| The dissertation, with the intension of sustainable agriculture as the starting-point andfrom the perspective of climate changes, discusses the factors that affect the sustainabledevelopment of agriculture. Applying a combination of quantitative and qualitative analysis, thedissertation tries to analysis the effects caused by climate changes upon the sustainableagriculture in Yunnan Province.In ploying temperature and precipitation as quantitative indexes, the dissertation focuseson analyzing the effects caused by climate changes on grain yield and sustainable supply. Onthe basis of statistical analysis of the temperature and precipitation data from 1951 to 1995 inYunnan Province, by applying temperature variability, temperature standardized deviation,precipitation variability, and abnormal index of precipitation, and by applying the five-yearsmoothing average method, the author systematically sums up the characteristic and regularpatterns of climate changes in the past 45 years in Yunnan Province. By the means of the extra-smoothing average prediction, the dissertation attempts to predict the tendency of climatechanges in the coming 5 or 9 years from 1995. By applying regression analysis and numericalvalue simulation in Excel and SPSS, the author sums up the fluctuation tendency of the grainyield in Yunnan Province in the past 45 years. By applying Lieth, the value of the climaticproductivity (Pv value) and the effects on the Pv value when temperature and precipitation arein varying combination are worked out.Research results show that the average temperature throughout Yunnan Province tended torise moderately from 1951-1995, while the summer temperature turned from low to high value.In the 1 950s and 1 980s, temperature in winter was high while in the 1 960s and 1 970s low,showing a -moderate rise. The average precipitation throughout the year demonstrates a modestrise. Precipitation during summer follows the pattern of "little-much-little", while the winterIIIA.precipitation follows the pattern of "three-hump-three-valley", generally on the risedemonstrating tremendous fluctuation. In the coming 5 to 9 years from 1995, the averagetemperature throughout the year in Yunnan tends to rise, bringing about more rainfall. However,there will be 2-3 years in fluctuation.Researches on the climate and grain yield changes over the past 45 years demonstrate thatgrain yields vary greatly from year to year, which is related to climate conditions, especially toprecipitation factors. Variation in grain yields corresponds to the changes in the value of theclimate productivity. In future, warm and humid climate with rising temperature and increasingprecipitation will turn out to be salutary to grain yields with the increase rate at 6.2% whentemperature and precipitation undergo changes. The cold and dry climate with temperature andprecipitation falling tends to do agriculture more harm with the decrease rate being at 6.9%.The relationship between climate changes and sustainable agriculture is discussed and aquantitative description is offered as to the effects caused by climate changes on the sustainabledevelopment of agriculture in Yunnan. Natural disasters are taken into detailed consideration asdroughts, floods, freezing and frost, crop diseases and pests which restrict grain yield in Yunnan.When climate gets warm, drought is likely to increase because of the rising rate of evaporationalthough precipitation will rise moderately. And some areas are also likely to be plagued withflood. Meanwhile the extend of disasters brought about by low temperature, freezing and frostwill be reduced; crop diseases caused by tropical pests will increase and even extend to otherareas. The analysis throughout the dissertation demonstrates that agricultural production in... |
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