Document: BRE-3-65-3

A spatial time series: Dynamics of openings in oak scrub vegetation

DUNCAN, B.W.*, P.A.SCHMALZER and C.A.DUNLEVY

Dynamac Corporation, Kennedy Space Center, Florida, USA ¹

Abstract:
Sand openings in oak scrub vegetation are important features for scrub biota. Fires create and maintain them; little information exists on their dynamics in space and time at the landscape scale. Recent historic landscape analysis of Happy Creek on Kennedy Space Center found the majority of openings transient, closing in the absence of fire, while some remained persistent during fire suppression. We used historic and current aerial photos to map openings into a GIS database where a change detection identified transient vs. stable openings. To help land managers in creating and managing openings, we used this spatial information to facilitate field data collection. We navigated to openings using a real time differentially corrected global positioning system and collected data on major and minor axis lengths, depth of depression measured in relation to surrounding ground height, probe depth to resistant soil layers, soil core profiles, and surrounding species composition. We sampled openings in the center of well-drained ridges (N=22), in the ecotone to mesic vegetation (N=11), anthropogenic openings (N=10) associated with previous clearings, and transient openings (N=10). Area, major axis depth, and minor axis depth differed among types (Kruskal-Wallis, p<0.001). Disturbed openings were largest (49.5m^2^), center (7.4m^2^), ecotone (8.3m^2^), and transitory the smallest (1.1m^2^). The ecotone openings had the deepest average depth with the ridge center, disturbance, and transitory openings following. Persistent openings occurred in microtopographic depressions and disturbed areas.

Keywords: Remote sensing, GIS, GPS, Florida, Oak Scrub, Sand Openings

This abstract is being presented at: 10:15 AM in session:
Oral Session #58: Landscape Ecology.