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Summary: The Kok and Laisk techniques can both be used to estimate light respiration Rlight. We investigated whether responses of Rlight to short‐ and long‐term changes in leaf temperature depend on the technique used to estimate Rlight.We grew Eucalyptus tereticornis in whole‐tree chambers under ambient temperature (AT) or AT + 3°C (elevated temperature, ET). We assessed dark respiration Rdark and light respiration with the Kok (RKok) and Laisk (RLaisk) methods at four temperatures to determine the degree of light suppression of respiration using both methods in AT and ET trees.The ET treatment had little impact on Rdark, RKok or RLaisk. Although the thermal sensitivities of RKok or RLaisk were similar, RKok was higher than RLaisk. We found negative values of RLaisk at the lowest measurement temperatures, indicating positive net CO2 uptake, which we propose may be related to phosphoenolpyruvate carboxylase activity. Light suppression of Rdark decreased with increasing leaf temperature, but the degree of suppression depended on the method used.The Kok and Laisk methods do not generate the same estimates of Rlight or light suppression of Rdark between 20 and 35°C. Negative rates of RLaisk imply that this method may become less reliable at low temperatures. [ABSTRACT FROM AUTHOR]

Impacts of climate warming depend on the degree to which plants are constrained by adaptation to their climate-of-origin or exhibit broad climatic suitability. We grew cool-origin, central and warm-origin provenances of Eucalyptus tereticornis in an array of common temperature environments from 18 to 35.5°C to determine if this widely distributed tree species consists of geographically contrasting provenances with differentiated and narrow thermal niches, or if provenances share a common thermal niche. The temperature responses of photosynthesis, respiration, and growth were equivalent across the three provenances, reflecting a common thermal niche despite a 2,200 km geographic distance and 13°C difference in mean annual temperature at seed origin. The temperature dependence of growth was primarily mediated by changes in leaf area per unit plant mass, photosynthesis, and whole-plant respiration. Thermal acclimation of leaf, stem, and root respiration moderated the increase in respiration with temperature, but acclimation was constrained at high temperatures. We conclude that this species consists of provenances that are not differentiated in their thermal responses, thus rejecting our hypothesis of adaptation to climate-of-origin and suggesting a shared thermal niche. In addition, growth declines with warming above the temperature optima were driven by reductions in whole-plant leaf area and increased respiratory carbon losses. The impacts of climate warming will nonetheless vary across the geographic range of this and other such species, depending primarily on each provenance's climate position on the temperature response curves for photosynthesis, respiration, and growth. [ABSTRACT FROM AUTHOR]

Understanding physiological acclimation of photosynthesis and respiration is important in elucidating the metabolic performance of trees in a changing climate. Does physiological acclimation to climate warming mirror acclimation to seasonal temperature changes?, We grew Eucalyptus tereticornis trees in the field for 14 months inside 9-m tall whole-tree chambers tracking ambient air temperature ( Tair) or ambient Tair + 3°C (i.e. 'warmed'). We measured light- and CO2-saturated net photosynthesis ( Amax) and night-time dark respiration ( R) each month at 25°C to quantify acclimation. Tree growth was measured, and leaf nitrogen (N) and total nonstructural carbohydrate (TNC) concentrations were determined to investigate mechanisms of acclimation., Warming reduced Amax and R measured at 25°C compared to ambient-grown trees. Both traits also declined as mean daily Tair increased, and did so in a similar way across temperature treatments. Amax and R (at 25°C) both increased as TNC concentrations increased seasonally; these relationships appeared to arise from source-sink imbalances, suggesting potential substrate regulation of thermal acclimation., We found that photosynthesis and respiration each acclimated equivalently to experimental warming and seasonal temperature change of a similar magnitude, reflecting a common, nearly homeostatic constraint on leaf carbon exchange that will be important in governing tree responses to climate warming. [ABSTRACT FROM AUTHOR]

Given the contrasting short-term temperature dependences of gross primary production (GPP) and autotrophic respiration, the fraction of GPP respired by trees is predicted to increase with warming, providing a positive feedback to climate change. However, physiological acclimation may dampen or eliminate this response., We measured the fluxes of aboveground respiration ( Ra), GPP and their ratio ( Ra/GPP) in large, field-grown Eucalyptus tereticornis trees exposed to ambient or warmed air temperatures (+3°C). We report continuous measurements of whole-canopy CO2 exchange, direct temperature response curves of leaf and canopy respiration, leaf and branch wood respiration, and diurnal photosynthetic measurements., Warming reduced photosynthesis, whereas physiological acclimation prevented a coincident increase in Ra. Ambient and warmed trees had a common nonlinear relationship between the fraction of GPP that was respired above ground ( Ra/GPP) and the mean daily temperature. Thus, warming significantly increased Ra/GPP by moving plants to higher positions on the shared Ra/GPP vs daily temperature relationship, but this effect was modest and only notable during hot conditions., Despite the physiological acclimation of autotrophic respiration to warming, increases in temperature and the frequency of heat waves may modestly increase tree Ra/GPP, contributing to a positive feedback between climate warming and atmospheric CO2 accumulation. [ABSTRACT FROM AUTHOR]

Climate change threatens the ability of agriculture and forestry to meet growing global demands for food, fibre and wood products. Information gathered from genotype-by-environment interactions ( G × E), which demonstrate intraspecific variation in phenotypic plasticity (the ability of a genotype to alter its phenotype in response to environmental change), may prove important for bolstering agricultural and forest productivity under climate change. Nonetheless, very few studies have explicitly quantified genotype plasticity-productivity relationships in agriculture or forestry. Here, we conceptualize the importance of intraspecific variation in agricultural and forest species plasticity, and discuss the physiological and genetic factors contributing to intraspecific variation in phenotypic plasticity. Our discussion highlights the need for an integrated understanding of the mechanisms of G × E, more extensive assessments of genotypic responses to climate change under field conditions, and explicit testing of genotype plasticity-productivity relationships. Ultimately, further investigation of intraspecific variation in phenotypic plasticity in agriculture and forestry may prove important for identifying genotypes capable of increasing or sustaining productivity under more extreme climatic conditions. [ABSTRACT FROM AUTHOR]

Leaf dark respiration ( Rdark) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits., Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark., Area-based Rdark at the prevailing average daily growth temperature ( T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark25) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark25 at a given photosynthetic capacity ( Vcmax25) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark25 values at any given Vcmax25 or [N] were higher in herbs than in woody plants., The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). [ABSTRACT FROM AUTHOR]

As rapid climate warming creates a mismatch between forest trees and their home environment, the ability of trees to cope with warming depends on their capacity to physiologically adjust to higher temperatures. In widespread species, individual trees in cooler home climates are hypothesized to more successfully acclimate to warming than their counterparts in warmer climates that may approach thermal limits. We tested this prediction with a climate-shift experiment in widely distributed Eucalyptus tereticornis and E. grandis using provenances originating along a ~2500 km latitudinal transect (15.5-38.0°S) in eastern Australia. We grew 21 provenances in conditions approximating summer temperatures at seed origin and warmed temperatures (+3.5 °C) using a series of climate-controlled glasshouse bays. The effects of +3.5 °C warming strongly depended on home climate. Cool-origin provenances responded to warming through an increase in photosynthetic capacity and total leaf area, leading to enhanced growth of 20-60%. Warm-origin provenances, however, responded to warming through a reduction in photosynthetic capacity and total leaf area, leading to reduced growth of approximately 10%. These results suggest that there is predictable intraspecific variation in the capacity of trees to respond to warming; cool-origin taxa are likely to benefit from warming, while warm-origin taxa may be negatively affected. [ABSTRACT FROM AUTHOR]

We tested whether snow gum ( Eucalyptus pauciflora) trees growing in thermally contrasting environments exhibit generalizable temperature ( T) response functions of leaf respiration ( R) and fluorescence ( Fo). Measurements were made on pot-grown saplings and field-grown trees (growing between 1380 and 2110 m a.s.l.). Using a continuous, high-resolution protocol, we quantified T response curves of R and Fo - these data were used to identify an algorithm for modelling R- T curves at subcritical T's and establish variations in heat tolerance. For the latter, we quantified Tmax [ T where R is maximal] and Tcrit [ T where Fo rises rapidly]. Tmax ranged from 51 to 57 ° C, varying with season (e.g. winter > summer). Tcrit ranged from 41 to 49 ° C in summer and from 58 to 63 ° C in winter. Thus, surprisingly, leaf energy metabolism was more heat-tolerant in trees experiencing ice-encasement in winter than warmer conditions in summer. A polynomial model fitted to log-transformed R data provided the best description of the T-sensitivity of R (between 10 and 45 ° C); using these model fits, we found that the negative slope of the Q10- T relationship was greater in winter than in summer. Collectively, our results (1) highlight high- T limits of energy metabolism in E. pauciflora and (2) provide a framework for improving representation of T-responses of leaf R in predictive models. [ABSTRACT FROM AUTHOR]

Understanding the impacts of atmospheric [CO] and drought on leaf respiration ( R) and its response to changes in temperature is critical to improve predictions of plant carbon-exchange with the atmosphere, especially at higher temperatures. We quantified the effects of [CO]-enrichment (+240 ppm) on seasonal shifts in the diel temperature response of R during a moderate summer drought in Eucalyptus saligna growing in whole-tree chambers in SE Australia. Seasonal temperature acclimation of R was marked, as illustrated by: (1) a downward shift in daily temperature response curves of R in summer (relative to spring); (2)≈60% lower R measured at 20C ( R) in summer compared with spring; and (3) homeostasis over 12 months of R measured at prevailing nighttime temperatures. R, measured during the day, was on average 30-40% higher under elevated [CO] compared with ambient [CO] across both watered and droughted trees. Drought reduced R by≈30% in both [CO] treatments resulting in additive treatment effects. Although [CO] had no effect on seasonal acclimation, summer drought exacerbated the seasonal downward shift in temperature response curves of R. Overall, these results highlight the importance of seasonal acclimation of leaf R in trees grown under ambient- and elevated [CO] as well as under moderate drought. Hence, respiration rates may be overestimated if seasonal changes in temperature and drought are not considered when predicting future rates of forest net CO exchange. [ABSTRACT FROM AUTHOR]

Patterns and mechanisms of short-term temperature acclimation and long-term climatic adaptation of respiration among intraspecific populations are poorly understood, but both are potentially important in constraining respiratory carbon flux to climate warming across large geographic scales, as well as influencing the metabolic fitness of populations. Herein we report on leaf dark respiration of 33-year-old trees of jack pine ( Pinus banksiana Lamb.) grown in three contrasting North American common gardens (0.9, 4.6, and 7.9 °C, mean annual temperature) comprised of identical populations of wide-ranging geographic origins. We tested whether respiration rates in this evergreen conifer acclimate to prevailing ambient air temperatures and differ among populations. At each of the common gardens, observed population differences in respiration rates measured at a standard temperature (20 °C) were comparatively small and largely unrelated to climate of seed-source origin. In contrast, respiration in all populations exhibited seasonal acclimation at all sites. Specific respiration rates at 20 °C inversely tracked seasonal variation in ambient air temperature, increasing with cooler temperatures in fall and declining with warmer temperatures in spring and summer. Such responses were similar among populations and sites, thus providing a general predictive equation regarding temperature acclimation of respiration for the species. Temperature acclimation was associated with variation in nitrogen (N) and soluble carbohydrate concentrations, supporting a joint enzyme and substrate-based model of respiratory acclimation. Regression analyses revealed convergent relationships between respiration and the combination of needle N and soluble carbohydrate concentrations and between N-based respiration ( RN, μmol mol N− 1 s− 1) and soluble carbohydrate concentrations, providing evidence for general predictive relationships across geographically diverse populations, seasons, and sites. Overall, these findings demonstrate that seasonal acclimation of respiration modulates rates of foliar respiratory carbon flux in a widely distributed evergreen species, and does so in a predictable way. Genetic differences in specific respiration rate appear less important than temperature acclimation in downregulating respiratory carbon fluxes with climate warming across wide-ranging sites. [ABSTRACT FROM AUTHOR]

The response of respiration to temperature in plants can be considered at both short- and long-term temporal scales. Short-term temperature responses are not well described by a constantQ10 of respiration, and longer-term responses often include acclimation. Despite this, many carbon balance models use a staticQ10 of respiration to describe the short-term temperature response and ignore temperature acclimation.We replaced static respiration parameters in the ecosystem model photosynthesis and evapo-transpiration (PnET) with a temperature-driven basal respiration algorithm (Rdacclim) that accounts for temperature acclimation, and a temperature-variableQ10 algorithm (Q10var). We ran PnET with the new algorithms individually and in combination for 5 years across a range of sites and vegetation types in order to examine the new algorithms' effects on modeled rates of mass- and area-based foliar dark respiration, above ground net primary production (ANPP), and foliar respiration–photosynthesis ratios.TheRdacclim algorithm adjusted dark respiration downwards at temperatures above 18°C, and adjusted rates up at temperatures below 5°C. TheQ10var algorithm adjusted dark respiration down at temperatures below 15°C. Using both algorithms simultaneously resulted in decreases in predicted annual foliar respiration that ranged from 31% at a tall-grass prairie site to 41% at a boreal coniferous site. The use of theRdacclim andQ10var algorithms resulted in increases in predicted ANPP ranging from 18% at the tall-grass prairie site to 38% at a warm temperate hardwood forest site.The new foliar respiration algorithms resulted in substantial and variable effects on PnETs predicted estimates of C exchange and production in plants and ecosystems. Current models that use static parameters may over-predict respiration and subsequently under-predict and/or inappropriately allocate productivity estimates. Incorporating acclimation of basal respiration and temperature-sensitiveQ10 have the potential to enhance the application of ecosystem models across broad spatial scales, or in climate change scenarios, where large temperature ranges may cause static respiration parameters to yield misleading results. [ABSTRACT FROM AUTHOR]

Plant temperature acclimation is closely related to maintaining a positive carbon gain under future climate change. However, no systematic summary of the field has been conducted. Based on this, we analyzed data on plant temperature acclimation from the Web of Science Core Collection database using bibliometric software R, RStudio and VOSviewer. Our study demonstrated that a stabilized upward trajectory was noted in publications (298 papers) from 1986 to 2011, followed by a swift growth (373 papers) from 2012 to 2022. The most impactful journals were Plant Cell and Environment, boasting the greatest count of worldwide citations and articles, the highest H-index and G-index, followed by Global Change Biology and New Phytologist, and Frontiers in Plant Science which had the highest M-index. The USA and China were identified as the most influential countries, while Atkin was the most influential author, and the Chinese Academy of Sciences was the most influential research institution. The most cited articles were published in the Annual Review of Plant Biology in 1999. “Cold acclimation” was the most prominent keyword. Future plant temperature acclimation research is expected to focus on thermal acclimation and photosynthesis, which have important significance for future agricultural production, forestry carbon sequestration, and global food security. In general, this study provides a systematic insight of the advancement, trend, and future of plant temperature acclimation research, enhancing the comprehension of how plants will deal with forthcoming climate change. [ABSTRACT FROM AUTHOR]