Authors: Wilkerson, Ethel¹; Hagan, John M.¹; Siegel, Darlene¹; Whitman, Andrew A.¹

Source: Forest Science, Volume 52, Number 3, June 2006 , pp. 221-231(11)

Abstract:

We evaluated the effect of timber harvesting on summer water temperature in first-order headwater streams in western Maine. Fifteen streams were assigned to one of five treatments: (1) clearcutting with no stream buffer; (2) clearcutting with 11-m, partially harvested buffers, both sides; (3) clearcutting with 23-m, partially harvested buffers; (4) partial cuts with no designated buffer; and (5) unharvested controls. Over a 3-year period we measured summer water temperature hourly before and after harvesting, above and below the harvest zone. Streams without a buffer showed the greatest increase in mean weekly maximum temperatures following harvesting (1.4-4.4°C). Streams with an 11-m buffer showed minor, but not significant, increases (1.0-1.4°C). Streams with a 23-m buffer, partial-harvest treatment, and control streams showed no changes following harvest. The mean weekly maximum temperatures never exceeded the thermal stress limit for brook trout (25°C) in any treatment group. The mean daily temperature fluctuations for streams without buffers increased from 1.5°C/day to 3.8°C/day, while with 11-m buffers fluctuations increased nonsignificantly by 0.5-0.7°C/day. Water temperatures 100 m below the harvest zone in the no-buffer treatment were elevated above preharvest levels. We concluded that water temperature in small headwater streams is protected from the effects of clearcutting by an 11-m buffer (with >60% canopy retention).

Keywords: Headwater stream; water temperature; riparian buffers; forest practices; buffer width

Document Type: Research article

Affiliations: 1: John M. Hagan, Director, Forest Conservation Program at Manomet Center for Conservation Sciences, 14 Maine St., Brunswick, ME 04011—Phone: (207) 721-9040;-9144; jmhagan@ime.net. Ethel Wilkerson, Stream Project Manager, Manomet Center for Conservation Sciences, 14 Maine St., Brunswick, ME 04011—Phone: (207) 721-9040; Fax: (207) 721-9144; ewilkerson@prexar.com. Darlene Siegel, Fisheries Biologist, Tetra Tech, Inc., 1020 SW Taylor St., Suite 530, Portland, OR 97205—Phone: (503) 223-5388 ext. 226; Darlene.Siegel@tetratech.com. Andrew A. Whitman, Project Director, Manomet Center for Conservation Sciences, 14 Maine St., Brunswick, ME 04011—Phone: (207) 721-9040; awhitman@prexar.com., Fax: (207)-721