Contents,Patterns And Main Influencing Factors Of Soil Carbon In Topsoil Of Grassland In Ningxia

Ningxia is an important ecological barrier in the northwestern part of China.The study on the distribution of soil carbon content and the influencing factors on the grassland ecosystem function evaluation and degraded grassland Restoring and responding to global climate change is important.In this study,we studied the soil organic carbon(SOC)and soil inorganic carbon(SIC),distribution pattern and environmental factors in 0?20 cm and 20?40 cm soil layers in Ningxia grassland,using redundancy analysis(RDA)and variance decomposition.Discuss the contribution rate of each environmental factor to soil carbon content.The main conclusions are as follows:(1)The SOC content in the 0?20 cm and 20?40 cm soil layers of Ningxia grassland were 9.19 g/kg and 8.45 g/kg,respectively,and the SOC content decreased with the increase of soil depth;0-20 cm and 20?40 The SIC content in the cm soil layer was 11.68 g/kg and 12.95 g/kg,respectively,and the SIC content increased with the depth of the soil layer.(2)The spatial differentiation of SOC and SIC content in the 0?20 cm and 20?40 cm soil layers of Ningxia grassland was significant.The SOC content in the 0?20 cm and 20-40 cm soil layers was negatively correlated with the longitude and latitude,and positively correlated with the altitude.The SIC content in the 0?20 cm soil layer was negatively correlated with the longitude,and in the 20-40 cm soil layer.There was no significant relationship between SIC content and longitude.The SIC content in the 0?20 cm and 20?40 cm soil layers of Ningxia grassland was negatively correlated with latitude and positively correlated with altitude.(3)There is no significant relationship between SOC content and Pielou evenness index in 0?20 cm soil layer,but positive correlation with Margalef richness index,Simpson dominance index and Shannon?Wiener diversity index,the SOC content in the 20?40 cm soil layer was positively correlated with the species diversity index.There was no significant relationship between the SIC content and the species diversity index in the 0?20 cm soil layer.The SIC content in the 20-40 cm soil layer was only related to the species.The rich index is positively correlated.(4)The SOC content in the 0?20 cm and 20?40 cm soil layers of Ningxia grassland decreased with the increase of annual average temperature,and increased with the increase of annual average rainfall;0?20 cm and 20?40 cm soil layers The SIC content was negatively correlated with the annual average temperature.The SIC content in the 0?20 cm soil layer was not significantly correlated with the annual average rainfall,but the SIC content in the 20?40 cm soil layer was positively correlated with the annual average rainfall.(5)Soil physical and chemical properties have a certain relationship with SOC and SIC content in 0?20 cm and 20?40 cm soil layers.The SOC content in 0?20 cm and 20?40 cm soil layers was negatively correlated with soil pH and positively correlated with soil total nitrogen and total phosphorus.The SIC content in 0?20 cm and 20?40 cm soil layers was not related to soil pH value and soil total nitrogen,but positively correlated with soil total phosphorus.(6)The climatic factors,species diversity and soil physical and chemical properties affect the SOC and SIC content in the soil.The three environmental variables explain the variance of SOC content of 56.15%and 58.03%in 0?20 cm and 20?40 cm soil layers.Among them,mean annual temperaturesmean annual precipitation and soil total nitrogen and total phosphorus are the main factors affecting SOC contentThe three environmental variables explained the variance of SIC content of 4.81%and 8.26%in 0?20 cm and 20?40 cm soil layers respectively,and the unexplained rate was as high as 95.19%and 91.74%From the unexplained ratio,soil parent material may be the main factor affecting SIC content.