Pacific Crab Apple Restoration at Kwiid Suu (Mayer Lake) on Haida Gwaii

  • Ravi Camire University of Victoria


Pacific crab apple (Malus fusca) is a plant of both cultural and ecological significance on Haida Gwaii. At Kwiid Suu (Mayer Lake), populations of Pacific crab apple have been severely reduced since the
introduction of the American beaver (Castor canadensis) and Sitka black tail deer (Odocoileus hemionus sitkensis). Beaver feed on the inner cambium layer of trees, often girdling them in the process, and fall stems to build their dams; while deer browse limits the recruitment of young crab apple. The rapid decline of crab apple at Kwiid Suu was first observed in 2000, leading to a series of beaver control and riparian plant protection projects. Through the spring and summer of 2022, I observed 178 mature crab apple trees across 10 plots to gather data on the health of the remaining groves. I also counted the number of stumps, felled trees, and gathered information on recruitment by recording the abundance of seedlings and young trees within the plots. A total of 160 felled trees were recorded within the surveys and the majority of standing mature trees had signs of beaver chewing. Despite this heavy impact from beaver, crown dieback was low in 58% of trees surveyed and fruit production was generally consistent with observations elsewhere on Haida Gwaii. Regeneration was recorded as high or moderate in 80% of plots, however, seedling survivorship appeared to be very low with only 27 young trees found within the plots. Based on these results, I constructed a total of 21 exclosures that focused on protecting seedlings. I built four large crab apple exclosures that protected a mature crab apple tree along with seedlings or shoots growing around its root mass, and 17 cone exclosures around individual seedlings or bunches of shoots. The surveys have highlighted an extreme lack of crab apple recruitment. In some of the larger groves where mature trees can support regeneration, seedlings should be protected by exclosures. In areas where mature trees are no longer existent, seedling may need to be planted on site with protection.

Technical Papers