Kou D, Ma WH, Ding JZ, Zhang BB, Fang K, Hu HF, Yu JC, Wang T, Qin SQ, Zhao X, Fang JY, Yang YH*
PubYear : 2018
Volume : 32  Issue : 6
Publication Name : Functional Ecology
Page number : 1620-1630
Abstract : 

1. Drylands, covering c. 45% of the Earth's terrestrial surface and supporting c. 38% of the global population, play a dominant role in the trend and interannual variability of global land carbon (C) sink. Given that a large proportion of organic C is stored in soils, our knowledge on soil C dynamics in drylands is crucial to evaluate terrestrial C-climate feedback. However, credible understanding on this issue is still greatly limited by the lack of direct observations.
2. Here, based on a regional resampling of historical sites collected during 2002-2004, we explored the soil organic C (SOC) changes in various layers over the past decade across the arid/semi-arid grasslands on the Inner Mongolian Plateau.
3. Our results revealed that the SOC density in this typical dryland increased significantly over the monitoring period, with a mean increase in 50.6 g C m^-2 year^-1 or 0.8% per year in the top 50 cm depth. Moreover, soil C dynamics exhibited contrasting spatial patterns between different layers: the rate of C accumulation in surface soils (0-10 cm) decreased, whereas that in deep soils (30-50 cm) exhibited an increasing trend along the aridity gradient.
4. Collectively, these findings demonstrate that dryland soils function as an important C sink, with the drier region tending to sequester C in deeper soils due to the greater root biomass allocation.