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The Potential Role of Urban Forests in Removing Nutrients from Stormwater
Author(s) -
Denman E. C.,
May P. B.,
Moore G. M.
Publication year - 2016
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2015.01.0047
Subject(s) - stormwater , biofilter , environmental science , surface runoff , nutrient , soil water , vegetation (pathology) , agronomy , environmental engineering , ecology , biology , soil science , medicine , pathology
Biofiltration systems can be used to improve the quality of stormwater by treating runoff using plants grown in a moderately permeable soil. Most biofilters use herbaceous species, but in highly urbanized locations, such as streets, trees may be a more suitable vegetation. Biofilters that use urban woody vegetation are less studied. This experiment investigated the use of four street tree species [ Eucalyptus polyanthemos Schauer, Lophostemon confertus (R. Br.) Peter G. Wilson & J.T. Waterh., Callistemon salignus (Sm.) Colvill ex Sweet, and Platanus orientalis L.] and an unplanted control in model biofilters. All four tree species are used in urban landscapes in southern Australia and were chosen to investigate potential species differences in biofiltration systems. The trees were grown in mesocosms as a randomized block factorial design in soils with three saturated hydraulic conductivity rates (4, 95, and 170 mm h ‐1 ). The trees were regularly flooded with mains water (tap water) or artificial stormwater. Tree growth and nutrient removal performance of the systems were investigated over 13 mo. All four species grew well in all three soils, including one chosen for its low, and potentially growth‐limiting, drainage rate. Tree growth increased significantly, except for E. polyanthemos , when flooded with stormwater. Unplanted controls were a source of nutrients; however, the presence of trees reduced oxidized nitrogen and filterable reactive phosphorus concentrations in leachate. There was little effect of species on the removal of nutrients from stormwater. Trees have the potential to be effective elements in urban biofiltration systems, but further field‐level evaluation of these systems is required to fully assess this potential. Core Ideas Street trees reduced N and P concentrations compared with unplanted profiles. Street trees receiving stormwater generally grew larger. Differences between tree species in nutrient removal performance were not large. It is relatively easy to reduce P in leachate, while nitrogen is more difficult. Organic matter addition to biofiltration soils is not recommended.