Soil Carbon and Nitrogen Qeserves of Shrubs in the Bailongj iang Dry Valley,Gansu Province
Obj ective]The obj ective of this study was to clarify the dynamics of soil organic carbon and nitrogen of different shrub communities in the Bailongjiang dry valley,Gansu province.[Method]Soil samples were collected from shrubs in the in the Bailongjiang dry valley of Gansu province.Soil bulk density was measured by ring-knife.Soil organic carbon was determined by potassium dichromate oxidation titration.Soil total nitrogen was analyzed by Kjeldahl nitrogen determination.[Results]With the increase of natural recovery time,the storages of soil organic carbon and total nitrogen increased significantly.Soil organic carbon was 58. 18 Mg/hm2 ,82. 48 Mg/hm2 ,127. 24 Mg/hm2 and 213. 41 Mg/hm2 ,respectively,in 5 a,8 a,15 a and primary stage. Soil Nitrogen was 4. 42 Mg/hm2 ,5. 75 Mg/hm2 ,6. 59 Mg/hm2 ,11. 85 Mg/hm2 ,respectively,in 5 a,8 a,15 a and primary stage.Moreover,the ratio of organic carbon to nitrogen was 13. 15, 14. 35,19. 31 and 18. 00 respectively,in 5 a,8 a,15 a and primary stage.[Conclusion]Soil bulk density decreased with increasing vegetation restoration ages and soil organic carbon and nitrogen increased with vegetation restoration.
dry valleyvegetation restorationsoil organic carbonsoil total nitrogenC/N