Temperature sensitivity of total soil respiration and its heterotrophic and autotrophic components in six vegetation types of subtropical China

The temperature sensitivity of soil respiration (Q(10)) is a key parameter for estimating the feedback of soil respiration to global warming. The Q(10) of total soil respiration (R-t) has been reported to have high variability at both local and global scales, and vegetation type is one of the most important drivers. However, little is known about how vegetation types affect the Q(10) of soil heterotrophic (R-h) and autotrophic (R-a) respirations, despite their contrasting roles in soil carbon sequestration and ecosystem carbon cycles. In the present study, five typical plantation forests and a naturally developed shrub and herb land in subtropical China were selected for investigation of soil respiration. Trenching was conducted to separate Rh and Ra in each vegetation type. The results showed that both R-t and R-h were significantly correlated with soil temperature in all vegetation types, whereas Ra was significantly correlated with soil temperature in only four vegetation types. Moreover, on average, soil temperature explained only 15.0% of the variation in Ra in the six vegetation types. These results indicate that soil temperature may be not a primary factor affecting R-a. Therefore, modeling of Ra based on its temperature sensitivity may not always be valid. The Q(10) of Rh was significantly affected by vegetation types, which indicates that the response of the soil carbon pool to climate warming may vary with vegetation type. In contrast, differences in neither the Q(10) of R-t nor that of R-a among these vegetation types were significant. Additionally, variation in the Q(10) of R-t among vegetation types was negatively related to fine root biomass, whereas the Q(10) of R-h was mostly related to total soil nitrogen. However, the Q(10) of R-a was not correlated with any of the environmental variables monitored in this study. These results emphasize the importance of independently studying the temperature sensitivity of R-t and its heterotrophic and autotrophic components. (C) 2017 Elsevier B.V. All rights reserved.