Dynamic Simulation Of Soil Organic Carbon In Dry Land Of Northeast China Based On GIS

With the aggravation of global warming,how to reduce the concentration of carbon dioxide(CO2)in the air is a common concern of all mankind.At present,the method that sequestrate CO2 by soil has become one of the carbon sequestration ways recognized by international scholars.Soil can increase its carbon density and productivity by absorbing CO2 from the air.Therefore,the accurate estimation of the dynamic change and carbon sequestration potential of soil organic carbon in regional scale can not only pave the way for the study of regional scale soil carbon cycle,but also provide theoretical support for the regional scientific formulation of agricultural management mode and realize the healthy and green development of agriculture.At present,the study of soil organic carbon mainly uses model simulation method,in which the CENTURY model is widely used in farmland soil ecosystem,and the simulation effect has been verified well,and the model application has been more mature.In this study,based on the CENTURY model,the dynamic evolution of organic carbon of typical soil in the study area is simulated first,and the simulation effect is tested according to the long-term actual record data of the monitoring points.Finally,using the most detailed China 1:1 million soil database and China 1:1 million land use database,through the geospatial analysis method,combined with the soil profile data,the dry land soil map spots in Northeast China are obtained as the smallest unit of the CENTURY model simulation.Based on the data of meteorology and farmland management in the study area,the dynamic change of soil organic carbon in dry farmland of Northeast China from 1985 to 2015 was simulated.The simulation results are validated on the regional scale by using the existing regional data.Finally,the model was used to predict the soil carbon sequestration potential of Northeast China in the next 30 years under straw returning.The main conclusions are as follows:1.The CENTURY model can simulate the dynamic change of organic carbon of typical soils in Northeast China.The verification results show that the simulation value of the model has a strong correlation with the actual value,the simulation effect of the model is satisfactory.2.The results of regional validation show that the CENTURY model can simulate the dynamic change of soil organic carbon in the dry farmland of Northeast China at the regional scale.From 1985 to 2015,the density and storage of soil organic carbon in the dry farmland of Northeast China decreased.The density of soil organic carbon(SOCD)in Northeast China was reduced 0.35 Mg C ha-1.The loss of soil organic carbon reserve was 13.89 Tg,the average annual loss rate was 0.45 Tg C yr-1.In spatial distribution,32.4%of the dry land soils in Northeast China had an SOCD of 50?70 Mg C ha-1 in 1985,which was reflected in the southwest and northeast of Heilongjiang Province and the north of Jilin Province.Only 4.6%of the dry land soils,its SOCD greater than 70 Mg C ha-1.In 2015,40.3%of dry land soil had an SOCD of 30?50 Mg C ha-1,which was concentrated in the southwest and northeast of Heilongjiang Province,the middle of Jilin Province and the south of Liaoning Province.Only 3%of dry land soil,its SOCD greater than 70 Mg C ha-1.The area of dry land soil carbon sequestration in Northeast China accounted for 62%of the total area,mainly distributed in the east and west of Heilongjiang Province near the border,and in the central part of Jilin Province and Liaoning Province.The area of soil carbon loss accounts for 38%of the total dry land area,which is mainly distributed in the northeast and southwest of Heilongjiang Province and the middle and west of Jilin Province.3.In different soil types,the dynamic changes of SOCD are quite different.From 1985 to 2015,the SOCD of most soil types showed a downward trend.The SOCD of meadow soil,black soil,chernozem and other soil types with large distribution areas decreased to different degrees.The SOCD of soil types with small distribution areas,such as swamp soil,cinnamon soil and brown soil,increased to different degrees.The dynamic change of soil organic carbon was also different among the three provinces.4.The simulation results of the amount of straw returning showed that increasing the proportion of straw returning could promote the increase of SOCD and reserves in dryland.At the end of the model,the SOCD under the straw returning measure was higher than that at the beginning of the model.With the increase of the proportion of straw returning to the field,the SOCD increased more and more quickly.Figure[36]Table[6]Reference[143]...