| Known as the "gene pool of Sanjiang Plain", Xingkai Lake Natural Reserve plays a great role in water conservation, groundwater recharge, the mediation of surface runoff, climate regulation and maintaining water balance etc. Based on the2005and2011SPOT5high resolution remote sensing data and with the support of GIS software, the present study extracts the land use types of Xingkai Lake for a better grasp of Xingkai Lake Nature Reserve and the land use and land cover change (LUCC) spatial distribution characteristics and landscape pattern variation. The present study makes an analysis of the characteristics of the LUCC and landscape pattern changing characteristics, seeking for the dynamic rules of changes. A quantitative analysis of evolution rules of land use and landscape patterns is made from the perspective of landscape index and the gradient belt. And nature and social and economic factors are also taken into account, aiming at finding out the driving forces of land use changes so as to promote the protection and utilization of the local resources.The main research findings:1. The research area of Xingkai Lake in the present study covers359750.03hm2in total. In2011, the arable land is139134.33hm2, accounting for38.68%of the total research area, among which the paddy field is94258.69hm2and the upland field is44875.64hm2, taking up26.20%and12.47%of the total study area respectively. Second to the arable land is the natural water area (131345.37hm2), with the lake area130367.04hm2and the area of river978.33hm2, accounting for36.24%and0.27%of the total study area separately. Swamp area, with58826.76hm2occupying16.35%of the research area, ranks the third. The vegetation area is20631.68hm2, taking up5.74%of the research area. The industrial and residential land area is4948.77hm2, the artificial water area4503.22hm2and the sandy area199.41hm2, which as a whole holds2.68%of the research area. In general, the research area is distributed by forest, dry fields, paddy fields, marshes and paddy fields again and then swamps from west to east.2. Most of the changes in the patch of the research area are trivial from2005to2011. In the study area, arable land, swamp, vegetation and lakes have been changed greatly relative to the rest of class. Large area of new-added arable land only occurs in individual districts. The changes of the land use types related to human activities are more obvious. The industrial and mining land increases with the largest area and at the fastest speed. The cultivated land accounts for a larger proportion in the research area and is still in the increase trend. The cultivated land in the research area occupies a large proportion and is still in an increasing trend. 3. From the perspective of the entropy of information, the increase of road, residential land and water channel leads to the disordered development of land use structure. What has been found in the analysis of comprehensive index of land use degree in the study area is that the degree of the natural landscape transformation is increasingly intense and although there is still potential for development, the government needs to make reasonable planning in the future development process. And the intensity of human activity is in decreasing trend in the nature reserve of the eastern part of the research area.4. The lake occupies a dominant position in natural waters and the lake area in northwest increases gradually. Water channel plays a leading role in artificial water and the canal area in southwest increase as well. The direction and distance of arable land mobility result from the joint efforts of the decrease of the dry land in west and increase of the paddy field in east. The industrial and residential land in west increases greatly larger than that in east, which is closely related to the fact that the east part of the research area is a national natural reserve.5. In the past six years, the transformation of swamp is relatively frequent and almost each type of land is partly transformed from swamp to some extent. The wetland protection policy contributes to the phenomenon of returning the farmland to forest and returning the farmland to wetland. However, the swamp reclamation still continues. During the increasing process of arable land, swamp exploitation remains to be the main measure and the farmland process of the marsh is deepening. Returning the farmland to forest leads to the small increase of vegetation covered area. Overall, there is a great amount of mutual transformation between paddy field and swamp in Xingkai Lake. There is also mutual transformation between dry land and vegetation, and paddy field and dry land as well.6. From the angle of landscape index, the patch number, patch area, the largest patch area and the fractal dimension of the swamp and vegetation landscape showed a trend of decrease from2005to2011, indicating that at this stage, swamp and vegetation patch experienced a trend of disappearing or decreasing, which is resulted from the direct exploitation to arable land by human beings. Rivers go through a declining trend and the connection between lakes and ponds is enhanced. The rivers and ponds which were isolated from each other before begin to connect with each other and the two are at the early stage of piecing development. With the gradual increase of no dominant landscape, such as the small area of the artificial landscape, the overall advantage of the landscape in2011is lower than that in2005. The vanishment of the small patches of such natural landscape as swamp and vegetation and the piecing development of artificial landscape co-work to decrease the patch density. |
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