Soil Organic Carbon Accumulation in Abandoned Croplands on the Loess Plateau

Abstract

The Grain to Green Program in China which began in 1999 led to the conversion of 0.64 million ha of cropland to grassland on steep sloping landscapes. However, the pattern of natural vegetation succession following cropland has not been well represented in previous regional syntheses of land use change effects on soil organic carbon (SOC). A chronosequence study focusing on the vegetation succession and soil carbon stocks was conducted in the center of the Loess Plateau. The chronosequence included fields of 0, 2, 5, 8, 9, 10, 12, 15 and 25 years of self‐restoration after cropland abandonment, as well as a natural grassland reference. Plant coverage, species richness and plant biomass increased significantly with time of cropland abandonment. Over time, the species composition more nearly resembled a natural grasslands community. Cropland abandonment replenished SOC stocks by 3.6 kg C m−2 during the 25‐year self‐restoration, but the SOC accumulation was restricted to the upper soil profiles (0–60 cm). SOC accumulation rate was 88 g C m−2 y−1 in 0–30 cm and 55 g C m−2 y−1 in 30–60 cm soil depth, respectively. These carbon stocks were still significantly lower than those found in the natural grassland soil. Our results suggest that the recovery of plant communities and SOC stocks appears to be slow in this semiarid environment without revegetation effort along with appropriate field management, although the post‐agricultural soils have a high potential for carbon sequestration. Copyright © 2016 John Wiley & Sons, Ltd.

Soil organic carbon sequestration and its stability after vegetation restoration in the Loess Hilly Region, China

“…The results showed that recovery years mainly affected SOC sequestration and active organic carbon content (C1 and C2) in 0–30 cm depths, which initially decrease and then increase with recovery years after the cultivation of CA, HR, and RP on SL, corroborating previous researches (Chang et al, ; Jia et al, 2014; Xu et al, ). This change can be explained by multiple reasons.…”

“…Soils for agriculture have bright prospect for carbon sequestration by the change of land‐use patterns (Zhang et al, ), vegetation reforestation has been proposed an effective approach to increasing carbon sequestration in both vegetation and soils (Lal, ). Vegetation restoration is a long process (Chang et al, ) and thus the stability of the sequestrated carbon over this process deserves equal attention to the carbon sequestration. When SOC stability is low, the sequestrated SOC can be released to atmosphere following changing environments, which may influence SOC resistance against degradation and alter the effect of soil microorganisms on SOC.…”

“…All above changes will cause an inhibition of plant growth (Zhu et al, ), an aggravated soil (Lal, , ), and ultimately unstable ecosystems. Surprisingly, thus far many studies have dedicated to examine SOC sequestration over vegetation restoration (Brahma et al, ; Chang et al, ), but very few work attempts to assess SOC stability. Therefore, thorough evaluation of both the sequestration and the stability of SOC is sufficiently necessary to track the dynamics of the carbon in soil for assessing the success of the restored area.…”

Soil enzyme activity and stoichiometry along a gradient of vegetation restoration at the Karst Critical Zone Observatory in Southwest China

“…Croplands on slopes greater than 25° were abandoned, and vegetative succession allowed to proceed naturally from nonwoody plants to woody shrubs and ultimately to mature secondary forest, with the ultimate objective of ecosystem restoration to conditions similar to pristine primary forest (Xu, Yin, Li, & Liu, ). The regeneration of plant communities under GGP in degraded karst landscapes has been largely successful, indicated by increased NPP and soil organic matter (SOM) stocks, and the stabilization of soil profiles by vegetative canopy cover and roots that moderate further loss by erosion (Chang et al, ; Ren, Lu, Fu, & Zhang, ; Tong et al, ). SOM contains soil organic carbon (C) and nutrients (including nitrogen [N] and phosphorus [P]) and is recognized as a key indicator of soil health and productivity in agricultural systems (Dungait et al, ).…”

Plant‐mycorrhizae association affects plant diversity, biomass, and soil nutrients along temporal gradients of natural restoration after farmland abandonment in the Loess Plateau, China

“…Natural restoration without human interference can effectively be used to recover ecosystems with degraded soil and to maintain soil fertility (Prach & Walker, ). Natural restoration helps to promote the recovery of vegetation cover and plant diversity and is conducive to increasing soil carbon and nitrogen contents (Chang et al, ; Deng, Wang, Liu, & Shangguan, ; Liu, Wu, Ding, Tian, & Shi, ). The rhizosphere is a biologically active zone where complex interactions among plant roots, soil, and microbes occur (Puglisi et al, ; Zoysa, Loganathan, & Hedley, ).…”