title: Transpiration and root development of urban trees in structural soil stormwater reservoirs.
abstract: Stormwater management that relies on ecosystem processes, such as tree canopy interception and rhizosphere biology, can be difficult to achieve in built environments because urban land is costly and urban soil inhospitable to vegetation. Yet such systems offer a potentially valuable tool for achieving both sustainable urban forests and stormwater management. We evaluated tree water uptake and root distribution in a novel stormwater mitigation facility that integrates trees directly into detention reservoirs under pavement. The system relies on structural soils: highly porous engineered mixes designed to support tree root growth and pavement. To evaluate tree performance under the peculiar conditions of such a stormwater detention reservoir (i.e., periodically inundated), we grew green ash (Fraxinus pennsylvanica Marsh.) and swamp white oak (Quercus bicolor Willd.) in either CUSoil or a Carolina Stalite-based mix subjected to three simulated below-system infiltration rates for two growing seasons. Infiltration rate affected both transpiration and rooting depth. In a factorial experiment with ash, rooting depth always increased with infiltration rate for Stalite, but this relation was less consistent for CUSoil. Slow-drainage rates reduced transpiration and restricted rooting depth for both species and soils, and trunk growth was restricted for oak, which grew the most in moderate infiltration. Transpiration rates under slow infiltration were 55% (oak) and 70% (ash) of the most rapidly transpiring treatment (moderate for oak and rapid for ash). We conclude this system is feasible and provides another tool to address runoff that integrates the function of urban green spaces with other urban needs.
authors.affiliation: Department of Horticulture, Virginia Tech, Blacksburg, 24061, USA. jbartens@vt.edu
authors.forename: Julia
authors.initials: J
authors.lastname: Bartens
authors.forename: Susan D
authors.initials: SD
authors.lastname: Day
authors.forename: J Roger
authors.initials: JR
authors.lastname: Harris
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Wynn
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Dove
mesh_terms: D002947:Cities; D004779:Environment Design; D005374:Filtration; D016062:Porosity; D011891:Rain; D014197:Trees; D014872:Water Movements; D014876:Water Pollution / Q000517:prevention & control*
references.citation: Environ Manage. 2006 May;37(5):589-605
references.pmid: 16508805
references.citation: J Environ Qual. 2008 Oct 23;37(6):2048-57
references.pmid: 18948457
references.citation: Environ Manage. 2006 Sep;38(3):338-49
references.pmid: 16752045
references.citation: Tree Physiol. 2000 Mar;20(4):257-263
references.pmid: 12651462
references.citation: Science. 2005 Jul 22;309(5734):570-4
references.pmid: 16040698
references.citation: Plant Physiol. 1980 Aug;66(2):267-71
references.pmid: 16661419
references.citation: Environ Manage. 2005 Dec;36(6):808-25
references.pmid: 16215652
references.citation: J Environ Qual. 2006 Oct 27;35(6):2123-31
references.pmid: 17071881
references.citation: Environ Manage. 2007 Aug;40(2):183-200
references.pmid: 17557170