Distribution pattern and driving factors of soil organic carbon of natural grassland in Ningxia
[Objective]Grassland is an important soil carbon pool. It is important to investigate the distribution pattern and influencing factors of organic carbon in grasslands in order to mitigate the greenhouse effect. The investi-gation is also of great significance in grassland ecosystem evaluation and ecological restoration of degraded grasslands.[Method]In this paper,three natural grassland types (meadow steppe,typical steppe and desert steppe) in Ningxia were taken as the research object.Soil organic carbon (SOC) in 0～20 cm and 20～40 cm soil layers was measured in 195 sample plots. The Composite structural equation model was used to reveal the relationship between soil organic carbon content and geography,climate,vegetation and soil factors.[Result]The results showed that in the horizontal direction,the average SOC content of natural grassland in 0～20 cm and 20～40 cm soil layers was 9.46 g/kg and 8.25 g/kg,respectively,with the order of meadow grassland>typical grassland>desert grassland. In the vertical section,SOC decreased with the increased of soil depth. There was a decreased trend from south to north. The seg-mental structural equation showed that in 0～20 cm and 20～40 cm soil layers,SOC content was positively correlated with TN,TP,and Margalef richness indices (P<0.01),and negatively correlated with pH and MAT (P<0.01),but had no significant relationship with MAP.In 0～20 cm soil layer,the total effect was in the order of climate factor (0.38)>soil factor (0.21)>Margale index (0.12). In the 20～40 cm soil layer,the total effect was in the order of soil factor (0.39)>climate factor (0.23)>Margale index (0.13).[Conclusion]The results of the fractional struc-tural equation showed that rain and heat conditions were the main factors affecting the SOC content of the surface soil.TN and TP were the main factors affecting the SOC content of the deep soil.
Ningxia natural grasslandsoil organic carbonenvironmental factorsstructural equation model
万方数据
维普
