;During the dynasty of Jiaqing and Daoguang, environmental variation started to appear one after and other. The area of the forest reduced a lot, grass gradually appeared, ecosystem damaged hugely; abnormal weather also was a major cause, highly related to the “sunspot minimum”. Human destroy biophysical environment, in order to face the rebounce of nature, varieties of disaster come in a throng. Based on the related statistical results showed, during the period of Jiaqing and Daoguang, “chilling injury”, “drought”, and “locust plague” occurred much more frequently compared with the era of Kangxi, Yongzheng, and Qianlong. Especially drought and locus plague. Emperors prayed for the rain repeatedly, people built temples everywhere, but those disasters eventually highly related to the man-made factors. Reclamation of forests, damage of vegetation, and scarce forests caused a catalytic effect to the drought, also increased the frequency of droughts. Unbalance of the ecosystem caused the natural enemies of locusts drop sharply and increased the possibility of locust plague.
Waterlogging and river disaster happened frequently especially during the period of Daoguang. Based on the statistic results, era of Jiaqing and Daoguang seems not that severe compared to the era of Kangxi, Yongzheng, and Qianlong. But if we evaluate from the dimension of single dynasty, the ratio and average number of waterlogging and river disaster during the period of Daoguang was higher than the period of Kangxi and Qianlong. Even easily appeared the situation about “people drowning and house destruction”, “river burst and drifting farm land”, and “a few deep feet water” happened. River disaster was a long-term challenge. If we take comprehensive statistic of river disaster of Yellow River, Yungting River, and Huaihe River to see, period of Jiaqing and Daoguang were truly higher than the period of Kangxi, Yongzheng, and Qianlong.
Although the ecological crisis during the era of Jiaqing and Daoguang which included drought, locust plague, waterlogging, and river disaster was getting worse and worse, deeply influenced the prosperity and decline of Qing Dynasty. Dominators still had solutions at the point, with the rapid growth of population, the era of Qianlong has grown explosively. The population already broke through to four billion which caused the deterioration of human-environment relationship. However, promotion of sweet potato and corns was also a major cause. Both of the sweet potato and corns were good at drought tolerance with short growing period, also are highly adaptable species, they had already become the most important food for those who suffered. Besides the growing population, the way of planting also caused the damage of the environment. And the climate also caused a direct correlation of the population growth, deeply influenced the potential productive forces and the cause of natural disasters.
The growth of population also brought potential worries, excessive growth caused declining quantity of land per capita. In order to survive, human went to reclaim the border also caused the problem of deforestation. The governor in order to reduce the population pressure, they unexpectedly let people to develop the area which was very far-off and caused a lot of refugees and turmoil. The improper behavior of the government caused severe resentment.
The way how government handled everything caused the chaos even more pessimistic. The epidemic disease occurred at the late period of Jiaqing , it was also occurred pretty often while the beginning period of Daoguang. When governments no longer be able to give expectance to their people, just like the White Lotus Rebellion and the Taiping Heavenly Kingdom and etc., social unrest started to occur, era of Jiaqing and Daoguang became the key of the prosperity and decline of Qing dynasty.