Introduction: Grass species may acquire different forms of nitrogen (N) to reduce competition for the same resources. Climate change influences the availability of soil N and is therefore likely to cause shifts in N forms acquired by plants, thereby affecting their competitive interactions. Methods: We investigated the effects of warming on the uptake of different N forms and competitive interactions of Festuca ovina and Anthoxanthum odoratum in a pot experiment. The plants were grown either in monocultures or mixture, and at ambient or elevated temperature (+10 °C), and supplied with 13C and 15N isotopes to test for treatment effects on the relative uptake of ammonium, alanine or tri-alanine. Results: Both grass species took up relatively more N supplied as ammonium than as alanine or tri-alanine when grown under ambient conditions in monoculture. In contrast, when grown in mixtures, F. ovina took up the three supplied N forms in equal amounts, whereas A. odoratum switched to tri-alanine as the main N form. Under warmed conditions, both species took up the N forms equally, irrespective of competition treatments. Conclusions: We have shown that grass species grown in mixture and under ambient conditions reduce competition by acquiring different N forms. Warming increased the availability of inorganic N in the soil and therefore deregulated the need for differential uptake of N forms.
CITATION STYLE
Kuster, T. M., Wilkinson, A., Hill, P. W., Jones, D. L., & Bardgett, R. D. (2016). Warming alters competition for organic and inorganic nitrogen between co-existing grassland plant species. Plant and Soil, 406(1–2), 117–129. https://doi.org/10.1007/s11104-016-2856-7
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