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1.
Plant Cell Environ ; 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-39101396

RESUMO

Photosynthetic acclimation to both warming and elevated CO2 of boreal trees remains a key uncertainty in modelling the response of photosynthesis to future climates. We investigated the impact of increased growth temperature and elevated CO2 on photosynthetic capacity (Vcmax and Jmax) in mature trees of two North American boreal conifers, tamarack and black spruce. We show that Vcmax and Jmax at a standard temperature of 25°C did not change with warming, while Vcmax and Jmax at their thermal optima (Topt) and growth temperature (Tg) increased. Moreover, Vcmax and Jmax at either 25°C, Topt or Tg decreased with elevated CO2. The Jmax/Vcmax ratio decreased with warming when assessed at both Topt and Tg but did not significantly vary at 25°C. The Jmax/Vcmax increased with elevated CO2 at either reference temperature. We found no significant interaction between warming and elevated CO2 on all traits. If this lack of interaction between warming and elevated CO2 on the Vcmax, Jmax and Jmax/Vcmax ratio is a general trend, it would have significant implications for improving photosynthesis representation in vegetation models. However, future research is required to investigate the widespread nature of this response in a larger number of species and biomes.

2.
Nat Commun ; 14(1): 4667, 2023 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-37537190

RESUMO

Warming shifts the thermal optimum of net photosynthesis (ToptA) to higher temperatures. However, our knowledge of this shift is mainly derived from seedlings grown in greenhouses under ambient atmospheric carbon dioxide (CO2) conditions. It is unclear whether shifts in ToptA of field-grown trees will keep pace with the temperatures predicted for the 21st century under elevated atmospheric CO2 concentrations. Here, using a whole-ecosystem warming controlled experiment under either ambient or elevated CO2 levels, we show that ToptA of mature boreal conifers increased with warming. However, shifts in ToptA did not keep pace with warming as ToptA only increased by 0.26-0.35 °C per 1 °C of warming. Net photosynthetic rates estimated at the mean growth temperature increased with warming in elevated CO2 spruce, while remaining constant in ambient CO2 spruce and in both ambient CO2 and elevated CO2 tamarack with warming. Although shifts in ToptA of these two species are insufficient to keep pace with warming, these boreal conifers can thermally acclimate photosynthesis to maintain carbon uptake in future air temperatures.


Assuntos
Ecossistema , Temperatura Alta , Larix , Picea , Aquecimento Global , Picea/crescimento & desenvolvimento , Picea/metabolismo , Dióxido de Carbono/metabolismo , Fotossíntese , Larix/crescimento & desenvolvimento , Larix/metabolismo
3.
AoB Plants ; 13(5): plab059, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34646435

RESUMO

Plant ecophysiology is founded on a rich body of physical and chemical theory, but it is challenging to connect theory with data in unambiguous, analytically rigorous and reproducible ways. Custom scripts written in computer programming languages (coding) enable plant ecophysiologists to model plant processes and fit models to data reproducibly using advanced statistical techniques. Since many ecophysiologists lack formal programming education, we have yet to adopt a unified set of coding principles and standards that could make coding easier to learn, use and modify. We identify eight principles to help in plant ecophysiologists without much programming experience to write resilient code: (i) standardized nomenclature, (ii) consistency in style, (iii) increased modularity/extensibility for easier editing and understanding, (iv) code scalability for application to large data sets, (v) documented contingencies for code maintenance, (vi) documentation to facilitate user understanding; (vii) extensive tutorials and (viii) unit testing and benchmarking. We illustrate these principles using a new R package, {photosynthesis}, which provides a set of analytical and simulation tools for plant ecophysiology. Our goal with these principles is to advance scientific discovery in plant ecophysiology by making it easier to use code for simulation and data analysis, reproduce results and rapidly incorporate new biological understanding and analytical tools.

5.
New Phytol ; 231(6): 2395-2397, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34405908
6.
Tree Physiol ; 41(12): 2341-2358, 2021 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-34077546

RESUMO

Climate warming is increasing the frequency of climate-induced tree mortality events. While drought combined with heat is considered the primary cause of this mortality, little is known about whether moderately high temperatures alone can induce mortality, or whether rising CO2 would prevent mortality at high growth temperatures. We grew tamarack (Larix laricina) under ambient (400 p.p.m.) and elevated (750 p.p.m.) CO2 concentrations combined with ambient, ambient +4 °C and ambient +8 °C growth temperatures to investigate whether high growth temperatures lead to carbon (C) limitations and mortality. Growth at +8 °C led to 40% mortality in the ambient CO2 (8TAC) treatment, but no mortality in the elevated CO2 treatment. Thermal acclimation of respiration led to similar leaf C balances across the warming treatments, despite a lack of photosynthetic acclimation. Photosynthesis was stimulated under elevated CO2, increasing seedling growth, but not leaf C concentrations. However, growth and foliar C concentrations were lowest in the +8 °C treatments, even with elevated CO2. Dying 8TAC seedlings had lower needle C concentrations and lower ratios of photosynthesis to respiration than healthy 8TAC seedlings, indicating that C limitations were likely the cause of seedling mortality under high growth temperatures.


Assuntos
Larix , Aclimatação , Dióxido de Carbono/farmacologia , Desidratação , Resposta ao Choque Térmico , Fotossíntese , Folhas de Planta , Temperatura
7.
New Phytol ; 231(6): 2371-2381, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-32805755

RESUMO

Understanding biological temperature responses is crucial to predicting global carbon fluxes. The current approach to modelling temperature responses of photosynthetic capacity in large scale modelling efforts uses a modified Arrhenius equation. We rederived the modified Arrhenius equation from the source publication from 1942 and uncovered a missing term that was dropped by 2002. We compare fitted temperature response parameters between the correct and incorrect derivation of the modified Arrhenius equation. We find that most parameters are minimally affected, though activation energy is impacted quite substantially. We then scaled the impact of these small errors to whole plant carbon balance and found that the impact of the rederivation of the modified Arrhenius equation on modelled daily carbon gain causes a meaningful deviation of c. 18% day-1 . This suggests that the error in the derivation of the modified Arrhenius equation has impacted the accuracy of predictions of carbon fluxes at larger scales since > 40% of Earth System Models contain the erroneous derivation. We recommend that the derivation error be corrected in modelling efforts moving forward.


Assuntos
Carbono , Fotossíntese , Ciclo do Carbono , Dióxido de Carbono , Modelos Biológicos , Folhas de Planta , Temperatura
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