The influence of photosynthetic acclimation to rising CO₂ and warmer temperatures on leaf and canopy photosynthesis models

Abstract

There is an increasing necessity to understand how climate change factors, particularly increasing atmospheric concentrations of CO 2 ([CO 2 ]) and rising temperature, will influence photosynthetic carbon assimilation (A). Based on theory, an increased [CO 2 ] concomitant with a rise in temperature will increase A in C3 plants beyond that of an increase in [CO 2 ] alone. However, uncertainty surrounding the acclimation response of key photosynthetic parameters to these changes can influence this response. In this work, the acclimation responses of C3 photosynthesis for soybean measured at the SoyFACE Temperature by Free-Air CO 2 Enrichment experiment are incorporated in a leaf biochemical and canopy photosynthesis model. The two key parameters used as model inputs, the maximum velocity for carboxylation (V c,max ) and maximum rate of electron transport (J max ), were measured in a full factorial [CO 2 ] by temperature experiment over two growing seasons and applied in leaf-and canopy-scale models to (1) reassess the theory of combined increases in [CO 2 ] and temperature on A, (2) determine the role of photosynthetic acclimation to increased growth [CO 2 ] and/or temperature in leaf and canopy predictions of A for these treatments, and (3) assess the diurnal and seasonal differences in leaf-and canopy-scale A associated with the imposed treatments. The results demonstrate that the theory behind combined increases in [CO 2 ] and temperature is sound; however, incorporating more recent parameterizations into the photosynthesis model predicts greater increases in A when [CO 2 ] and temperature are increased together. Photosynthetic acclimation is shown to decrease leaf-level A for all treatments; however, in elevated [CO 2 ] the impact of acclimation does not result in any appreciable loss in photosynthetic potential at the canopy scale. In this analysis, neglecting photosynthetic acclimation in heated treatments, with or without concomitant rise in [CO 2 ], leads to modeled overestimates of carbon gain for soybean under future predicted conditions.

Surveying Rubisco diversity and temperature response to improve crop photosynthetic efficiency

“…Nevertheless, this demonstrates the potential gains in photosynthetic capacity through Rubisco substitution. This data set characterizing a broad range of species at multiple temperatures will also be of use in modeling of photosynthesis at different scales (Smith and Dukes, 2013) and complement in planta studies seeking to adapt models of various scales for the increased temperatures expected in many regions in the coming decades (Bagley et al, 2015).…”

Vegetation growth enhancement in urban environments of the Conterminous United States

“…More broadly, vegetation response to urbanization could provide the insight into the long‐term effects and interactions of multiple global‐change drivers and adaptation strategy by plants. Current manipulative experiments rely on micro‐ to plot‐scale facilities to manipulate one or more factors at a time to monitor the plant responses (Bagley et al., ; Dieleman et al., ; Kupper et al., ; Löw et al., ; Ma et al., ; Nunn et al., ). In addition, manipulative experiments usually employ abrupt changes of variables (e.g., 50% precipitation reduction, doubling of CO 2 ) rather than gradual changes, which might result in instantaneous and pulsatile plant responses (Zhao et al., ).…”

Prevalent vegetation growth enhancement in urban environment

“…One of the main scientific thrusts of our time is to understand how vegetation growth would be affected by projected changes of temperature, atmospheric CO 2 concentration, and other factors (28). Numerous expensive manipulative experiments have been designed for this purpose at species and ecosystem levels (e.g., 29,30). Although these experiments have provided various types of evidence, they have suffered from several issues that are intrinsically associated with the methods themselves.…”