Assistant Professor Gretchen Coffman and Two Graduating MSEM Students Present Redwood Creek Restoration Research Results

Assistant Professor Gretchen Coffman and two graduating MSEM students, Jacqueline McCrory and Brian Piontek, presented their Master's thesis research on Redwood Creek Restoration at the California Society of Ecological Restoration - SERCAL Conference in Santa Rosa in May of 2014. The title was: Ecological constraints of willow growth at a restored riparian corridor.

Here is the abstract:

Ecological constraints of willow growth at a restored riparian corridor.  Jacqueline McCrory, Brian Piontek, and Gretchen Coffman.  Environmental Management Program, Environmental Science Department, University of San Francisco, San Francisco, CA 94117-1080

Recently many stream restoration efforts in the Western U.S. have focused on restoration of habitat for anadromous fish populations. Effective, rapid revegetation of riparian trees is critical to the restoration process, providing necessary shading to cool stream temperatures. This study investigated stunted growth of arroyo willow (Salix lasiolepis) cuttings planted along the banks of Redwood Creek in riparian ecosystems restored as part of the National Park Service’s Muir Beach restoration to support the southernmost Coho Salmon population in California. We hypothesized that deer herbivory and soil characteristics were potential stressors limiting willow growth along the 1,200 foot (366m) long restored riparian corridor. To test our hypothesis we measured the change in willow growth from the beginning to the end of the 2013 growing season. Our study design consisted of two treatments: exclusionary deer fencing (versus not fenced) and willow age (1 and 2 year old). Soil moisture, compaction, and texture were sampled next to each of 10 willows measured in all treatments. Mean height, volume, and canopy width were all significantly greater for willows grown inside the exclusionary fencing. The largest effect of fencing on willow growth was for the height of younger, one year old cuttings (fenced, 99.4 ± SE 8.6cm, unfenced, 38.5cm ± SE 6.9cm). Soil characteristics were also found to influence willow growth, but to a lesser degree. Results suggest that exclusionary fencing should be used to reduce the stress of ungulate herbivory on willow growth in restored riparian systems in the Western U.S.