Remote Sensing Assessment Of Wetland Protection Ecological Effects In Sanjiang Plain

Since the middle of the 20th century,great changes have taken place in the original wetlands of the Sanjiang Plain.In order to strengthen wetland protection,regulations called "The National Wetland Protection Project(2002-2030)" were issued by China's central government.Among the projects,wetlands in the Sanjiang Plain were given priority for restoration and protection.At present,the project has been implemented for more than 12 years.It is of great significance to evaluate the effectiveness of the project.This study used remote sensing data,combined with geographic information systems and model simulation methods,and used 1990,2000,and 2015 as time nodes,mainly from the changes in wetland area and distribution,wetland landscape structure,and regional ecosystem service capacity before and after the implementation of the project.Assess the changes in ecosystem service capabilities of 9 national-level nature reserves,etc.The main conclusions are as follows:(1)Under the dual effects of natural conditions and human factors,the area of wetlands in the Sanjiang Plain continued to decrease from 1990 to 2015,and fragmentation increased.In 25 years,the total number of wetlands decreased by 10329.3 km2,and the reduction rate was 50.6%.However,the wetland protection project has slowed down the degradation of wetlands and the expansion of farmland.During the period from 1990 to 2000,the wetland reduction in the Sanjiang Plain was extremely significant,with an area reduction of 7500.5 km2 and a reduction rate of 36.8%.However,after the implementation of the wetland protection project from 2000 to 2015,the decrease in wetland area was significantly reduced(2828 km2),and the reduction ratio was reduced to 21.9.%.The analysis of the wetland landscape in the Sanjiang Plain shows that during the period from 1990 to 2000,the degree of fragmentation of the wetland in the Sanjiang Plain has intensified and the stability of the wetland has deteriorated.During the period from 2000 to 2015,the degree of fragmentation of the wetland in the Sanjiang Plain has been reduced,and the stability of the wetland has increased.In addition,the area of farmland in the Sanjiang Plain increased rapidly from 1990 to 2000,with an increase of 8645.7 km2.Between 2000 and 2015,a certain amount of farmland was transformed into forests along with the implementation of the policy of "returning farmland to forests and returning farmland to wetlands".In wetlands,the increase rate of farmland area has slowed down,with an increase of 2119.2 km2.(2)Since the implementation of the wetland protection project,the annual net primary productivity in the Sanjiang Plain has been increasing,and the habitat quality and water conservation capacity have increased significantly.From 2000 to 2015,the annual variation range of NPP in the Sanjiang Plain was 297.7-405.9 g C m-2 a-1 with an average of 357.8 g C m-2 a-1.From 2000 to 2015,the NPP decreased first and then increased.In general,there is a trend of increasing volatility.The area with the best suitability in the Sanjiang Plain is consistent with the spatial distribution of the wetland and the spatial distribution of the protected area.The area of the habitat with better habitat increased from 5,050.09 km2 in 2000-2015,and the average area of the habitat was reduced by 4278.39.In km2,the area with poor habitat decreased by 777.7 km2.The total amount of water conservation in Sanjiang Plain from 2000 to 2015 showed an upward trend,rising from 11.156 billion m3 to 13.962 billion m3,an increase of 2.806 billion m3,an increase rate of 25.15%,and a water conservation capacity of 102.85 m3 hm-2.To 1287.37 m3 hm-2,an increase of 25.13%.(3)Wetland Nature Reserve plays an important role in the protection of wetlands.In comparison,it was found that since 2000,the proportion of wetland reduction in the national-level protected areas(10.7%)was significantly lower than that of the entire Sanjiang Plain(21.9%),and the proportion of wetland converted into farmland(9.03%)was also significantly lower than that of the entire Sanjiang Plain(25.10%),while the proportion of farmland converted to wetland(3.13%)was significantly higher than that of the entire Sanjiang Plain(0.82%).In addition,the total carbon reserve reduction ratio in wetlands within national-level nature reserves(12.04%)was significantly lower than that in the entire Sanjiang Plain(27.36%),and the growth rate of water conservation capacity(52.21%)was significantly higher than that of the entire Sanjiang Plain(25.13%).