Investment vs. Returns for Healthy Urban Trees: Lifecycle Cost Analysis
Posted on Jul 30, 2017 | DeepRoot Green Infrastructure, LLC; The Kestrel Design Group, Inc.
Innovative techniques, such as suspended pavement, can extend rooting volume under HS-20 load bearing surfaces and create favorable tree growing conditions in urban areas. While such techniques do involve higher up-front costs, they enable trees to grow to their mature size and provide the stormwater and ecological benefits commensurate with mature trees. This analysis investigates how the initial investment into suspended pavement pays off over the long term in light of the ecological and stormwater benefits provided by large mature trees.
Mature trees can contribute significantly to healthier soil, air, and water in cities. According to the US Forest Service, a large tree with a trunk diameter 10 times larger than a small tree produces 60-70 times the ecological services (McPherson et al, 1994). But cities are not typically hospitable places for plant growth so trees seldom live long enough to reach maturity and provide meaningful ecological services. Studies have found that trees surrounded by pavement in most urban downtown centers in North America only live for an average of 13 years (Skiera and Moll, 1992). This short lifespan deprives the areas most in need - the built environment - of the myriad benefits that trees can provide.
Innovative techniques, such as suspended pavement, can extend rooting volume under HS-20 load bearing surfaces and create favorable tree growing conditions in urban areas. While such techniques do involve higher up-front costs, they enable trees to grow to their mature size and provide the stormwater and ecological benefits commensurate with mature trees. This analysis investigates how the initial investment into suspended pavement pays off over the long term in light of the ecological and stormwater benefits provided by large mature trees.