Analysis Of Wetland Landscape Pattern Changes In Ziya River Basin

Wetlands are land-water ecotone, they play an irreplaceable role in the aspects of climate regulation, flood storage, soil and water conservation, pollutant removement, ecosystem balance maintenance, biological diversity protection,,etc. In the past few decades, wetlands degradation became more and more serious because of the increasing of human activities, many wetlands have been converted into farmland, residential areas, unoccupied wetlands have also been seriously polluted, the area of wetlands was greatly reduced. As the Earth’s "kidneys", wetlands need to restore its ecological functions to better play its role. Therefore,this study from the perspective of remote sensing and landscape ecology, using 2000,2004,2009 and 2014 Landsat TM/ETM+/OLI remote sensing data to study the dynamic changes of wetlands landscape patterns in Ziya River basin. Specific studies are as follows:(1) Wetland area interpretation and statistics in Ziya River basin. Combining water distribution results through MNDWI, using visual interpretation methods, obtained the wetlands area were 1861.99km~2,1890.42km~2,1823.19km~2,1885.43km~2 in Ziya River Basin from 2000 to 2014, the results showed that from 2000 to 2014, the overall wetland area showed an increasing trend, in 2014, total wetlands area have increased 23.44km~2; natural wetlands area first reducedand and then increased, but in 2014, the area of natural wetlands did not more than that in 2000; artificial wetlands area in general increasing trend changes, annual variation fluctuated. To some extent, mankind have realized the importance of protecting the wetland environment, they gradually reduced the speed of development of natural wetlands, and made natural wetlands have returned.(2) The statistics of Ziya River Basin water surface area and wetland vegetation area From 2000 to 2014, the extracted water surface area were 463.14km~2,629.74km~2, 562.69km~2,796.69km~2. Water mainly in the west and east of the study area, and there was smaller amount water in central area. Wetland vegetation area were 1025.22km~2, 936.55km~2,1058.76km~2,764.34km~2. The wetland vegetation in 2009 had the largest area of the 4 periods, and had the largest proportion of growing well vegetation. However, the proportion of the growing well vegetation area in 2014 was declined.(3) Selected 3 wetlands and their surrounding non-wetland features to interpret in eastern, central and western parts of Ziya River Basin. Constructed the transition matrix to determine the origin and fate of wetlands to represent Ziya River wetlands conversions. From 2000 to 2014, natural wetland area mainly from arable land. Among them, the eastern region-Tuanbowa, Beidagang, Nandagang and their surrounding areas, from 2000 to 2014, the intensity of land reclamation projects were gradually increased, land use types transformed in accordance with the sea/beach-salt pans/mariculture zones-unused land-urban village and industrial land/road trend, Salt pans, had the expansion of occupying the ocean. In 2014, wetland area was restored, mainly due to the repairation of Tuanbowa reservoir and its surroundings. Hengshui Lake and its surrounding areas, the central regin, Besides arable lands, urban village and industrial lands were also parts of the refund of wetlands, the lake surface area first decreased and then increased; Gangnan and Huangbizhuang reservoirs had the largest area in 2004, caused the reduction of surrounding farmland, and wetlands; 2009 to 2014, there was a slight increase in natural wetland area artificial wetlands showed an increasing trend, mainly from the conversion of arable lands, while the woodlands transformed to arable lands and unused land.(4) Using landscape indices analyzed the landscape pattern changes in the 3 parts and found that the landscape in all 3 parts are increasingly fragmented, largest patch index fell, landscape heterogeneity enhanced because of the increasing of human disturbance, various types of landscape were more and more evenly distributed, dominant landscape gradually disappeared. Compared changes of landscape indices in 2014 of the 3 regions, found that the central region had the largest patch density, the degree of fragmentation was the strongest; the east part had the smallest dimension, suffered the largest human disturbance, the west part had the largest dimension means that this rigion was the closest part to the natural constitution; in addition, the heterogeneity was the strongest in eastern region, means that land use degree was the highest, and the landscape types was the most uniform distribution in the east area.In sum, the wetlands management and restoration should be kept enhancing. What’s more, at the time of taking into account the restoration and pretection of wetlands, people should also consider preventing and reducing fragmentation of wetlands, controling the degree of human disturbance and trying returning farmlands to wetlands.