Study On Land Use Pattern Changes Of Dufuchuan Watershed In Northern Shaanxi

Four tributaries of Dufuchuan Watershed were selected as typical study area in this paper.Among them, Caojiagou Valley and Xiangyanggou Valley were in the middle part, Chaijiagouand Shibangou Valley were two tributaries near the eastern and western source separately. Onthe basis of extensive investigation, the land use type of Dufuchuan Watershed was gradedinto three classes. Under the AUTOCAD working platform, the current status and dynamicchanges of four tributaries were deeply analyzed, and the interrelated conclusions wereelaborated as follows: 1. The analysis of overall landscape diversity characteristics showed: diversity index,evenness index, fractal dimension index, fragmentation index and isolation index inCaojiagou Valley were all the highest. The following three ones successively appeared inXiangyanggou Valley, Chaijiagou Valley and Shibangou Valley. But the order of landscapedominance index in the four valleys was contrary to the diversity index. The land use degreein the four valleys was all far from the top level. It showed that the development potentialityof local land resources was very huge. Therefore, based on scientific planning, the localgovernments and policymakers should exploit these resources more powerfully. 2. In Class I of land use, the dominance, diversity, evenness and relative evenness ofartificial landscape were gradually decreased from Chaijiagou Valley to Shibangou Valley.These indexes of natural landscape, however, were on the contrary. It showed that the humandisturbance level had positive relations with artificial landscape percentage, and had negativerelations with natural landscape. Fractal dimension analysis showed that the patches'complexity was not simply declined with disturbance's weakening, but effected by manyfactors. 3.In Class II of land use, the dominance index of abandoned farmland in ChaijiagouValley was very high, and this stated that the land was seriously wasted in this area.The spatial features of each land use type were complicated and had no obvious laws.But generally, the complexity would increase with the disturbance's enhancement. 4. Fractal analysis stated: the fractal dimension of terrace was more higher thanthose of steep gradient cultivated land and gentle slope cultivated land, its areapercentage and patch numbers were also the highest. The fractal features of steepgradient cultivated land and gentle slope cultivated land had no typical laws, thereason which caused this might have relations with cultivating style and topography. 5. The dynamic degree of land use could be divided into four types which weresharp changing type, high-speed changing type, slow changing type and extremely slowchanging type. Analysis showed that the dynamic degree would decline with the increasingdistance from Yan'an city. However, it became complicated to each specific land use type.Changes of land use degree showed that Chaijiagou, Caojiagou, Xiangyanggou all belongedto land use developing period, and the land use degree of Shibangou had slightly declinedduring the past ten years. Because of wasted land in Chaijiagou being very serious, itschanging degree was smaller than that of Caojiagou. Changes of the Class III indexesindicated: Terrace, artificial eco-forest, residential areas, orchards had increased fast since thepast ten years. And the abandoned farmland also increased, especially in Chaijiagou valley.On the contrary, Steep Gradient Cultivated Land, secondary natural woodland, shrubs andnatural grassland all decreased sharply. 6. Contrasting to 1993, except Chaijiagou Valley, the landscape diversity and evenness ofother three tributaries were all increasing with the passage of years, and the dominancedecreased. The general spatial analysis showed that the structure and shape of most land usetype became more and more complicated. Among them, the artificial eco-forest, orchards,farmland, shrubs and natural grassland were especially notable d...