How robust is the evidence for beneficial hydrological effects of urban tree planting?

Henry J Baker,Michael G Hutchins,James D Miller

doi:10.1080/02626667.2021.1922692

Henry J Baker, Michael G Hutchins + Show 1 more

Open Access

https://doi.org/10.1080/02626667.2021.1922692

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Abstract

ABSTRACT Sustainable urban water management initiatives are increasingly required to combat rapid urbanization and climate pressures. Initiatives include the role of tree planting, for which there is a need for strong evidence of benefits and drawbacks to support effective future planning. We report on the robustness of evidence from an assimilated database of urban hydrological impact studies which often had differing primary purposes. Consistent impacts were found at the local level, with trees reducing runoff and infiltration. Despite the consistency of evidence, much is undermined by the studies being somewhat lacking in robustness and scientific rigour. Many studies lack adequate controls, and models are often not strongly tested against observations. Moreover, evidence of impact at larger scales is lacking. Effects of tree characteristics were also investigated, such as maturity and species (for which evidence is consistent and detailed) and arrangement (for which there is less evidence). Realizing the full potential of trees in urban water management decision-making would benefit from more rigorous evidence.

Highlights

1.1 Urban water managementThere is growing pressure on urban water management (UWM), exacerbated by population growth, climate change and the deterioration of current urban infrastructure systems
The aim of the present study is to evaluate the impacts of urban tree planting on hydrology
3.1 Type, spatial extent and outcome/population of study Studies on urban tree planting and the impacts on hydrology have become more common over the last few years

Summary

Introduction

There is growing pressure on urban water management (UWM), exacerbated by population growth, climate change and the deterioration of current urban infrastructure systems. As Romano and Akhmouch (2019) point out, there is currently no “one size fits all” approach to UWM. This is a concept that varies significantly with context, and there is an increasing need for more widely applicable approaches to solving these issues of UWM (Hurlimann et al 2017). Degrading water quality and increased urban flooding are among the concerns for UWM, in conjunction with both population growth and climate change (Miller and Hutchins 2017)

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