The response of swamp harebell (Campanula californica) to timber harvest: a case study

Abstract

A perennial herb of the Campanulaceae (bellflower) family, swamp harebell (Campanula californica) is endemic to the north and central coast of California. The California Department of Fish and Wildlife (CDFW) considers the species to be moderately threatened, and is concerned with the severity of impacts from land use activities, and the effectiveness of mitigation measures proposed under California Environmental Quality Act compliance. A timber harvesting plan (THP) submitted during 2000 reported the species distributed in several clusters in the proposed Sonoma County logging area. During review, CDFW and the landowner agreed to evaluate the impacts of some standard timber harvest practices. Following a repeated-measures design with sampling the year prior to harvest and post-harvest years 1, 3, and 5, we enumerated swamp harebell plants in five 30 cm x 30 cm subplots systematically placed within twenty 3 m x 1 m cover-class quadrants. We situated the cover-class quadrants to assess four immediate on-site impacts: road reopening/hauling, timber falling and skidding, reducing canopy, and minimal direct impact. The number of plants on roadways declined substantially in the first year post harvest, and remained low in subsequent years. Likewise, the number of plants declined between pre-harvest and post-harvest year 1 where trees were felled and skidded, but some recovery was apparent by the final year. Reduced canopy plots did not show substantive response attributable to harvest. Of the un-impacted sites, one declined continually and substantially (to 2 percent of its original count) over study period, while the others also generally declined. Drought conditions during the monitoring period likely impacted swamp harebell numbers more than many impacts of timber harvest, other than those resulting from road construction and use.

Parent Publication

• Coast redwood science symposium—2016: Past successes and future direction

Citation

Valentine, Brad; Nelson, Tracy; Golec, Clare; LaBanca, Tony; Martinelli, Stacey. 2017. The response of swamp harebell (Campanula californica) to timber harvest: a case study. In: Standiford, Richard B.; Valachovic, Yana, tech cords. Coast redwood science symposium—2016: Past successes and future direction. Proceedings of a workshop. Gen. Tech. Rep. PSW-GTR-258. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 295-305.