| The river basin is an important geographic unit in the regional environment, and it palys a very significant role on the ecological environment. Based on the MODIS data and GIS, this paper studied the landscape pattern, dynamic changes, the driving mechanism and the trend of the middle and lower reaches Yangtze River basin in the year2002,2006and2010.This study in order to provide decision support on the planning and managing of landscape in the basin, which promoting the sustainables development of the resources in the river basin. The results of this study are shown as follows:(1) The forest land and farmland are the main landscape types in the river basin. Between2002and2010, the area proportion of farmland decreased from36.65%in to35.85%in2010, and the area reduced5735.61km2; the wetland decreased from5.31%to4.98%; the forest land increased from56.48%to57.54%, and the area increased7599.38km2; the built land increased from1.47%to1.50%; the area of the grassland and the bare land had small changes. The land use changes mainly showed the decrease of the farmland and wetland, the increase of the forest land and built land.(2) The study area landscape pattern in the landscape-level is that, the number of the patches and the patch density have increased the overall trend, the MPS gradually reduced, the fragmentation of the landscape trended to be heavier. The indices which reflect the complexity of the patch shape were rising, and there was a big increasing range between2002and2006. The difference between the ratios of the landscape types has enlarged, the landscape diversity has reduced slowly in the study period, the unevenness of the landscape has risen. These all lead to the declining of the landscape heterogeneity, which goes against the maintenance of biological diversity in the river basin.(3) From the changes of the various landscape types, the number of patches (NP), patch density (PD), landscape shape index (LSI) and the mean euclidean nearest neighbor distance (ENN_MN) of the farmland are the highest in all the landscape types, and have an increasing trend, which indicates that the farmland has some superiority in this region and the area changed greatly. The forest land has the highest largest patch index, it increased from22.7595hm2in2002to26.5842hm2in2010, the area increased16.65%. It shows that the forest land has been protected and extended in some degree. The ENN_MN of the built land is the maximum in all types, but it has been decreased in the study period. The NP and LPI has a certain increase, which indicates that the built land trends to be centralized, and the built land patches shows a trend of focusing on the development of a large area. The wetland is the only landscape type of which the NP, LPI and LSI decreased. It reflects that the shape complexity of the wetland patches declined, and the continuity between patches decreased, it will be a threat to the environment where the aquatic birds and other wetland species.(4) In the study period, the maximum of the average annual change was the forest land, and the minimum was the bare land, which were949.92km2/a and5.20km2/a respectively. The average annual change of the farmland, forest land and wetland; and the growth in2006-2010a is faster than it in2002-2006. The average annual change of the built land was in a declining state, which illustrates the built land was developed faster between2002and2006.(5) In the transfer matrix of the2002-2006a and2006-2010a, the landscape transformation mainly happened in farmland, forest land, built land and wetland, which four have the large area. The converted area of the farmland was the largest, the farmland mainly converted to forest land, the transfer ratios were2.45%and5.43%respectively. That was closely related with the conversion of farmland to forest and the shelterbelt construction in Yangtze, which happened in the1990s and the beginning of this centery. The ratios of the forest land converted to farmland are0.92%and2.13%in the two periods respectively. The ratios of the wetland transformed into the farmland, forest land and built land are4.67%,0.29%and1.22%(2002-2006a),9.24%,3.26%and1.91%(2006-2010a). The maintenance rates of the forest land are always the highest in the two periods, which are98.83%and97.46%respectively.(6) The analysis of driving factors about the landscape change shows:the natural factors determine the basic pattern, and change the landscape pattern in a slow progress; and the human interference is the main reason which causes the changing of the landscape. The main driving factors of the landscape changing are the population growth, the conversion of farmland to forest, the shelterbelt construction in Yangtze, the urban and rural development.(7) Based on the CA-MARKOV model, the prediction of the landscape pattern in2018shows that the major type in the region is still the forest land, it accounts for57.66%of the total area. The dynamic changes of landscape are consistent with the trend from2002-2010, the farmland area continues to decline; the area is increasing about the forest land, built land, grassland and bare land. The main tasks of the sustainable management in the study region are the basic farmland protection, the control of expansion in urban, the use of bare land, and the vegetation restoration. |
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