科研之友
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摘要
Quantifying the adjustments of leaf respiration in response to seasonal temperature variation and climate warming is crucial because carbon loss from vegetation is a large but uncertain part of the global carbon cycle. We grew fast-growing Eucalyptus globulus Labill. trees exposed to + 3 degrees C warming and elevated CO2 in 10-m tall whole-tree chambers and measured the temperature responses of leaf mitochondrial respiration, both in light (R-Light) and in darkness (R-Dark), over a 20-40 degrees C temperature range and during two different seasons. RLight was assessed using the Laisk method. Respiration rates measured at a standard temperature (25 degrees C-R-25) were higher in warm-grown trees and in the warm season, related to higher total leaf nitrogen (N) investment with higher temperatures (both experimental and seasonal), indicating that leaf N concentrations modulated the respiratory capacity to changes in temperature. Once differences in leaf N were accounted for, there were no differences in R-25 but the Q(10) (i. e., short-term temperature sensitivity) was higher in late summer compared with early spring. The variation in R-Light between experimental treatments and seasons was positively correlated with carboxylation capacity and photorespiration. R-Light was less responsive to short-term changes in temperature than RDark, as shown by a lower Q(10) in R-Light compared with R-Dark. The overall light inhibition of R was similar to 40%. Our results highlight the dynamic nature of leaf respiration to temperature variation and that the responses of R-Light do not simply mirror those of R-Dark. Therefore, it is important not to assume that RLight is the same as R-Dark in ecosystem models, as doing so may lead to large errors in predicting plant CO2 release and productivity.
- 出版日期2017-8
