Soil Organic Carbon, Total Nitrogen and Their Densities of Nitraria Tangutorum Nebkhas at Different Succession Stages on the Edge of Ulan Buh Desert

This study aimed to determine if the succession of Nitmria Tangutorum nebkhas could change soil nutrients in the Jilantai desert, Inner Mongolia. Four succession stages including rudimental stage (RUD), developing stage (DEV), stabilizing stage (STA) and degrading stage (DEG) were regarded as succession patterns. We collected 588 soil profile samples within a 0-100 cm depth from different succession stages of N. tangutorum nebkhas. We determined the vertical distributions of soil organic carbon (SOC), total nitrogen (TN) and their densities to 1 m depth. The results indicated that soil depths and successional stages had significantly impact on SOC and soil organic carbon density (SOCD), and soil depths had significant impact on TN and soil nitrogen density (SND). SOCD showed firstly increased and then decreased, and SND showed an increasing trend with the succession of N. tangutorum nebkhas. SOCD and SND showed as the following order: STA (860.60 g/m(2)) >DEG (753.00 g/m(2))>DEV (737.60 g/m(2))>RUG (678.18 g/m(2)) and DEG (83.75 g/m(2))>STA (83.68 g/m(2))>DEV (83.06 g/m(2))>RUG (73.42 g/m(2)), respectively. The stratification ratios (SR) of SOC and TN gradually decreased with soil depth in different succession stages, and there was no significant difference in SRs of SOC and IN for each succession stage. Redundancy analysis (RDA) revealed that soil depth, silt content, soil water content (SWC) and successional stage directly drove SOCD and SND of N. tangutorum nebkhas. Therefore, understanding the vertical distribution of the SOC and TN at different succession stages has great significance for accurately estimating the SOCD and SND storage in the desert areas.