TY - JOUR T1 - Gap analysis of the vegetation of the Intermountain Semi-Desert Ecoregion JF - Great Basin Naturalist Y1 - 1998 A1 - Stoms, D. M. A1 - Davis, F. W. A1 - Driese, K. L. A1 - Cassidy, K. M. A1 - Murray, M. P. KW - actual vegetation KW - alliance KW - gap analysis KW - Intermountain Semi-Desert ecoregion KW - National Vegetation Classification Standards KW - NVCS AB - A conservation gap analysis was conducted for the Intermountain Semi-Desert ecoregion to assess the representation of land-cover types within areas managed primarily for biodiversity objectives. Mapped distributions of plant communities were summarized by land management status categories. The total amount of land permanently protected in the ecoregion is less than 4% and most types that are characteristic of the region have less than 10%. Of 48 land-cover types, 20 were found to be particularly vulnerable to potential loss or degradation, because of low level of representation in biodiversity management areas and the impact of expected land use activities. The gap analysis data and findings will be useful in providing a regional perspective in project impact assessment and future conservation planning within this ecoregion. VL - 58 UR - ://000074765200001 ER - TY - JOUR T1 - Map-guided classification of regional land-cover with multi-temporal AVHRR data JF - Photogrammetric Engineering and Remote Sensing Y1 - 1998 A1 - Stoms, D. M. A1 - Bueno, M. J. A1 - Davis, F. W. A1 - Cassidy, K. M. A1 - Driese, K. L. A1 - Kagan, J. S. KW - accuracy assessment KW - AVHRR KW - gap analysis KW - Intermountain Semidesert ecoregion KW - map-guided classification KW - National Vegetation Classification Standards KW - NVCS KW - remote sensing AB - Cartographers often need to use information in existing land-cover maps when compiling regional or global maps, but there are no standardized techniques for using such data effectively. An iterative, map-guided classification approach was developed to compile a spatially and thematically consistent, seamless land-cover map of the entire Intermountain Semi-Desert ecoregion from a set of semi-independent subregional maps derived by various methods. A multi-temporal dataset derived from AVHRR data was classified using the subregional maps as training data. The resulting regional map attempted to meet the guidelines of the proposed National Vegetation Classification Standards for classification at the alliance level. The approach generally improved the spatial properties of the regional mapping, while maintaining the thematic detail of the source maps. The methods described may be useful in many situations where mapped information exists but is incomplete, compiled by different methods, or is based on inconsistent classification systems. VL - 64 UR - ://000075109200012 ER - TY - CHAP T1 - Sierran vegetation: A gap analysis T2 - Sierra Nevada Ecosystem Project: Final Report to Congress, vol. II, Assessments and scientific basis for management options Y1 - 1996 A1 - Davis, F. W. A1 - Stoms, D. M. KW - California KW - gap analysis KW - land management KW - Sierra Nevada KW - vegetation AB - Gap analysis assesses the distribution of plant community types and vertebrate species distributions among land classes defined by ownership and levels of protection of biodiversity. Gap analysis helps to identify which plant communities and species might be especially vulnerable to different human activities that can lead to habitat conversion or degradation. This chapter presents a gap analysis of plant community types the Sierra Nevada region, an area of 63,111 km2 (24,368 mi2). Ownership of the region is 37% private, 47% national forests, 10% national parks, 5% Bureau of Land Management, and less than 2% in other public lands. Land ownership and land management patterns contrast sharply between the northern Sierra Nevada versus the central and southern subregions. Parks and reserve lands contribute less than 2% of the northern region versus 27% of the central/southern. We mapped eighty-eight natural plant community types within the region. Sixty-seven types were mapped over areas greater than 25 km2 (9.65 mi2). The ownership profiles of Sierran plant communities systematically reflect the concentration of private lands at lower elevations and of national parks in the central and southern portion of the range. Less than 1% of the foothill woodland zone of the Sierra Nevada is in designated reserves or other areas managed primarily for native biodiversity, and over 95% of the distribution of most foothill community types is available for grazing. Low to middle elevation Sierran forests are not well represented in designated reserves, especially in the northern Sierra Nevada. However, large areas of most of these forest types on U.S. Forest Service lands have been administratively withdrawn from intensive timber management based on current forest plans. Many high-elevation forest and shrubland community types are well represented in parks and ungrazed wilderness areas. Our analysis identifies thirty-two widespread community types whose conservation status warrants concern and twelve types that appear well protected based on their present distributions. JF - Sierra Nevada Ecosystem Project: Final Report to Congress, vol. II, Assessments and scientific basis for management options PB - University of California, Centers for Water and Wildlands Resources CY - Davis, California ER - TY - CHAP T1 - A spatial analytical hierarchy for Gap Analysis T2 - Gap Analysis: A Landscape Approach to Biodiversity Planning Y1 - 1996 A1 - Davis, F. W. A1 - Stoms, D. M. ED - Scott, J. M. ED - Tear, T. H. ED - Davis, F. W. KW - gap analysis KW - reserve selection KW - scale AB - Representation in the nature reserve system is determined by comparing the distribution of vegetation and vertebrates with that of land ownership and management over a region of interest. Locating potential places to increase representation is typically done by a systematic selection algorithm over a set of spatial units larger than the landscape units of the vegetation map. The landscape is thus the basic spatial unit at which biodiversity data are compiled for Gap Analysis. However, it is only one of four levels of spatial entity that must be explicitly defined in order to complete a Gap Analysis. We refer to these entities as the planning region, the planning unit, the landscape, and the landscape feature. The objective of this paper is to describe a spatial analytical hierarchy for Gap Analysis based on these four entities. Within this broader theme we also present results of a more focused analysis on the effect of planning unit size on the selection of priority conservation areas in southwestern California. JF - Gap Analysis: A Landscape Approach to Biodiversity Planning PB - American Society for Photogrammetry and Remote Sensing CY - Bethesda, MD ER - TY - JOUR T1 - Validating large-area land cover databases with maplets JF - Geocarto International Y1 - 1996 A1 - Stoms, D. M. KW - gap analysis KW - map accuracy assessment KW - maplet AB - Point sampling methods traditionally used for assessing accuracy of small-area thematic maps are less suitable for large-area, lower resolution maps. Maplets, or detailed maps of small areas, are proposed here as an alternative source of independent reference data for accuracy assessment. As a land cover census instead of a sparse sample of points, maplets can provide information on the composition, heterogeneity, and accuracy of individual map units, on boundary locational accuracy, and the spatial pattern of errors in the large-area map. The techniques is illustrated by a case study for a wildlife habitat map of southern California, USA. Overall agreement between the maplet and the large-are map was 63%. However, the total area of map units in which the label agreed with the majority maplet class was 84%. This result suggests that much of the "error" was actually generalization rather than misclassification. VL - 11 ER - TY - JOUR T1 - Gap analysis of the actual vegetation of California: 1. The Southwestern Region JF - Madrono Y1 - 1995 A1 - Davis, F. W. A1 - Stine, P. A. A1 - Stoms, D. M. A1 - Borchert, M. I. A1 - Hollander, A. D. KW - California KW - gap analysis KW - vegetation AB - Gap Analysis is a method of conservation risk assessment that evaluates the protection status of plant communities, animal species and vertebrate species richness by overlay of biological distribution data on a map of existing biological reserves. The National Biological Survey has undertaken a national Gap Analysis that is being conducted by individual states but that will eventually produce regional and national assessments. Given California's size and complexity, we are conducting separate Gap Analyses for each of the state's 10 ecological regions, as delineated in The Jepson Manual. Here we summarize our findings on the distribution of plant communities and dominant plant species in the Southwestern Region of California, exclusive of the Channel Islands. We tabulate and discuss regional distribution patterns, management status and patterns of land ownership for 76 dominant woody species and 62 natural communities. Nineteen of 62 mapped communities appear to be at risk, as determined by their poor representation in existing reserves, parks or wilderness areas. Communities restricted largely to the lower elevations, such as non-native grasslands and coastal sage scrub types, are clearly at considerable risk. A majority of the lands at these elevations have already been converted to agricultural or urban uses and most of the remaining lands are threatened with future urbanization. Areas that appear to be of highest priority for conservation action based on agreement between our analysis and a recent assessment by The Nature Conservancy include the Santa Margarita River, San Mateo Creek, Miramar Mesa, Santa Clara floodplain near Fillmore, Sespe and Piru Canyons, and Tejon Pass. VL - 42 ER - TY - JOUR T1 - Distribution and conservation status of coastal sage scrub in southwestern California JF - Journal of Vegetation Science Y1 - 1994 A1 - Davis, F. W. A1 - Stine, P. A. A1 - Stoms, D. M. KW - gap analysis KW - information analyis KW - vegetation classification AB - A landscape-based characterization of vegetation has been developed for southwestern California using satellite imagery, air photos, existing vegetation maps, and field data. Distribution maps of nine dominant coastal scrub species and 13 species assemblages that were identified by divisive information analysis have been analyzed to quantify spatial patterns of species co-occurrence. Three general distribution patterns are identified that suggest the Diegan, Venturan and Riversidian Associations identified by other workers. Vegetation data have also been related to land ownership and management to assess the conservation status of upland plant communities. A large proportion of the mapped distribution of species and vegetation types is on private land, and several taxa show less than 4% of mapped distribution in nature reserves. The analysis highlights the need to extend current conservation planning efforts into the northern part of the region to encompass areas where Salvia leucophylla is a frequent community dominant. VL - 5 UR - ://A1994PX87300011 ER -