Mapping the distribution of Kretzschmaria deusta fruiting bodies along trails in mature Acer macrophyllum-dominant stands in Pacific Spirit Regional Park from 2022 to 2023

There has been a documented decline in Acer macrophyllum (bigleaf maple) since 2011 in the Pacific Northwest and climate change is predicted to heighten their vulnerability to infection from fungal pathogens, making this study extremely relevant (Betzen et al., 2021). Kretzschmaria deusta (brittle cinder fungus) is a fungal pathogen that causes soft rot in the tissues of hardwood trees, like A. macrophyllum, and is often correlated with a decline in the health of the trees (Guglielmo et al., 2012). The distribution of K. deusta on A. macrophyllum along British Columbia’s Pacific Spirit Regional Park’s Trail 3, Trail 4, Trail 6, Trail 7, Salish Trail, and unsanctioned trails south of Trail 7 were mapped. The surveying was conducted by documenting all occurrences of visible fruiting bodies (VFB) of K. deusta found on A. macrophyllum trees and was completed from October 2022 to March 2023. VFB were found on every trail and out of the 689 A. macrophyllum trees surveyed, 65 had VFB. Trail 4 had the highest percentage of A. macrophyllum with VFB, at 50.0%, followed by the unsanctioned trails at 29.7%, Trails 3 at 21.4%, and Trail 7 at 25.0%. Trail 6 and Salish Trail had the lowest percentages, with only 2.6% and 1.1%, respectively. The presence of VFB was positively correlated with the diameter at breast height (DBH) of A. macrophyllum (rpb = 0.367, p-value = 8.216 x 10-12). Currently, Metro Vancouver Regional Parks has management practices in place, but additions such as thorough cleaning of equipment after working in infected areas to reduce the spread of infection; and ensuring not to damage any trees while doing maintenance work to reduce the weakening of A. macrophyllum would be beneficial. Future research should involve continued monitoring and surveying of the park and investigating the potential biological control of K. deusta by a Trichoderma species native to British Columbia.Science, Faculty ofEarth, Ocean and Atmospheric Sciences, Department ofUnreviewedUndergraduat