Soil Organic Carbon Contents And The Influencing Factors In Natural Ecosystems Of Northern China

Soil organic carbon(SOC)is the most active part in terrestrial carbon pool.Small changes in the SOC stock could result in significant impacts on the atmospheric CO2 concentration and contribute to global climate change.In this study,we collected soil samples from typical natural ecosystems(desert,grassland,shrubland and forest)in northern China.We compared the differences of SOC contents in different ecosystems and analyzed its influencing factors.The key findings are as follows:(1)We found remarkable differences in SOC contents in different ecosystems.The results showed that SOC contents was highest in the forest and declined as follows:forest>shrubland>grassland>desert.(2)Correlation analysis showed that SOC contents were significantly positively correlated with soil fractal dimension in desert and forest.SOC contents were significantly positively correlated with mean annual precipitation(MAP)and plant species richness in grassland,but significantly negatively correlated with soil pH and mean annual temperature(MAT)in grassland and forest.At the regional scale,SOC contents were significantly positively correlated with mean annual precipitation,soil fractal dimension and plant species richness,but significantly negatively correlated with mean annual temperature and soil pH.In addition,we found positive but insignificant correlation between SOC contents and plant alpha diversity.(3)Multiple linear regression analysis indicated that environmental factors influenced SOC contents differently in different ecosystems.We found that MAP,MAT and soil texture were main factors influencing SOC contents in desert.In grassland,SOC contents were mainly determined by MAP,MAT and soil pH.In shrubland,SOC contents were mainly determined by plant alpha diversity and plant species richness.In forest,SOC contents were mainly determined by MAP,plant alpha diversity and soil pH.(4)Variation partitioning showed that SOC contents were influenced by soil factors,climate factors and plant community,and mainly determined by MAP,MAT,soil pH and soil texture at the regional scale.This study was conducted at the regional scale,analyzed the differences of SOC contents in different ecosystems and its influencing factors in northern China,and provided strong supports for SOC management and also dataset for elucidating carbon cycle and carbon sequestration at the regional and global scales.