The Economic Definition For The Change Of Soil Organic Carbon Storage In Northern Agro-ecological Zones Of China

Today, population, resources, environment and development are becoming the most difficult problems to trouble people. However, global climate change is the key issue cared by multilateral governments and the researchers. It is not only a science item in the field of global environment, but an important problem in connection with society and economy development fields, such as producing, consumption, life style and living space. The international negotiation about climate change is a focus on the integrated comparison of most country interest groups about politics, economy, science and technology, environment and diplomacy. It has become another significant flatform of international multilateral activities after WTO.The storage of soil organic carbon (SOC) in terrestrial ecological system is twice as much as that in atmosphere. It has become a hotspot for a minimal fluctuation of SOC might bring .about great change of global climate. Because of large variety of soil types and anthropic action of high intensity, land use/cover in China has changed much in recent decades under the associated influence of natural and anthropic activity, which have great effects on global climate through affecting the stability of SOC and the release of CO₂. Economic factors have intrinsically driving forces on "greenhouse effect". Taking typical counties in the Huang Huai-hai Plain, the Loessial Plateau, and Northeastern Plain for case studys, this paper computed the storage of SOC and its change, and delivered its explain using principles and methods of economic science. The main conclusions are as follows:(1) As accurate methods are the bases of computing, the methods of calculating the density and storage of SOC were studied. As the content of SOC is interrelated spatially at both vertical and horizontal direction in soil, the methods for simulating the distribution of SOC in vertical and horizontal were employed to calculate the density of SOC and the storage of SOC in research area, based on the data of 30 soil profiles of Situan town, Quzhou county. The different results are duo to the difference of calculating methods that organize the data from different way. The two methods are suitable to different soils that are different in soil organic matter distribution.(2) For analyzing the changes of SOC, 130 soil profiles and 1184 surface layer soil samples were collected from farmlands in the three agro-ecological zones, and the SOC content of these samples were analyzed and the storage of SOC were calculated respectively. The results are as followings: the SOC density and the SOC storage increased 0.84kgC m^-2 and 2.06 × 10¹⁰kgC respectively in the Huang Huai-hai Plain; the SOC density and the SOC storage increased 1.78kgC m^-2 and 2.72 × 10¹⁰kgC respectively in the Loess Plateau; the SOC density and the SOC storage decreased 1.57kgC m^-2and 3.60×10¹⁰kgC respectively in the Northeastern China. The increase of SOC in the Huang Huai-hai Plain and the Loess Plateau indicates that China was under the stress of a great demand of food, fiber and cultivated land for food security strategy because of its large population. However, the stress has not reached the threshold of net releasing SOC, which showed that the intensive land use at current level can't destroy the productivity of cultivated land still.(3) Through analyzing the balance between input and output of the soil organic carbon (SOC) in three research regions, the results are as follows: there are SOC surplus in the Huang Huai-hai Plain, 113.5kg ha"1 increased in Daxing county, 123.2 kg ha'1 in Quzhou county. The same result appears in the Loess Plateau, 41.5 kg ha"' increased in Lishi county and 44.6 kg ha"1 in Xing county. However, it has a deficit of SOC in Northeastern China, 598.7 kg ha"1 decreased in Gong Zhu-ling and 1130.0 kg ha'1 in Hailun. This result is consistent with the change of SOC Storage through experimentation.(4) Forecasting and simulating the SOC storage and SOC content using Janny model, the results show as follows: if keeping the curren...