David Theobald

David Theobald
Colorado State University | CSU · Department of Fish, Wildlife and Conservation Biology

Doctor of Philosophy

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197
Publications
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Publications

Publications (197)
Article
Species distribution models (SDMs) have become an essential tool for the management and conservation of imperiled species. However, many at‐risk species are rare and characterized by limited data on their spatial distribution and habitat relationships. This has led to the development of species distribution models that integrate multiple types and...
Article
Natural habitats on private lands are potentially important components of national biodiversity conservation strategies, yet they are being rapidly lost to development. Conservation easements and other means of protecting these habitats have expanded in use and will be most effective if they target private lands of highest biodiversity value and ri...
Article
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Protecting or restoring habitat connectivity in landscapes undergoing rapid environmental change requires multiple conservation and restoration strategies. These strategies have different risk profiles, costs, and require various types of technical expertise to conduct. This diversity in landscape context and strategic approach requires more nuance...
Article
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As both plant and animal species shift their ranges in response to a changing climate, maintaining connectivity between present habitat and suitable habitat in the future will become increasingly important to ensure lasting protection for biodiversity. Because the temporal period commensurate with planning for mid-century change is multi-generation...
Article
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Although natural habitats are being lost globally, the extent and fate of natural habitats on private lands in the United States have not been quantified at the resolution relevant for conservation planning. Here we provide information on the locations and risk of loss of areas of natural vegetation cover (NVC) on private lands across the northwest...
Article
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Urban land-use maps outlining the distribution, pattern, and composition of various land use types are critically important for urban planning, environmental management, disaster control, health protection, and biodiversity conservation. Recent advances in remote sensing and social sensing data and methods have shown great potentials in mapping urb...
Book
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En ecosistemas terrestres, dulceacuícolas y marinos, los corredores ecológicos son una designación de conservación necesaria para asegurar la salud de los ecosistemas. Los corredores son elementos fundamentales de las redes ecológicas para la conservación y complementan los objetivos de las áreas protegidas y OMEC al conectar estos hábitats con otr...
Technical Report
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La connectivité écologique est le mouvement sans entrave des espèces et le flux des processus naturels qui soutiennent la vie sur Terre. Il est impérieux que les pays du monde entier s’orientent vers une approche globale et cohérente de la conservation de la connectivité écologique, et qu’ils entreprennent de mesurer et de contrôler l’efficacité de...
Article
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Data on the extent, patterns, and trends of human land use are critically important to support global and national priorities for conservation and sustainable development. To inform these issues, we created a series of detailed global datasets for 1990, 2000, 2010, and 2015 to evaluate temporal and spatial trends of land use modification of terrest...
Book
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Executive summary: Ecological connectivity is the unimpeded movement of species and the flow of natural processes that sustain life on Earth. This definition has been endorsed by the Convention on Migratory Species (CMS, 2020) and underlines the urgency of protecting connectivity and its various elements, including dispersal, seasonal migration, fl...
Article
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Leading up to the Convention on Biological Diversity Conference of the Parties 15, there is momentum around setting bold conservation targets. Yet, it remains unclear how much of Earth's land area remains without significant human influence and where this land is located. We compare four recent global maps of human influences across Earth's land, A...
Preprint
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Data on the extent, patterns, and trends of human land use are critically important to support global and national priorities for conservation and sustainable development. To inform these issues, we created a series of detailed global datasets for 1990, 2000, 2010, and 2015 to evaluate temporal and spatial trends of land use modification of terrest...
Article
Full-text available
In Kennedy et al. (2019), we presented findings that terrestrial ecosystems have higher human modification than previously reported and that most ecoregions are intermediately modified. Our findings were based on the Global Human Modification (HM), which maps the degree of land modification based on the spatial extent and the potential intensity of...
Article
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Context With underrepresentation of habitats in publicly protected areas, attention has focused on the function of alternative land conservation mechanisms. Private conservation easements (CEs) have proliferated in the United States, yet assessing landscape-level function is confounded by varying extent, resolution, and temporal scale. Objectives...
Article
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An increasing number of international initiatives aim to reconcile development with conservation. Crucial to successful implementation of these initiatives is a comprehensive understanding of the current ecological condition of landscapes and their spatial distributions. Here, we provide a cumulative measure of human modification of terrestrial lan...
Article
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Riparian habitats have been frequently identified as priority areas for conservation under climate change because they span climatic gradients and have cool, moist microclimates relative to surrounding areas. They are therefore expected to act as dispersal corridors for climate-induced species range shifts and to provide microclimatic refugia from...
Data
Potential relative radiation (R), a unit-less measure of solar radiation that takes into account temporal changes in solar orientation as well as shading effects from neighboring topography [38], based on a 30 m digital elevation model from the National Elevation Dataset [36]. (TIFF)
Data
Landscape condition (L), provided by the Western Governors’ Association’s Crucial Habitat Assessment Tool (WGA 2013) as a measure of the degree to which potential riparian areas have been affected by human activities using the landscape condition model [39], where higher values correspond to lower landscape intactness. (TIFF)
Data
Riparian climate-corridor index values averaged across individual watersheds (5th field HUCs). (TIFF)
Data
Riparian climate-corridor index values averaged across individual watersheds (6th field HUCs). (TIFF)
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Riparian area (A), based on the potential riparian area data layer from Theobald et al [32]. (TIFF)
Data
Riparian climate-corridor index values averaged across individual watersheds (3th field HUCs). (TIFF)
Data
Riparian climate-corridor index values averaged across individual watersheds (2nd field HUCs). (TIFF)
Data
Mean annual temperature (T), based on the 30-year mean of mean annual temperatures from 1961–1990, using a 90 m digital elevation model and the ClimateWNA tool [34], which extracts and downscales PRISM [35] monthly data and calculates climate variables for specific locations based on latitude, longitude, and elevation. (TIFF)
Data
Canopy cover (C), based on the percent tree canopy cover dataset from the National Land Cover Dataset [36]. (TIFF)
Data
Riparian climate-corridor index values averaged across individual watersheds (4th field HUCs). (TIFF)
Article
Full-text available
Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habita...
Article
Powerful innovations can occur when a concept is taken from one field and used to solve a problem in an unrelated field. In fact, it has been shown that as the distance between a problem solver's field of technical expertise and the focal field of a problem increase, so does the probability of success. This article is protected by copyright. All ri...
Article
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We evaluate the world terrestrial network of protected areas (PAs) for its partnership potential in responding to climate change. That is, if a PA engaged in collaborative, trans-boundary management of species, by investing in conservation partnerships with neighboring areas, what climate change adaptation benefits might accrue? We consider core te...
Article
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Context Projected increases in human population size are expected to increase forest loss and fragmentation in the next century at the expense of forest-dwelling species. Objectives We estimated landscape carrying capacity (Nk) for Ovenbirds in urban, suburban, exurban, and rural areas for the years 2000 and 2050, and compared changes in Nk with c...
Article
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Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects o...
Article
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One of the most influential environmental laws in the US – the 1972 Clean Water Act – included the visionary objective of maintaining and restoring aquatic ecological integrity. However, the efficacy of the Act depends on how integrity is assessed. Reviewing the assessment literature for fresh waters over the past 40 years, we found evidence of met...
Article
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Biotic and abiotic factors are increasingly acknowledged to synergistically shape broad-scale species distributions. However, the relative importance of biotic and abiotic factors in predicting species distributions is unclear. In particular, biotic factors, such as predation and vegetation, including those resulting from anthropogenic land-use cha...
Data
Supplementary Files 1, 2, 3, 4, and 5 for the paper "Biotic and abiotic factors predicting the global distribution and population density of an invasive large mammal" by Lewis et al (2017) Scientific Reports
Article
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Competitive interactions between species are fundamental to understanding species assemblages, community dynamics, and ecological processes. Anthropogenic landscape change, particularly resulting from urbanization, can alter interspecific interactions; however, different forms of urbanization are predicted to have contrasting effects on competitive...
Article
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Under rapid landscape change, there is a significant need to expand and connect protected areas (PAs) to prevent further loss of biodiversity and preserve ecological functions across broad geographies. We used a model of landscape resistance and electronic circuit theory to estimate patterns of ecological flow among existing PAs in the western Unit...
Article
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A variety of land-use and land-cover (LULC) models operating at scales from local to global have been developed in recent years, including a number of models that provide spatially explicit, multi-class LULC projections for the conterminous United States. This diversity of modeling approaches raises the question: how consistent are their projection...
Article
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Recent guidance on environmental modeling and global land-cover validation stresses the need for a probability-based design. Additionally, spatial balance has also been recommended as it ensures more efficient sampling, which is particularly relevant for understanding land use change. In this paper I describe a global sample design and database cal...
Article
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The contiguous United States contains a disconnected patchwork of natural lands. This fragmentation by human activities limits species’ ability to track suitable climates as they rapidly shift. However, most models that project species movement needs have not examined where fragmentation will limit those movements. Here, we quantify climate connect...
Chapter
Forests of the Appalachian Landscape Conservation Cooperative provide critical ecological and management functions. The moist climate of the eastern United States fosters productive stands that store relatively high amounts of carbon; for example, the Appalachian Landscape Conservation Cooperative (Appalachian LCC) accounts for only 7.6 percent of...
Article
Global threats to freshwater resources are prompting widespread concern about their management and implications for well-being. In recent decades, hydrologic ecosystem services (HES) have emerged as an innovative concept to evaluate freshwater resources, providing opportunity for researchers to engage in decision-relevant science. We conducted a sy...
Article
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Conservation scientists emphasize the importance of maintaining a connected network of protected areas to prevent ecosystems and populations from becoming isolated, reduce the risk of extinction, and ultimately sustain biodiversity. Keeping protected areas connected in a network is increasingly recognized as a conservation priority in the current e...
Data
Cost-weighted distance from the protected core areas based on linear (top) and non-linear (bottom) versions of resistance surfaces using wildness (left) and human modification (right). (TIF)
Data
Mean and range of composite corridor values for federal, state, and local management agencies among units with varying GAP status values (1 = most protected; 4 = least protected). The number of units (N) is also reported. Agencies are rank ordered based on their overall mean corridor value so that agencies with the best corridor values are ranked h...
Data
Normalized least-cost corridors from Linkage Mapper connectivity models based on linear (left) and non-linear (right) versions of resistance surfaces using wildness (top) and human modification (bottom). The mapped outputs shown here do not eliminate linkages between protected core areas based on any maximum geographic or cost-weighted distance, an...
Data
Least cost paths classified into declines from best (low cost, blue) to the 10% worst (high cost, red) for connectivity models based on linear (left) and non-linear (right) versions of resistance surfaces using wildness (top) and human modification (bottom). (TIF)
Data
Original scaling of the wildness index (A) and human modification (B) in relation to the linear (hashed line) and non-linear (solid line) transformations used to produce resistance surfaces (maps shown in Fig 2). (TIF)
Data
Modeled corridors vary depending on the number of cores (black polygons) to be connected, as well as the maximum Euclidean distance between cores. Here, we show a model experiment where we vary the maximum distance from 100 km to 300 km and cross this “treatment” with different number of cores (black polygons). The model runs with “few cores” inclu...
Data
Table of mean composite corridor values for all Inventoried Roadless Areas or Wilderness Study Areas ≥ 3,000 ha. USFS = US Forest Service; BLM = Bureau of Land Management; FWS = Fish and Wildlife Service; IRA = Inventoried Roadless Area; WSA = Wilderness Study Area. (CSV)
Article
Riparian zones are important for their contribution to biodiversity and ecosystem services, especially in the western USA where riparian zones occupy a small proportion of the landscape but support a majority of the biodiversity. However, few accurate datasets of riparian zone locations are available over broad spatial extents, and cost efficient m...
Article
Riparian zones in semi-arid, mountainous regions provide a disproportionate amount of the available wildlife habitat and ecosystem services. Despite their importance, there is little guidance on the best way to map riparian zones for broad spatial extents (e.g., large watersheds) when detailed maps from field data or high-resolution imagery and ter...
Chapter
In this chapter, we examine how climate change will likely affect areas of the Great Northern Landscape Conservation Cooperative (Great Northern LCC), but rather than using a fine-filter approach that focuses on a particular species, as has been done in many of the other chapters (e.g., chaps. 9, 10, and 12), we have applied a coarse-filter approac...
Chapter
Only five years ago, Halofsky et al. (2011) wrote: “For climate change adaptation, there is no recipe, no road map, and yet no time to lose; science and management partners must tackle the climate change issue in a timely way, despite uncertainty.” Later that same year, the National Wildlife Federation, in partnership with authors from federal, sta...
Chapter
The chapters of this book have delved into the timely and important topic of science and management of wildland ecosystems in the face of climate and land use change. The period of the book’s development (2011–2015) was one of rapid advancement in science, policy, agency infrastructure, and understanding of climate change adaptation (chaps. 2, 3, a...
Chapter
Ecosystem processes are the physical, chemical, and biological actions or events that link organisms and their environment. These processes include water and nutrient cycling, plant growth and decomposition, and regulation of community dynamics (Millennium Ecosystem Assessment 2003). The ecological characteristics of many parks and protected areas...
Article
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Key to understanding the implications of climate and land use change on biodiversity and natural resources is to incorporate the physiographic platform on which changes in ecological systems unfold. Here, we advance a detailed classification and high-resolution map of physiography, built by combining landforms and lithology (soil parent material) a...
Data
Data flow diagram of landforms. Landforms were defined using basic topographic measures derived directly from the USGS 10 meter Digital Elevation Model, as well as latitude. Physiographic classes were generated by overlaying the landforms and lithology (parent material) converted from polygons (1:1,000,000 scale) to 270 m raster grid. The program u...
Article
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This study estimates a generalized spatial hedonic pricing model to assess how residential property values are impacted by inclusion within cluster developments and by proximity to various types of protected land. The estimated model simultaneously controls for the spatial dependence of residential housing prices and for the presence of spatial aut...
Article
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Wild pigs (Sus scrofa), also known as wild swine, feral pigs, or feral hogs, are one of the most widespread and successful invasive species around the world. Wild pigs have been linked to extensive and costly agricultural damage and present a serious threat to plant and animal communities due to their rooting behavior and omnivorous diet. We modele...
Article
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As species' geographic ranges and ecosystem functions are altered in response to climate change, there is a need to integrate biodiversity conservation approaches that promote natural adaptation into land use planning. Successful conservation will need to embrace multiple climate adaptation approaches, but to date they have not been conveyed in an...