730 research outputs found
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Demographic trends, the wildland-urban interface, and wildfire management
Testimony of Roger B. Hammer, Assistant Professor, Department of Sociology, Sustainable Rural Communities Initiative,
Oregon State University before the House Interior, Environment & Related Agencies Appropriations Subcommittee,
Oversight Hearing on Wildfire Management, February 12, 200
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Mapping Multiple Forest Threats in the Northwestern United States
US forestlands are increasingly subject to disturbances including wildfire, insects and disease, and urban and exurban development. Devising strategies for addressing these "forest threats" depends on anticipating where individual disturbances are most likely and where they might occur in combination. However, many spatial data sets describing forest threats are produced at fine scales but are intended only for coarse-scale planning and policy purposes. We demonstrate one way to combine and display forest threat data at their appropriate spatial scales, using spatial data characterizing wildfire, insects and disease, and urban and exurban development in the northwestern United States. We use a novel 25-km radius neighborhood analysis to highlight locations where threats may be more concentrated relative to others and to identify where multiple threats intersect. Such neighborhood analyses and overlays can help policymakers and managers to anticipate and weigh the implications of potential threats and their intersections in regional- and national-level assessments.Keywords: wildfire, insects and disease, landscape planning and assessment, forest health, wildland-urban interfac
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Spatial and temporal residential density patterns from 1940 to 2000 in and around the Northern Forest of the Northeastern United States
Over the past 60 years, housing growth has outpaced population growth
in the United States. Conservationists are concerned about the far-reaching environmental
impacts of housing development, particularly in rural areas. We use
clustering analysis to examine the pattern and distribution of housing development
since 1940 in and around the Northern Forest, a heavily forested region with high
amenity and recreation use in the Northeastern United States. We find that both
proximity to urban areas and an abundance of natural amenities are associated with
housing growth at the neighborhood level in this region. In the 1970s, counterurbanization
led to higher rates of growth across rural areas. The Northern Forest now
has extensive interface between forest vegetation and residential development,
which has the potential to profoundly alter the ecological and social benefits of these
forests.Keywords: Housing density, Amenity growth, Sprawl, Housing growth, Cluster analysis, Northern ForestKeywords: Housing density, Amenity growth, Sprawl, Housing growth, Cluster analysis, Northern Fores
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Using structure locations as a basis for mapping the wildland urban interface
The wildland urban interface (WUI) delineates the areas where wildland fire hazard most directly impacts human communities and threatens lives and property, and where houses exert the strongest influence on the natural environment. Housing data are a major problem for WUI mapping. When housing data are zonal, the concept of a WUI neighborhood can be captured easily in a density measure, but variations in zone (census block) size and shape introduce bias. Other housing data are points, so zonal issues are avoided, but the neighborhood character of the WUI is lost if houses are evaluated individually. Our goal was to develop a consistent method to map the WUI that is able to determine where neighborhoods (or clusters of houses) exist, using just housing location and wildland fuel data. We used structure and vegetation maps and a moving window analysis, with various window sizes representing neighborhood sizes, to calculate the neighborhood density of both houses and wildland vegetation. Mapping four distinct areas (in WI, MI, CA and CO) the method resulted in amounts of WUI comparable to those of zonal mapping, but with greater precision. We conclude that this hybrid method is a useful alternative to zonal mapping from the neighborhood to the landscape scale, and results in maps that are better suited to operational fire management (e.g., fuels reduction) needs, while maintaining consistency with conceptual and U.S. policy-specific WUI definitions.Keywords: Structure locations, Wildland urban interface, MappingKeywords: Structure locations, Wildland urban interface, Mappin
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Wildland-urban interface maps vary with purpose and context
Maps of the Wildland-Urban Interface (WUI) are both pragmatic policy tools and powerful visual images with broad appeal. While the growing number of WUI maps serve the same general purpose, this paper demonstrates that WUI maps based on the same data can differ in ways related to their purpose, and discusses the use of ancillary data in modifying census data. A comparison of two methods suggests GIS methods used for mapping the WUI be tailored to specific questions. Dasymetric mapping to improve census data precision is useful but dependent on data quality, and land ownership datasets suffer problems that argue for caution in their use. No single mapping approach is “best,” and analysts must be clear about the problem addressed, the methods used, and data quality. These considerations should apply to any analysis, but are especially important to analyses of the WUI upon which public-sector decisions will be made
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Epitaxial growth of ultrathin palladium films on Re{0001}
Ultrathin bimetallic layers create unusual magnetic
and surface chemical effects through the modification of electronic structure brought on by low dimensionality, polymorphism, reduced screening, and epitaxial strain. Previous studies have related valence and core-level shifts to surface reactivity through the d-band model of Hammer and Nørskov, and in heteroepitaxial films this band position is determined by competing effects of coordination, strain, and hybridization of substrate and overlayer states. In this study we employ the epitaxially matched Pd on Re{0001} system to grow films with no lateral strain. We use a recent advancement in low-energy electron diffraction to expand the data range sufficiently for a reliable determination of the growth sequence and out-of-plane surface relaxation as a function of film thickness. The results are supported by scanning tunneling
microscopy and X-ray photoemission spectroscopy, which show that the growth is layer-by-layer with significant core-level shifts due to changes in film structure, morphology, and bonding
Quantifying unpredictability: A multiple-model approach based on satellite imagery data from Mediterranean ponds.
Fluctuations in environmental parameters are increasingly being recognized as essential features of any habitat. The quantification of whether environmental fluctuations are prevalently predictable or unpredictable is remarkably relevant to understanding the evolutionary responses of organisms. However, when characterizing the relevant features of natural habitats, ecologists typically face two problems: (1) gathering long-term data and (2) handling the hard-won data. This paper takes advantage of the free access to long-term recordings of remote sensing data (27 years, Landsat TM/ETM+) to assess a set of environmental models for estimating environmental predictability. The case study included 20 Mediterranean saline ponds and lakes, and the focal variable was the water-surface area. This study first aimed to produce a method for accurately estimating the water-surface area from satellite images. Saline ponds can develop salt-crusted areas that make it difficult to distinguish between soil and water. This challenge was addressed using a novel pipeline that combines band ratio water indices and the short near-infrared band as a salt filter. The study then extracted the predictable and unpredictable components of variation in the water-surface area. Two different approaches, each showing variations in the parameters, were used to obtain the stochastic variation around a regular pattern with the objective of dissecting the effect of assumptions on predictability estimations. The first approach, which is based on Colwell's predictability metrics, transforms the focal variable into a nominal one. The resulting discrete categories define the relevant variations in the water-surface area. In the second approach, we introduced General Additive Model (GAM) fitting as a new metric for quantifying predictability. Both approaches produced a wide range of predictability for the studied ponds. Some model assumptions-which are considered very different a priori-had minor effects, whereas others produced predictability estimations that showed some degree of divergence. We hypothesize that these diverging estimations of predictability reflect the effect of fluctuations on different types of organisms. The fluctuation analysis described in this manuscript is applicable to a wide variety of systems, including both aquatic and nonaquatic systems, and will be valuable for quantifying and characterizing predictability, which is essential within the expected global increase in the unpredictability of environmental fluctuations. We advocate that a priori information for organisms of interest should be used to select the most suitable metrics estimating predictability, and we provide some guidelines for this approach
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