The Distribution Pattern Of Soil Carbon Pool In Sanjiang Wetland, Northeast Of China

For mitigating the green-house-gas induced global warming, studies on pattern ofsoil carbon pool distribution and change have become the new hot spot in global changefield. Since the founding of new China, in order to solve food security problem for thelarge population, the Great Northern Wilderness had been changed into the GreatNorthern Granary. This might bring environmental pressure on soil carbon sequestration.Therefore, it is crucial important to make reasonable mitigation policy that clearly andobjectively evaluating the trend and reason of soil carbon pool change in the land usechanging dramatically area of the country.The purposes of this study are:1) preliminarily expounded soil carbon storage inSanjiang wetland at present (2010) in different layers, surface layer (0-20cm), middlelayer (0-100cm) and deep layer (0-180cm);2) study the distribution pattern andinfluence factors by analyzing different soil types, different land uses, different regionalclimate pattern and carbon related geochemical index;3) get the change pattern ofSanjiang wetland soil carbon pool between1980to2010, by comparing soil survey of thisstudy to the Second National Soil Survey.This study combined literature investigation and experiment together. Throughsearching the "CNKI" and ’Vip" Chinese Journal Databases, research papers of soilcarbon pool change since1990were acquired. Meanwhile, by using grid sample methodof soil geochemical exploration, soil samples from surface layer, middle layer and deeplayer were collected. Soil bulk densities from different layers were measured as well. Soilcarbon storage and density were estimated by using the calculating method derived fromthe Multi-purpose regional geochemical survey of China. Distribution pattern, trend andinfluencing factor of soil carbon in Sanjiang wetland were discussed by applying dataintegrated analysis method. The results indicated:1) the surface layer of soil organic carbon content wassignificantly higher than the the middle (80-100cm) and deep layers. Soil organic carboncontent was different from soil types. In the surface layer, dark brown forest soil, swampsoil, peat soil had the highest organic carbon content (more than3.5%of average).Meanwhile, dark brown soil had the highest inorganic carbon content in the surface layer,followed by meadow and swamp soil (more than0.5%of average).2) according to thestatistics of different land uses, unused land (mainly marshes) had the highest soilorganic carbon content(more than4%of average); upland field, woodland, paddy fieldhad the same soil organic carbon content(about3.5%of average); woodland had thehighest inorganic carbon content of0.8%.3) The correlation between soil organic carbonin different land use types and yearly averaged temperature was negative, especially forwoodland and unused land. While the correlation between precipitation and soil organiccarbon in different land use types was positive. Soil texture and soil organic carbon hadobviously relationship that the sandier, the more soil organic carbon and vice versa.4)Soil organic carbon density in the most study area was increasing, except for severalsmall areas. The soil organic carbon density was increasing from north to south and fromwest to east, especially for meadow and swamp soil. The average value was increasingmore than4000t/km2. From the statistics of the whole study area, soil organic carbondensity was averagely decreasing5661t/km2in the carbon source area, while wasincreasing33044t/km2in the carbon sink area. Take the area of carbon source and sinkinto estimation, the surface soil organic carbon storage in Sanjiang Plain was increasing0.202Pg. Sanjiang plain had great attribution on carbon sequestration.