Flat Branch monitoring project: stream water temperature and sediment responses to forest cutting in the riparian zone
Stream water protection during timber-harvesting activities is of primary interest to forest managers. In this study, we examine the potential impacts of riparian zone tree cutting on water temperature and total suspended solids. We monitored stream water temperature and total suspended solids before and after timber harvesting along a second-order tributary of the Coleman River in northeastern Georgia, where logging with rubber-tired skidders was conducted in the riparian area along alternating 60-m stream reaches on the east side of the stream. We monitored temperature above the management unit (reference), at a location within the cut area (within cut), and at a third site 150 m below the cut area (below cut). We measured total suspended solids during base flow and storm flow, taking weekly stream water grab samples above the site and above and below each riparian area, for a total of six sampling locations. We found that stream water temperature following harvest increased within the cut area relative to the reference but decreased at the below sample site back to reference conditions. Overall, total suspended solids responses were minimal or nonexistent during base and storm flows within the cut relative to the reference site, and temperature responses were minimal. Unusually warm and dry weather existed for most of the logging period, which may have minimized the potential for runoff, erosion, and sediment; however, low flows may have contributed to the small increases in water temperature. Hence, we observed only marginal effects of riparian zone cutting on water temperature and total suspended solids in this study.