Responses of soil respiration to soil management changes in an agropastoral ecotone in Inner Mongolia, China

Abstract

Studying the responses of soil respiration (R s) to soil management changes is critical for enhancing our understanding of the global carbon cycle and has practical implications for grassland management. Therefore, the objectives of this study were (1) quantify daily and seasonal patterns of R s, (2) evaluate the influence of abiotic factors on R s, and (3) detect the effects of soil management changes on R s. We hypothesized that (1) most of daily and seasonal variation in R s could be explained by soil temperature (T s) and soil water content (S w), (2) soil management changes could significantly affect R s, and (3) soil management changes affected R s via the significant change in abiotic and biotic factors. In situ R s values were monitored in an agropastoral ecotone in Inner Mongolia, China, during the growing seasons in 2009 (August to October) and 2010 (May to October). The soil management changes sequences included free grazing grassland (FG), cropland (CL), grazing enclosure grassland (GE), and abandoned cultivated grassland (AC). During the growing season in 2010, cumulative R s for FG, CL, GE, and AC averaged 265.97, 344.74, 236.70, and 226.42 gC m−2 year−1, respectively. The T s and S w significantly influenced R s and explained 66%–86% of the variability in daily R s. Monthly mean temperature and precipitation explained 78%–96% of the variability in monthly R s. The results clearly showed that R s was increased by 29% with the conversion of FG to CL and decreased by 35% and 11% with the conversion of CL to AC and FG to GE. The factors impacting the change in R s under different soil management changes sequences varied. Our results confirm the tested hypotheses. The increase in Q 10 and litter biomass induced by conversion of FG to GE could lead to increased R s if the climate warming. We suggest that after proper natural restoration period, grasslands should be utilized properly to decrease R s.

Soil moisture controls the spatio-temporal pattern of soil respiration under different land use systems in a semi-arid ecosystem of Delhi, India

“…3a). An earlier study (Xue and Tang 2018) reported an increase of 29% in the S R during the conversion of free grazing grassland into cropland in a semi-arid agropastoral ecotone in North China and suggested that soil management activities, mainly tillage and fertilizer input, decrease the level and storage of S C and that the soil aeration enhances S MA and SOM decomposition in cropland. In this study, the S C and S N varied significantly among all land use sites and decreased by 76-82% in the AF and 52-64% in the VF compared with the PFC and MFC (Fig.…”

Soil warming increases soil temperature sensitivity in subtropical Forests of SW China

“…Numerous studies have shown that R S rates typically increase over the course of short-term soil warming experiments (Gonzalez-Meler et al, 2017; Xue & Tang, 2018; Zhao et al, 2018) and long-term warming experiments (Noh et al, 2016; Zhou et al, 2016) and likely due to the promotion of soil microbial activity and a lack of restrictions on soil organic matter during warming treatment periods. Some studies also report that warming decreases R S levels during long-term warming experiments (Melillo et al, 2002; Marañón Jiménez et al, 2017; García-Palacios et al, 2018) and mainly due to the excessive consumption of carbon pools.…”

Soil respiration and its Q10 response to various grazing systems of a typical steppe in Inner Mongolia, China

“…This result indicated that grazing had a significant impact on Rs in a temperate typical steppe that was not only inhibitory, thus contradicting our first hypothesis that grazing inhibited Rs. Similarly, a study conducted under different land uses in Inner Mongolia reported that the average Rs during the growing season was 1.43 ± 0.04 μmol·m −2 ·s −1 for free grazing (only during the growing season with nine sheep ha −1 ) and 1.37 ± 0.03 μmol·m −2 ·s −1 for enclosed grassland grazing (Xue & Tang, 2018). In contrast to the findings of the study, the higher Rs observed under rest-rotation grazing system in our study was likely due to the lower grazing intensity (2–4.5 vs 9 sheep ha −1 ).…”