Construction and Proactive Management Led to Tree Removals on an Urban College Campus

Abstract

Urban trees in lawns and along streets are anthropogenically constructed systems, in that these tree communities are formed by human planting and removal actions. Tree mortality studies are essential to understanding the temporal dynamism of urban forests, and in particular, it is critical to incorporate institutional records and human decision-making regarding tree removals. In this study, we investigated tree removals on a highly urbanized college campus in Philadelphia, Pennsylvania (US) by analyzing field inventories and institutional records, and by considering firsthand accounts of the University Landscape Architect. The annual mortality rate was 4.3%, higher than typical for comparable studies, which we attribute to construction pressure and proactive management to promptly remove unhealthy trees and manage risk. Capital projects and other construction caused 48.5% of all removals, other human land use decisions caused 2.0%, and tree health decline and risk management collectively accounted for 48.7%. The number of removed trees exactly equaled the number of new trees, and the campus has high taxonomic diversity, reflecting the extensive oversight by university tree and landscape professionals regarding tree removal and planting decisions. This study demonstrates the value of mixed-methods and transdisciplinary research to understand how urban forests change over time.

Conceptualizing the human drivers of low tree diversity in planted urban landscapes

“…Trees in the planted urban landscape (as opposed to trees in urban forest natural areas) are subject to intensive human control over species composition and community structure, with trees typically arising from planting decisions with minimal natural regeneration (Roman et al 2014;Roman et al 2022). The planted urban landscape includes trees along streets, in parking lots, and other hardscape settings, as well as trees in lawns and other manicured ground cover at neighborhood parks, institutional settings, and residential landscapes (van Doorn et al 2020).…”

Greening development: Reducing urban tree canopy loss through incentives

“…Land development and redevelopment are significant factors in urban tree canopy loss (Hill et al, 2010;Croeser et al, 2020;Roman et al, 2022). Mitigating the pressures and impacts of development on urban trees is a top issue for urban forestry experts (Wirtz et al, 2021).…”

“…Developers are key influencers of tree canopy as planners, financers, and builders in and around urban areas, both currently and historically (Maruani and Amit-Cohen, 2011;Roman & Eisenman, 2022). While some developers recognize the benefits of trees (Despot and Gerhold, 2003;Kellogg et al, 2017) and follow regulatory requirements (Maruani and Amit-Cohen, 2011), rapid urbanization and redevelopment often result in trees being prematurely removed (Hilbert et al, 2019;Roman et al, 2022) and insufficiently replanted (Croeser et al, 2020;Romero, 2021;Conway et al, 2022).…”

Perceptual Differences of Tree Removal in Development Areas Among Landscape Professionals

“…As a result, a significant number of trees are removed on properties undergoing redevelopment compared to undeveloped ones (Guo et al, 2018). As tree removal is costly (Roman et al, 2022), factor influencing tree removal decisions include the tree-related characteristics, particularly the size of trees (Croeser et al, 2020;Guo et al, 2018;Morgenroth et al, 2017) and the health of trees (Conway, 2016;Guo et al, 2019). For instance, large trees require technical support and specialised equipment (Guo et al, 2018).…”

“…For instance, large trees require technical support and specialised equipment (Guo et al, 2018). Another reason for removal is poor tree health or risk perception, such as concerns about the dangers of falling branches or trees (Conway, 2016;Roman et al, 2022). According to Morton (2006), a tree in good health and condition and with a long-life expectancy is considered the optimal choice for retention on a development site.…”