Under future climates, leaf temperature (T ) will be higher and more variable. This will affect plant carbon (C) balance because photosynthesis and respiration both respond to short-term (subdaily) fluctuations in T and acclimate in the longer term (days to months). This study asks the question: To what extent can the potential and speed of photosynthetic acclimation buffer leaf C gain from rising and increasing variable T ? We quantified how increases in the mean and variability of growth temperature affect leaf performance (mean net CO assimilation rates, A ; its variability; and time under near-optimal photosynthetic conditions), as mediated by thermal acclimation. To this aim, the probability distribution of A was obtained by combining a probabilistic description of short- and long-term changes in T with data on A responses to these changes, encompassing 75 genera and 111 species, including both C3 and C4 species. Our results show that (a) expected increases in T variability will decrease mean A and increase its variability, whereas the effects of higher mean T depend on species and initial T , and (b) acclimation reduces the effects of leaf warming, maintaining A at >80% of its maximum under most thermal regimes.
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http://dx.doi.org/10.1111/pce.13525 | DOI Listing |
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