Status surveys for the endangered plant species Narthecium americanum (bog asphodel, Liliaceae) in the New Jersey Pine Barrens, using remote sensing and geographic information systems1
2018
Kelly, Jay F.
Systematic field surveys were conducted for Narthecium americanum in the New Jersey Pine Barrens in order to determine its status and distribution. Surveys were carried out for 61 extant populations (98% of total) and 12 historic/extirpated populations (60% of total), and in approximately 180 km of potential habitat in riverside bogs and fens for de novo populations. Potential habitat was identified using infrared aerial photography and was systematically surveyed at each site, with GPS data collected on the perimeters of all Narthecium patches found. Notable findings included the discovery of 33 de novo populations, increasing the number of known occurrences by 57% and the total areal coverage by 86%. Other populations that previous surveys had failed to find were rediscovered, and several extirpations were confirmed. Spatial analyses found the total area of N. americanum to be 32 ha, ranging from less than 1 m² to more than 4 ha per site. Populations were clustered along portions of 10 rivers, and a reassessment of occurrence delineations based on their spatial distribution resulted in a reduction to 18 extant and 10 historic/extirpated occurrences. Ninety-four percent of N. americanum by area occurred on publically owned lands, 96% within state and federal Pinelands boundaries, and 81% in the Pinelands Preservation Area. Present status and threats to the species, and the usefulness of remote sensing, geographic information systems, and systematic survey methods for rare plant monitoring and research are discussed.
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