PARENT SESSION
Contributed Oral Session 129: Biodiversity: Disturbance; Landscapes; Heterogeneity
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal
Landscape disturbance and biodiversity patterns of vegetation and ants in a complex regional ecotone.
Krzysik, Anthony*,1, Kovacic, David2, Graham, John3, Zak, John4, Duda, Jeffrey5, Balbach, Harold6, 1 Prescott College, Prescott, AZ2 University of Illinois, Champaign-Urbana, IL3 Berry College, Mount Berry, GA4 Texas Tech University, Lubbock, TX5 USGS-BRD-WFRC, Seattle, WA6 U.S. Army-ERDC-CERL, Champaign, IL
ABSTRACT- The relationship between habitat disturbance and biodiversity metrics has strong implications for both ecological theory and land conservation strategies. Research to quantify this association was conducted in the upland Fall-Line Sandhills of Fort Benning Georgia in southeastern USA. This region represents the complex ecotone of the Piedmont and Coastal Plain physiographic provinces with an intrusion of Loamy Hills from Alabama. The military training landscape provided the selection of sites that ranged from relatively pristine to those severely degraded by mechanized infantry training activities. Phase I research at 9 mixed pine-hardwoods sites (three each in Low, Medium, and High classes of military training disturbance) identified 12 promising habitat ecological indicators (EIs) of landscape condition. In Phase II research, forty sites were selected representing the full range of military training disturbance, and available upland vegetation communities, from mesic oak - hickory forest to xeric scrub oak - pine savanna. Four 100m perpendicular transects with a random orientation were established in the center of each site where the 12 EIs were measured. Further EI selection by statistical criteria derived 7 final EIs: soil A-horizon depth, soil compaction, soil organics, litter cover, canopy cover, basal area, and tree density. Each EI was standardized and weighed by statistically derived parameters to develop a composite Site Condition Index (SCI) for each of the 160 transects. SCI transect scores were grouped into five ordinal disturbance classes. Within this disturbance gradient, over 50 parameters of biodiversity of ground cover, trees, and ants were evaluated. Biodiversity metrics included: species richness, abundance, dominance; and Simpson, Shannon, Brillouin diversity and evenness indices. The effect of disturbance on biodiversity varied dramatically with the metric employed. The Intermediate Disturbance Hypothesis was substantiated for species richness and diversity indices of ants; and cover of legumes, Opuntia, total forbs, and all ground cover, but not species richness of ground cover. Highly disturbed transects had a high abundance of ants and grasses, but low evenness of ants. All tree biodiversity metrics decreased as disturbance increased.
Key words: ecological indicators, site condition index, fall-line sandhills, forest disturbance