Currently, 56% of the world's population inhabits urban areas that are exposed to numerous environmental stressors such as air pollution, higher temperatures, noise, and greenhouse gas emissions. These stressors collectively affect the quality of life for city residents. These stresses are expected to increase with rising temperatures caused by climate change and projected increases in urban population. Average air temperatures in cities can be 1°C to 3°C higher than in nearby rural areas due to massive energy consumption and heat generation by urban infrastructure and geometry. Therefore, urgent measures are needed to mitigate and adapt to these stressful conditions.

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Increasing tree canopy cover is considered an efficient tool to improve living conditions for city residents, by reducing energy consumption, reducing air pollution, and by increasing overall well-being. Trees reduce local temperatures and heat index by shading and transpiration. To achieve these benefits, healthy trees with functioning hydraulic systems and a positive carbon balance are needed. However, urban trees face many abiotic and biotic stressors that are exacerbated by climate change, which threaten their functionality, productivity, and survival.

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The survival rate of newly planted trees is only 10-20% of their lifespan in natural conditions, mainly due to poor habitat, species-site discrepancy, and/or bad management (e.g., poor irrigation, pruning timing, soil quality, etc.). Urban trees also face stressors such as constrained rooting depth, soil volume and sunlight, high temperatures, and VPD. These stressors not only lead to early tree mortality but also reduce trees' ability to cool local temperatures.

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​The goal of the Urban Tree Ecophysiology Network (UTEN) is to establish an international collaboration platform for urban trees’ ecophysiology, below and aboveground, including multiple stakeholders, municipalities governments, and research institutions.