Ecosystems

, Volume 9, Issue 2, pp 254–267

Spring-water Nitrate Increased with Removal of Livestock Grazing in a California Oak Savanna

Authors

    • Department of AgronomyUniversity of Wisconsin-Madison
  • Barbara Allen-Diaz
    • Ecosystem SciencesUniversity of California, Berkeley
  • Lawrence G. Oates
    • Ecosystem SciencesUniversity of California, Berkeley
  • Kenneth W. Tate
    • Department of Agronomy and Range ScienceUniversity of California, Davis
Article

DOI: 10.1007/s10021-005-0166-7

Cite this article as:
Jackson, R.D., Allen-Diaz, B., Oates, L.G. et al. Ecosystems (2006) 9: 254. doi:10.1007/s10021-005-0166-7

Abstract

We characterized spatial and temporal changes in nitrate concentrations of the leachate from annual grasslands and subsequently emergent spring-waters and tested the effect of livestock grazing removal on them. Nitrate patterns indicated that annual grassland soils are a likely N source to spring-fed wetlands, which appear to intercept and transform N along its hydrologic path from upland soils to spring-fed, headwater streams. Aboveground biomass and soil N extractions suggested that removal of livestock grazing from these wetlands impaired this function by allowing dead plant material to accumulate inhibiting plant production (hence, plant N demand), resulting in elevated stream-water nitrate (NO3) concentrations. Nitrous oxide (N2O) fluxes indicated that grazing removal may increase the relative importance of this N-loss pathway. Microbial biomass varied with season but was not affected by grazing treatments suggesting that N2O losses were related to differences in NO3 availability rather than grazing effects on microbial community composition or their activity. Spring-fed wetlands provide important ecosystem services such as plant uptake and denitrification at transition zones between terrestrial and aquatic ecosystems. These N-retention and transformation functions may be enhanced through biomass harvesting by livestock.

Keywords

water qualitywetlandsnitrogen losslivestock grazingmixed effects modeling, Mediterranean ecosystems

Copyright information

© Springer Science+Business Media, Inc. 2006