Boreal and temperate trees show strong acclimation of respiration to warming

Abstract

Plant respiration results in an annual flux of carbon dioxide (CO2) to the atmosphere that is six times as large as that due to the emissions from fossil fuel burning, so changes in either will impact future climate. As plant respiration responds positively to temperature, a warming world may result in additional respiratory CO2 release, and hence further atmospheric warming. Plant respiration can acclimate to altered temperatures, however, weakening the positive feedback of plant respiration to rising global air temperature, but a lack of evidence on long-term (weeks to years) acclimation to climate warming in field settings currently hinders realistic predictions of respiratory release of CO2 under future climatic conditions. Here we demonstrate strong acclimation of leaf respiration to both experimental warming and seasonal temperature variation for juveniles of ten North American tree species growing for several years in forest conditions. Plants grown and measured at 3.4 °C above ambient temperature increased leaf respiration by an average of 5% compared to plants grown and measured at ambient temperature; without acclimation, these increases would have been 23%. Thus, acclimation eliminated 80% of the expected increase in leaf respiration of non-acclimated plants. Acclimation of leaf respiration per degree temperature change was similar for experimental warming and seasonal temperature variation. Moreover, the observed increase in leaf respiration per degree increase in temperature was less than half as large as the average reported for previous studies, which were conducted largely over shorter time scales in laboratory settings. If such dampening effects of leaf thermal acclimation occur generally, the increase in respiration rates of terrestrial plants in response to climate warming may be less than predicted, and thus may not raise atmospheric CO2 concentrations as much as anticipated.

No growth stimulation of Canada’s boreal forest under half-century of combined warming and CO 2 fertilization

“…6A), parallel with rapid warming and growth decline, may reflect a temperature-dependent increase in respiration and depletion in carbon reserves, as was recently suggested by process-based modeling of productivity in black spruce stands (16). Such temperature responses are not static, and plants have the capacity to adjust to a warming environment via physiological acclimation (33). However, the extent to which acclimation of respiration to warming can help in maintaining trees' carbon balance in these boreal regions remains poorly known.…”

Thermal acclimation of leaf photosynthetic traits in an evergreen woodland, consistent with the coordination hypothesis

“…There are plenty of data on the instantaneous (minutes to hours) temperature responses of photosynthetic uptake (Hikosaka et al, 2006;Sage and Kubien, 2007;Way and Sage, 2008), but data on the responses of photosynthetic traits on ecologically relevant timescales (days to years) are scarce (Wilson et al, 2000;Lin et al, 2013). Nonetheless there is evidence that temperature responses of biochemical processes are a function of plant growth temperature, and not just instantaneous temperature, from studies comparing species (Miyazawa and Kikuzawa, 2006;Kattge and Knorr, 2007), to experiments or serial measurements on single species (Medlyn et al, 2002b;Onoda et al, 2005).…”

The combination of gas-phase fluorophore technology and automation to enable high-throughput analysis of plant respiration

“…Using standard leaf gas exchange methods, recent surveys have greatly increased our understanding of biome-to-biome variation in leaf R dark [11–13]; our understanding of how sustained changes in the environment affect respiratory rates is also improving [11, 28–31]. Yet, limitations in available data (e.g.…”