PARENT SESSION
Poster Session # 11: Disturbance Ecology.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
The legacy of landscape disturbance on small southeastern coastal plains streams.
Maloney, Kelly*,1, Feminella, Jack1, Mulholland, Patrick2, Mitchell, Richard1, Olsen, Lisa2, 1 Department of Biological Sciences, Auburn, AL2 Environmental Sciences Division, Oak Ridge, TN
ABSTRACT- We present results of a study designed to assess the relationships between measures of contemporary stream conditions and historical versus current measures of disturbance from land use. In 1999 we began quantifying in-stream physicochemical and biotic conditions (streambed organic matter and coarse woody debris; streamwater NO3 and SRP; benthic macroinvertebrates) within 8 low-order catchments varying in contemporary disturbance intensity at Fort Benning, GA. Land use was quantified from 1974, 1983, 1990, and 1999 remotely sensed imagery using an ArcView extension (ATtILA). Catchment-specific disturbance was estimated as the sum of the percentage of bare ground and early transitional forest on slopes >3%, and the percentage of road cover. Contemporary sediment % organic matter and Bray-Curtis macroinvertebrate community similarity with an undisturbed reference stream were negatively and more strongly correlated with historical disturbance. Contemporary measures of macroinvertebrate functional feeding groups also correlated more strongly with 1974 disturbance conditions than more recent disturbance levels, with % of shredders decreasing and % of collector-gatherers increasing with increasing catchment disturbance. Contemporary Shannon diversity also reflected historical conditions, and was negatively correlated with disturbance in both the 1983 and 1990 classifications. In contrast, contemporary measures of streamwater SRP and NO3 concentrations, and streambed % coarse woody debris abundance were more closely associated with contemporary (1999) than historical disturbance conditions. Our results suggest that knowledge of historical land use may be critical in interpreting present-day habitat conditions and macroinvertebrate communities in streams.
Key words: disturbance, macroinvertebrate, land use legacy, stream