| Wetland is an important ecological system.The unique function of wetland has significant ecological,social,and economic values,which cannot be substituted.In recent years,due to climate warming and anthropogenic pressures,wetland ecological process and ecological functions have been weaken gradually,resulting in wetland area loss and wetland resource destruction.Meanwhile,this would have a harmful impact on the habitat of wild animals.Therefore,combined with relevant theory and technology,this study explored the spatio-temporal changes of wetland and evaluated the habitat quality of wild animals,which has great significance in the improvement of wetland ecosystem and biodiversity.The areas along Heilongjiang River have the greatest concentration of marsh wetlands.Depending on its suitable climate,terrain and hydrology features,this area also serves as an important stopover and wintering site for migratory waterbirds in the North-South line of East Asia.A large area of natural wetland and waterbirds habitat in this area has been severely impacted by climate change and intensive human activities.This study selected the areas along Heilongjiang River as the study area.Based on the Landsat TM remote sensed imagery,land cover data,geographic basic data and field sampling data,this study firstly obtained the spatial distribution of the wetland and evaluated the habitat quality of waterbirds.And then,we analysed the seasonal change features and interannual change features,and predited the distribution of potential habitat of waterbirds.First,the wetland information was extracted accurately by using object-oriented method.Second,a suitable habitat quality assessment model was selected and the seasonal and interannual change features were analysed.Lastly,suitable resistance model was applied to simulate the process of waterbirds habitat’s expansion,obtaining the spatial distribution map of potential habitat for waterbirds in the areas along Heilongjiang River.The conclutions of this study are as follows:(1)The wetlands in the areas along Heilongjiang River are mainly distributed in the middle and lower reaches of the river.The wetland type includes herb marsh,shrub marsh,forest marsh,river wetland and so on.The area of wetland decreased about 8.71×10~3 km~2 from 1990-2013,mainly distributed in the middle reaches of Heilongjiang River.The increased wetland areas were distributed in Russia and the area was about 1.24×10~3 km~2.The wetland areas were mainly transformed into dry land and paddy field,the area was 4.09×10~3 km~2 and 3.77×10~3 km~2,respectively.The wetland area and the number of patches were decreasing apparently.Meanwhile,the nearest neighbor distance was increasing,indicating that wetland fragmentation was becoming more and more serious.(2)From 1990-2013,there existed great difference between China and Russia on the wetland area and landscape structure in the areas along Heilongjiang River.The wetland area decreased from 2.20×10~4 km~2 to 1.37×10~4 km~2 in China during 1990-2013,which had been reduced by 38%.The wetland area increased from 3.15×10~4 km~2 to 3.22×10~4 km~2 in Russia during 1990-2013.On the aspect of landscape,the patches fragmentation was becoming more and more serious in China.While the wetland area and patches were well preserved in Russia,it not only did not decrease,but increased.This is inseparable from the intensity of human activities and the protection of wetlands in the two countries.(3)The habitat quality of waterbirds was good in the whole areas along Heilongjiang River.The suitable habitats of best and good grades measured 2.21 × 104 km~2 and 9.89 × 104 km~2,comprising 7.80 % and 34.91 % of the total study area.The suitable habitat of general grade measured 1.62×10~5 km~2,comprising 57.18 % of the total study area.There was less area in poor and not suitable grades of habitat quality.In the study area,the habitat quality of waterbirds had distinct seasonal change features,higher in June-August,lower in other months,due to the vegetation changed with season changes.The spatial distribution of habitat quality grades for waterbirds did not change basically from 1990-2013,with the patches of best grade transforming to good grade.This was directly related to the change of land cover type.(4)Based on the expansion resistance surface of waterbirs habitat in the areas along Heilongjiang River,the spatial distribution of potential habitat for waterbirds was obtained.If the lower resistance zone was adjusted properly,the waterbirds habitat area could increase to 8.59×10~4 km~2.If the general resistance zone was modified,the waterbirds habitat area could increase to 1.30×10~5 km~2.Based on the improvement of higher resistance zone,it could provide suitable ecological environment for the source,lower and general resistance zone,which was good for waterbirds maintaining healthy conditions.The protection strategies of waterbirds habitat were proposed in this study,including: reducing human activities;water complement;constructing habitat structures;bird attracted using artificial nests;international cooperation. |
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