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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 lands based on modeling the physical extents of 13 anthropogenic stressors and their estimated impacts using spatially explicit global datasets with a median year of 2016. We quantified the degree of land modification and the amount and spatial configuration of low modified lands (i.e., natural areas relatively free from human alteration) across all ecoregions and biomes. We identified that fewer unmodified lands remain than previously reported and that most of the world is in a state of intermediate modification, with 52% of ecoregions classified as moderately modified. Given that these moderately modified ecoregions fall within critical land use thresholds, we propose that they warrant elevated attention and require proactive spatial planning to maintain biodiversity and ecosystem function before important environmental values are lost.

Connectivity conservation is essential for managing healthy ecosystems, conserving biodiversity and adapting to climate change across all biomes and spatial scales. Well-connected ecosystems support a diversity of ecological functions such as migration, hydrology, nutrient cycling, pollination, seed dispersal, food security, climate resilience and disease resistance. These Guidelines are based on the best available science and practice for maintaining, enhancing and restoring ecological connectivity among and between protected areas, other effective areas based conservation measures (OECMs) and other intact ecosystems. For the first time, this publication introduces a common definition and recommends formal recognition of ecological corridors to serve as critical building blocks of ecological networks in conjunction with protected areas and OECMs. Furthermore, these Guidelines also include 25 case studies that demonstrate current approaches to conserving ecological connectivity and ecological networks for different ecosystems and species, and at different spatial and temporal scales.

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-generational for most species, connectivity designed to facilitate climate adaptation requires pathways with 'stepping-stones' between current and future habitat. These areas should have habitats suitable not only for dispersal, but for all aspects of species lifecycles. We integrated present-day land use, topographic diversity, and projections of shifting climate regimes into a single connectivity modeling approach to identify pathways for mid-century shifts in species ranges. Using Omniscape we identified climate linkages, or areas important for climate change-driven movement, as the areas with more current flow than would be expected in the absence of climate considerations. This approach identified connectivity potential between natural lands in the present climate and natural lands with future analogous climate following topo-climatically diverse routes. We then translated the model output into a strategic framework to improve interpretation and to facilitate a more direct connection with conservation action. Across modified landscapes, pathways important to climate-driven movement were highly coincident with the last remaining present-day linkages, reinforcing their importance. Across unfragmented lands, the presence of climate-adapted pathways helped inform the prioritization of conservation actions in areas where multiple connectivity options still exist. Many climate linkages follow major watercourses along elevational gradients, highlighting the importance of protecting or managing for these natural linear pathways that provide movement routes for climate adaptation. By integrating enduring landscape features with climate projections and present-day land uses, our approach reveals "no-regrets" pathways to plan for a connected landscape in an uncertain future.

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 United States. We applied these results to areas previously identified as having high conservation value to distinguish those best positioned to maintain and enhance ecological connectivity and integrity. We found that current flow centrality was highest and effective resistance lowest in areas that spanned the border between southern Oregon and Idaho, and in northern Arizona and central Utah. Compared to other federal jurisdictions, Bureau of Land Management lands contributed most to ecological connectivity, forming “connective tissue” among existing PAs. Our models and maps can inform new conservation strategies and critical land allocation decisions, within or among jurisdictions.

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 systematic review of studies published within the last decade, documenting approaches for mapping and quantifying HES and classifying the decision context. To gauge the relevance of HES science, we evaluated 49 case studies using multiple criteria for credibility, legitimacy, and saliency. We found compelling evidence that much of the variability in the quantification of HES can be explained by research motivations and scoping, reflecting the decision-oriented framing of the ecosystem services concept. Our review highlights key knowledge gaps in the state of the science including the need to articulate beneficiaries and to make connections to policy and ma...

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 integrated way to help support immediate conservation planning and action in the face of inherent spatial uncertainty about future conditions. Instead, these multiple approaches are often conveyed as competing or contradictory alternatives, when in fact, they are complementary. We present a framework that synthesizes six promising spatially explicit adaptation approaches for conserving biodiversity. We provide guidance on implementing these adaptation approaches and include case studies that highlight how biodiversity conservation can be used in planning. We conclude with general guidance on choosing appropriate climate adaptation approaches to amend f...

Increasingly, natural resources agencies and organizations are using measures of ecological integrity to monitor and evaluate the status and condition of their landscapes, and numerous methods have been developed to map the pattern of human activities. In this paper I apply formal methods from decision theory to develop a transparent ecological indicator of landscape integrity. I developed a parsimonious set of stressors using an existing framework to minimize redundancy and overlap, mapping each variable as an individual data layer with values from 0 to 1.0, and then combined them using an “increasive” function called fuzzy sum. A novel detailed land use dataset is used to generate empirical measures of the degree of human modification to map important stressors such as land use, land cover, and presence, use, and distance from roads. I applied this general framework to the US and found that the overall average degree of human modification was 0.375. Regional variation was fairly predictable, but aggregation of these raw values into terrestrial or watershed units resulted in large differences at local to regional scales. I discuss three uses of these data by land managers to manage protected areas within a dynamic landscape context. This approach generates an internally-valid model that has a direct, empirical, and physical basis to estimate the degree of human modification.

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 connectivity, the capacity of landscape configuration to allow species movement in the face of dynamically shifting climate. Using this metric, we assess to what extent habitat fragmentation will limit species movements in response to climate change. We then evaluate how creating corridors to promote climate connectivity could potentially mitigate these restrictions, and we assess where strategies to increase connectivity will be most beneficial. By analyzing fragmentation patterns across the contiguous United States, we demonstrate that only 41% of natural land area retains enough connectivity to allow plants and animals to maintain climatic parity as the climate warms. In the eastern United States, less than 2% of natural area is sufficiently connected. Introducing corridors to facilitate movement through human-dominated regions increases the percentage of climatically connected natural area to 65%, with the most impactful gains in low-elevation regions, particularly in the southeastern United States. These climate connectivity analyses allow ecologists and conservation practitioners to determine the most effective regions for increasing connectivity. More importantly, our findings demonstrate that increasing climate connectivity is critical for allowing species to track rapidly changing climates, reconfiguring habitats to promote access to suitable climates.

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, and 13). During this period, evidence of climate change and its consequences was ever more apparent. This was the warmest five-year period on record (http://www.ncdc.noaa.gov). Extreme climate events, such as droughts in California, Amazonia, and Australia, caused fundamental changes in allocating water to people and managing human risk from fire. Evidence of the ecological impacts of climate change became pervasive, including forest die-offs in many parts of the world and massive bleaching of coral ecosystems.

Widespread human modification and conversion of land has led to loss and fragmentation of natural ecosystems, altering ecological processes and causing declines in biodiversity. The potential for ecosystems to adapt to climate change will be contingent on the ability of species to move and ecological processes to operate across broad landscapes. We developed a novel, robust modeling approach to estimate the connectivity of natural landscapes as a gradient of permeability. Our approach yields a map capable of prioritizing places that are important for maintaining and potentially restoring ecological flows across the United States and informing conservation initiatives at regional, national, or continental scales. We found that connectivity routes with very high centrality intersected proposed energy corridors in the western United States at roughly 500 locations and intersected 733 moderate to heavily used highways (104–106 vehicles per day). Roughly 15% of the most highly connected locations are currently secured by protected lands, whereas 28% of these occur on public lands that permit resource extraction, and the remaining 57% are unprotected. The landscape permeability map can inform land use planning and policy about places potentially important for climate change adaptation.

Assessing threats to protected areas is a critical step to ensure effective resource conservation and to leverage future conservation actions. It is equally important to assess external and internal threats because human activities both in and around a protected area can impair the area's ecological goals or impart important ecological benefits to adjacent lands. We applied a threat framework that accounts for both local and surrounding threats to identify areas in the conterminous United States that provide or offer opportunities for ecological conservation. We find that, of the lands that are least threatened locally, 49% have some existing formal protection, but that more than 35% of the existing protected portfolio is at risk from external threats. However, over 20% of currently unprotected lands provide potential opportunities for conservation. Of the area identified with highest potential conservation opportunities, over 50% is on private lands, highlighting the need to engage owners of private land in conservation. There is greater potential for large, buffered, core conservation areas in the West, but other areas require networks of stepping-stone conservation islands. We summarize our results by ecoregions and within 40 national parks, identifying areas that are notably unthreatened (Colorado Plateau and Northwestern Glaciated Plains ecoregions and Great Basin and Canyonlands parks) versus those that may require more intense management actions (Eastern Great Lakes and Hudson Lowlands and Southeastern Wisconsin Till Plains ecoregions and Cuyahoga Valley and Great Smoky Mountains parks). Finally, we discuss how the approach could be applied and improved for finer-grained, local assessments.

Park managers realized more than 130 years ago that protected areas are often subsets of larger ecosystems and are vulnerable to change in the unprotected portions of the ecosystem. We illustrate the need to delineate protected area—centered ecosystems (PACEs) by using comprehensive scientific methods to map and analyze land-use change within PACEs around 13 US national park units. The resulting PACEs were on average 6.7 times larger than the parks in upper watersheds and 44.6 times larger than those in middle watersheds. The sizes of these PACEs clearly emphasized the long-term reliance of park biodiversity on surrounding landscapes. PACEs in the eastern United States were dominated by private lands with high rates of land development, suggesting that they offer the greatest challenge for management. Delineating PACEs more broadly will facilitate monitoring, condition assessment, and conservation of the large number of protected areas worldwide that are being degraded by human activities in the areas tha...

The Rocky Mountain West is experiencing rapid land use change in the form of residential development. Public land managers, like the U.S. Forest Service, Bureau of Land Management, and National Park Service are increasingly concerned with ecological and management implications of private land use adjacent to public lands. Using fine-grain land use data, collected from high resolution aerial photographs, we quantify human land use composition, patterns, and trends at the interface of public and private land in the Southern Rocky Mountain Ecoregion (SRE) of Colorado. We developed two metrics for assessing land use impacts. The first quantifies the amount of land cover modified (HM c ) by human land use and the second estimates the amount of wildlife habitat that is functionally modified (HM fd ). In 2005, we estimate that human land use modifies 8% of the total land cover in the Colorado SRE and that 13% of the study area was functionally modified. Agriculture had the greatest impact in terms of area of modified land cover (282,305 ha). Residential (exurban) land use had a smaller footprint (HM c ) but the close proximity to public lands, dispersed spatial pattern (high HM fd ), and rapid increase in rural and exurban housing density observed in the SRE have important implications. This research demonstrates how fine scale land cover data can be used to examine land use pattern and composition as well as track land use change.

Quantifying landscape dynamics is a central goal of landscape ecology, and numerous metrics have been developed to measure the influence of human activities on natural landscapes. Composite scores that characterize human modifications to landscapes have gained widespread use. A parsimonious alternative is to estimate the proportion of a cover type (i.e. natural) within a spatial neighborhood to characterize both compositional and structural aspects of natural landscapes. Here I extend this approach into a multi-scale, integrated metric and apply it to national datasets on land cover, housing density, road existence, and highway traffic volume to measure the dynamics of natural landscapes in the conterminous US. Roughly one-third of the conterminous US (2.6 million km2) in 1992 was classified as human-dominated. By 2001 this expanded by 80,800 km2, and forecasted residential growth by 2030 will potentially lead to an additional loss of up to 92,200 km2. Wetland cover types were particularly affected. The natural landscapes metric developed here provides a simple, robust measure of landscape dynamics that has a direct physical interpretation related to proportion of natural habitat affected at a location, represents landscapes as a gradient of conditions rather predicated on patch/matrix definition, and measures the spatial context of natural areas.

The dual goals of the Organic Act of 1916 and Wilderness Act of 1964 are to protect natural resources and provide quality visitor experiences. Park managers need metrics of trail conditions to protect park resources and quality of visitor experiences. A few methods of sampling design for trails have been developed. Here, we describe a relatively new method, spatially balanced sampling, and compare it to systematic sampling. We evaluated the efficiency of sampling designs to measure recreation-related impacts in Rocky Mountain National Park. This study addressed two objectives: first, it compared estimates of trail conditions from data collected from systematic versus spatially balanced sampling data; second, it examined the relationship between sampling precision and sampling efficiency. No statistically significant differences in trail condition were found between the 100-m interval and the spatially balanced datasets. The spatially balanced probability-based dataset was found to be a good estimate of trail conditions when analyses were conducted with fewer sample points. Moreover, spatially balanced probability-based sampling is flexible and allows additional sample points to be added to a sample.

Management and conservation of large carnivores increasingly includes conflicts with humans. Consequently, a greater understanding of spatiotemporal trends of conflicts is needed to efficiently allocate resources and apply targeted management. Therefore, we examined spatial and temporal distribution of American black bear (Ursus americanus; hereafter, bear)–human conflicts in Colorado, USA, related to 3 conflict types (agriculture operations, human development, and road kills). We used the Getis–Ord spatial clustering statistic to describe location and assess magnitude of bear–human conflicts in Colorado during 1986–2003 and investigated temporal trends of bear–human conflicts by type. Bear–human conflicts showed distinct spatial clustering by type, and areas of high clustering overlapped conflict types. Clustering for agriculture operations conflicts had the largest overall value and overlapped counties with high sheep production. Both human development and road-kill conflict clusters were high ...

Conservation of private land through conservation easements, development agreements, and clustered housing has increased greatly as have criticisms of the laws, public programs, and incentives that motivate landowners to use them. Rapid land-use change at the urban-rural interface in Larimer County, Colorado, has given rise to programs that provide a variety of land-conservation options for landowners. As of January 2005, roughly 60% of Larimer County was publicly owned, and 3% or 16,200 ha was privately owned with some form of protection. We used document analysis, a landowner survey, targeted interviews, and a landscape-level spatial analysis to analyze the patterns, quantities, and qualities of private land conservation. We created a jurisdiction-specific typology of desired benefits from local government-planning documents to help evaluate conservation parcels. Most easements and other conservation documents used general terms and did not describe the site-specific values of the land being conserved. Landowners were able to describe some benefits not included in parcel-specific documents, and our spatial analysis revealed parcel-specific and cumulative conservation benefits such as the amount of buffering, infill, connectivity, protected agricultural land, riparian protection, and other benefits not referenced by either documents or landowners. Conservation benefits provided by a parcel varied depending on its geographic location, the specific institution such as a land trust or open space program that a landowner worked with, and the conservation mechanism used, such as voluntary easement or residential clustering requirements. The methods we used provide a template for jurisdictions wishing to undertake a similar analysis. Our findings may assist other jurisdictions and institutions interested in improving how land-conservation benefits are described; justify and inform future investments in private land conservation; assist local governments and other institutions with the assessment of program effectiveness; and be useful for conservation planners who wish to become more involved in on-the-ground implementation of conservation actions.

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) at multiple spatial scales. We used only relatively static abiotic variables (i.e., excluded climatic and biotic factors) to prevent confounding current ecological patterns and processes with enduring landscape features, and to make the physiographic classification more interpretable for climate adaptation planning. We generated novel spatial databases for 15 landform and 269 physiographic types across the conterminous United States of America. We examined their potential use by natural resource managers by placing them within a contemporary climate change adaptation framework, and found our physiographic databases could play key roles in four of seven general adaptation strategies. We also calculated correlations with common empirical measures of biodiversity to examine the degree to which the physiographic setting explains various aspects of current biodiversity patterns. Additionally, we evaluated the relationship between landform diversity and measures of climate change to explore how changes may unfold across a geophysical template. We found landform types are particularly sensitive to spatial scale, and so we recommend using high-resolution datasets when possible, as well as generating metrics using multiple neighborhood sizes to both minimize and characterize potential unknown biases. We illustrate how our work can inform current strategies for climate change adaptation. The analytical framework and classification of landforms and parent material are easily extendable to other geographies and may be used to promote climate change adaptation in other settings.

How can ecologists be more effective in supporting ecologically informed rural land-use planning and policy? Improved decision making about rural lands requires careful consideration of how ecological information and analyses can inform specific planning and policy needs. We provide a brief overview of rural land-use planning, including recently developed approaches to conservation. Effective participation in land-use planning requires ecologists to understand trade-offs—for example, the need to balance a land owner's desire for a fair and predictable process with the “learn as you go” approach of adaptive management—and the importance of integrating local knowledge with landscape-level information. Four primary challenges require attention from ecologists to improve rural land-use planning. First is the mismatch between the spatial and temporal scales in which ecological processes occur and the scales and tempos of land-use planning. Second, ecologists must engage in interdisciplinary research to critica...

Emerging research on human-modified ecosystems can better inform land-use planning by integrating information from ecological and social science. In particular, low-density land use beyond the urban fringe (exurban) has been poorly defined and under-studied. Here I develop the human modification framework that characterizes landscapes by the degree to which natural processes are free or controlled and landscape patterns are natural or artificial. Ecologists are encouraged to explicitly place their researchwithin such a framework using quantitative metrics. As society's concern over ecological degradation and loss of biodiversity grows, ecologists must recognize that research on human-modified landscapes, particularly beyond the urban fringe, is not just an unexploited opportunity, but is critical to protecting biodiversity on private land.

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 autocorrelation. The sample includes 4,008 single-family housing sales transactions within the non-urban portions of Larimer County in northern Colorado. The empirical framework accounts for topographical diversity across the study region, as well as distinguishing between several distinct types of publicly and privately protected land. The key findings of the study are: (i) proximity to national or state park land and to city or county open space has a significant positive impact on property values, while proximity to national forest land or to privately conserved land exhibits no significant effects; and, (ii) inclusion of a property within a cluster development decreases its value by 17 to 26 percent. These findings are robust to different estimation techniques and model specifications, which suggests important considerations for policymakers who design development rules and alternative land protection measures aimed at preserving open space in non-urban areas.

Land cover maps reasonably depict areas that are strongly converted by human activities, but typically are unable to resolve low-density but widespread development patterns. Data products specifically designed to resolve land uses complement land cover datasets and likely improve our ability to understand the extent and complexity of human modification. Methods for developing a comprehensive land use classification system are described, and a map of land use for the conterminous United States is presented to reveal what we are doing on the land. The comprehensive, detailed and high-resolution dataset was developed through spatial analysis of nearly two-dozen publicly-available, national spatial datasets – predominately based on census housing, employment, and infrastructure, as well as land cover from satellite imagery. This effort resulted in 79 land use classes that fit within five main land use groups: built-up, production, recreation, conservation, and water. Key findings from this study are that built-up areas occupy 13.6% of mainland US, but that the majority of this occurs as low-density exurban/rural residential (9.1% of the US), while more intensive built-up land uses occupy 4.5%. For every acre of urban and suburban residential land, there are 0.13 commercial, 0.07 industrial, 0.48 institutional, and 0.29 acres of interstates/highways. This database can be used to address a variety of natural resource applications, and I provide three examples here: an entropy index of the diversity of land uses for smart-growth planning, a power-law scaling of metropolitan area population to developed footprint, and identifying potential conflict areas by delineating the urban interface.

Human settlement is a formidable agent of change affecting fundamental ecological processes. Decisions governing these land-use changes occur almost exclusively at the local level and, as a result, they are made at many different locations and times. Consequently, it is difficult for ecologists to provide needed scientific support for these choices. We built an information system designed to support conservation decisions at local scales by offering data over the Internet. We collaborated with local stakeholders (e.g., developers, planners, politicians, land owners, environmental activists) to design the system. This collaboration produced several generalizations about effective design of information systems to support conservation. The most important of these is the idea that ecological data and analysis must be understood by those who will be affected by the decisions. Also, planning for conservation is a process that uses scientific data, but that ultimately depends on the expression of human values. A major challenge landscape ecologists face is to extend general landscape principles to provide specific scientific information needed for local land-use planning.

This chapter describes important geographical and socio-economic characteristics and trends in the Southwest—such as population and economic growth and changes in land ownership, land use, and land cover—that provide the context for how climate change will likely affect the Southwest. The chapter also describes key laws and institutions relevant to adaptive management of resources.

Understanding the impacts of climate change on people and the environment requires an understanding of the dynamics of both climate and land use/land cover changes. A range of future climate scenarios is available for the conterminous United States that have been developed based on widely used international greenhouse gas emissions storylines. Climate scenarios derived from these emissions storylines have not been matched with logically consistent land use/cover maps for the United States. This gap is a critical barrier to conducting effective integrated assessments. This study develops novel national scenarios of housing density and impervious surface cover that are logically consistent with emissions storylines. Analysis of these scenarios suggests that combinations of climate and land use/cover can be important in determining environmental conditions regulated under the Clean Air and Clean Water Acts. We found significant differences in patterns of habitat loss and the distribution of potentially impaired watersheds among scenarios, indicating that compact development patterns can reduce habitat loss and the number of impaired watersheds. These scenarios are also associated with lower global greenhouse gas emissions and, consequently, the potential to reduce both the drivers of anthropogenic climate change and the impacts of changing conditions. The residential housing and impervious surface datasets provide a substantial first step toward comprehensive national land use/land cover scenarios, which have broad applicability for integrated assessments as these data and tools are publicly available.

We appreciate the perspectives provided by Fitzsimmons (1) in response to our recent PNAS paper (2). The goal of our study was to provide an independent, methodologically transparent spatial analysis of fuel-reduction treatments, using data provided directly by federal agencies, in order to quantitatively assess the degree to which treatments have been located near the wildland–urban interface (WUI). A critical aspect of our work is that we applied a quantitative definition of the WUI based on census data—listed in the January 4, 2001 Federal Register (3). This yielded results consistent with the only other census-derived WUI map that spans the West (4). A quantitatively defined WUI offers a defensible, objective way to assess fire-mitigation effort and to better target the WUI zone across agencies, regions, and legislative authorities.

Many of America’s national forests and grasslands—collectively called the National Forest System—face increased risks and alterations from escalating housing development on private rural lands along their boundaries. National forests and grasslands provide critical social, ecological, and economic benefits to the American public. This study projects future housing density increases on private rural lands at three distances—2, 3, and 10 miles—from the external boundaries of all national forests and grasslands across the conterminous United States. Some 21.7 million acres of rural private lands (about 8 percent of all private lands) located within 10 miles of the National Forest System boundaries are projected to undergo increases in housing density by 2030. Nine national forests are projected to experience increased housing density on at least 25 percent of adjacent private lands at one or more of the distances considered. Thirteen national forests and grasslands are each projected to have more than a half-million acres of adjacent private rural lands experience increased housing density. Such development and accompanying landscape fragmentation pose substantial challenges for the management and conservation of the ecosystem services and amenity resources of National Forest System lands, including access by the public. Research such as this can help planners, managers, and communities consider the impacts of local land use decisions.

"In the United States, citizens, policy makers, and natural resource managers alike have become concerned about urban sprawl, both locally and nationally. Most assessments of sprawl, or undesired growth patterns, have focused on quantifying land-use changes in urban and metropolitan areas. It is critical for ecologists to examine and improve understanding of land-use changes beyond the urban fringe-also called exurban sprawl-because of the extensive and widespread changes that are occurring, and which often are located adjacent to or nearby 'protected' lands. "The primary goal of this paper is to describe the development of a nationwide, fine-grained database of historical, current, and forecasted housing density, which enables these changes to be quantified as a foundation for inference of possible ecological effects. Forecasted patterns were generated by the Spatially Explicit Regional Growth Model, which relates historical growth patterns with accessibility to urban and protected lands. Secondary goals are to report briefly on the status and trend of exurban land-use changes across the U.S., and to introduce a landscape sprawl metric that captures patterns of land-use change. In 2000, there were 125 729 km2 in urban and suburban (

Landscape connectivity is crucial for many ecological processes, including dispersal, gene flow, demographic rescue, and movement in response to climate change. As a result, governmental and non-governmental organizations are focusing efforts to map and conserve areas that facilitate movement to maintain population connectivity and promote climate adaptation. In contrast, little focus has been placed on identifying barriers-landscape features which impede movement between ecologically important areas-where restoration could most improve connectivity. Yet knowing where barriers most strongly reduce connectivity can complement traditional analyses aimed at mapping best movement routes. We introduce a novel method to detect important barriers and provide example applications. Our method uses GIS neighborhood analyses in conjunction with effective distance analyses to detect barriers that, if removed, would significantly improve connectivity. Applicable in least-cost, circuit-theoretic, and simulation modeling frameworks, the method detects both complete (impermeable) barriers and those that impede but do not completely block movement. Barrier mapping complements corridor mapping by broadening the range of connectivity conservation alternatives available to practitioners. The method can help practitioners move beyond maintaining currently important areas to restoring and enhancing connectivity through active barrier removal. It can inform decisions on trade-offs between restoration and protection; for example, purchasing an intact corridor may be substantially more costly than restoring a barrier that blocks an alternative corridor. And it extends the concept of centrality to barriers, highlighting areas that most diminish connectivity across broad networks. Identifying which modeled barriers have the greatest impact can also help prioritize error checking of land cover data and collection of field data to improve connectivity maps. Barrier detection provides a different way to view the landscape, broadening thinking about connectivity and fragmentation while increasing conservation options.

Residential and commercial land development quickened during the 1990s throughout the U.S. Rocky Mountains, especially in Colorado, increasing the pace and extent of regional land use and landscape change. Unlike previous booms in mining, cattle, or energy, the current development wave is driven by growth in the secondary and tertiary economies--services, recreation, and information businesses-instead of commodity production. The result is sprawling land-use conversion, mostly from agricultural to residential, in even the most rural areas. This development pattern is examined in light of mountain and rural land-use theory, and its effects are evaluated at three scales in the Colorado mountains-regional, landscape, and site. The social and ecological impacts cited in previous rural development literature are evident, but also documented are landscape effects associated with the particular affluence of Colorado mountain development and the emergence of far-reaching rural sprawl and gentrification. Current development tends more than in the past to fragment land ownership, steepen land-use gradients at public/private boundaries, and increase human presence and disturbance in the urban/wildland interface. The paper concludes with suggestions for planning focused at the landscape scale.