While a true forest is rare in urban environments, trees are common where buildings and asphalt dominate the landscape. Cities parks often feature wooded areas, but trees also line streets lined and stand in courtyards or landscaped areas near buildings. Water shapes how these trees function in cities. From establishing new trees to managing stormwater, urban forestry plays a role in healthier communities.

Understanding these connections helps communities reduce flooding, improve water quality, and support healthier urban ecosystems.

Urban forestry specialists pay close attention to two major relationships between trees and water: how young trees rely on consistent watering, and how mature canopies influence the movement of water through cities. Eric Wiseman, associate professor of urban forestry in the Department of Forest Resources and Environmental Conservation, says both factors are central to how urban forests function.

For newly planted trees, water is the lifeline that determines whether they survive long enough to benefit the community.

“Water is absolutely critical for establishing trees that we newly plant,” Wiseman said. “We need a reliable source of water and means to water trees to get them through that initial establishment period.”

Wiseman said mature urban forests influence the entire hydrologic system. He described tree canopies as “scruffy umbrellas” that intercept rainfall before it hits hard surfaces.

“A lot of that rain stays in the canopy,” he said.

This reduces stormwater runoff, limits flash flooding, and helps protect streams and rivers from erosion and pollution because leaves, branches, and bark capture moisture that later evaporates rather than flowing into storm drains.

Soil around trees allows water to soak in rather than run across pavement, helping filter pollutants and maintain a more natural water cycle.

As communities grow, understanding how trees slow and store water will remain essential for building resilient cities.

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