Yujuan Chen

Urban forests have been widely recognized as a nature-based solution to address urban environmental changes like urban heat islands. Although previous studies have explored the cooling effects of urban forests, the extent of this effect and related influencing factors remain unclear and have not been comprehensively synthesized yet. To fill this research gap, we conducted a systematic literature review using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) method with 20 keywords and their combinations in Web of Science to address 3 main research questions: (1) what is the cooling range of urban forests; (2) what are the factors that may affect the cooling effects; and (3) how can we better manage urban forests to optimize cooling effects? We systematically reviewed 73 peer-reviewed articles selected from an initial pool of 4,072 search results following the PRISMA method. We found that urban greenspaces generally have cooling effects, but it is challenging to draw a clear conclusion on the cooling range due to variation in study design, measurement approaches, spatial scales, and local climate contexts. Moreover, the main influencing factors include land cover compositions, tree cover and canopy structures, leaf area index, forest types and tree species, and spatial arrangements of urban vegetation. Additionally, the cooling benefits of urban forests might be affected by local background climate and weather conditions, as well as distances from water bodies. These findings can help guide urban greening efforts (e.g., land cover types, tree species selection, and spatial arrangements) to achieve a greener and cooler future.

Background: Hurricanes and other wind events are significant disturbances that affect coastal urban forests around the world. Past research has led to the creation of wind resistance ratings for different tree species which can be used in urban forest management efforts to mitigate the effects of these storms. While useful, these ratings have been limited to species common to one global region (Florida, USA).Methods: Drawing on past ratings and data from a global literature review on tropical storm research, we created a machine learning model to broaden both the geographic coverage and the variety of species currently assessed for their resistance to wind.Results: We were able to assign wind resistance ratings to 281 new species based on the available data and our modelling efforts. The model accuracy and agreement with the original ratings when applied to the testing data set was high with 91% accuracy.Conclusions: The resulting list of wind resistance ratings has been adapted into a spreadsheet-based decision aid for managers, allowing them to assess the overall susceptibility of their urban forest to wind events like hurricanes.

Urban forests are essential green infrastructure for sustainable cities. However, existing studies are mainly focused on the general public’s perception and needs of urban forestry, and little is known about non-traditional educators like extension agents. To address this gap, the main objective of this study is to explore extension agents’ perceptions, practices, and future training needs. Specifically, a statewide online survey consisting of 33 questions was designed and disseminated to extension agents in Tennessee via email with 64 responses. We found that the majority of respondents valued urban forestry, with 68.9% of them believing that urban forests are very important, especially for providing shade, cooling, energy saving, aesthetic values/beautification, increasing property values, and wildlife habitat and biodiversity. Their main clientele includes homeowners, farmers, and landowners, and 63.3% of extension agents reported that they have received urban forestry-related requests. However, less than half of them are comfortable addressing these requests, and over 50% of them reported that they are slightly or not knowledgeable about urban forestry. Additionally, the interest in urban forestry is high, with 98.3% of respondents having some level of interest in urban forestry. This demonstrates great potential for urban forestry education, extension, and training in the region.