Carbon storage and vertical distribution in three shrubland communities in Gurbantünggüt Desert, Uygur Autonomous Region of Xinjiang, Northwest China

This study was carried out in the Gurbantunggut Desert, Uygur Autonomous Region of Xinjiang, Northwest China in August, 2009. To quantify the storage, contribution and vertical distribution patterns of plant biomass carbon (PBC) and soil organic carbon (SOC) in the study area, we investigated the carbon concentrations and its vertical distribution in three different desert shrubland communities dominated by Reaumuria soongorica, Haloxylon ammodendron + R. soongorica and Tamarix ramosissima + R. soongorica, respectively. We analyzed vertical distribution of root biomass carbon and soil carbon contents by excavating soil profiles for each dominated community. The results show that SOC is considerably the larger carbon pool in the soil layers of 1.0–3.0 m (the mean value of three shrubland communities is 38.46%) and 3.0–5.0 m (the mean value is 40.24%). In contrast, 70.74% of belowground biomass carbon storage in 0–1.0 m layer, and its content decrease with increasing soil depth. The Haloxylon ammodendron + R. soongorica shrubland community has the highest belowground biomass carbon among three selected communities. This study highlights the importance of SOC stored in deep soil layers (lower than 3.0 m from the surface) in arid shrubland communities in the global carbon balance. In addition, it provides the data support for revealing deep soil solid carbon potential, and offers scientific basis for the further research in the carbon cycle of terrestrial ecosystem.