethy
Montana State University | MSU · Department of Earth Sciences

PhD

About

77
Publications
20,858
Reads
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1,757
Citations
Citations since 2016
51 Research Items
1264 Citations
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Introduction
My research focuses on how past and present human and natural disturbances shape vegetation and influence the structure and function of ecosystems across important biophysical and environmental gradients. My research is inherently interdisciplinary, spanning the disciplines of fire ecology, forest ecology, biogeography and paleoecology.
Additional affiliations
June 2010 - present
Montana State University
Position
  • Research Assistant

Publications

Publications (77)
Article
Full-text available
Cultural layers are deposits resulting from settlement and human activity on natural soil in the past. Materials from past domestic activities that become buried into the soil can be used to reconstruct human impact in a specific area in the past. For instance, humans have used fire for millennia, and charcoal in soils and sediments is applied as e...
Article
Full-text available
Fire is an integral component of ecosystems globally and a tool that humans have harnessed for millennia. Altered fire regimes are a fundamental cause and consequence of global change, impacting people and the biophysical systems on which they depend. As part of the newly emerging Anthropocene, marked by human-caused climate change and radical chan...
Article
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Extensive portions of high‐latitude grasslands worldwide have recently experienced increased vegetative productivity (i.e., greening) and have undergone a rapid transition towards woody plant dominance via the process of woody plant expansion (WPE). This raises the underlying question: To what degree are WPE and greening spatiotemporally linked? Gi...
Article
As the dominant large herbivore in midcontinent North America since the terminal Pleistocene, bison (Bison spp.) have been a fundamental component of ecosystems and economies. Despite the importance of bison in late Quaternary North America, large-scale (regional to continental) patterns of bison biogeography are not well understood. Here we integr...
Article
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Western juniper (Juniperus occidentalis Hook.) woodlands have persisted for millennia in semiarid parts of the northern Great Basin, USA, providing critical habitat for plant and animal species. Historical records suggest that the establishment of western juniper is strongly associated with regional climatic variability. For example, the abundance...
Technical Report
Full-text available
This publication and the activities described herein were supported with funding from Joint Fire Science Program award 16-3-01-24. We are grateful to the workshop participants, who generously and collegially shared their time, expertise, and creative ideas. Abstract Land management and fire management goals are increasingly framed in terms of resil...
Article
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Rano Raraku, the crater lake constrained by basaltic tuff that served as the primary quarry used to construct the moai statues on Rapa Nui (Easter Island), has experienced fluctuations in lake level over the past centuries. As one of the only freshwater sources on the island, understanding the present and past geochemical characteristics of the lak...
Article
Full-text available
New Zealand was among the last habitable places on earth to be colonized by humans¹. Charcoal records indicate that wildfires were rare prior to colonization and widespread following the 13th- to 14th-century Māori settlement², but the precise timing and magnitude of associated biomass-burning emissions are unknown1,3, as are effects on light-absor...
Article
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The small and remote Easter Island (Rapa Nui) has a complex and still partially unknown history of human colonization and interactions with the environment. Previous research from sedimentary archives collected in the three freshwater bodies of Rapa Nui document dramatic environmental changes over the last two millennia. Yet, the characteristics of...
Article
The Last Glacial Maximum (LGM) remains an enigmatic period in southeast Australia due to the limited spatial and temporal resolution of its palaeoclimatic records. A major feature of the LGM landscape was the existence of the Bassian Land Bridge, joining Tasmania with the mainland of Australia during periods of low sea level, and potentially facili...
Article
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Ice patches are an irreplaceable archive of past events. With atypical melting now occurring around the world, it is important to be able to quantify and interpret the potential of what remains in areas of archaeological interest. A ground-penetrating radar (GPR) survey was conducted at an archaeologically productive ice patch in the Greater Yellow...
Article
Recent, widespread tree mortality in the western U.S. resulting from changes in climate, pathogens, insect activity, and forest management practices has led to concerns for many ecologically and culturally important species. Within conifers, resin-based defenses have long been recognized as a primary defense mechanism against a variety of insects a...
Article
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Species are frequently responding to contemporary climate change by shifting to higher elevations and poleward to track suitable climate space. However, depending on local conditions and species’ sensitivity, the nature of these shifts can be highly variable and difficult to predict. Here, we examine how the American pika (Ochotona princeps), a phi...
Article
Full-text available
The unprecedented size of the 2017 wildfires that burned nearly 600,000 hectares of central Chile highlight a need to better understand the climatic conditions under which large fires develop. Here we evaluate synoptic atmospheric conditions at the surface and free troposphere associated with anomalously high (active) versus low (inactive) months o...
Article
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Urgency and deliberateness are often at odds when executing conservation projects, especially as the scale and complexity of objectives increases. The pace of environmental degradation supports immediate and measurable action. However, best practices for adaptive governance and building resilient social-ecological systems call for more deliberate e...
Article
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Paleoclimate records from ice cores generally are considered to be the most direct indicators of environmental change, but are rare from mid-latitude, continental regions such as the western United States. High-elevation ice patches are known to be important archaeological archives in alpine regions and potentially could provide records important f...
Article
Glacial Lake Outburst Floods (GLOFs) constitute a major threat in glacierized regions. Despite a recent increase in the size and number of glacial lakes worldwide, there is only limited evidence that climate change is affecting GLOF frequency. GLOFs are particularly common in the Baker River watershed (Patagonia, 47°S), where 21 GLOFs occurred betw...
Chapter
Full-text available
Fire history is the study of the spatial and temporal patterns of past wildland fires. Information on recent wildland fires comes from documentary records and satellite observations that span years to decades. On longer time scales, fire history is reconstructed from tree rings, including fire scars and the origin dates of postfire cohorts of trees...
Article
Full-text available
In recent decades, Rocky Mountain accumulated snowpack levels have experienced rapid declines, yet long-term records of snowpack prior to the installation of snowpack observation stations in the early and mid 20th century are limited. To date, a small number of tree-ring based reconstructions of April 1 Snow Water Equivalent (SWE) in the northern R...
Article
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Warm summer temperatures and longer fire seasons are promoting larger, and in some cases, more fires that are severe in low- and mid-elevation, dry mixed-conifer forests of the Northern Rocky Mountains (NRM). Long-term historical fire conditions and human influence on past fire activity are not well understood for these topographically and biophysi...
Article
Whitebark pine (Pinus albicaulis) is a critical forest species of Northern Rocky Mountain upper subalpine ecosystems, yet little is known about the physiological response of whitebark pine to disturbance (e.g. fire, bark beetles, and pathogens) across a range of diverse environmental gradients. Resin-based defenses have long been recognized as the...
Article
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Record-breaking fire seasons are becoming increasingly common worldwide, and large wildfires are having extraordinary impacts on people and property, despite years of investments to support social–ecological resilience to wildfires. This has prompted new calls for land management and policy reforms as current land and fire management approaches hav...
Article
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Resilience has become a common goal for science-based natural resource management, particularly in the context of changing climate and disturbance regimes. Integrating varying perspectives and definitions of resilience is a complex and often unrecognized challenge to applying resilience concepts to social-ecological systems (SESs) management. Using...
Article
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[This corrects the article DOI: 10.1371/journal.pone.0201195.].
Article
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In recent decades large fires have affected communities throughout central and southern Chile with great social and ecological consequences. Despite this high fire activity, the controls and drivers and the spatiotemporal pattern of fires are not well understood. To identify the large-scale trends and drivers of recent fire activity across six regi...
Data
Pre-screening of variables for model comparison using importance values for variables included in final GLM and GAM model comparison. Highly correlated variables (Pearson’s correlation coefficient > 0.60) and variables with importance values < 0.05 were not included in model comparison. (DOCX)
Data
Comparison of Random Forests variable importance values for the entire study area and the North and South bioclimatic zone models. Variables ranked according to their Random Forests variable importance values shown as the estimated mean decrease in accuracy (MDA). (DOCX)
Data
Spatial distribution of the probability of fire occurrence based on best GLM. (EPS)
Data
Summary of GAM model comparison for study area and North and South bioclimatic zone model sets. Model AIC, delta AIC between best model and model shown, % deviance explained, model r-squared, degrees of freedom and predictor variables included in each model. All continuous variables were significant at the p < 0.0001 significance level. (DOCX)
Data
Image of high severity fire that occurred in an Araucaria araucana forest in 2015, China Muerta National Reserve, Araucanía region, south-central Chile (photo D. McWethy). (JPG)
Data
Fire selective ‘preference’ for specific vegetation types using R-package ‘Resource Selection Function’. (EPS)
Article
Full-text available
Deforestation associated with the initial settlement of New Zealand is a dramatic example of how humans can alter landscapes through fire. However, evidence linking early human presence and land-cover change is inferential in most continental sites. We employed a multi-proxy approach to reconstruct anthropogenic land use in New Zealand's South Isla...
Article
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Mixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over th...
Article
Lebanon lacks a system for forecasting wildfire danger with the combined use of dynamic weather forecasts and comprehensive fire risk information (i.e., hazard and vulnerability). Accordingly, the aim of this study was to develop a new national fire danger forecast system for use as an operational fire management tool in Lebanon. The specific objec...
Article
Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fir...
Article
Full-text available
Invasive plant species that have the potential to alter fire regimes have significant impacts on native ecosystems. Concern that pine invasions in the Southern Hemisphere will increase fire activity and severity and subsequently promote further pine invasion prompted us to examine the potential for feedbacks between Pinus contorta invasions and fir...
Article
Full-text available
To evaluate the influence of climate and Aboriginal landscape management on Holocene vegetation and fire activity. Flinders Island, Bass Strait, Tasmania where archaeological data document extended periods of human presence and absence over the past 12,000 years. We evaluated climate–human–fire interactions through high-resolution pollen, charcoal...
Article
Full-text available
Few long-term climate and environmental records are available for southeast Africa where millennial scale shifts in the north-south position of the Intertropical Convergence Zone (ITCZ) and changes in Indian Ocean sea surface temperatures interact with local controls (e.g., fire, hydrology) to influence vegetation and ecosystem dynamics. Reconstruc...
Conference Paper
Full-text available
Although much is known about the environmental history of the Yellowstone region, comparatively little is known about the vegetation and fire history of the Rocky Mountains of northwestern Montana. The Mission Range was intensively glaciated in late-Pleistocene time, and has been occupied by humans for at least 10,000 years. These two factors make...
Article
Full-text available
During the past decade, Lebanon has experienced a large number of severe wildfires that have had significant social and ecological consequences. In this context, the assessment of wildfire risk is important to support planning of fire prevention measures and risk mitigation. The purpose of this study was to assess the spatial distribution of wildfi...
Article
Full-text available
The relative importance of people and climate in shaping prehistoric fire regimes is debated around the world, and this discussion has helped inform our understanding of past and present ecosystem dynamics. Evidence for extensive anthropogenic burning of temperate closed-canopy forests prior to European settlement is geographically variable, and th...
Article
Full-text available
Human-caused forest transitions are documented worldwide, especially during periods when land use by dense agriculturally-based populations intensified. However, the rate at which prehistoric human activities led to permanent deforestation is poorly resolved. In the South Island, New Zealand, the arrival of Polynesians c. 750 years ago resulted in...
Article
Full-text available
Fire has an influence on regional to global atmospheric chemistry and climate. Molecular markers of biomass burning archived in lake sediments are becoming increasingly important in paleoenvironmental reconstruction and may help determine the interaction between climate and fire activity. Here, we present a high performance anion exchange chromatog...
Article
Full-text available
The increased incidence of large fires around much of the world in recent decades raises questions about human and non-human drivers of fire and the likelihood of increased fire activity in the future. The purpose of this paper is to outline a conceptual framework for examining where human-set fires and feedbacks are likely to be most pronounced in...
Article
Natural factors and human activity influence fire variability including changes in temperature and precipitation, increasing greenhouse gas concentrations, altering ignitions, vegetation cover and fuel availability. Ice cores archive chemical signatures of both past climate and fire activity, and understanding this interaction is increasingly impor...