Implications of improved representations of plant respiration in a changing climate

Abstract

Land-atmosphere exchanges influence atmospheric CO2. Emphasis has been on describing photosynthetic CO2 uptake, but less on respiration losses. New global datasets describe upper canopy dark respiration (R d) and temperature dependencies. This allows characterisation of baseline R d, instantaneous temperature responses and longer-term thermal acclimation effects. Here we show the global implications of these parameterisations with a global gridded land model. This model aggregates R d to whole-plant respiration R p, driven with meteorological forcings spanning uncertainty across climate change models. For pre-industrial estimates, new baseline R d increases R p and especially in the tropics. Compared to new baseline, revised instantaneous response decreases R p for mid-latitudes, while acclimation lowers this for the tropics with increases elsewhere. Under global warming, new R d estimates amplify modelled respiration increases, although partially lowered by acclimation. Future measurements will refine how R d aggregates to whole-plant respiration. Our analysis suggests R p could be around 30% higher than existing estimates.

Elevated CO2 does not affect stem CO2 efflux nor stem respiration in a dry Eucalyptus woodland, but it shifts the vertical gradient in xylem [CO2]

“…Stem respiration (R S ) holds a significant role in tree C balances with stem CO 2 efflux to the atmosphere (E A ) being 11% and 20% of global forest ecosystem gross primary production and net primary production, respectively (Yang, He, Aubrey, Zhuang, & Teskey, ). However, relative to photosynthetic CO 2 assimilation, respiratory processes are less understood (Huntingford et al, ; Smith, ), particularly in woody tissues, wherein methodological constraints hinder both quantification of respiratory rates at the organ level (Salomón, Rodríguez‐Calcerrada, & Staudt, ; Teskey, McGuire, Bloemen, Aubrey, & Steppe, ) and scaling up to larger spatial levels (Meir et al, ).…”

The role of thermal acclimation of plant respiration under climate warming: Putting the brakes on a runaway train?

“…Because of thermal acclimation, predictions of respiration through time based solely on fixed short‐term temperature response functions are rendered invalid, typically resulting in overestimation of respiration in warmer seasons and locations and underestimation in cooler seasons and places (Figure ). Global land surface models that omit foliar temperature acclimation are likely to overestimate the temperature sensitivity of terrestrial carbon exchange (Smith et al, ); however, when aggregated across the globe, respiratory carbon losses were found to be 30% higher than prior estimates (Huntingford et al, ). But the consequences of root respiratory temperature acclimation are not known.…”

Core principles which explain variation in respiration across biological scales

“…Respiratory metabolism is a fundamental process in plants, providing energy and carbon (C) skeletons needed for growth, survival and agricultural production. In addition, respiratory gas consumption and production by plants also play a crucial role in regulating the chemistry of the atmosphere, and associated rates of global warming (Huntingford et al ., ). Understanding the variation in plant respiratory rate stemming from genetic, developmental and environmental factors provides an opportunity for more predictive modelling of C flows both within plants and between terrestrial land surfaces and the atmosphere (Atkin et al ., ; Tcherkez et al ., ).…”