PARENT SESSION
Oral Session #16: Landscape Ecology: Fragmentation, ecotones, and models.
Presiding: X. Wu
Monday, August 5. 1:00 PM to 3:45 PM. Gila Meeting Room, TCC.
Montane ecotone hierarchies in Arizona sky islands.
KUPFER, JOHN*,1, JONES, JAMES1, SMITH, JACKIE, 1 UNIVERSITY OF ARIZONA, TUCSON, AZ
ABSTRACT- Abiotic conditions, biotic processes and relationships, and disturbance form a complex, often complicated relationship that influences vegetation pattern and montane ecotone location. The abrupt changes in climate and vegetation in the Santa Catalina-Rincon Mountain complex of southeastern Arizona provide an ideal setting in which to examine not only the effects of these factors on ecotone location but also how ecotone locations are related to differing variables at different spatial scales and resolutions. The purpose of this study was to better understand montane ecotone patterns by linking GIS, remote sensing, and statistical techniques to relate ecotone location to abiotic influences and disturbance history. Plant community distributions were mapped using a classification of 2000 Enhanced Thematic Mapper imagery. Training and test data were collected in summer 2001, and a range of topographic indices (e.g., slope, aspect, slope position) were mapped using a 30m digital elevation model. Fire disturbance history for the study site came from fire perimeter maps provided by forest managers at Saguaro National Park. Ecotone locations were statistically determined using wombling (local rates of change), and the relationship between ecotone locations and independent predictor variable were assessed using subboundary test statistics and ecotone overlap measures. Data were then aggregated to coarser resolutions, and ecotone patterns and correlates were recalculated to examine the effects of scale and resolution on ecotone patterns. Results of our analyses indicated that: 1) both abiotic conditions and time since fire were important in shaping current ecotone patterns and 2) fine-scale ecotone patterns were correlated to a different set of variables than coarse-scale patterns.
KEY WORDS: landscape ecology, ecotone, vegetation pattern, Arizona