Open Collections

Abstract

Urban trees and vegetation are becoming increasingly vulnerable to harsh growing conditions brought on by climate change. For example, the trees on the UBC Vancouver campus must overcome increased drought periods during summer months and increased storm events during winter months. This issue is becoming more prominent due to the widespread use of manufactured soil blends (MSBs) across campus soft landscapes, which is a relatively new growing medium codified within the Canadian Landscape Standard that is not well studied. This project examines the physical and biochemical properties of soil blends installed over a period of 33 years on the UBC Campus, to understand whether MSBs are developing favourable characteristics over time to support urban trees and vegetation. The properties of depth, bulk density, and carbon and nitrogen content were analyzed across 56 study sites, covered by 3 vegetation cover classes. Data collection was completed by students in the Urban Forest Ecosystems Lab within the Faculty of Forestry between June to August 2022. The implications of this research project are aligned with the UBC Climate Action Plan 2030 and will be used to inform the Integrated Stormwater Management Plan and the UBC Green Building Action Plan. Key findings of this project are as follows: There are 3 major takeaways from the results of this project: 1. Currently, there is no evidence of carbon accumulation over time in MSBs on the UBC Vancouver 2. 3. campus. Soil carbon accumulation is influenced by vegetation cover. Soil depth, a key factor in climate resilience, is influenced by vegetation cover. Overall, it appears as though MSBs did not develop favourable qualities over time to support trees and other vegetation against climate stressors. More importantly, soil depth was found to be relatively shallow across UBC campus due to the abundance of turf grass landscapes, which is a major limiting factor for increasing campus biodiversity. Since depth dictates what type of vegetation can be planted, transformations from lawn to pollinator gardens in future landscape designs may be challenging. Lastly, it is important to acknowledge that soils set the foundation for all biodiversity on campus. Therefore, it is crucial to recognize the role soils play in climate resilience in the renewal of UBC climate policy documents. Further research into differences between native soils and MSBs can provide a better understanding of how urban soils can be sustainably managed to provide better growing conditions. Expansion of the current soil inventory is also critical to enhance the baseline understanding of belowground biodiversity across UBC Vancouver’s Campus. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”