Compared with the other regions of China, the average soil organic carbon (SOC) stock in cropland has a decreasing trend in Northeast China. Cropland reclamation from different natural land also leads to negative effects. It is essential to monitor the SOC change of cropland in Northeast China.

There are many studies on SOC monitoring using remote sensing technology, but the study on effects of crop reclamation on SOC changes is rare. It is still unclear how much SOC has been lost in Northeast China over the past 35 years due to long-term use of cropland and cropland reclamation.

In a recent study published in Global Change Biology, a research team led by Prof. SONG Kaishan from the Northeast Institute of Geography and Agroecology (IGA) of the Chinese Academy of Sciences completed SOC mapping of Northeast China from 1985 to 2020 and extracted different reclamation periods based on Landsat images and land cover data.

Long-term use of cropland led to a 3.07 g kg^-1 and 6.71 Mg C ha^-1 decrease in SOC content and density, respectively, and the decrease of SOC stock was 0.32 Pg over the past 35 years. Nearly 64% of cropland had a negative change in terms of SOC content from 1985 to 2020.

Cropland reclamation track changed from high to low SOC content, and almost no cropland was reclaimed on the ‘Black soils’ after 2005. Cropland reclamation from wetlands resulted in the highest decrease, and reclamation period of years 31–35 decreased when SOC density and SOC stock were 16.05 Mg C ha^-1 and 0.005 Pg, respectively.

The results provide a reference for SOC change in the black soil region of Northeast China and can attract more attention to the area of the protection of ‘Black soils’ and natural ecosystems.

Contact:

SONG Kaishan

Northeast Institute of Geography and Agroecology (IGA) of the Chinese Academy of Sciences

Tel: 86-159-044-14023

E-mail: songkaishan@iga.ac.cn

Reference