A State‐Space Analysis of Soil Organic Carbon in China's Loess Plateau

Abstract

An accurate estimation of soil organic carbon (SOC) is important for the evaluation and management of carbon (C) flux in terrestrial ecosystems. However, there is little work on the spatial variability of SOC in deep soils and its driving factors. Thus, the objective of the study was to derive the primary factors dominating the spatial distribution of SOC in different soil layers with the use of the autoregressive state‐space approach. The concentration of SOC was measured to the depth of 500 cm (n = 86) along a south–north transect of China's Loess Plateau. The mean SOC of the 500‐cm soil profile generally decreased from south to north following the decreasing rainfall gradient. Based on the investigated factors, the state‐space model was able to capture 90.3–99.9% of the spatial variability of SOC in the various soil layers. According to the coefficients in the optimal state‐space model for each soil layer, climatic factors such as precipitation and temperature had a dominant control over the spatial distribution of SOC at shallow depths. However, both climatic and edaphic (e.g. soil texture) factors, and to a small extent land use, influenced the spatial behavior of SOC at the 40–200 cm soil depth. For soil layers below 200 cm, the importance of land use was revealed, and the spatial characteristics of SOC were together driven by land use, climatic and edaphic factors. This is critical for the management of soil C flux in deep soils and the C stock and cycle in terrestrial ecosystems. Table SI. Basic properties of soils and climate and elevation under three land uses along the south–north transect on the Loess Plateau (mean ± standard deviation). Note that SWC is gravimetric soil water content. Copyright © 2016 John Wiley & Sons, Ltd.

Variable response of inorganic carbon and consistent increase of organic carbon as a consequence of afforestation in areas with semiarid soils

“…High MAP and MAT also resulted in a high litter decomposition rate on the land surface and a large release of organic carbon (Han et al, ; W. Zhao et al, ), which accelerated the accumulation of organic carbon in the soil. In addition to climate, high clay content usually leads to the association of organic carbon compounds with fine soil particles (Bazzoffi, Mbagwu, & Chukwu, ; Bronick & Lal, ; Jia, Yang, et al, ), which provided chemical protection for SOC against microbial decomposition (Razafimbelo et al, ). Moreover, high SOM and clay content stimulated aggregation of soil particles (Bazzoffi et al, ), which in turn provided physical protection for SOC from decomposition (Bronick & Lal, ).…”

“…The restoration and reconstruction of degraded ecosystems are essential for the development of degraded lands and for increasing the functionality of the ecosystem in the Loess Plateau (Jia, Shao, et al, ; Jia, Shao, Yu, Zhang, & Binley, ). Afforestation on abandoned farmlands is one of the most effective ways to prevent soil erosion, to remedy degraded lands, and to sequester C, and this approach is used widely around the world (Deng, Dong, Cai, & Ding, ; García‐Díaz et al, ; Jia, Shao, et al, ; Jia, Yang, Zhang, Shao, & Huang, ; John, Chen, Lu, & Wilske, ).…”

Mesoscale spatial variability of soil‐water content in an alpine meadow on the northern Tibetan Plateau

“…Fine particles and high capillary porosity would improve the water‐holding capacity of the soil. Soil organic carbon can also increase the capacity of the soil to store and retain water by improving soil structure (Jia, Yang, Zhang, Shao, & Huang, ). The elevation varied little within the plot, and the vegetation was sparse and slightly degraded, which would contribute little to the distribution of SWC on the scale of this study (Wang, Zhang, Chen, et al, ; Zhang, Zhang, et al, ).…”

Identifying the Main Factors Contributing to the Spatial Variability of Soil Saline–Sodic Properties in a Reclaimed Coastal Area

“…This result was similar to Xu et al (2014), who found that land‐use types and reclamation time significantly influenced soil salinity in coastal areas. Jia et al (2017) also reported that land‐use patterns could significantly affect solute transports and water balances in soil systems. Vegetation coverage and clay content were significantly and negatively correlated to SSC in the two transects, which was consistent with previous findings that greater vegetation coverage corresponded to lower SSC (Mackinnon et al, 2001; Fernández‐Buces et al,2006).…”