Abstract
The microbial decomposition respiration of plant litter generates a major CO2 efflux from terrestrial ecosystems that plays a critical role in the regulation of carbon cycling on regional and global scales. However, the respiration from root litter decomposition and its sensitivity to temperature changes are unclear in current models of carbon turnover in forest soils. Thus, we examined seasonal changes in the temperature sensitivity and decomposition rates of fine root litter of two diameter classes (0–0.5 and 0.5–2.0 mm) of Quercus serrata and Ilex pedunculosa in a deciduous broad-leaved forest. During the study period, fine root litter of both diameter classes and species decreased approximately exponentially over time. The Q 10 values of microbial respiration rates of root litter for the two classes were 1.59–3.31 and 1.28–6.27 for Q. serrata and 1.36–6.31 and 1.65–5.86 for I. pedunculosa. A significant difference in Q 10 was observed between the diameter classes, indicating that root diameter represents the initial substrate quality, which may determine the magnitude of Q 10 value of microbial respiration. Changes in these Q 10 values were related to seasonal soil temperature patterns; the values were higher in winter than in summer. Moreover, seasonal variations in Q 10 were larger during the 2-year decomposition period than the 1-year period. These results showed that the Q 10 values of fine root litter of 0–0.5 and 0.5–2.0 mm have been shown to increase with lower temperatures and with the higher recalcitrance pool of the decomposed substrate during 2 years of decomposition. Thus, the temperature sensitivity of microbial respiration in root litter showed distinct patterns according to the decay period and season because of the temperature acclimation and adaptation of the microbial decomposer communities in root litter.
Highlights
Soil respiration in terrestrial ecosystems is critical for assessing the net ecosystem carbon (C) balance because it represents the second largest global C flux (68–80 PgC/year) between ecosystems and the atmosphere [1]
The response of microbial respiration rates from root litter to various temperatures strongly differed among seasons (Fig. 1)
There were seasonal patterns in the Q10 values of microbial respiration in both species and diameter classes with temperature; Q10 was highest in winter and lowest in summer, even when compared at the same measurement temperatures (Fig. 3E and 3F)
Summary
Soil respiration in terrestrial ecosystems is critical for assessing the net ecosystem carbon (C) balance because it represents the second largest global C flux (68–80 PgC/year) between ecosystems and the atmosphere [1]. This amount is over 10 times of that currently produced by fossil. Temperature Sensitivity of Microbial Respiration of Fine Root Litter fuel combustion. The global warming could substantially stimulate soil respiration, resulting in more release of CO2 to the atmosphere. Increasing efforts have been made to develop a mechanistic understanding of how temperature and other environmental factors affect soil respiration [3]
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