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Do plant species with different growth strategies vary in their ability to compete with soil microbes for chemical forms of nitrogen?

Harrison, Kathryn A. and Bol, Roland and Bardgett, Richard D. (2008) Do plant species with different growth strategies vary in their ability to compete with soil microbes for chemical forms of nitrogen? Soil Biology and Biochemistry, 40 (1). pp. 228-237. ISSN 0038-0717

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Abstract

We used dual labelled stable isotope (13C and 15N) techniques to examine how grassland plant species with different growth strategies vary in their ability to compete with soil microbes for different chemical forms of nitrogen (N), both inorganic and organic. We also tested whether some plant species might avoid competition by preferentially using different chemical forms of N than microbes. This was tested in a pot experiment where monocultures of five co-existing grassland species, namely the grasses Agrostis capillaris, Anthoxanthum odoratum, Nardus stricta, Deschampsia flexuosa and the herb Rumex acetosella, were grown in field soil from an acid semi-natural temperate grassland. Our data show that grassland plant species with different growth strategies are able to compete effectively with soil microbes for most N forms presented to them, including inorganic N and amino acids of varying complexity. Contrary to what has been found in strongly N limited ecosystems, we did not detect any differential uptake of N on the basis of chemical form, other than that shoot tissue of fast-growing plant species was more enriched in 15N from ammonium-nitrate and glycine, than from more complex amino acids. Shoot tissue of slow-growing species was equally enriched in 15N from all these N forms. However, all species tested, least preferred the most complex amino acid phenylalanine, which was preferentially used by soil microbes. We also found that while fast-growing plants took up more of the added N forms than slow-growing species, this variation was not related to differences in the ability of plants to compete with microbes for N forms, as hypothesised. On the contrary, we detected no difference in microbial biomass or microbial uptake of 15N between fast and slow-growing plant species, suggesting that plant traits that regulate nutrient capture, as opposed to plant species-specific interactions with soil microbes, are the main factor controlling variation in uptake of N by grassland plant species. Overall, our data provide insights into the interactions between plants and soil microbes that influence plant nitrogen use in grassland ecosystems.

Item Type: Article
Journal or Publication Title: Soil Biology and Biochemistry
Uncontrolled Keywords: Amino acids ; Grassland ; Organic nitrogen ; Inorganic nitrogen ; Microbial biomass ; Plant-microbial competition ; Stable isotopes ; Growth strategies ; Nitrogen
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 31346
Deposited By: Mr Richard Ingham
Deposited On: 11 Jan 2010 12:14
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 16:56
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/31346

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