Urban Trees Enhance Water Infiltration
A group of researchers from Virginia Tech, Cornell, andUniversity of California at Davis have been investigatinginnovative ways to maximize the potential of trees to addressstormwater in a series of studies supported by the U.S. ForestService’s Urban and Community Forestry Grants Program.
Virginia Tech scientists used two container experiments to establish that urban tree roots have the potential to penetrate compacted subsoils and increase infiltration rates in reservoirs being used to store stormwater. In one study, roots of both black oak and red maple trees penetrated clay loam soil compacted to 1.6 g cm-3, increasing infiltration rates by an average of 153%.
In another experiment, researchers created a small-scale version of the stormwater best management practice (BMP) under study by the three universities. This BMP includes a below-pavement stormwater detention reservoir constructed of structural soil. Structural soils are engineered mixes designed to both support pavement loads and simultaneously provide rooting space for trees. In this study, green ash trees increased the average infiltration rate by 27 fold compared with unplanted controls. In the experiment, a structural soil reservoir (CUSoil, Amereq Corp., New York) was separated from compacted clay loam subsoil (1.6 g cm-3) by a woven geotextile in 102-liter containers. The roots of ash trees planted in the structural soil penetrated both the geotextile and the subsoil within two years.
[from article]ScienceDaily
November 2008
ScienceDaily
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Stormwater Management, Soil Properties, Hydrology, Rooting Area
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