5. Conclusion
Desert soil organic carbon contents ranged from 0.54 to 24.34 g/kg with
high variation coefficient around 81.14% in Qaidam Basin. Mean and
median value of SOC contents were approximate 4.86 and 3.80 g/kg.
Cluster analysis revealed that soils organic carbon contents were
divided into four groups by multivariate regression trees. The largest
group was around 3.32 g/kg (145 samples), when precipitation was lower
than 371.5 mm, air temperature and altitude were higher than 1.49oC and 2793 m.
All TN and pH and precipitation were main driven factors on SOC by
structural equation model with R2 of 0.87. Affected
coefficients were 0.99 and −0.21 and −0.16, separately
(P<0.001). Furthermore, air temperature significantly affected
soil pH (P<0.05). With nitrogen deposition increasing, deserts
soil organic carbon contents would increase significantly in Qaidam
basin.