Sources of nitrogen to the riparian zone of a desert stream: Implications for riparian vegetation and nitrogen retention

John D. Schade, Eugenia Marti, Jill R. Welter, Stuart G. Fisher, Nancy Grimm

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Riparian zones effectively remove nitrogen (N) from water flowing through riparian soils, particularly in agricultural watersheds. The mechanism of N removal is still unclear, especially the role of vegetation. Uptake and denitrification are the two most commonly studied mechanisms. Retention of groundwater N by plant uptake is often inferred from measurements of N in net incremental biomass. However, this assumes other sources of N are not contributing to the N demand of plants. The purpose of this work was to investigate the relative importance of three sources of available N to riparian trees in a desert stream - input in stream water during floods, input during baseflow, and mineralization of N from soil organic matter. Two approaches were used; a mass balance approach in which the mass of available N from each source was estimated, and a correlational approach in which indexes of each source were compared to leaf N for individual willow trees. Total N from all sources was 396 kg ha-1 y-1, with 172 kg ha-1 y-1 from mineralization, 214 kg ha-1 y-1 from the stream during baseflow, and 9.6 kg ha-1 y-1 from floods. Leaf N was significantly related to N mineralization rates and flood inputs; it was not related to baseflow inputs. We conclude that mineralization is a major source of available N for willow trees, subsidized by input of N from floods. Baseflow inputs are most likely removed by rapid denitrification at the stream-riparian edge, while higher rates of flood supply exceed the capacity of this "filter".

Original languageEnglish (US)
Pages (from-to)68-79
Number of pages12
JournalEcosystems
Volume5
Issue number1
DOIs
StatePublished - Jan 2002

Fingerprint

riparian vegetation
riparian zone
riparian areas
deserts
baseflow
Nitrogen
desert
mineralization
vegetation
nitrogen
Salix
Denitrification
denitrification
riparian soils
Soils
agricultural watersheds
Water
Watersheds
Biological materials
soil organic matter

Keywords

  • Denitrification
  • Desert stream
  • N mineralization
  • Nitrogen retention
  • Plant uptake
  • Riparian zone

ASJC Scopus subject areas

  • Ecology

Cite this

Sources of nitrogen to the riparian zone of a desert stream : Implications for riparian vegetation and nitrogen retention. / Schade, John D.; Marti, Eugenia; Welter, Jill R.; Fisher, Stuart G.; Grimm, Nancy.

In: Ecosystems, Vol. 5, No. 1, 01.2002, p. 68-79.

Research output: Contribution to journalArticle

Schade, John D. ; Marti, Eugenia ; Welter, Jill R. ; Fisher, Stuart G. ; Grimm, Nancy. / Sources of nitrogen to the riparian zone of a desert stream : Implications for riparian vegetation and nitrogen retention. In: Ecosystems. 2002 ; Vol. 5, No. 1. pp. 68-79.
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