NPScape Interpretive Guide
Monahan, W. B., J. E. Gross, L. K. Svancara, and T. Philippi. 2012. A guide to interpreting NPScape data and analyses. Natural Resource Technical Report NPS/NRSS/NRTR—2012/578. National Park Service, Fort Collins, Colorado.
NPScape: Landscape Dynamics Monitoring of National Parks
NPScape is a NPS landscape dynamics monitoring project designed to help parks better understand the landscape-level opportunities and challenges they face in protecting park natural resources. To support these needs, NPScape produces and delivers landscape-level data, maps, analyses, and interpretations to inform natural resource management and planning at local, regional, and national scales.
Key NPScape objectives are to provide:
- A coherent conceptual and analytical framework for conducting landscape-scale analyses and evaluations that can inform decisions
- Useful Geographic Information System (GIS) data and maps at broad scales not typically available to individual parks
- Well-documented methods founded on strong science, and readily repeatable and extensible with local data
- Assistance to parks in interpreting results
The NPScape Interpretive Guide
This interpretive guide is intended to help NPS scientists and natural resource managers understand and evaluate landscape data and results from NPScape. In particular, the guide focuses on how the landscape-scale data and analyses provided by NPScape relate to past, current, and potential future conditions of park natural resources. Example questions that may be addressed using NPScape and are illustrated in this guide include:
- What types of human mediated landscape change are occurring around my park? How do these vary in intensity? How do they vary spatially in relation to park boundaries? What are the mechanisms by which human mediated drivers of landscape change might impact park resources?
- What are the major forms of land cover change occurring around my park, and how do these affect the amount, intactness, and connectivity of natural habitats? How much habitat loss is too much? What are some habitat thresholds that — when exceeded — lead to large ecological change?
- Who owns and manages lands around my park? To what extent do they manage their resources to meet the same goals and objectives? How much protected area around my park is sufficient for maintaining park natural resources?
- What are ecologically relevant areas of analysis? How does the selection of an appropriate analysis area vary according to the landscape-level question being asked? By extension, how should the spatiotemporal resolution of the source data affect my choice of analysis area?
Conceptual Ecological Foundation of NPScape
NPScape products are developed under a conceptual framework that links measurable attributes of landscapes to resources within parks. NPScape focuses on broad-scale factors and measures that are founded on consistent data available at a regional to national scale. Most NPScape data sources and products are best (or only) suited for analysis of areas that are hundreds to thousands of square kilometers. Information at these broad scales is increasingly needed to identify wildlife corridors, isolated habitats, and areas with important resources that may be at risk from projected land use changes around parks.
Broad categories of measures considered in this guide, and how they contribute to understanding the landscape context of parks and park resources.
Consider by way of example a focal resource occurring inside a particular park. That resource is capable of persisting in part because of the ecological attributes of the larger natural system within which it exists. However, the value of the natural system with respect to the focal resource can be challenged by human-mediated drivers of landscape change. Precisely how these drivers interact with the natural system to impact the resource and, by extension, resource conservation vulnerability and opportunity, depends further on the stewardship of all management units within the natural system.
Together, these measures describe landscape condition at a range of scales of space and time. Historical information provides a context for change: how, and how fast, did we reach our present state or condition? Historical rates and magnitudes of change help determine the urgency of decisions, and they provide a social context important for understanding and relating to people who experienced these changes. Current information reflects status, and projections help identify trajectories in resource conditions or ecological drivers that are important for planning.
The historic, current, and future context provided by NPScape can help identify and evaluate opportunities to prevent resource damage or loss, assess actions for restoration, and identify key areas or threats to park resources. The relationships between park natural resources, nearby protected areas, and connecting corridors can determine opportunities for preserving resources.
NPScape Metrics for Landscape-scale Monitoring
NPScape products focus on a set of information-rich, landscape-scale measures and metrics that represent 'vital sign' indicators. Analyses summarize and deliver measures in six major categories (population, housing, roads, land cover, pattern, and conservation status) that broadly address the environmental drivers, natural attributes, and conservation context of NPS units.
An updated table summarizing all NPScape measures and metrics is available here.
Ecologically Informative Areas of Analysis
Landscape attributes important to park resources often vary with scale or spatial extent. Relevant scales or areas of analysis (AOAs) include the landscape within the park itself, the 'boundary' area immediately adjacent to the park (e.g., 1-3 km), the local area surrounding a park (e.g., within approximately 15-40 km of the park), watersheds upstream from the park, and the ecoregion. All of these AOAs are relevant for at least certain measures and metrics analyzed by NPScape. The park examples included in the guide provide basic guidance on when and how to select a particular AOA from this list. NPScape also provides standardized GIS data for all AOAs referenced above in an effort to streamline analysis and statistical reporting of NPScape metrics. In addition, NPScape enables users to consider other AOAs that may be more relevant to a particular park or question, such as AOAs established by 'protected area centered ecosystems', or PACEs, developed originally as part of the NASA-funded project, Park Analysis for Landscape Monitoring Support (PALMS). Parks may also wish to consider NPScape statistics within a local park planning region, or within the distributions of particular resources. In all such cases, NPScape users can recompute metrics on these AOAs using our well-documented, standardized and repeatable methods.
Land Cover and Land Use: Area and Pattern
In the US, habitat loss and fragmentation have profoundly affected biodiversity and other resources important to parks. Measures of habitat availability and pattern address these key threats and they can indicate the suitability of landscapes to support species or sustain populations. Many parks are too small, by themselves, to permanently sustain all species that once lived there, particularly in the face of broad-scale environmental change. In these cases, species living in protected areas need adequate expanses of habitat outside parks to persist long into the future.
Related to area, patterns in land cover composition, configuration, and connectivity reflect the dynamics of natural ecological processes, biophysical constraints, and extensive modification resulting from a long history of human occupation and habitat alteration. In turn, these land cover patterns help shape overall patterns in biological diversity, including the complex array of species occurring in an area, movements of individual organisms, and flows of energy and material. All landscapes are more or less heterogeneous due to variation in topography, geology, and soils; natural disturbances like fire, windthrow, and floods; and anthropogenic disturbances like forest clearing, construction, or agriculture. The major difference between natural and anthropogenic disturbances is that habitats lost to natural disturbances usually 'recover', while anthropogenic disturbances usually result in permanent or semi-permanent conversion of habitat to non-habitat types.
The importance of habitat area and pattern are thus readily apparent for parks, but it is nonetheless difficult to identify a small suite of metrics that adequately describe area and pattern characteristics in ways that generally inform decisions on how to manage park resources. Most or all of the NPScape land cover and pattern data and analyses can be used to assess important attributes of plant and animal habitat. These attributes include indices of availability, connectivity, patch sizes and structure, and multi-scale context. NPScape land cover and pattern metrics are calculated using readily available land cover data from the National Land Cover Database, the North American Land Change Monitoring System, and the NOAA Coastal Change Analysis Program.
Natural vs. converted land cover around Cowpens National Battlefield and Ninety Six National Historic Site (left map), with corresponding estimates of forest area density (right map).
Effects of Roads on Natural Resources
Roads provide remarkable access to lands within the continental US, including access to most national parks. While easy access is often deemed a good thing, roads and associated activities can negatively impact a broad range of physical, ecological, and social attributes important to parks. By physically altering the landscape, roads result in the direct loss of habitat, fragmentation of the remaining habitat, altered landscape structure, increased influence of edge effects, and disruption of hydrological processes. Indeed, some have asserted that roads may be the single most destructive element in the process of habitat fragmentation.
Two major distinctions are useful for understanding landscape-level effects of roads on natural resources. The first distinction is between the effects of roads per se that are independent of traffic level, and the effects of road traffic, with strengths dependent on traffic density. Some road effects such as habitat fragmentation, disturbed or open margins for predatory or invasive species, and increased intensity and unpredictability of runoff, vary with road size and construction, but are relatively independent of the traffic volume. Conversely, the magnitudes of effects such as vehicle collision mortality, dust, hydrocarbon and metal runoff, sound, and propagule pressure of invasive species increase relative to traffic volume. This distinction can be blurred by road effects that are sensitive to very low volumes of traffic, and many resources are impacted by both roads and traffic.
The second major distinction is between direct and indirect effects of roads and traffic. Mortality from vehicle collision is perhaps the most obvious direct effect, but non-lethal direct effects include road avoidance, which may be traffic dependent or independent, and traffic noise masking communication, which is generally traffic dependent. Roads have positive direct effects on some species, notably by creating disturbed habitat for some plants and increasing resource concentration for scavengers. Few direct effects of roads extend beyond 1 km, so roads primarily in or adjacent to parks have direct effects on park resources, but roads near a park can also exert important indirect effects. Indirect effects of roads include road avoidance or mortality modifying home ranges and migrations, limiting access to resources, and leading to subdivided or isolated subpopulations with limited gene flow.
NPScape road metrics are derived from readily available spatial road maps and include road density, distance from roads and — by extension — roadless area. Road density (km/km2), traffic-weighted road density, and distance from nearest road are perhaps the most common and intuitive road metrics. Distance from road, measured by NPScape as the Euclidean distance (m) between any pixel on the landscape and the nearest road, is useful for considerations of 'road zones' and patch size distributions of roadless area. Together, these metrics provided by NPScape can be used to explore a number of important questions related to the direct vs. indirect effects of roads, as well as the effects of roads vs. traffic.
NPScape estimates of distance from road (top map) and corresponding patch size distributions of roadless area, > 500 m from all roads (bottom map), for Crater Lake National Park. In the bottom map, white areas are less than 500 m from a road.
Human Population and Housing around on Parks
Anthropogenic impacts on park resources may originate directly from the behaviors of humans, or indirectly from the roads, houses, landscaping, and other infrastructure used to support humans. Although the extent of impact is often difficult to measure, data on human population size, density, and infrastructure usually provide relevant and timely information about the magnitude of human impacts in lands adjacent to parks. Because human land uses tend to expand over time, and growth models are available to make projections into the future, these data also provide insights into potential near-term threats to park resources.
Historic and contemporary changes in human population density by county for counties intersecting the 30 km AOA of Buffalo National River. In time series plots around the map, population density on the y-axis is reported as the number of people per km2. Vertical line is 1972, the year Buffalo was established as a park unit.
High human population density can adversely affect the persistence of habitats and species. In addition, human settlements as measured by housing density can alter ecosystems and affect biodiversity by replacing habitat with structures and non-habitat cover types, fragmenting habitat, increasing disturbance by people and their animals (e.g., dogs, cats, horses), altering vegetation types, and increasing light and noise. Population exerts important indirect effects on water quality via housing density, roads, and traffic. By doubling as major sources of anthropogenic impervious surface, such development also affects water quantity (flow and retention) when it is located in park upstream watersheds.
NPScape population metrics are based on historical data from the US Census Bureau and projections from state offices. Derived also in part from Census data, the Spatially Explicit Regional Growth Model provides corresponding estimates of how housing densities have changed over a similar timespan. Combined, the human population and housing metrics furnished by NPScape provide parks with decadal estimates of two major anthropogenic drivers of landscape change occurring around their boundaries.
Evaluating Resource Protection and Risk
The traditional response to preserving biodiversity has been the creation or expansion of protected areas. Yet the conservation status or stewardship of land surrounding these protected areas often dictates and directs potential changes in land use that can have profound impacts on park resources. Impacts — positive or negative — can be categorized by changes in the effective size of reserves, in ecological flows, in the size of critical habitat, and in the amount of exposure to humans. Within each category, the mechanisms that drive these changes include such factors as species area effects, trophic structure, migration habitats outside parks, and hunting and poaching. A common feature of these drivers is that they are known, or at least strongly postulated, to be directly related to land use intensification.
Knowing the condition and changes of land stewardship and resulting land use near and adjacent to parks is important for assessing current threats and impacts and for evaluating how the situation around parks might change in the future. For example, broad-scale patterns of habitat conversion (e.g., to urban or agriculture) and protection (stewardship) are used to estimate conservation risk and help identify areas at greatest risk. Combined with patterns of potential threats (e.g., roads, development), assessments of the level of resource protection have also helped identify areas at risk and refine conservation strategies on a statewide basis.
Although protected areas occur in nearly every country across the globe, they are by no means equal. Even within the United States, protected areas are managed by many different entities for a wide variety of purposes. Defining what is, or is not, a protected area is no trivial task. For nearly 80 years, the International Union for Conservation of Nature (IUCN) and the World Commission of Protected Areas have discussed, defined, and revised such definitions. In the latest revision by the IUCN, a protected area is defined as, "A clearly defined geographical space, recognized, dedicated and managed, through legal or other effective means, to achieve the long-term conservation of nature with associated ecosystem services and cultural values." The IUCN further categorizes protected areas based on management intent and many countries, including the United States, have similar programs (e.g., US Gap Analysis Program) to further refine and define what is protected.
NPScape metrics used for measuring and monitoring conservation status are derived from the currently available land ownership and management maps, including the Protected Areas Database of the US, the World Database on Protected Areas, and the National Marine Protected Areas database. The first of these metrics, the percentage of land area protected, provides an indication of conservation status by offering insight into potential threats (e.g., how much land is available for conversion and where it is located in relation to the park boundary) as well as opportunities (e.g., connectivity and networking of protected areas) for conserving park resources. Land ownership or stewardship is the second metric, which — by informing parks of who manages other protected areas around them — also provides useful insight into whether and how resources may be effectively co-managed across boundaries of different management units.
Conservation status of lands surrounding Sequoia and Kings Canyon National Parks (top) and Pipestone National Monument (bottom) as identified by the Protected Areas Database of the United States, version 1.2. NPScape metrics of conservation status identify all GAP status 1 and 2 lands as 'protected'.
Bibliography of Scientific Papers Foundational to Landscape Ecology
In each chapter, we describe the ecological relevance of NPScape metrics based on the scientific literature. This literature is foundational to helping parks understand how the landscape-level data and results originating from NPScape may be used to evaluate the influence of broad-scale dynamics on park resources. The Interpretive Guide concludes with an extensive bibliography of in-text citations, which we encourage readers to consult as they pursue more in-depth analysis and interpretation.