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Leaf functional response to increasing atmospheric CO 2 concentrations over the last century in two northern Amazonian tree species: a historical δ 13 C and δ 18 O approach using herbarium samples
Author(s) -
BONAL DAMIEN,
PONTON STÉPHANE,
LE THIEC DIDIER,
RICHARD BÉATRICE,
NINGRE NATHALIE,
HÉRAULT BRUNO,
OGÉE JÉRÔME,
GONZALEZ SOPHIE,
PIGNAL MARC,
SABATIER DANIEL,
GUEHL JEANMARC
Publication year - 2011
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2011.02333.x
Subject(s) - rainforest , stomatal conductance , isotopes of carbon , photosynthesis , δ13c , stomatal density , botany , biology , tropical rainforest , stable isotope ratio , horticulture , ecology , total organic carbon , physics , quantum mechanics
We assessed the extent of recent environmental changes on leaf morphological (stomatal density, stomatal surface, leaf mass per unit area) and physiological traits (carbon isotope composition, δ 13 C leaf , and discrimination, Δ 13 C leaf , oxygen isotope composition, δ 18 O leaf ) of two tropical rainforest species ( Dicorynia guianensis ; Humiria balsamifera ) that are abundant in the Guiana shield (Northern Amazonia). Leaf samples were collected in different international herbariums to cover a 200 year time‐period (1790–2004) and the whole Guiana shield. Using models describing carbon and oxygen isotope fractionations during photosynthesis, different scenarios of change in intercellular CO 2 concentrations inside the leaf ( C i ), stomatal conductance ( g ), and photosynthesis ( A ) were tested in order to understand leaf physiological response to increasing air CO 2 concentrations ( C a ). Our results confirmed that both species displayed physiological response to changing C a . For both species, we observed a decrease of about 1.7‰ in δ 13 C leaf since 1950, without significant change in Δ 13 C leaf and leaf morphological traits. Furthermore, there was no clear change in δ 18 O leaf for Humiria over this period. Our simulation approach revealed that an increase in A , rather than a decrease in g , explained the observed trends for these tropical rainforest species, allowing them to maintain a constant ratio of C i / C a .