title: The effect of elevated CO2concentration and nutrient supply on carbon-based plant secondary metabolites in Pinus sylvestris L.
abstract: This study investigated changes in carbon-based plant secondary metabolite concentrations in the needles of Pinus sylvestris saplings, in response to long-term elevation of atmospheric CO2, at two rates of nutrient supply. Experimental trees were grown for 3 years in eight open-top chambers (OTCs), four of which were maintained at ambient (∼350 μmol mol-1) and four at elevated (700 μmol mol-1) CO2concentrations, plus four open air control plots. Within each of these treatments, plants received either high (7.0 g N m-2year-1added) or low (no nutrients added) rates of nutrient supply for two years. Needles from lateral branches were analysed chemically for concentrations of condensed tannins and monoterpenes. Biochemical determinations of cellulase digestibility and protein precipitating capacity of their phenolic extracts were made because of their potential of importance in ecological interactions between pine and other organisms including herbivores and decomposers. Elevated CO2concentration caused an increase (P<0.05) in dry mass per needle, tree height and the concentration of the monoterpene α-pinene, but there were no direct effects of CO2concentration on any of the other chemical measurements made. High nutrient availability increased cellulase digestibility of pine needles. There was a significant negative effect of the OTCs on protein precipitating capacity of the needle extracts in comparison to the open-air controls. Results suggest that predicted changes in atmospheric CO2concentration will be insufficient to produce large changes in the concentration of condensed tannins and monoterpenes in Scots pine. Processes which are influenced by these compounds, such as decomposition and herbivore food selection, along with their effects on ecosystem functioning, are therefore unlikely to be directly affected through changes in these secondary metabolites.
authors.affiliation: MLURI, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK Fax: (0) 1224 311556; email: g.iason@mluri.sari.ac.uk, , , , , , GB.
authors.forename: C J
authors.initials: CJ
authors.lastname: Heyworth
authors.affiliation: MLURI, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK Fax: (0) 1224 311556; email: g.iason@mluri.sari.ac.uk, , , , , , GB.
authors.forename: G R
authors.initials: GR
authors.lastname: Iason
authors.affiliation: Institute of Ecology and Resource Management, University of Edinburgh, Darwin building, Edinburgh EH9 3JU, UK, , , , , , GB.
authors.forename: V
authors.initials: V
authors.lastname: Temperton
authors.affiliation: Institute of Ecology and Resource Management, University of Edinburgh, Darwin building, Edinburgh EH9 3JU, UK, , , , , , GB.
authors.forename: P G
authors.initials: PG
authors.lastname: Jarvis
authors.affiliation: MLURI, Craigiebuckler, Aberdeen AB15 8QH, Scotland, UK Fax: (0) 1224 311556; email: g.iason@mluri.sari.ac.uk, , , , , , GB.
authors.forename: A J
authors.initials: AJ
authors.lastname: Duncan
keywords: Elevated CO2; Key words Carbon-nutrient balance; Pinus sylvestris L.; Tannins; Terpenes