The impact of engineered tree pit solutions on street tree growth and survival

Bell, Dean

Abstract

Internationally, cities are setting tree planting targets in recognition of tree-based ecosystem services. However, establishing street trees presents significant challenges and traditional techniques are associated with elevated tree mortality. Engineered tree pit solutions integrate engineering and tree requirements within a shared design, providing improved rooting environments over traditional tree pits. Therefore, they should improve tree growth and survival in street environments.

To test this hypothesis, the impact of engineered tree pit solutions on street tree growth and survival was investigated in two planting programmes comprising retrofitting in a central borough and a new development in London, UK. This was accompanied by a questionnaire to understand the perspectives and professional practices of international built environment practitioners with first-hand experiences with engineered solutions.

The studies indicate a consistent superiority of crate systems among the studied engineered solutions and compared to traditional tree pits. Crate systems yielded greater tree growth in both planting programmes and increased tree survival compared to traditional tree pits in the retrofit scenario. The questionnaire reinforced these findings; practitioners consistently ranked crate systems as the top engineered solution to secure the best tree growth and survival rates. Fieldwork was particularly informative on the impact of crate systems during the tree establishment period. The findings indicate that crate systems can accelerate transplant recovery and efficiently establish large trees.

These results represent new contributions to urban forestry science. Importantly, the research has produced an analysis independent from the commercial interests of engineered solution manufacturers. Accelerated transplant recovery could bring fundamental improvements in street tree performance and lessen the high mortality experienced during tree establishment. The results should be used to inform tree planting practices, as well as the broader design and engineering of urban streets, to construct tree pit infrastructure conducive to tree longevity.

• Thesis Type: Thesis
• Deposit Date: Mar 24, 2024
• Publicly Available Date: Sep 5, 2024
• Public URL: https://uwe-repository.worktribe.com/output/11841072
• Award Date: Sep 5, 2024