Intersecting urban forestry and botanical gardens to address big challenges for healthier trees, people, and cities

Societal Impact Statement The need for urban greening increases with global urbanization. Trees are major assets to livable urban areas, providing valuable environmental services to combat challenges such as pollution, urban heat, and flooding, as well as to improve social cohesion, human health, and well-being. Investments in tree planting and arboriculture yield valuable returns, but trees face many challenges in the unnatural and stressful urban environment and in a rapidly changing climate. Botanical gardens have expertise in growing plants in designed landscapes. We urge their increased involvement with urban forestry to improve sustainability of cities and human lives. Summary Improving urban forests is one of the solutions to achieving several of the United Nations Sustainable Development Goals and making cities healthier and more livable for people. Priority should be given to protecting mature trees and promoting long-lived trees in the future. Achievement of this goal requires recognition of the myriad stresses trees face in built landscapes as well as the challenges related to climate change. Because all people living in communities are affected by the urban forest, developing solutions and forestry action plans should be a social endeavor and include diverse partnerships. Botanical gardens and arboreta can provide key resources in support of these efforts. They have a significant public reach, maintain a strong professional network, and can make important contributions to address key priorities including (a) protecting existing trees; (b) improving tree selection, diversity, and age structure; and (c) improving planning, standards, training, and management. A focus on below-ground aspects, such as root development and soil composition, is a critical component for success. Horticultural and scientific knowledge combined with extensive public reach make botanical gardens and arboreta important potential partners in achieving urban forest objectives, but a greater call to action is needed.