The impact of timber harvest using an individual tree selection silvicultural system on the hydrology and sediment yield in a coastal California watershed
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There is still widespread concern regarding the environmental impact of timber harvest. This is certainly true for timber harvest activities that occur on the Swanton Pacific Ranch, the school forest for the California Polytechnic State University, located in Santa Cruz County, California. A paired watershed study was carried out to help determine the impact of contemporary forest practices on the hydrology and sediment yield of the Little Creek watershed in the Swanton Ranch. Discharge and suspended sediment were measured at two gauging stations, the North Fork and South Fork of Little Creek, from 2002 to 2009. The calibration period extended from 2002 to 2008. Timber harvest occurred in the summer of 2008 and three storms occurred during the winter after timber harvest. During the summer of 2009, the Lockheed Fire occurred and significant portions of both watersheds were burned, thus the South Fork lost its value as a control watershed. Hourly peak flows, total storm quickflow volume, and total storm sediment yield were analyzed for 35 storms during the calibration period and for the three storms that occurred during the post-harvest winter. There was no evidence that the timber harvest had any impact on the hydrology or sediment yield of the Little Creek watershed.