Browsing by Author "Price, John P."

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    Mapping plant species ranges in the Hawaiian Islands: developing a methodology and associated GIS layers.
    (2007-11) Price, John P.; Gon III, Samuel M.; Jacobi, James D.; Matsuwaki, Dwight
    This report documents components of a methodology for projecting the geographic ranges of plant species in the Hawaiian Islands. This consists primarily of the creation of several GIS data layers depicting attributes related to the geographic ranges of plant species. The most important data layer generated here is an objectively-defined classification of climate as it pertains to the distribution of plant species. By examining previous zonal vegetation classifications in light of spatially detailed climate data, we explicitly define broad zones of climate relevant to contemporary concepts of vegetation in the Hawaiian Islands. A second spatial data layer presented here considers substrate age, since large areas of the island of Hawai‘i in particular are covered by very young lava flows, which are inimical to the growth of many plant species. The third data layer presented here divides larger islands, which are composites of multiple volcanoes, into definable biogeographic regions, since many species are restricted to a given topographically isolated mountain or a specified group of these. A final spatial data layer depicts human impact, which reduces the range of many species relative to where they formerly occurred. Several other factors that influence the geographic ranges of species, including topography, soils, and disturbance, are discussed here but not developed further due to limitations in rendering them spatially. We describe a method for analyzing these base layers in a geographic information system (GIS), in conjunction with a database of species distributions, to project the ranges of plant species, including the potential range prior to human disturbance and the projected present range. Examples of range maps for several species are given as case studies that demonstrate different spatial characteristics of range. We discuss several potential applications of species range maps including facilitation of field surveys, informing restoration efforts, studies of range size and rarity, studies of biodiversity, conservation planning, and invasive species management.
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    Rapid assessment of vegetation at six potential `Alala release sites on the island of Hawai`i
    (2007-10) Price, John P.; Jacobi, James D.
    The U.S Fish and Wildlife Service (FWS), as part of its participation in the effort to recover the endangered ‘Alalā (Corvus hawaiiensis), is supporting efforts by the ‘Alalā Recovery Team (ART) to rank areas for suitability as reintroduction sites for this species. A part of this ranking exercise is determination of the current state of the vegetation present at the sites. Although some of these sites have been surveyed using various methods in the recent past, specific, comparable measurements of key aspects of the plant communities are needed for ranking sites for ‘Alalā recovery. Here we summarize new and compiled data for each of the release sites that address the current status and potential recovery of the tree canopy and understory vegetation relative to potential suitability for ‘Alalā release. This project focused on two objectives: 1) Assess the current status and distribution of forest canopy cover based on an analysis of recent satellite imagery and other spatial datasets, and 2) Collect new field data from the six potential release sites to provide quantitative information on the status of the vegetation, with particular focus on density and species composition of plants used by ‘Alalā as food, overall density of forest understory, and degree of closure of tree canopy. The field data also served as ground-truth points for the spatial analysis. The methods of assessing habitat potential for ‘Alalā recovery presented here represent a simple measure of vegetation attributes taken from a limited number of plots within each study area. A primary problem is in attempting to summarize large study areas that incorporate considerable variation in climate, substrate, and land use history. An examination of several versions of the preferred food species richness value ranks the two Ka‘ū study sites first and second. This study does not consider the amount of fruit produced by different species, and therefore it is possible that some additional weighting of preferred food plants might better quantify food resource availability in different landscapes. We also assessed continuity of forest units with other similar habitats outside the study areas, the amount of site disturbance as indicated by percent cover by alien grass species, as well as several other combinations of variables that may help in ranking the sites.