Urban Ecosystems

, Volume 15, Issue 1, pp 195–214 | Cite as

Water sources of urban trees in the Los Angeles metropolitan area

  • Neeta S. BijoorEmail author
  • Heather R. McCarthy
  • Dachun Zhang
  • Diane E. Pataki


In semi-arid cities, urban trees are often irrigated, but may also utilize natural water sources such as groundwater. Consequently, the sources of water for urban tree transpiration may be uncertain, complicating efforts to efficiently manage water resources. We used a novel approach based on stable isotopes to determine tree water sources in the Los Angeles basin, where we hypothesized that trees would rely on irrigation water in the soil rather than develop deep roots to tap into groundwater. We evaluated the oxygen (δ18O) and hydrogen (δD) isotope ratios of xylem water, irrigation water, soil water, and groundwater in a study of temporal patterns in water sources at two urban sites, and a study of spatial patterns at nine urban sites and one “natural” riparian forest. Contrary to our hypothesis, we found that despite frequent irrigation, some trees tap into groundwater, although in most species this was a small water source. Some trees appeared to be using very shallow soil water at <30 cm depth, suggesting that these mature urban trees were quite shallowly rooted. In the natural site, trees appeared to be using urban runoff in addition to shallow soil water. We were able to identify tree uptake of precipitation at only 3 sites. The results show that some irrigated trees utilize groundwater and do not rely solely on irrigation water, which may make them able to withstand drought and/or water conservation measures. However, some irrigated trees may develop very shallow root systems, which may make them more susceptible.


Tree water sources Urban forest Ecohydrology Irrigation Stable isotopes 



We thank UC Irvine Facilities Management, the City of Los Angeles Urban Forestry Division, the Los Angeles Zoo and Botanical Gardens, The Los Angeles County Arboretum and Botanic Garden, the Los Angeles Police Academy, and the Starr Ranch Audubon Sanctuary for access to their properties. Ibrahima Diallo, Gabriel Giannini, and Eric Sun provided valuable assistance with field sampling and laboratory analyses. We thank Dr. Theodore von Bitner of the Orange County Public Works Department and Vivian Marquez, Jonathan Ball, and Bryan Truong of the Pollution Assessment Section of the City of Los Angeles, Watershed Protection Division, Bureau of Sanitation for help with groundwater sampling. This research was funded by the U.S. National Science Foundation grant 0624342, EPA Star grant RD-83336401-0, and a U.S. National Science Foundation Graduate Research Fellowship.


  1. Akbari H (2002) Shade trees reduce building energy use and CO2 emissions from power plants. Environ Pollut 116:S119–S126PubMedCrossRefGoogle Scholar
  2. Allison GB (1982) The relationship between 18O and deuterium in water in sand columns undergoing evaporation. J Hydrol 55:163–169CrossRefGoogle Scholar
  3. Allison GB, Hughes MW (1983) The use of natural tracers as indicators of soil-water movement in a temperate semi-arid region. J Hydrol 60:157–173CrossRefGoogle Scholar
  4. Bowen GJ, Ehleringer JR, Chesson LA, Stange E, Cerling TE (2007) Stable isotope ratios of tap water in the contiguous United States. Water Resour Res 43Google Scholar
  5. Brunel JP, Walker GR, Kennettsmith AK (1995) Field validation of isotopic procedures for determining sources of water used by plants in a semiarid environment. J Hydrol 167:351–368CrossRefGoogle Scholar
  6. Busch DE, Ingraham NL, Smith SD (1992) Water-uptake in woody riparian phreatophytes of the southwestern United States - a stable isotope study. Ecol Appl 2:450–459CrossRefGoogle Scholar
  7. Bush SE, Pataki DE, Hultine KR, West AG, Sperry JS, Ehleringer JR (2008) Wood anatomy constrains stomatal responses to atmospheric vapor pressure deficit in irrigated, urban trees. Oecologia 156:13–20PubMedCrossRefGoogle Scholar
  8. Canadell J, Jackson RB, Ehleringer JR, Mooney HA, Sala OE, Schulze ED (1996) Maximum rooting depth of vegetation types at the global scale. Oecologia 108:583–595CrossRefGoogle Scholar
  9. Clark I, Fritz P (1997) Environmental isotopes in hydrogeology. Lewis, Boca RatonGoogle Scholar
  10. Corbin JD, Thomsen MA, Dawson TE, D’Antonio CM (2005) Summer water use by California coastal prairie grasses: fog, drought, and community composition. Oecologia 145:511–521PubMedCrossRefGoogle Scholar
  11. Dansgaard W (1964) Stable isotopes in precipitation. Tellus 16:436–468CrossRefGoogle Scholar
  12. Dawson TE, Mambelli S, Plamboeck AH, Templer PH, Tu KP (2002) Stable isotopes in plant ecology. Ann Rev Ecol Syst 33:507–559CrossRefGoogle Scholar
  13. Day SD, Bassuk NL (1994) A review of the effects of soil compaction and amelioration treatments on landscape trees. J Arboriculture 20:9–17Google Scholar
  14. DWR (2003) California’s Groundwater, Bulletin 118 - Update 2003. California Department of Water Resources (DWR)Google Scholar
  15. Ellsworth P, Williams D (2007) Hydrogen isotope fractionation during water uptake by woody xerophytes. Plant Soil 291:93–107CrossRefGoogle Scholar
  16. Gat JR (1996) Oxygen and hydrogen isotopes in the hydrologic cycle. Annu Rev Earth Pl Sc 24:225–262CrossRefGoogle Scholar
  17. Gat JR, Matsui E (1991) Atmospheric water-balance in the Amazon Basin - an isotopic evapotranspiration model. J Geophys Res-Atmos 96:13179–13188CrossRefGoogle Scholar
  18. Gehre M, Geilmann H, Richter J, Werner RA, Brand WA (2004) Continuous flow 2H/1H and 18O/16O analysis of water samples with dual inlet precision. Rapid Commun Mass Sp 18:2650–2660CrossRefGoogle Scholar
  19. Gilman EF, Leone IA, Flower FB (1987) Effect of soil compaction and oxygen content on vertical and horizontal root distribution. J Environ Hort 5:33–36Google Scholar
  20. Gleick PH, Haasz D, Henges-Jeck C, Srinivasan V, Wolff G, Kao Cushing K, Mann A (2003) Waste not, want not: the potential for urban water conservation in California. Pacific Institute, OaklandGoogle Scholar
  21. Grabosky J, Gilman E (2004) Measurement and prediction of tree growth reduction from tree planting space design in established parking lots. J Arboriculture 30:154–164Google Scholar
  22. Kendall C, Coplen TB (2001) Distribution of oxygen-18 and deuterium in river waters across the United States. Hydrol Process 15:1363–1393CrossRefGoogle Scholar
  23. McCarthy HR, Pataki DE (2010) Drivers of variability in water use of native and non-native urban trees in the greater Los Angeles area. Urban Ecosyst 13:393–414CrossRefGoogle Scholar
  24. McPherson G, Simpson JR, Peper PJ, Maco SE, Xiao QF (2005) Municipal forest benefits and costs in five US cities. J Forest 103:411–416Google Scholar
  25. Mueller EC, Day TA (2005) The effect of urban ground cover on microclimate, growth and leaf gas exchange of oleander in Phoenix, Arizona. Int J Biometeorol 49:244–255PubMedCrossRefGoogle Scholar
  26. Nowak D, Dwyer J (2007) Understanding the Benefits and Costs of Urban Forest Ecosystems. 586 In: Urban and Community Forestry in the Northeast, pp 25-46Google Scholar
  27. Nowak DJ, Crane DE, Stevens JC (2006) Air pollution removal by urban trees and shrubs in the United States. Urban For Urban Green 4:115–123CrossRefGoogle Scholar
  28. Ortega-Guerrero A, Cherry JA, Aravena R (1997) Origin of pore water and salinity in the lacustrine aquitard overlying the regional aquifer of Mexico City. J Hydrol 197:47–69CrossRefGoogle Scholar
  29. Pataki DE, McCarthy HR, Litvak E, Pincetl S (2011) Transpiration of urban forests in the Los Angeles metropolitan area. Ecol ApplGoogle Scholar
  30. Phillips DL, Gregg JW (2001) Uncertainty in source partitioning using stable isotopes. Oecologia 127:171–179CrossRefGoogle Scholar
  31. Renée Brooks J, Barnard HR, Coulombe R, McDonnell JJ (2009) Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nat Geosci 3:100–104CrossRefGoogle Scholar
  32. Rhymer JM, Simberloff D (1996) Extinction by hybridization and introgression. Ann Rev Ecol Syst 27:83–109CrossRefGoogle Scholar
  33. Schenk HJ, Jackson RB (2002) The global biogeography of roots. Ecol Monogr 72:311–328CrossRefGoogle Scholar
  34. Schenk HJ, Jackson RB (2005) Mapping the global distribution of deep roots in relation to climate and soil characteristics. Geoderma 126:129–140CrossRefGoogle Scholar
  35. Tang KL, Feng XH (2001) The effect of soil hydrology on the oxygen and hydrogen isotopic compositions of plants’ source water. Earth Planet Sc Lett 185:355–367CrossRefGoogle Scholar
  36. Wang J, Endreny TA, Nowak DJ (2008) Mechanistic simulation of tree effects in an urban water balance model. J Am Water Resour As 44:75–85CrossRefGoogle Scholar
  37. West AG, Patrickson SJ, Ehleringer JR (2006) Water extraction times for plant and soil materials used in stable isotope analysis. Rapid Commun Mass Sp 20:1317–1321CrossRefGoogle Scholar
  38. Williams AE (1997) Stable isotope tracers: natural and anthropogenic recharge, Orange County, California. J Hydrol 201:230–248CrossRefGoogle Scholar
  39. Williams AE, Rodoni DP (1997) Regional isotope effects and application to hydrologic investigations in southwestern California. Water Resour Res 33:1721–1729CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Neeta S. Bijoor
    • 1
    • 2
    Email author
  • Heather R. McCarthy
    • 1
  • Dachun Zhang
    • 1
  • Diane E. Pataki
    • 1
    • 3
  1. 1.Department of Earth System Science, Croul HallUniversity of CaliforniaIrvineUSA
  2. 2.University of California Center for Hydrologic ModelingIrvineUSA
  3. 3.Department of Ecology and Evolutionary Biology, Steinhaus HallUniversity of CaliforniaIrvineUSA

Personalised recommendations