A Non-Native Riparian Tree (<Emphasis Type="Italic">Elaeagnus angustifolia</Emphasis>) Changes Nutrient Dynamics in Streams |
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Authors: | Madeleine M Mineau Colden V Baxter Amy M Marcarelli |
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Institution: | (1) Stream Ecology Center, Department of Biological Sciences, Idaho State University, 921 S 8th Ave, Stop 8007, Pocatello, Idaho 83209-8007, USA;(2) Present address: Department of Biological Sciences, Michigan Technological University, 1400 Townsend Dr., Dow 740, Houghton, Michigan 49931, USA |
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Abstract: | Russian olive (Elaeagnus angustifolia) is a non-native riparian tree that has become common and continues to rapidly spread throughout the western United States.
Due to its dinitrogen (N2)-fixing ability and proximity to streams, Russian olive has the potential to subsidize stream ecosystems with nitrogen (N),
which may in turn alter nutrient processing in these systems. We tested these potential effects by comparing background N
concentrations; nutrient limitation of biofilms; and uptake of ammonium (NH4-N), nitrate (NO3-N), and phosphate (PO4-P) in paired upstream-reference and downstream-invaded reaches in streams in southeastern Idaho and central Wyoming. We found
that stream reaches invaded by Russian olive had higher organic N concentrations and exhibited reduced N limitation of biofilms
compared to reference reaches. However, at low inorganic N background concentrations, reaches invaded by Russian olive exhibited
higher demand for both NH4-N and NO3-N compared to their paired reference reaches, suggesting these streams have the potential to retain the N subsidy from Russian
olive N2 fixation and diminish its downstream export and effects. Our findings demonstrate the potential for a non-native riparian
plant to significantly alter biogeochemical cycling in streams. Finally, we used our results to develop a conceptual model
that describes predicted effects of Russian olive and other non-native riparian N2 fixers on in-stream N dynamics. |
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