Climatic Change and Agricultural Production in Japan over the Last 100 Years

抄録

First, general trends of agricultural production and changes of air temperature, precipitation and sunshine hours in Japan over the last 100 years are described. In agricultural production or yield, three periods can generally be recognized: period 1, from the end of the 19 century to about 1920, Period 2, from about 1921 to 1945-47, the end or just a few years after the 2nd world war, and Period 3, after the end of the 2nd world war. Secondly, fluctuation of climatic conditions and its effects on the paddy rice yield over the last 104 years were studied statistically in order to evaluate the different impacts according to the periods. By applying the principal component analysis method, their distributions, periodicities and relations to monthly mean air temperature, monthly total precipitation, and monthly total sunshine hours were studied. The first component has a significant correlation to the all three climatic elements in July, and to air temperature and sunshine hours in August and precipitation and sunshine hour in September, In the second part of this study, we classify the 104 years into three periods according to interannual changes of paddy rice yield. For these three periods, the general trends and fluctuations are described and the relationship between the yield and climatic elements are analyzed for five region, respectively.