Abstract
AbstractPast research has shown that plants possess the capacity to alter their instantaneous response of photosynthesis to temperature in response to a longer-term change in temperature (i.e. acclimate). This acclimation is typically the result of processes that influence net photosynthesis (Anet), including leaf biochemical processes such as the maximum rate of Rubisco carboxylation (Vcmax) and the maximum rate of photosynthetic electron transport (Jmax), stomatal conductance (gs) and dark respiration (Rd). However, these processes are rarely examined in the field or in concert with other environmental factors, such as precipitation amount. Here, we use a fully factorial warming (active heating up to +4 °C; mean = +3.1 °C) by precipitation (−50 % ambient to 150 % ambient) manipulation experiment in an old-field ecosystem in the north-eastern USA to examine the degree to which Ulmus americana saplings acclimate through biochemical and stomatal adjustments. We found that rates of Anet at ambient CO2 levels of 400 µmol mol−1 (A400) did not differ across climate treatments or with leaf temperatures from 20 to 30 °C. Canopy temperatures rarely reached above 30 °C in any treatment, suggesting that seasonal carbon assimilation was relatively homeostatic across all treatments. Assessments of the component processes of A400 revealed that decreases in gs with leaf temperature from 20 to 30 °C were balanced by increases in Vcmax, resulting in stable A400 rates despite concurrent increases in Rd. Photosynthesis was not affected by precipitation treatments, likely because the relatively dry year led to small treatment effects on soil moisture. As temperature acclimation is likely to come at a cost to the plant via resource reallocation, it may not benefit plants to acclimate to warming in cases where warming would not otherwise reduce assimilation. These results suggest that photosynthetic temperature acclimation to future warming will be context-specific and that it is important to consider assimilatory benefit when assessing acclimation responses.
Highlights
Photosynthetic carbon uptake and respiratory carbon release by land plants are the two largest fluxes of carbon between the atmosphere and the Earth’s surface (Ciais et al 2013)
We found that rates of Anet at ambient CO2 levels of 400 μmol mol−1 (A400) did not differ across climate treatments or with leaf temperatures from 20 to 30 °C
Model sensitivity studies have shown that the inclusion of temperature acclimation of leaf carbon exchange can alter future climate (Smith et al 2017) and carbon cycling (Wythers et al 2005; King et al 2006; Atkin et al 2008; Friend 2010; Lombardozzi et al 2015; Smith et al 2016a) projections
Summary
Photosynthetic carbon uptake and respiratory carbon release by land plants are the two largest fluxes of carbon between the atmosphere and the Earth’s surface (Ciais et al 2013). This rate of increase slows and eventually peaks at an optimum temperature (Medlyn et al 2002a; Lin et al 2012; Yamori et al 2014). This response may change over longer time periods (e.g. days to weeks) as a result of temperature acclimation (Atkin and Tjoelker 2003; Smith and Dukes 2013; Way and Yamori 2014)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
