China has the largest area of degraded cropland due to erosion. Cropland degradation is especially widespread in southwest China. The vegetation restoration, Grain for Green project (GGP) have been proposed to enhance soil C sequestration. However, whether the vegetation restoration in this karst region will lead to substantial C sequestration is still not clear. Besides, how the different types of vegetation restoration strategies impact soil C sequestration has not been well investigated in the karst region.

In order to evaluate soil C and N stock (0- 15cm) change, a team of researchers in the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) have spent 13 years to measure soil C and N of after cropland conversion in a karst area, southwest China. They selected four restoration strategies through spontaneous- for- time substitution approach as reference: restoration with an economic tree species Toona sinensis (TS), restoration with Guimu-1 hybrid elephant grass (GG), restoration with a combination of Zenia insignis and Guimu-1 hybrid elephant grass (ZG), and spontaneous regeneration (SR).

The researchers found a significant correlation between soil C and N stock changes with rate of relative N stock change greater than that of C stock change. They also found that similar to soil N stock, nitrate concentration, net nitrification rate and δ15N values in TS, ZG and SR were greater than those in GG or CR. Moreover, the exchangeable calcium mainly responsible for the dynamics of both soil C and N was indicated through a stepwise multiple linear regression. The results suggested that plantation with economic tree species and spontaneous regeneration is likely equally effective in soil C sequestration.

This work was supported by the National Natural Science Foundation of China (31460135), the National Key Research and Development Program of China (2016YFC0502404), and the Chinese Academy of Sciences through its Hundred Talent Program to Dejun Li (Y523101030).

The study entitled “Impacts  of  vegetation  restoration  strategies  on  soil  organic  carbon and  nitrogen  dynamics  in  a  karst  area,  southwest  China” has been published in volume 101, April 2017, Pages 247- 254 of Ecological Engineering, details could be found at http://www.sciencedirect.com/science/article/pii/S0925857417300460.