Optimum air temperature for tropical forest photosynthesis: mechanisms involved and implications for climate warming

Tan, Zheng-Hong; Zeng, Jiye; Zhang, Yong‐Jiang; Slot, Martijn; Gamo, Minoru; Hirano, Takashi; Kosugi, Yukio; Rocha, Humberto Ribeiro da; Saleska, S. R.; Goulden, Michael L.; Wofsy, Steven C.; Miller, S. D.; Manzi, A. O.; Nobre, Antônio Donato; Camargo, P. B. D.; Restrepo‐Coupe, Natalia

doi:10.1088/1748-9326/aa6f97

Cited by 61 publications

(77 citation statements)

References 49 publications

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“…In the case of Dacryodes excelsa at the wet tropical field site, A opt was significantly lower (4.9 µmol CO 2 m −1 s −2 ) than that of the tropical moist species (average 9.8 µmol CO 2 m −1 s −2 ) and Acer saccharum (7.3 µmol CO 2 m −1 s −2 ) in the temperate forest (Table 2). Even though A opt was much lower for our study's tropical wet species than the temperate forest, due to the ability to photosynthesize year-round, net canopy photosynthesis may actually be higher in tropical forests [38,97,98].…”

Section: Relationships Between Optimal Temperatures For Photosynthesimentioning

confidence: 68%

“…Recent evidence suggests that lowland tropical forests, which are already consistently warm throughout the year, may already be operating close to their photosynthetic thermal optima, beyond which carbon uptake declines [5,22,[34][35][36][37][38]. Due to greater diurnal, seasonal, and inter-annual variability in temperature in temperate ecosystems, the range of temperature from ambient to T opt will likely be greater in temperate species and therefore these high latitude species may not be operating as close to their thermal thresholds as tropical species [25,32,[39][40][41].…”

Section: Introductionmentioning

confidence: 99%

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Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis

Mau

Reed

Wood³

et al. 2018

Forests

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Tropical tree species have evolved under very narrow temperature ranges compared to temperate forest species. Studies suggest that tropical trees may be more vulnerable to continued warming compared to temperate species, as tropical trees have shown declines in growth and photosynthesis at elevated temperatures. However, regional and global vegetation models lack the data needed to accurately represent such physiological responses to increased temperatures, especially for tropical forests. To address this need, we compared instantaneous photosynthetic temperature responses of mature canopy foliage, leaf temperatures, and air temperatures across vertical canopy gradients in three forest types: tropical wet, tropical moist, and temperate deciduous. Temperatures at which maximum photosynthesis occurred were greater in the tropical forests canopies than the temperate canopy (30 ± 0.3 • C vs. 27 ± 0.4 • C). However, contrary to expectations that tropical species would be functioning closer to threshold temperatures, photosynthetic temperature optima was exceeded by maximum daily leaf temperatures, resulting in sub-optimal rates of carbon assimilation for much of the day, especially in upper canopy foliage (>10 m). If trees are unable to thermally acclimate to projected elevated temperatures, these forests may shift from net carbon sinks to sources, with potentially dire implications to climate feedbacks and forest community composition.

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Section: Relationships Between Optimal Temperatures For Photosynthesimentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis

Mau

Reed

Wood³

et al. 2018

Forests

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“…While we could use a model to adjust our measurements to the 25°C convention, we prefer to report the standard temperature that was in fact used. All measurements were made at a leaf temperature of 31°C, which is close to optimal for net photosynthesis (Lloyd & Farquhar, ; Slot & Winter, ; Tan et al., ; Tribuzy, ). We report both photosynthesis and dark respiration at this leaf temperature.…”

Section: Methodsmentioning

confidence: 99%

Causes of reduced leaf‐level photosynthesis during strong El Niño drought in a Central Amazon forest

Santos

Ferreira

Rodrigues

et al. 2018

Global Change Biology

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Sustained drought and concomitant high temperature may reduce photosynthesis and cause tree mortality. Possible causes of reduced photosynthesis include stomatal closure and biochemical inhibition, but their relative roles are unknown in Amazon trees during strong drought events. We assessed the effects of the recent (2015) strong El Niño drought on leaf-level photosynthesis of Central Amazon trees via these two mechanisms. Through four seasons of 2015, we measured leaf gas exchange, chlorophyll a fluorescence parameters, chlorophyll concentration, and nutrient content in leaves of 57 upper canopy and understory trees of a lowland terra firme forest on well-drained infertile oxisol. Photosynthesis decreased 28% in the upper canopy and 17% in understory trees during the extreme dry season of 2015, relative to other 2015 seasons and was also lower than the climatically normal dry season of the following non-El Niño year. Photosynthesis reduction under extreme drought and high temperature in the 2015 dry season was related only to stomatal closure in both upper canopy and understory trees, and not to chlorophyll a fluorescence parameters, chlorophyll, or leaf nutrient concentration. The distinction is important because stomatal closure is a transient regulatory response that can reverse when water becomes available, whereas the other responses reflect more permanent changes or damage to the photosynthetic apparatus. Photosynthesis decrease due to stomatal closure during the 2015 extreme dry season was followed 2 months later by an increase in photosynthesis as rains returned, indicating a margin of resilience to one-off extreme climatic events in Amazonian forests.

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“…Moreover, the photosynthetic temperature response is controlled not only by the photosynthetic biochemistry, but also by stomatal and respiratory processes. Sensitivity analysis suggests that all three component processes are equally important in determining the T optA at leaf scale (Lin et al, 2012) as well as at canopy scale (Tan et al, 2017) but none of the previous review studies addressed how the latter two components affected T optA .…”

Section: Introductionmentioning

confidence: 99%

Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale

et al. 2019

Self Cite

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Summary The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common‐garden datasets, respectively. The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

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Optimum air temperature for tropical forest photosynthesis: mechanisms involved and implications for climate warming

Cited by 61 publications

References 49 publications

Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis

Temperate and Tropical Forest Canopies are Already Functioning beyond Their Thermal Thresholds for Photosynthesis

Causes of reduced leaf‐level photosynthesis during strong El Niño drought in a Central Amazon forest

Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale

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