Regional Impacts Of Climate Change On Chinese Agriculture And Forestry Biomass Research

Climate is an important part of environments that human beings depend on. As the AR4 of IPCC reported, in the resent 100 years, the global surface temperature has increased by 0.74(0.56-0.92)℃。Climate change is not only scientific and environmental issue but also energy, economic and socio-political issues. Under the climate change conditions, development of bioenergy can contribute the development of rural area of China and improve the livelihoods of farmers, as well as protect eco-environment, secure energy supply of China and alleviate energy crises. An understanding of the energy resources and distribution is a prerequisite for utilization of bio-energy. Therefore, in 2008 General Office of the State Council of the People's Republic of China released the document on accelerating the promotion of comprehensive utilization of crop straw to find out the situation of crop straw resource, current utilization of crop straw and its future development trends. This will provide fundamental information for comprehensive utilization of crop straw and assessment of agriculture resource, as well as provide evidences for the constitution of special planning of comprehensive utilization of crop straw and resource utilization and evaluation of crop straw. So quantifying the resource reserve of bioenergy, analyzing the impacts of climate change on resource reserve of bioenergy and predicting its development trends under future climate will contribute the medium and long term development plan of energy of China.In this study, Chinese bioenergy from agriculture and forestry under current and future climate was investigated using the methods of statistical analysis, evaluation of field experiment and model simulation. Based on the meteorology records and statistical information of China, climate change in China, changes in rice straw, maize straw and wheat straw and the impacts of temperature and rainfall on crop straw were analyzed. The effect elevated CO₂ concentration on wheat straw was evaluated through Free-air CO₂ enrichment (FACE) experiment. The CERES crop model was used to simulate future trends in the main crop straw of China under the future climate scenarios. Also the impacts of change on bioenergy from forestry were assessed, which will provide evidence for development and utilization of bioenergy of China. The main conclusions of this study are:(1) In China, the air surface temperature increased significantly, and there is a slight decrease in rainfall. The warming up period in China begins at the middle of the 1970s and becomes significant in 1990s for the last 50 years. The warming trend of the average temperature of China is obvious. The average temperature of 2004 is 1.09℃higher than 1974. With the exception of 1986, the average temperature of the other years (1987-2004) is higher than the average temperature of 31 years(1974-2004).(2)The effect of climate change on the straw production. Based on the Yearbook of Agricultural Statistics of China (1983-2005), this paper gets the three major crop straw productions by computing the economic coefficient and the crop yield of per unit. The annual average yields of the three major crops are 1.814×10⁸t (rice), 1.636×10⁸t (wheat) and 1.206×10⁸t (maize). The total amounts of China's three major crop straw productions are increasing while the rice and the wheat are decreasing. With increasing temperature, rice and wheat straw production decreases while the maize straw production has an increasing trend. But the trend is varies in different regions of China. The increasing temperature leads to the increasing trend of major crop straw and it has passed the 0.01 level of correlation test. But only parts of the precipitation pass the test. It shows that the temperature plays an important part on the effect of crop straw yield than the precipitation.(3)It can be drawn through the increased CO₂ concentration on the impact of winter wheat experiment (FACE) that the increased CO₂ concentration can promote the plant height, biomass and the straw field of the winter wheat based on the control value. The economic coefficient of the winter wheat decreases which means an increase of straw field. Under the conditions of increased CO₂ concentration, the average economic coefficient of the two varieties decreases. The average economic coefficient is 0.38 under the high CO₂ concentration while the control value is 0.40. This is in line with the international law of FACE results that in the role of increased CO₂ concentration, the crop plant is getting higher and higher. For the control test conditions and compared FACE conditions, the economic coefficient is inversely proportional to the plant height which means the economic coefficient decreases when the plant height increased significantly under the conditions of the FACE experiment.(4)Under the emission scenarios A2 and B2 of the IPCC climate change SRES (Special Report on Emissions Scenarios), taking the fertilizer effect of the CO₂ into account, this paper uses the crop models to simulate the future change of the trends of major crop straw production. Under the A2 scenario, the production reduced in general. The average per unit production of the straw increased 0.13% in the 2020s and decreased 0.24 and 2.08% in the 2050s and 2080s. Under the B2 scenario, wheat production increased significantly and the per unit production of crops straw of the three major crops increased respectively by 8.64%,11.99% and 18.10%. And the amplitude is increasing with time under the two scenarios.(5) Based on the security of food supply of China, the energy utilization of crop strews and no bio-energy crop can be further strengthened.In China, crop strews and energy crops are the main resource of bioenergy under the condition of secure food safe. There are lots of resource of crop strew, and only the main tree food crop can produce about 0.5 billion ton strew, which can maintain soil carbon and was used as the resource of bioenergy. In addition, there are about 0.1 billion hm2 waste hills and and that is suitable for farming or forestry can be used for the development of agriculture and forestry energy. The main energy source crops in China are cassava,sugarcane,sweet sorghum,rape,beet,groundnut,sunflower and so on. The main forestry energy sources are Pistacia chinensi,Xanthoceras sorbifolia,Jatropha curcasL,Cornusw ilsoniana W anger and so on. All these can be used as energy resource of China to strengthen utilization of bio-liquid energy.(6) The comprehensive utilization of crop strews and non agriculture economic forestry can be further developed to increase the income of farmer.The development and utilization of bioenergy can resolve the problem from agriculture famer, rural area of China. And it can further improve the income of farmer by altering the crop strews into useful bioenergy and saling crop strew, in addition increase the work opportunity for the farmer. The comprehensive utilization pattern with biogas engineering as link such as the eco-agricultural model (Four-in-One)in North China, which can greatly improve the income of farmer. Also, there is great development in household biogas and large and medium biogas engineering under the support of governmental funding and policy. There is 21.4 million hm2 economic forestry and the total area of woody oil plant exceeds 4 million hm2. The fruit production of woody oil plant is above 2 million ton per year, which can be used as resource of bio-diesel oil. Also, the management of forestry resource such as woods, fruit tree and Forestry by-products can enhance the income of agriculture and forestry.(7) From the view of environment protection, alternative bioenergy engineering from agriculture and forestry can be brought into line with the state plan when enough crop strew is return to the field.Utilization of bioenergy from crop strew can reduce the burning of strew, hence reduce the environment pollution and improve the use efficiency of bioenergy. Compared with the traditional burning of energy, bioenergy can save energy use and improve life environment and eco-environment of rural area of China. Fertilizing soil through straw returned into field can reduce emission of CO₂ and SO₂ and increase soil carbon, which would contribute the protection of environment and relieve the warming.(8)In this study, meta method was used to analyze the amount of straw returned into field based on the literature, and it is estimated that in China the optimal amount of straw returned into field is 4.78t/hm2. In theory, the amount of crop straw returned into field only accounts for 87% of total strew resource of China. The main three crop straw returned into field only 0.61⁰.81×10⁸t, which accounts for 13¹7% of total strew resource. Under the A2 and B2 climate scenarios, the change in crop strew yield and the total strew production is similar to that of current climate on the assumption that the planting area is same. Under the B2 climate scenario, the production of main crop strew and utilization of bioenergy will increase over time, and it will reach above 0.92¹.66×10⁸t billion t by 2050s...