title: The effects of oxalates produced by Salsola tragus on the phosphorus nutrition of Stipa pulchra.
abstract: Oxalic acid is produced by some species of plants and mycorrhizal fungi and it may solubilize unavailable soil phosphorus (P) bound by cations (Ca++, Al++, Fe+++). Field and greenhouse experiments were conducted to show whether oxalate produced by the annual Salsola tragus or added oxalic acid would solubilize P from the inorganic-bound soil P pool, making it available for uptake by Stipa pulchra. Oxalate could be leached in the laboratory from the senescent canopy of Salsola, and leaching by rainfall was hypothesized to be a source of potential increased soil P under the Salsola canopy. Both oxalate leached from the canopy of Salsola and added oxalic acid increased the availability of soil P in greenhouse experiments. The source of the increase in available soil P in the greenhouse experiment was shown to be the inorganic-bound P pool, as the total P concentration of the soil decreased with increasing oxalate. There were significant increases in Stipa shoot P in response to Salsola leachates and in response to added oxalate in the greenhouse studies. These results suggest an important role for oxalate in P cycling. On disturbed sites where Salsola invades it may act to facilitate the establishment of later seral species like Stipa by creating a nutrient island of available P.
authors.affiliation: Department of Biology, San Diego State University, 92182-0057, San Diego, CA, USA.|Systems Ecology Research Group, San Diego State University, 92182-0057, San Diego, CA, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Cannon
authors.affiliation: Department of Botany and Plant Sciences, University of California, 92521-0124, CA, Riverside, USA.
authors.forename: E B
authors.initials: EB
authors.lastname: Allen
authors.affiliation: Department of Biology, San Diego State University, 92182-0057, San Diego, CA, USA.|Systems Ecology Research Group, San Diego State University, 92182-0057, San Diego, CA, USA.
authors.forename: M F
authors.initials: MF
authors.lastname: Allen
authors.affiliation: Department of Plants, Soils, and Biometeorology, Utah State University, 84322-4820, Logan, UT, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Dudley
authors.affiliation: Department of Plants, Soils, and Biometeorology, Utah State University, 84322-4820, Logan, UT, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Jurinak
keywords: Facilitation; Oxalate Phosphorus; Salsola tragus; Stipa pulchra