Plant and soil lipid modifications under elevated atmospheric CO2 conditions: I. Lipid distribution patterns

摘要

Grassland soils are regarded as one potential sink for atmospheric CO2 via photosynthetic fixation in plant biomass and subsequent transformation into soil organic matter upon degradation. In the future, an enrichment in atmospheric CO2 concentration is expected, leading to modified photosynthetic activity in plant biomass. Free air CO2 enrichment (FACE) experiments provide an opportunity for investigating under field conditions plant behaviour expected under future atmospheric composition. Lipid components are important constituents of plant surfaces, whereby their position at the plant/ atmosphere interface leads to a high susceptibility towards environmental change. The main focus of this study was an investigation of the modification in lipid distribution patterns within plant biomass and the translocation of these lipids towards, and fixation within, soil organic matter as a result of enhanced CO2 concentration. We demonstrate which lipids are mainly influenced under modified CO2 concentrations and show how this affects the lipid composition of plant biomass and soil. Carboxylic acid, alcohol and aliphatic hydrocarbon distribution patterns of plant biomass and soils are discussed. While short chain acids reveal a uniform depletion in unsaturated C-18 acids in plants and soils under enhanced CO2 concentration, the alcohol fraction shows diverse trends for Lolium perenne and Trifolium repens plants and soil. Long chain alcohols increase in abundance for L. perenne and decrease for T repens samples. The n-alkanes in soil, as degradation products of plant-derived acids and alcohols, exhibit minor compositional variation. Decreasing amounts of plant-derived acids vs. increasing concentrations of alcohols are noted for T repens samples. The study demonstrates the response on the molecular level of selected plants under enhanced atmospheric CO2 concentration. Lipid compositional variation is modified by photosynthetic activity and adapted biosynthesis under future atmospheric conditions may be expected. (c) 2007 Elsevier Ltd. All rights reserved.