Effect of elevated CO₂ on carbon partitioning in young Quercus ilex L. during resprouting

Abstract

Stored carbon (C) represents a very important C pool with residence times of years to decades in tree organic matter. With the objective of understanding C assimilation, partitioning and remobilization in 2‐year‐old Quercus ilex L., those trees were exposed for 7 months to different [CO2] (elevated: 700 µmol mol−1; and ambient: 350 µmol mol−1 CO2). The 13C‐isotopic composition of the ambient CO2 (ca. −12.8‰) was modified (to ca. −19.2‰) under the elevated CO2 conditions in order to analyze C allocation and partitioning before aerial biomass excision, and during the following regrowth (resprouting). Although after 7 months of growth under elevated [CO2], Q. ilex plants increased dry matter production, the absence of significant differences in photosynthetic activity suggests that such an increase was lower than expected. Nitrogen availability was not involved in photosynthetic acclimation. The removal of aboveground organs did not enable the balance between C availability and C requirements to be achieved. The isotopic characterization revealed that before the cutting, C partitioning to the stem (main C sink) prevented leaf C accumulation. During regrowth the roots were the organ with more of the labelled C. Furthermore, developing leaves had more C sink strength than shoots during this period. After the cutting, the amount of C delivered from the root to the development of aboveground organs exceeded the requirements of leaves, with the consequent carbohydrate accumulation. These findings demonstrate that, despite having a new C sink, the responsiveness of those resprouts under elevated [CO2] conditions will be strongly conditioned by the plant's capacity to use the extra C present in leaves through its allocation to other organs (roots) and processes (respiration). Copyright © 2011 John Wiley & Sons, Ltd.

Increased sink capacity enhances C and N assimilation under drought and elevated CO2 conditions in maize

“…Instead, the source of C remobilization varied among species. An increase in the C remobilization has been demonstrated in young Quercus ilex L. and was mostly derived from roots (Aranjuelo et al 2011b).…”

BMSS ISO‐SIG (27–28 April), SIMSUG 2010 (28–30 April) and SIBAE (28–29 April 2010), University of Exeter, UK

“…Hence, there appears to be a strong coupling of climate responses in carbon and nitrogen cycling at this temperate heath ecosystem. Aranjuelo et al (paper not presented at the meeting) reported on the finding that, despite having a new C sink, the responsiveness of young Quercus ilex L. resprouts under elevated [CO 2 ] conditions will be strongly conditioned by the plant's capacity to use the extra C present in leaves through its allocation to other organs (roots) and processes (respiration). Gómez‐Muñoz et al determined the gross and net rates of nitrogen mineralisation in soil amended with composted olive mill pomace (COMP; a waste product from the olive oil industry).…”