Conceptual Framework for Human Drivers of Low Tree Diversity in Urban Landscapes

Keywords: urban forestry, tree diversity, urban landscapes, human actors
Session Type: Virtual Paper Abstract
Day: Friday
Session Start / End Time: 2/25/2022 09:40 AM (Eastern Time (US & Canada)) - 2/25/2022 11:00 AM (Eastern Time (US & Canada))
Room: Virtual 39

Abstract

With more than half of the world’s population now living in urban areas and some countries, such as the United States, exceeding 80% urbanized, there is increasing interest and need to incorporate trees as green infrastructure to make cities healthier and more livable. Despite the immense diversity of tree species worldwide, only a limited number of species dominate urban spaces. In the US, the average community relies on just six species for a majority (61.5%) of park and street trees (Ma et al. 2020). A global assessment of 108 public tree inventories found that a single species accounted for 20% of a city’s tree populations (Lohr et al. 2016). Low species diversity makes a community’s urban forest less resilient in the face of abiotic and biotic pressures and may result in staggering financial and functional losses if dominant species are affected. The human drivers of low species diversity include many actors: horticultural researchers, nursery producers, policy makers and planners, property developer, landscape consultants, urban foresters, homeowners, and more. We have proposed a conceptual framework that explores the selection process that narrows species diversity, the human actors involved at each level of decision making, the spatial scales and urban landscape types affected, and finally direct and indirect effects of various actors. This framework may be used to develop additional research aimed at multi-actor and systemic questions that may address the “diversity funnel” that leaves our urban forests vulnerable to threats stemming from low tree diversity.