Study On Carbon Isotope Characteristics Of Plant-Litter-soil Continuum In Wetland Of Changbai Mountains

In order to explore the different degrees of plant-litter-soil fractionation and the rate of soil organic matter turnover at different altitudes in the forest under wetland.The study was carried out plants,litter and soil on the northern slope of Changbai Mountain at an altitude of 700m-1818m,with 6 elevation gradients of in July 2018.The soil was measured,and the correlation between ?13C value of dominant plant leaves.Analyzing climatic factors and soil factors which are main controlling on litter and soil profile stable carbon isotope techniques.The characteristics of soil organic matter turnover in different altitude gradients in the study area were studied.With further understanding,the research results are as follows:1)The main controlling factors of carbon isotope composition of arbor plants were temperature and soil total phosphorus content.The main controlling factors of carbon isotope composition of shrub plants were temperature and soil total nitrogen content.The main controlling factors of carbon isotope composition of herb plants were temperature and soil total phosphorus content;and the water use efficiency of evergreen plants is higher than that of deciduous shrubs,so the cost of carbon sequestration is relatively low.2)Except for the plot with an elevation of 700m,the soil organic carbon content of the other five plots decreased with the increase of soil depth.The ?13C value of soil organic matter showed a trend of positive bias and then negative with the elevation gradient.It reached the maximum at 1300m above sea level;it was found that the total phosphorus content of soil had the greatest influence on the carbon isotope composition of soil organic matter.3)The ?13C value of plant-litter-soil continuum organic matter is gradually positive,the maximum fractionation is herbaceous-litter,and the smallest is litter-soil.The change of carbon isotope composition of plant dominant species has a direct impact on soil organic matter.4)The soil turnover rate was the fastest at 700m altitude,while the soil turnover rate was the slowest at 1818m.With the increase of altitude gradient,the absolute value of the turnover rate coefficient K.first decreases and then increases and then decreases.The temperature and soil total phosphorus content have the greatest influence on the turnover rate coefficient K,followed by the soil organic carbon content.