Research Of Locust Outbreaks In Jiangsu And Anhui During Ming And Qing Dynasties

Locust outbreak, flood and drought were the three biggest natural disasters in Chinese history. Flood and drought had been studied by many researchers, but locust outbreak did not draw enough attentions. Jiangsu and Anhui, located in eastern China, were the important breeding bases for locust, which had superior agriculture conditions and abundant historical documents. Based on the historical records of locust outbreak in Jiangsu and Anhui Provinces, this study established and updated the database of Qing and Ming Dynasties to reconstruct locust outbreak grades sequence,10-year scale locust outbreaks frequency sequence and 1-year scale counties sequence. The spatial-temporal characteristics of locust outbreak, as well as its environmental mechanisms were explored. The social influence resulted from locust outbreaks was analyzed according to historical records. The results illustrated that:(1) 268 locust years occurred in Jiangsu and Anhui during this period. Locusts tended to appear in summer and autumn during the whole year and Jiajing (1522-1566) and Kangxi (1662-1722) periods had the highest frequencies and most counties in Ming and Qing Dynasties.(2) The locust frequency was at an average of 3.7 years every ten years. Analysis revealed significant a high-low volatility trend of five high-incidence periods and five low-incidence periods. The locust counties had violent inter-annul variation with an average of 3 counties every years.1528～1532AD,1616～1618AD,1638～1642AD,1667～1672AD and 1856～1857AD were the five large～scale locust outbreak periods, and 17 century took account for the most locust counties in Jiangsu and Anhui Province.(3) The spatial distribution of locust outbreaks revealed a wide distribution feature, and the plain area located at Jiangsu and Anhui was the high frequency region, owing to factors like terrain, the distribution of river and lakes, and the different precipitation patterns.(4) Analysis revealed locust outbreak at the same period with drought. Locust had close correction with drought especially in the middle and lower reaches of bothe Huaihe River and Yangtze River. Locust outbreak was insignificantly affected by temperature change and E1Nino, but it had a close relationship with overflow of Yellow River.(5) Locust outbreak depressed crop production and resulted in high rice price and economy decline, as well as widespread famine. However, famine would usually have a positive effect on the epidemic plagues, which helped to form "locust-famine-plague" chain. It had important effect on the social stability when locust appeared in history. The government of Ming and Qing Dynasties took steps to response to locusts, for example, cuting the agricultural taxes, distributing food and organizing people to exterminated locusts and so on.