SOC Content May Recover Rapidly Following Agricultural Abandonment in the Karst Region of Southwest China
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The soil organic carbon (SOC) pool is much greater than the sum of C stored in plants and the atmosphere. The trivial dynamics in SOC pool may have a great impact on atmospheric CO2 level and subsequently the global climate. In spite of many years of studies, many uncertainties still exist in terms of the rate of SOC accumulation and the underlying mechanisms following agricultural abandonment or afforestation, the controls of soil variables on SOC sequestration also have not been well understood so far.

Researchers in the Institute of Subtropical Agricultural, Chinese Academy of Sciences (ISA) selected two post-agriculture succession sequences including grassland, shrubland, secondary forest and primary forest, measured SOC and other soil physicochemical variables in the soil depth of 0-15 cm, investigated the direction and magnitude of SOC dynamics and the underlying mechanisms following agricultural abandonment in a subtropical karst area, southwest China.

The team found that SOC content in the shrubland reached the level of the primary forest. "On average, SOC content for the forest was 92.6 +4.2 Mg C ha-1, representing an increase of 120.4 +10.0% or 50.6+4.2 Mg ha-1 relative to the cropland," said leader researcher LI DeJun from ISA. "Following agricultural abandonment, SOC recovered to the primary forest level in about 40 years with a rate of 1.38 Mg C ha-1yr-1." The members also found that exchangeable Ca and Mg were the strongest predictors of SOC dynamics. The researchers suggest that SOC content may recover rapidly following agricultural abandonment in the karst region of southwest China.

This research was supported by the National Key Research and Development Program of China (2016YFC0502404), the National Key Basic Research Program of China (2015CB452703), the Chinese Academy of Sciences through its One-Hundred Talent Program to Dejun Li (Y523101030), and the National Natural Science Foundation of China (41571295).

The study entitled "Soil organic carbon accumulation during post-agricultural succession in a karst area, southwest China" has been published on Scientific Reports, doi: 10.1038/srep37118 (2016), more details could be found at http://www.nature.com/articles/srep37118/ 

Contact: LI Dejun  

E-mail: dejunli@isa.ac.cn 

Institute of Subtropical Agriculture, Chinese Academy of Sciences