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

Abstract

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 3700 km north-south transect in eastern China (NSTEC). For 8 weeks these soils were incubated under a periodically changing temperature range of 6-30°C while frequently measuring soil microbial respiration rate (Rs; each sample about every 20 min). This experimental design allowed us to investigate Rs and the temperature sensitivity of Rs (Q 10 ) along the NSTEC. Both Rs at 20°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.

Strong pulse effects of precipitation events on soil microbial respiration in temperate forests

“…); C is the slope of the change in CO 2 concentration; V is the volume of the incubation bottle and gas tube; m is the soil weight (g); α is the conversion coefficient for CO 2 mass (12/44, from CO 2 to C); and β is a conversion coefficient of time (3600, from s to h) (Wang et al, 2016). …”

Asymmetric responses of soil heterotrophic respiration to rising and decreasing temperatures

“…5). Chemical properties (pH, ORP), substrate (DOC), and temperature primarily exerted an influence on Q 10 by regulating microbial activity (Wang et al, 2016). Similarly, Wei et al (2014) confirmed that Q 10 depends on the structure of the soil microbial community.…”

“…2). R S and soil temperature were simultaneously and continuously measured during the model of varying temperature over 24-h based on the program of Wang et al (2016). Measuring R S more frequently (i.e., at intervals of several minutes) allows for an improved exploration of the relationship between R S and changing temperatures, as well as a more accurate calculation of Q 10 .…”

“…This method was modified from He et al (2013) based on the designated program of Wang et al (2016). Furthermore, a button thermometer (DS1922L) was used to measure the actual soil temperature when we measured R S , providing accurate paired data for R S and soil temperature to calculate Q 10 (Wang et al, 2016). To reduce the error in button thermometer readings, we used five button thermometers to monitor soil temperature in the incubation bottles.…”

“…For instance, the temperature in the incubator ranged from 6 C to 30 C during the first 12-h, and from 30 C to 6 C in the following 12-h, whereas the temperature measurements ranged from 5 C to 31 C during the first 12-h, and from 31 C to 5 C in the next 12-h. This method was modified from He et al (2013) based on the designated program of Wang et al (2016). Furthermore, a button thermometer (DS1922L) was used to measure the actual soil temperature when we measured R S , providing accurate paired data for R S and soil temperature to calculate Q 10 (Wang et al, 2016).…”