Dai Junhu

Farming and forestry land use changes in China and their driving forces from 1900 to 1980

A variety of agricultural and forestry land use materials, especially those in the first half of 20th century, were collected. According to land use change in this period, the whole country is demarcated into seven regions, Northeast China, North China, Northwest and Loess Plateau, Southeast and Coastal Region, Southwest China, Qinghai-Tibetan Plateau, Inner Mongolia and Xinjiang, in proper order by using Cluster Analysis. The farming and forestry land use change in these regions were analyzed. The results show that the total cultivated land areas increased in this period, especially in the 1950s and 1960s the cultivated land area increased more significantly, but differed in different regions, and the most rapid increasing rate was 2.63 percent a year. On the other hand, the forestry land area was increasing in most parts of this period, especially after 1949. But in most regions, the decrease of forestry land area at the end of 1970s is also very obvious. It is regarded that the population increase, food production, natural disasters and some related government policies were among the main driving factors for farming and forestry land use change.

Ecosystem Service Assessment of Grasslands in the Sanjiangyuan Region

Grassland ecosystem in the Sanjiangyuan Region(Three-River Headwater Region) plays an important role in maintaining ecological balance and guaranteeing sustainable development of social-economic system.By using multiple methods,we assessed the value of nine types of ecosystem services in the Sanjiangyuan region based on the ecosystem services classification system of MA.The results showed that the total value of grassland ecosystem in the Sanjiangyuan Region was 56.26 billion RMB yuan in 2000.The top two values of ecosystem services were climate regulation and food production,which were 11.17 billion RMB yuan and 2.59 billion RMB yuan,with the contribution rate of 46.05% and 19.85% respectively.With respect to different grassland types,alpine meadow and alpine grassland have the values of 49.10 billion RMB yuan and 6.47 billion RMB yuan,contributing 87.42% and 11.52% to the whole value.Swamp has the highest value of 4230.77 RMB yuan per hm2,but its area is small,thus a relatively low value in total.The results of this study provide the scientific support for policy making in ecosystem protection and the practice of ecological compensation.