Winter Soil CO2 Flux from Different Mid-Latitude Sites from Middle Taihang Mountain in North China

Abstract

Winter soil respiration is a very important component of the annual soil carbon flux in some ecosystems. We hypothesized that, with all other factors being equal, shorter winter SR result in reduced contribution to annual soil C flux. In this study, the contribution of winter soil respiration to annual soil respiration was measured for three sites (grassland: dominated by Artemisia sacrorum, Bothriochloa ischaemum and Themeda japonica; shrubland: dominated by Vitex negundo var. heterophylla; plantation: dominated by Populus tomatosa) in a mountainous area of north China. Diurnal and intra-annual soil CO2 flux patterns were consistent among different sites, with the maximum soil respiration rates at 12∶00 or 14∶00, and in July or August. The lowest respiration rates were seen in February. Mean soil respiration rates ranged from 0.26 to 0.45 µmol m−2 s−1 in the winter (December to February), and between 2.38 to 3.16 µmol m−2 s−1 during the growing season (May-September). The winter soil carbon flux was 24.6 to 42.8 g C m−2, which contributed 4.8 to 7.1% of the annual soil carbon flux. Based on exponential functions, soil temperature explained 73.8 to 91.8% of the within year variability in soil respiration rates. The Q10 values of SR against ST at 10 cm ranged from 3.60 to 4.90 among different sites. In addition, the equation between soil respiration and soil temperature for the growing season was used to calculate the “modeled” annual soil carbon flux based on the actual measured soil temperature. The “measured” annual value was significantly higher than the “modeled” annual value. Our results suggest that winter soil respiration plays a significant role in annual soil carbon balance, and should not be neglected when soil ecosystems are assessed as either sinks or sources of atmospheric CO2.

Effects on rhizospheric and heterotrophic respiration of conversion from primary forest to secondary forest and plantations in northeast China

“…Our estimated average R S , R H and R R values, as well as the RC values in the growing season for the four forest types, were within the range of reported values for temperate forests [10,32,33]. The four forest types used for this study had the similar original vegetation and soil conditions in the history.…”

Response of Soil Respiration and Its Components to Precipitation Exclusion in Vitex negundo Var. Heterophylla Shrubland of the Middle Taihang Mountain in North China

“…The lowest average temperature in January is −4°C, and the highest average air temperature in July is 26°C (Zeng et al, 2014). Annual mean precipitation is about 560 mm concentrated from June to September (Shen et al, 2014). Monthly accumulated precipitation and average air temperature during the experimental period are shown in Figure 1.…”

“…The most abundant shrub is Vitex negundo var. heterophylla, which forms a relatively closed canopy (Shen et al, 2014).…”

“…All measurements of R s and R h were carried out from 8:00 to 11:00 a.m. R a was calculated by subtracting R h from R s (Sun et al, 2019). The soil temperature and humidity sensors equipped with the LI-COR 8100 system were used to record T s and M s at a soil depth of 10 cm (Shen et al, 2014).…”

Spatio-temporal Variation of Soil Respiration and Its Driving Factors in Semi-arid Regions of North China

“…Currently, secondary forests in this region are mainly composed of Robinia pseudoacacia and Populus tomentosa, whereas economic plantations are dominated by Armeniaca sibirica, Ziziphus jujuba, Punica granatum, Diospyros kaki, and Carya cathayensis. Tremendous changes of vegetation strongly influence soil carbon efflux and regional carbon cycling, hampering accurate predictions of the regional carbon budget (Shen et al, 2014). However, studies on soil respiration and its controlling factors after land use change in Taihang Mountains are still scarce.…”