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

Abstract

Assessing the response of soil heterotrophic and autotrophic respiration to climate change is critical for forecasting terrestrial carbon cycle behavior in the future. In the present study, we conducted a drought experiment in Vitexnegundo var. heterophylla shrub ecosystem of the Middle Taihang Mountain. Three precipitation manipulation treatments (natural conditions/ambient precipitation (CK), reduced precipitation by 30% (PE30), and reduced precipitation by 60% (PE60)) were used to study the impact of different levels of precipitation exclusion on total soil respiration (Rs) and its heterotrophic (Rh) and autotrophic (Ra) components. Our results showed that the rates of Rs and its components were significantly decreased under the precipitation exclusion treatments. The proportion of Rh in Rs reduced from 72.6% for CK to 71.9% under PE60. The annual cumulative C fluxes of Rs decreased by 47.8 g C m−2 in PE30 and 106.0 g C m−2 in PE60, respectively. An exponential relationship was observed between the rate of each soil respiration component and soil temperature in all treatments ( p < 0.01). Moreover, each soil respiration component rate was better represented by a quadratic model which included soil moisture ( p < 0.01). However, including both of soil temperature and soil moisture did not explain more variation in soil respiration components compared than the regression model with soil moisture only. In addition, excluding precipitation increased the temperature sensitivity (Q10 values) of Rs and its Ra and Rh components compared to the control. Collectively, our findings suggest that increased drought will inhibit the release of carbon from the soil to the atmosphere, and will likely decrease the contribution of Rh to Rs in this semiarid shrubland ecosystem.

Soil Carbon Fluxes and Sensitivity Analysis – A Study in Pinus roxburghii Forest

“…4) of the soil water effect on SR of this study could better define the forest soil water model on soil carbon emission. The highly significant exponential relationship between these variables in Subtropical mixed forests (Dhital et al unpublished), temperate forests (Klimek et al 2021), semiarid shrub-land (Shen et al 2021) and grassland (Dhital et al 2020) well explained the SWC is specific to define the SR variations. Moreover, the invisibly non-significant dependency of soil water effect on SR detected previously (Dhital et al 2010;Balogh et al 2011) explained that the particular data point area could better represent and define the SWC effect on SR.…”

“…The SR was estimated with the relation of ST; an equation of exponential regression (Dhital et al 2010;Shen et al 2021), which were used as follows:…”

“…One of the most effective and influencing ecological factors of soil carbon emission was represented by the soil moisture in different biomes (Zeng & Gao 2016;Deng et al 2017;Kochiieru et al 2021;Watts et al 2021), and it is the most effective parameter to estimate the SR (Shen et al 2021). The positive significant exponential regression model (Fig.…”

Effects of Precipitation Variation on Annual and Winter Soil Respiration in a Semiarid Mountain Shrubland in Northern China

“…These changes in precipitation are expected to greatly affect terrestrial carbon C cycling [6]. In general, manipulation experiments on precipitation reduction significantly inhibited [7], substantially stimulated [8], and had no effect [9] on soil respiration. These inconsistent results may have resulted from the different ecosystems and the level of precipitation reduction across the experiments.…”