Western red cedar regeneration on Haida Gwaii, British Columbia: Comparing the performance of four browse barrier types, and recommendations for management

Abstract

This report presents the results of a study undertaken on Haida Gwaii in 2008 to qualitatively and quantitatively assess the long-term performance of four seedling protector (or browse barrier) types used in the protection of regenerating Western redcedar (Thuja plicata ). The assessment is provided to inform stakeholders and improve silvicultural practices on Haida Gwaii. In the study, 187 free-growing 11-year-old cedars protected by either Vexar, metal cages, Sinocast or Growcone protectors are assessed for 20 growth, form and health variables, and the browse barriers are assessed for their durability and condition. Findings suggest that, although cedars in metal cages generally perform significantly better in many aspects of growth, form and health when unbrowsed, the high variability between unbrowsed and browsed cedars in cages does not compare favourably with the performance of Growcone-protected seedlings. Results are contextualized in a discussion of the legislative requirements for cedar regeneration and the variety of challenges facing it on Haida Gwaii most notably the high population of introduced Sitka black-tailed deer Odocoileus hemionus sitkensis). The report also reviews the available literature regarding browse barriers, and finds that solid-walled protectors have frequently been show to improve seedling growth and survival. Seven key recommendations are outlined for consideration by the Haida Gwaii Forest District, local timber licensees, and the Council of the Haida Nation to promote sustainable cedar management on Haida Gwaii. The recommendations are to 1) undertake long-term protection trials, 2) discontinue the use of Vexar and Sinocast, 3) use metal cages in low­browse areas or for spruce, 4) use Growcone or similar protector types, 5) consider implementing cedar underplanting trials in protected areas, 6) consider developing a protector removal policy, and 7) to monitor regenerating cedar stands for stand health and composition after free-growing declaration has been established, preferably more than once per rotation cycle.