Research Of Evaluation On Carbon Sequestration For Different Types Of Wetlands In Yinchuan Plain

Wetland ecosystem has a strong capacity of carbon, and plays an important role in the global carbon cycle. As the study area of wetland ecosystems in Yinchuan Plain, the paper constructed remote sensing estimation model of 4 types wetland of which is the river, lakes, marshes, artificial wetland wetlands on AGB (Above-ground biomass) and BGB (below-ground biomass) and organic carbon content,soil organic carbon content, discusses the quantitative relationship between vegetation spectrum index and band value and biomass of vegetation, and vegetation carbon content, and soil content and its influencing factors, based on the remote sensing data from Land-sat TM image in Yinchuan Plain and field sampling data, as the theoretical guidance of ecosystem succession theory, the theory of ecosystem management,carbon sequestration theory,combined with theoretical analysis and field surveys, qualitative analysis and quantitative analysis, the traditional method and "3S" technology based on previous studies. This methods based on vegetation indexes, band value, texture feature value and principal component analysis value in this study are mainly used in vegetation biomass inversion in a large area, and have conducted quite successful algorithms and models.At the same time, uses the optimal estimate model evaluating vegetation biomass and carbon content, soil carbon content of four types wetlands four years,in 2000-2014 years,and use ARCGIS spatial analysis and statistics. The results of their research has a large application value to promote the regional carbon cycle, to improve the regional carbon sink capacity to provide theory and methods of innovation, while providing scientific basis and theoretical guidance for researching on China’s arid region carbon sequestration function.Reference value for further study of the wetland carbon dynamics under global climate background.The main conclusions of this study are as follows:(1) Construct remote sensing estimation model of the Yinchuan Plain Optimum different types of wetlands. Vegetation biomass remote sensing estimation model for RVI (ratio vegetation index), NDVI (normalized difference vegetation index), ME (texture measure mean values), PC2 (the second principal component) 4-factor model; rivers biomass estimation models for MSVI (modify the soil adjusted vegetation index), PC2 2-factor;lake wetland biomass model for RVI,NDVI, ME3 factor; marsh biomass estimation model for RVI, NDVI, ME, PC24-factor; artificial wetland biomass estimation model for RVI, NDVI, EN (texture measure values entropy mean), DVI (difference vegetation index), PC2, ME 6 factor; Soil organic carbon content estimation models for AGB, TN (soil total nitrogen) 2-factor model is the optimal estimation model.Author in this paper puts variety of vegetation indexes, band value, texture feature value and principal component analysis value together as the comprehensive input factors, and constructing biomass,vegetation carbon content, soil carbon content estimation model in wetland by using multiple linear regression analysis method. Therefore, it improves largely the precision and reliability of vegetation biomass,vegetation carbon content, soil carbon content inversion based on multiple remote sensing information. Authors inspect the precision of inversion by comparing the estimate results from RS-MLRM(remote sensing-multiple linear regression model) biomass models,LAI (leaf area index) biomass models,vegetation content models and soil content models with field sampling data. Results showed that these RS-MLRM have good precision and prediction ability by using vegetation indexes, band value, texture feature value and principal component analysis value extracted from TM remote sensing data which can be well applied to estimate the wetland biomass,vegetation content and soil content.(2) In 2000-2014 years, the fluctuation range of wetland biomass is 2230.89～4058.07g/m2, average value is 2931.03 g/m2 in Yinchuan Plain; the total biomass distributed in 1745.88-6773.78g/m2,which experienced by unbalanced development to balanced development process, tend to balance direction. Annual average biomass of different types of wetlands Marsh> Lakes> artificial wetland> river, and there is a big difference in annual fluctuation. Biomass distribution is a big difference in space, showing a higher biomass and higher stability in central and southwestern regions, and lower in northeast.(3) In 2000-2014 years, wetland carbon storage density distribution in the Yinchuan Plain experienced by unbalanced development to balanced development process, vegetation carbon content and soil organic carbon density showed a decreased firstly and then increasing trend, showing increasing carbon sink capacity. There is a big difference in annual fluctuation in different types of wetlands, spatial distribution is decreasing from northeast to southwest. The fluctuation range of vegetation carbon content is 891.54-1629.49 gC/m2, annual average is 1174.31 gC/m2, CV (coefficient of variation) value is 29.42%, the fluctuation range of soil carbon density is 2913.58-3342.29 gC/m2, annual average is 2461.03 gC/m2, CV value is 27.39%. soil carbon density is higher than the vegetation content in Yinchuan Plain wetland, the soil carbon density is about 1.27 times of the vegetation carbon content, and is major carbon storage carrier in Yinchuan Plain wetland, it has an important position and role in the Yinchuan Plain wetland carbon cycle.(4) In 2000-2014 years, wetland carbon sinks experienced the process of declining firstly and then rising in Yinchuan Plain. From 2000 to 2005 years, carbon sinks showed downward trend; an upward trend from 2010 to 2014 years; wetland carbon sinks increase significantly in 2014. Different types of wetlands absolute carbon sinks and relative carbon sinks changes consistently as to Marsh> Lakes> artificial wetland> river.7 typical wetlands carbon sinks distribution is to Qingtongxia Reservoir> Wuzhong Yellow River wetland> Shahu lake> huangshagudu wetland> Xinghai Lake> Yuehai lake> Mingcui Lake. In 2000-2014 years, four types of wetlands carbon sequestration and releasing oxygen have appeared trend of decreased firstly and then increased, and increasing trend on the whole, increased respectively by 37.68% and 38.21%. Spatial distribution of the overall trend is higher in the central and southwest regions, is lower in western and southeastern regions, consistents with the wetland biomass and carbon density distribution. In 2014, high-density storage of carbon plaque area increased significantly. Wetlands total carbon sink capacity is close to the average Chinese carbon sink capacity of forests, wetlands carbon sequestration capacity enhanced significantly, it suggests that wetland restoration and protection is remarkable.