Soil microbial respiration rate and temperature sensitivity along a north-south forest transect in eastern China: Patterns and influencing factors

摘要

Soil organic matter is one of the most important carbon (C) pools in terrestrial ecosystems, and future warming from climate change will likely alter soil C storage via temperature effects on microbial respiration. In this study, we collected forest soils from eight locations along a 3700km north-south transect in eastern China (NSTEC). For 8weeks these soils were incubated under a periodically changing temperature range of 6-30 degrees C while frequently measuring soil microbial respiration rate (Rs; each sample about every 20min). This experimental design allowed us to investigate Rs and the temperature sensitivity of Rs (Q(10)) along the NSTEC. Both Rs at 20 degrees C (R-20) and Q(10) significantly increased (logarithmically) with increasing latitude along the NSTEC suggesting that the sensitivity of soil microbial respiration to changing temperatures is higher in forest soils from locations with lower temperature. Our findings from an incubation experiment provide support for the hypothesis that temperature sensitivity of soil microbial respiration increases with biochemical recalcitrance (C quality-temperature hypothesis) across forest soils on a large spatial scale. Furthermore, microbial properties primarily controlled the observed patterns of R-20, whereas both substrate and microbial properties collectively controlled the observed patterns of Q(10). These findings advance our understanding of the driving factors (microbial versus substrate properties) of R-20 and Q(10) as well as the general relationships between temperature sensitivity of soil microbial respiration and environmental factors.