Tree Mortality Undercuts Ability of Tree-Planting Programs to Provide Benefits: Results of a Three-City Study

Abstract

Trees provide numerous benefits for urban residents, including reduced energy usage, improved air quality, stormwater management, carbon sequestration, and increased property values. Quantifying these benefits can help justify the costs of planting trees. In this paper, we use i-Tree Streets to quantify the benefits of street trees planted by nonprofits in three U.S. cities (Detroit, Michigan; Indianapolis, Indiana, and Philadelphia, Pennsylvania) from 2009 to 2011. We also use both measured and modeled survival and growth rates to "grow" the tree populations 5 and 10 years into the future to project the future benefits of the trees under different survival and growth scenarios. The 4059 re-inventoried trees (2864 of which are living) currently provide almost $40,000 (USD) in estimated annual benefits ($9-$20/tree depending on the city), the majority (75%) of which are increased property values. The trees can be expected to provide increasing annual benefits during the 10 years after planting if the annual survival rate is higher than the 93% annual survival measured during the establishment period. However, our projections show that with continued 93% or lower annual survival, the increase in annual benefits from tree growth will not be able to make up for the loss of benefits as trees die. This means that estimated total annual benefits from a cohort of planted trees will decrease between the 5-year projection and the 10-year projection. The results of this study indicate that without early intervention to ensure survival of planted street trees, tree mortality may be significantly undercutting the ability of tree-planting programs to provide benefits to neighborhood residents.

The Biodiversity of Urban and Peri-Urban Forests and the Diverse Ecosystem Services They Provide as Socio-Ecological Systems

“…Widney et al [8] examine the growth and survival of urban tree planting initiatives in three US cities (Detroit, Indianapolis, and Philadelphia) to model the expected ecosystem service benefits 5 and 10 years in the future. The news is not good, because the current (and accepted) levels of planted tree mortality in these three cities means that these new tree planting initiatives cannot keep up with concurrent mortality and the loss of the larger "legacy" trees already in the urban landscape.…”

“…The news is not good, because the current (and accepted) levels of planted tree mortality in these three cities means that these new tree planting initiatives cannot keep up with concurrent mortality and the loss of the larger "legacy" trees already in the urban landscape. Widney et al [8] make a plea for improved and early intervention measures to raise tree survival rates in those crucial establishment years, so that the social, ecological, and ecosystem service benefits these trees were planted to maintain, if not increase, can be realised.…”

Health and Establishment of Highway Plantings in Florida (United States)

“…Urban tree growth and longevity has gained greater attention from researchers and practitioners in recent years [1][2][3][4][5][6], including those looking to increase long-term ecosystem services through planting initiatives [1,7,8]. In addition to documented benefits like improved human health [9], increased tourism [10], building energy conservation [11], and storm water management [12], urban trees provide transportation corridor-specific benefits such as improved driver mentality [13], enhanced roadway definition [14], and slowed asphalt degradation through shading [15].…”

Revisión y evaluación técnico-económica de los sistemas de micro - riego usados en repoblación forestal

“…Otros trabajos (Sander et al, 2010;Saphores y Li, 2012) calculan la elasticidad-precio de la demanda, obteniendo en espacios verdes abiertos y públicos (Brander y Coetse, 2011) efectos similares. Un último grupo de estudios (Widney et al, 2016) hallan el beneficio anual por árbol urbano, en el rango de 8,91 a 15,70 $2016 para varias ciudades en Estados Unidos. A partir de esos datos y de la entrada en producción, e = 10 años, Widney et al (2016) plantean un modelo para determinar el valor de ALF, que estiman del 7% en su caso de estudio.…”

“…Un último grupo de estudios (Widney et al, 2016) hallan el beneficio anual por árbol urbano, en el rango de 8,91 a 15,70 $2016 para varias ciudades en Estados Unidos. A partir de esos datos y de la entrada en producción, e = 10 años, Widney et al (2016) plantean un modelo para determinar el valor de ALF, que estiman del 7% en su caso de estudio. Como consecuencia de él, concluyen la necesidad de realizar actuaciones tempranas para garantizar al menos ese nivel de supervivencia en los árboles que forman parte de la infraestructura verde urbana.…”