Maryland Today | A unique weapon in rainwater management: Urban…

It’s hard to overstate the environmental importance of trees, which, among other functions, remove climate change-inducing carbon from the atmosphere, purify the air of toxins, and help control runoff.

While it may also be difficult to quantify some of these effects, a new study by researchers at the University of Maryland is helping to clarify the role of urban trees in mitigating stormwater flows, and finds that even isolated trees lining a street or planted in a park can have a significant effect.

A study published yesterday in the newspaper Scientific reports by Assistant Professor Mitch Pavao-Zuckerman and PhD student Sara Ponte, both from the Department of Environmental Science and Technology, discovered that individually planted trees capture, store, and release stormwater into the atmosphere – a process called “transpiration” – at a rate of three times that of trees in a forest. The study was conducted in partnership with the US Forest Service and the nonprofit Center for Watershed Protection, with funding from the Chesapeake Bay Trust.

The publication explores how trees work in different urban contexts, from streets to small patches of forest – knowledge that can help support the management of green infrastructure, including the growing practice of tracking the environmental service provided by trees to calculate the storm water or other charges assessed by municipalities.

“Our data can help ensure that tree credit policies better reflect the real benefits of trees in cityscapes, as they interact with water and their environment differently in cities than outside cities.” , did he declare. “Our next step is to take this dataset of how each tree is functioning and scale it to see how an entire stand or patch of trees dampens stormwater flows.”

Pavao Zuckerman’s team measured transpiration in three separate urban settings: isolated trees on grass and a cluster of trees on grass in Montgomery County, and a closed canopy forest in Baltimore. They built and used sap flow sensors to get a clearer picture of how trees access groundwater, installing them in 18 mature red maples to continuously monitor transpiration rates during the growing season. They also measured soil water content, air temperature, relative humidity and precipitation at each site.

“Quantifying the impacts of urban trees affects different parts of the water balance, such as the evapotranspiration component discussed in the article by Mitch and Sarah, allows us to better understand the benefits of urban trees and to know where and how to plant and plant them. preserve to get the greatest benefit. said Deb Caraco, senior watershed engineer at the Center for Watershed Protection.

Pavao-Zuckerman said the results can serve as guidelines for managers of urban stormwater runoff, and that the current method of relying on data collected from non-urban locations to determine the effect of urban trees should be abandoned.

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