Chin J Plan Ecolo ›› 2018, Vol. 42 ›› Issue (3): 327-336.

• Research Articles •

Effects of enclosure on carbon density of plant-soil system in typical steppe and desert steppe in Nei Mongol, China

YAN Bao-Long,WANG Zhong-Wu*(),QU Zhi-Qiang,WANG Jing,HAN Guo-Dong*()

1. College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Huhhot 010019, China
• Online:2018-03-27 Published:2018-03-20
• Contact: Zhong-Wu WANG,Guo-Dong HAN E-mail:zhongwuwang1979@163.com;hanguodong@imau.edu.cn
• Supported by:
Supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05050402-6);the National Key Research and Development Project of China(2016YFC0500504);the Science and Technology Projects in Inner Mongolia Autonomous Region and West Light Foundation of Chinese Academy of Sciences.

Abstract:

Aims As an immense carbon (C) stock, grassland ecosystem plays a crucial role in global C cycling. The objective of this research was to reveal the effects of enclosure on C density of the plant-soil system by comparing the aboveground biomass (AGB), belowground biomass (BGB) and soil C density in enclosure plots with those in grazing plots in the typical steppe (TS) and desert steppe (DS) in Nei Mongol, China.

Methods At each of the 19 study sites, we set up a 100 m × 100 m plot and 5 quadrats (1 m × 1 m) along the diagonal transect within each plot. At each quadrat, AGB was harvested first and then a soil core (0-100 cm depth, 7 cm inner diameter) was taken for BGB and soil C content measurement. Each soil core was divided into 7 depth increments (0-5 cm, 5-10 cm, 10-20 cm, 20-30 cm, 30-50 cm, 50-70 cm, 70-100 cm).

Important findings (1) Enclosure significantly increased C density of AGB and BGB in TS. In DS, enclosure significantly increased C density of AGB, but had no significant effect on the C density of BGB. (2) Enclosure significantly increased soil C density in TS, but had no significant impact in DS although there was an increasing trend. (3) For all increments along the soil profile, enclosure significantly increased BGB and soil C density compared to grazing plots in TS, but this effect was not found in DS. (4) Enclosure increased C density of the plant-soil system by 2.2 and 1.6 times in TS and DS, respectively. 65% and 89% C was stored in soil in TS and DS, respectively, and BGB C stock accounted for more than 90% of total biomass C in both TS and DS. Enclosure is an effective approach to improve C sequestration in grassland ecosystems.