Soil Respiration under Different Land Uses in Eastern China

Abstract

Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were influenced by SOC, SWC, pH, and WSAl.

Soil carbon dioxide and methane fluxes from forests and other land use types in an African tropical montane region

“…Furthermore, the soil carbon concentrations (7.1%) in the 0-0.2 m soil layer of the grazing lands in our study were 2-3 times higher than in the grazing lands in the study by Pelster et al (2017) (2.3%) and that by Rosenstock et al (2016) (2.2-3.7%) with similar bulk densities, which could partly explain the higher soil CO 2 fluxes in our study. Strong responses of soil CO 2 to soil temperature have been reported in studies where variations in soil temperature are wide, for instance in a study by Fan et al (2015) at a forest site exposed to a subtropical monsoon climate in Eastern China, with soil temperatures varying over the year in a range of 0 to 35°C. However, variations in soil temperature in our study region were smaller than the variation in temperate zones (ranging between 14 and 18°C for the forest, tea plantations, eucalyptus plantations and croplands, and ranging between 17 and 22°C for the grazing lands).…”

Soil respiration in Chinese tea gardens: autotrophic and heterotrophic respiration

“…For a detailed description of the area's climate and the experimental sites used in this study, refer to Fan et al . (). Briefly, the experimental fields included tea gardens with HP, MP and LP.…”

“…We measured the rate of R S biweekly from October 2013 to October 2014 using the closed chamber method connected to a portable CO 2 analyser (GXH‐3051A, Beijing JUN FANG Institute, Beijing, China), as described in Fan et al . (). Autotrophic respiration ( R A ) was calculated by subtracting R H (which was measured in the subplots) from R S ( R A = R S – R H ) (Li et al ., ), and the relative contribution (RC%) of R A to R S was calculated as RC = R A / R S × 100.…”

“…Soil temperature was measured at a depth of 5 cm with a handheld long‐stem thermometer because Fan et al . () reported that soil temperature at 5 cm was better than that at the surface to explain the seasonality of soil respiration. Soil close to the measurement point was sampled to measure soil water content at 0–15 cm.…”

“…Fan et al . () described the seasonal characteristics of R S in tea gardens, and Yang et al . () analysed short‐term laboratory incubation observations of basal R S .…”