The relationship between population pressure growth and environmental change in recent 600 years in the upper reaches of the Fenhe River

Abstract

The aim of this study is mainly to deal with the impact of human farming activities on the environmental changes especially the soil erosion in the upper reaches of the Fenhe River in recent 600 years.Through field investigation and the analysis of the long-term data of hydrology and landscape,the authors used the historical documentation method to make a quantitative analysis and estimate farming population,farmland and soil erosion development process of the study area. The study indicates that: (1)In recent 600 years,the population of the area increased by 716%,while the farmland merely 432%.So the farmland per capita available decreased by 34.8%.At the same time,per mu(15mu=1ha) average corn yield mu was only about 50kg lower than that in the middle reaches of the Yellow River in the Han Dynasty.The trend of reclamation still exited. (2)Through the analysis of the result of land measurement of Yangqu county in later Qing Dynasty,we thought the data of farmland area were far less from the actual amount,which was possiblely less than the half. (3)From the Qianlong to the Guangxu years of the Qing Dynasty,soil erosion amount increased because of slope farming,which was only 2%~3% of the total eroded amount and cannot play the dominant role. (4)From the Guangxu years of the Qing Dynasty to modern times,much scarp and steep slope land was reclaimed in the Fenhe river basin which led to the soil erosion increased to 30% of the total amount.But the amount of the gully erosion induced by natural force was also 70%.So the farming activity was merely the second factor for the soil erosion.