Premium
The effects on Arbutus unedo L. of long‐term exposure to elevated CO 2
Author(s) -
JONES M.B.,
BROWN J. CLIFTON,
RASCHI A.,
MIGLIETTA F.
Publication year - 1995
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.1995.tb00028.x
Subject(s) - stomatal conductance , evergreen , sclerophyll , carbon dioxide , photosynthesis , photoinhibition , chemistry , chlorophyll fluorescence , transpiration , horticulture , botany , mediterranean climate , environmental chemistry , biology , ecology , photosystem ii , organic chemistry
Arbutus unedo is a sclerophyllous evergreen, characteristic of Mediterranean coastal scrub vegetation. In Italy, trees of A. unedo have been found close to natural CO 2 vents where the mean atmospheric carbon dioxide concentration is about 2200 μmol mol −1 . Comparisons were made between trees growing in elevated and ambient CO 2 concentrations to test for evidence of adaptation to long‐term exposure to elevated CO 2 . Leaves formed at elevated CO 2 have a lower stomatal density and stomatal index and higher specific leaf area than those formed at ambient CO 2 , but there was no change in carbon to nitrogen ratios of the leaf tissue. Stomatal conductance was lower at elevated CO 2 during rapid growth in the spring. In mid‐summer, under drought stress, stomatal closure of all leaves occurred and in the autumn, when stress was relieved, the conductance of leaves at both elevated and ambient CO 2 increased. In the spring, the stomatal conductance of the new flush of leaves at ambient CO 2 was higher than the leaves at elevated CO 2 , increasing instantaneous water use efficiency at elevated CO 2 . Chlorophyll fluorescence measurements suggested that elevated CO 2 provided some protection against photoinhibition in mid‐summer. Analysis of A/C i curves showed that there was no evidence of either upward or downward regulation of photosynthesis at elevated CO 2 . It is therefore anticipated that A. unedo will have higher growth rates as the ambient CO 2 concentrations increase.