SREL Reprint #3293

Defining the reference condition for wadeable streams in the Sand Hills subdivision of the Southeastern Plains ecoregion, USA

Ely Kosnicki1, Stephen A. Sefick1, Michael H. Paller2, Miller S. Jarrell1, Blair A. Prusha3, Sean C. Sterrett4,
Tracey D. Tuberville5, and Jack W. Feminella1

1Department of Biological Sciences, 331 Funchess Hall, Auburn University, Auburn, AL 36849, USA
2Savannah River National Laboratory, Aiken, SC, USA
3Midwest Biodiversity Institute, 4673 Northwest Parkway, Hilliard, OH 43235, USA
4Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA
5Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, USA

Abstract: The Sand Hills subdivision of the Southeastern Plains ecoregion has been impacted by historical land uses over the past two centuries and, with the additive effects of contemporary land use, determining reference condition for streams in this region is a challenge. We identified reference condition based on the combined use of 3 independent selection methods. Method 1 involved use of a multivariate disturbance gradient derived from several stressors, method 2 was based on variation in channel morphology, and method 3 was based on passing 6 of 7 environmental criteria. Sites selected as reference from all 3 methods were considered primary reference, whereas those selected by 2 or 1 methods were considered secondary or tertiary reference, respectively. Sites not selected by any of the methods were considered nonreference. In addition, best professional judgment (BPJ) was used to exclude some sites from any reference class, and comparisons were made to examine the utility of BPJ. Non-metric multidimensional
scaling indicated that use of BPJ may help designate non-reference sites when unidentified stressors are present. The macroinvertebrate community measures Ephemeroptera, Plecoptera, Trichoptera richness and North Carolina Biotic Index showed no differences between primary and secondary reference sites when BPJ was ignored. However, there was no significant difference among primary, secondary, and tertiary reference sites when BPJ was used. We underscore the importance of classifying reference conditions, especially in regions that have endured significant anthropogenic activity. We suggest that the use of secondary reference sites may enable construction of models that target a broader set of management interests.

Keywords: Reference condition, Sand Hills ecoregion, Stream management, Historical land use, Macroinvertebrates, Stressors

SREL Reprint #3293

Kosnicki, E., S. A. Sefick, M. H. Paller, M. S. Jarrell, B. A. Prusha, S. C. Sterrett, T .D. Tuberville, and J. W. Feminella. 2014. Defining the reference condition for wadeable streams in the Sand Hills subdivision of the Southeastern Plains ecoregion, USA. Environmental Management 54(2014): 494-504.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).