Urban tree inventories as a tool to assess tree growth and failure: The case for Australian cities

The delivery of services and benefits provided by urban forests is threatened by tree limited growth, decline and mortality. Determining drivers of tree decline and mortality is challenging but essential in urban forestry planning to reduce environmental and socio-economic losses associated with tree failures. Urban tree inventories (UTI) are essential for managing and monitoring urban forests, which can help to identify successes (i.e., good tree growth/health) and failures (i.e., removals/dead trees). However, UTI are rarely implemented to assess urban tree growth and failure rates. Here, we used UTI from two Australian cities to demonstrate how these inventories can aid in (1) assessing species' relative growth rates and (2) identifying species failures and their determinant. We found UTI are useful to assess tree growth and failures. However, they require recording trees at the time of planting, long-term monitoring (e.g., recording tree size, health), and incorporating management actions (e.g., irrigation, pruning, removals) to inform species performance and improve urban planning and management.