PARENT SESSION
Oral Session # 72: GIS and Remote Sensing I.
Presiding: J Drake
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 203.
Aerial census of Haleakala silverswords using high resolution color-infrared imagery.
Landenberger, Rick*,1, McGraw, James, Warner, Timothy, Brandtberg, Tomas, 1 Department of Biology, Morgantown, WV, USA
ABSTRACT- High spatial resolution remote sensing offers largely untapped potential for censusing and monitoring rare plant populations. The Haleakala silversword is a federally listed threatened species whose natural range is restricted to the highest elevations on Maui. With its distinctive foliage set against the volcanic background, the species provides an excellent test of the capabilities of color-infrared remote sensing to provide a spatially explicit, individual-based approach to monitoring. We used a helicopter-mounted, high spatial resolution digital camera system with a color-infrared filter to image a series of permanent census plots. Ground-based censuses from 2001 were compared to photointerpretation and automated computer classification of super-high resolution color-infrared imagery. Errors of omission and commission occurred in both methods, although at low rates. Photointerpreters and automated classification accurately estimated silversword size in aerial images, with higher accuracy in the larger size classes. Although imperfect, both photointerpretation and classification effectively differentiated between living and dead individuals. Relative to photointerpreters, flowering individuals presented challenges for the classification. Although not as accurate as localized ground-based censuses, high resolution aerial censuses provide a rapid partial population census over larger areas, which may be adequate for monitoring rare plants growing in barren landscapes.
Key words: aerial census, color-infrared imagery, remote sensing, Haleakala silverswords