Agroforestry systems play a central role in the global carbon (C) cycle and contain approximately 12% of the Earth’s terrestrial C. Agroforestry is a management system that integrates trees with farms in an agricultural landscape and usually encompasses a wide variety of understory vegetation management methods. Many studies have shown that management of understory vegetation can greatly influence soil fertility, tree nutrition, and fruit quality. However, little has been reported regarding how understory vegetation management affects soil C sequestration in agroforestry systems, especially in subtropical or tropical orchards.

Associate professor LIU ZHANFENG and senior engineer LIN YONGBIAO from Restoration Ecology Research Group led by professor FU SHENGLEI at South China Botanical Garden, CAS, investigated the effects of understory management (clean tillage vs sod culture) on soil carbon sequestration in four subtropical orchards and estimated the soil carbon sequestration potential. The results of a 10-year study indicated that the maintenance of sod significantly enhanced the soil C stock in the top 1 m of orchard soils. Relative to clean tillage, sod culture increased annual soil C sequestration by 2.85 t C ha-1, suggesting that understory management based on sod culture offers promising potential for soil carbon sequestration. Considering that China has the largest area of orchards in the world and that few of these orchards currently have sod understories, the establishment and maintenance of sod in orchards can help China increase C sequestration and greatly contribute to achieving CO₂ reduction targets at a regional scale and potentially at a national scale.

These works have been published in the international journal PLoS ONE (Liu et al., 2013. 8(10): e76950. Doi: 10.1371/journal.pone.0076950). The National Science Foundation of China, the Knowledge Innovation Program of Chinese Academy of Sciences and the Strategic Priority Research Program of the Chinese Academy of Sciences funded these works.