Response of root respiration to changes in temperature and its relevance to global warming

Abstract

Global warming over the next century is likely to be associated with a change in the extent to which atmospheric and soil temperatures fluctuate, on both a daily and a seasonal basis. The average annual temperature of the Earth's surface is expected to increase, as is the frequency of hot days. In this review, we explore what effects short-term and long-term changes in temperature are likely to have on root respiratory metabolism, and what impacts such changes will have on daily, seasonal and annual CO # release by roots under field conditions. We demonstrate that Q "! values, and the degree of acclimation, differ between and within plant species. Changes in the temperature sensitivity of respiration with measuring temperature are highlighted. Temperature-dependent changes in adenylate control and substrate supply are likely to control the Q "! and degree of acclimation of root respiration. Limitations in respiration capacity are unlikely to control respiratory flux at most temperatures. The potential role of nonphosphorylating pathways such as the alternative oxidase in controlling Q "! values is highlighted. The possibility that potentially rapid changes in adenylate control might underlie the acclimation response (rather than slow changes in enzyme capacity) has implications for the total amount of CO # respired by roots daily and annually. Our modelling suggests that rapid acclimation will result in near-perfect homeostasis of respiration rates and minimize annual CO # release. However, annual CO # release increases substantially if the speed of full acclimation is lower. Our modelling exercise also shows that high Q "! values have the potential to increase daily and annual CO # release substantially, particularly if the frequency of hot days increases after global warming.

Soil temperature and biotic factors drive the seasonal variation of soil respiration in a maize (Zea mays L.) agricultural ecosystem

“…Recent field experiments have shown that as much as half of the soil respiratory carbon release is derived from recent photosynthate (Hö gberg et al 2001;Steinmann et al 2004). An increase in the carbon availability to the root system often causes an increase in root respiration (Atkin et al 2000). Kirschbaum (2006) reported that changes in substrate availability may confound the apparent temperature dependence of SR.…”

A meta-analysis of the effects of experimental warming on soil carbon and nitrogen dynamics on the Tibetan Plateau

“…Our findings suggested that the effects of warming on gross and net primary production, net ecosystem exchange, ecosystem respiration, plant biomass, soil carbon and nitrogen, soil microbial biomass, net nitrogen mineralization and nitrification did not change with the warming duration (Bai et al, 2013;Lin et al, 2010;Lu et al, 2013a;Rustad et al, 2001;Wu et al, 2011) due to the significant, warming-induced increases in the labile carbon and nitrogen availability in the soil (Bai et al, 2013;Lu et al, 2013a;Rustad et al, 2001). In contrast, many studies indicated that the warming duration had a significant negative relationship between the warming effects and plant nitrogen uptake and R s (Atkin et al, 2000;Bai et al, 2013;Melillo et al, 2002), which could be caused by the loss of labile carbon and nitrogen in soils Melillo et al, 2002;Wu et al, 2011). Therefore, whether the effects of warming on carbon and nitrogen were correlated with the warming duration was likely dependent on the conditions of the labile carbon and nitrogen.…”

Terrestrial carbon-cycle feedback to climate warming: experimental evidence on plant regulation and impacts of biofuel feedstock harvest

“…Warming stimulated heterotrophic respiration by 11% without clipping and 9% with clipping. Although photosynthetic sensitivity to temperature is smaller than respiration sensitivity (Pearcy and Ehleringer 1984;Atkin et al 2000;Luo 2007), NPP is regulated by many other processes, rendering a possibility that NPP is more sensitive than soil respiration to climate warming.…”