Using temperature‐dependent changes in leaf scaling relationships to quantitatively account for thermal acclimation of respiration in a coupled global climate–vegetation model

Abstract

The response of plant respiration (R) to temperature is an important component of the biosphere's response to climate change. At present, most global models assume that R increases exponentially with temperature and does not thermally acclimate. Although we now know that acclimation does occur, quantitative incorporation of acclimation into models has been lacking. Using a dataset for 19 species grown at four temperatures (7, 14, 21, and 28 1C), we have assessed whether sustained differences in growth temperature systematically alter the slope and/or intercepts of the generalized log-log plots of leaf R vs. leaf mass per unit leaf area (LMA) and vs. leaf nitrogen (N) concentration. The extent to which variations in growth temperature account for the scatter observed in log-log R-LMA-N scaling relationships was also assessed. We show that thermal history accounts for up to 20% of the scatter in scaling relationships used to predict R, with the impact of thermal history on R-LMA-N generalized scaling relationships being highly predictable. This finding enabled us to quantitatively incorporate acclimation of R into a coupled global climate-vegetation model. We show that accounting for acclimation of R has negligible impact on predicted annual rates of global R, net primary productivity (NPP) or future atmospheric CO 2 concentrations. However, our analysis suggests that accounting for acclimation is important when considering carbon fluxes among thermally contrasting biomes (e.g. accounting for acclimation decreases predicted rates of R by up to 20% in high-temperature biomes). We conclude that acclimation of R needs to be accounted for when predicting potential responses of terrestrial carbon exchange to climatic change at a regional level.

Interactions between land use change and carbon cycle feedbacks

“…While the future yield projections are very sensitive to assumptions about the ability of humans to innovate both agricultural management methods and crop genetic attributes [e. g., Fischer et al, 2005], some evidence suggests that yield improvements may already be decreasing [Ray et al, 2012] and that agricultural crops may be more sensitive to temperature than previously estimated [Lobell et al, 2011]. On the other hand, estimates of net primary production and respiration in Earth system models assume a static response to temperature [e.g., Oleson et al, 2010], although there is evidence that plants can acclimate to higher temperatures on seasonal and interannual timescales [Kattge and Knorr, 2007;Atkin et al, 2008;Sendall et al, 2015]. This is consistent with other evidence that Earth system models may be overly pessimistic about the impact of higher temperatures on land carbon [Frank et al, 2010;Keenan et al, 2013;Mahecha et al, 2010], and studies which include temperature acclimation indicate that including the effects of acclimation would increase the terrestrial carbon in Earth system models [Arneth et al, 2012;Atkin et al, 2008;King et al, 2006].…”

“…On the other hand, estimates of net primary production and respiration in Earth system models assume a static response to temperature [e.g., Oleson et al, 2010], although there is evidence that plants can acclimate to higher temperatures on seasonal and interannual timescales [Kattge and Knorr, 2007;Atkin et al, 2008;Sendall et al, 2015]. This is consistent with other evidence that Earth system models may be overly pessimistic about the impact of higher temperatures on land carbon [Frank et al, 2010;Keenan et al, 2013;Mahecha et al, 2010], and studies which include temperature acclimation indicate that including the effects of acclimation would increase the terrestrial carbon in Earth system models [Arneth et al, 2012;Atkin et al, 2008;King et al, 2006]. Thus, the IAM models used to predict future land use conversion may be underestimating the threat to forests from deforestation, while Earth system models may be overestimating the threat to forests from higher temperatures.…”

Sources of variation in simulated ecosystem carbon storage capacity from the 5th Climate Model Intercomparison Project (CMIP5)

“…Plant R a is not parameterised very well in current biogeochemical models (Atkin et al, 2008), further limiting the ability to accurately estimate NPP and its response to climate change. In most models, the sensitivity of R a to temperature is represented by a Q 10 function or a modified Arrhenius equation (similar function), but different models have different Q 10 (Ruimy et al, 1996), ranging from 1.9 to 2.5 based on estimates inferred from global forest database (Piao et al, 2010).…”

Metabolism and Growth in Arabidopsis Depend on the Daytime Temperature but Are Temperature-Compensated against Cool Nights

“…Like photosynthesis, respiratory acclimation is more marked in leaves that develop at the new temperature (Campbell et al, 2007). Several factors contribute, including the general increase in protein content (Atkin et al, 2005(Atkin et al, , 2008Campbell et al, 2007;Tjoelker et al, 2008) and changes in the activities or levels of specific respiratory enzymes, in particular alternative oxidase and uncoupling protein (Armstrong et al, 2007;Campbell et al, 2007). Respiration is often subdivided into growth respiration (R g ) and maintenance respiration (R m ; Penning de Vries et al, 1974;Amthor, 2000).…”