Livelihood succession and land use/cover change in the Upper Reaches of Dadu River watershed

Based on field survey, family questionnaire, historical datum analysis and interpretation of remote sensing data, this study presents livelihood succession during 1950～2000 and land cover change during 1967～2000 in Rangtang County, Maerkang County and Jinchuan County in the Upper Reaches of Dadu River watershed, by the combined using of geographic information systems (GIS) method and remote sensing (RS) method. The results show: there are different livelihood succession in the valley areas, middle-mountain areas, forest areas and pasture aresa in the Upper Reaches of Dadu River watershed. At the collective economy stage, livelihoods of all the residents rest on agriculture and herds, which resulting in involution of agriculture. As labor forces transferred to the second and third industry to seek better livelihoods after the 1980s, livelihood of the whole region has diverse successions, as it is easier for the labor forces in valley areas to transfer to the second and third industry, harder for labor forces in middle-mountain areas, impossible for labor forces in pasture areas. As a result, involution cultivation system in the valley areas and middle-mountain areas is given up and agricultural structure is adjusted according to market needs, while the mountain nomadism has no marked changes. The residents in the valley areas and forest areas are positive to environmental degradation, while residents in the middle-mountain areas and pasture areas are passive to it. Driven by diverse livelihood successions, land use change successions and response models, the land cover change dynamics are also different in the four regions. This paper also shows that changing livelihood models and transferring the labor forces to the second and third industry are the key countermeasures for social and economic development and ecological rehabilitation of ecotone.