Abstract
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) .
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Claims 8
Claim · model-written summary
Dicorynia guianensis leaf δ13C decreased by about 1.7‰ since 1950 under rising atmospheric CO2.
- Taxon
- Dicorynia guianensis
Dicorynia guianensise0 - Treatment
- increasing atmospheric CO2 concentrationst0
- Outcome
- δ(13)C(leaf)e1
- Direction
- decreasee1
- Value
- about 1.7‰e1
- Qualifier
- since 1950e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“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”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Humiria balsamifera leaf δ13C decreased by about 1.7‰ since 1950 under rising atmospheric CO2.
- Taxon
- Humiria balsamifera
Humiria balsamiferae0 - Treatment
- increasing atmospheric CO2 concentrationst0
- Outcome
- δ(13)C(leaf)e1
- Direction
- decreasee1
- Value
- about 1.7‰e1
- Qualifier
- since 1950e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“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”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Dicorynia guianensis showed no significant change in leaf Δ13C or leaf morphological traits.
- Taxon
- Dicorynia guianensisDicorynia guianensise0
- Outcome
- Δ(13)C(leaf) and leaf morphological traitse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“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”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Humiria balsamifera showed no significant change in leaf Δ13C or leaf morphological traits.
- Taxon
- Humiria balsamiferaHumiria balsamiferae0
- Outcome
- Δ(13)C(leaf) and leaf morphological traitse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“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”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Humiria balsamifera leaf δ18O showed no clear change since 1950.
- Taxon
- Humiria balsamiferaHumiria balsamiferae0
- Outcome
- δ(18)O(leaf)e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“there was no clear change in δ(18)O(leaf) for Humiria over this period”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Simulation indicated that an increase in photosynthesis rather than a decrease in stomatal conductance explained the observed leaf trends of the tropical rainforest species.
Verbatim
e3“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)”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
Simulation indicated that the tropical rainforest species maintained a constant ratio of Ci/Ca.
Verbatim
e3“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)”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”
Claim · model-written summary
The tropical rainforest species displayed a physiological response to changing atmospheric CO2 concentration.
Verbatim
e4“Our results confirmed that both species displayed physiological response to changing C(a)”
e0“two tropical rainforest species (Dicorynia guianensis; Humiria balsamifera)”
t0“Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species”