呼伦贝尔沙地风沙土有机质和碳酸钙含量特征

Content characteristics of organic matter and calcium carbonate of Aeolian soils in Hulun Buir Sandy Land

土壤有机质和碳酸钙是影响土壤风蚀可蚀性的重要因子,研究揭示其含量特征有助于深入理解土壤风蚀过程。以呼伦贝尔沙地流动、半固定、固定沙丘地表风沙土为研究对象,采用重铬酸钾稀释热法和钙离子浓度计分别测定土壤有机质和碳酸钙含量,计算分析不同类型沙丘土壤有机质和碳酸钙含量的相关性与空间异质性。研究结果显示:1)呼伦贝尔沙地表层风沙土有机质与碳酸钙平均质量分数分别为31.05和2.73 g/kg,且均随沙丘的固定显著增加(P<0.05)。2)碳酸钙与有机质含量呈极显著幂函数正相关关系(R 2=0.539,P<0.01)。随风沙土碳酸钙含量的不断增加,固定沙丘有机质含量的增加速率低于流动沙丘与半固定沙丘。3)随沙丘的固定,呼伦贝尔沙地表层风沙土有机质和碳酸钙含量的空间异质性不断增强,同质范围呈整体增大趋势,随机性因素对有机质含量空间变异的影响愈加重要。土壤的结构性因素是引起呼伦贝尔沙地风沙土有机质和碳酸钙含量空间变异的主要原因。

[Background]Soil organic matter(SOM),playing an important role in increasing the stability of soil aggregates,effectively leads to a reduction of wind erosion.Soil calcium carbonate(CaCO 3),existing massively in the arid and semi-arid soil,also significantly affects soil wind erodibility.Thus revealing the content characteristics of SOM and CaCO 3 helps understand the process of wind erosion.Previous studies show that SOM has an effective role to play in the generation process of CaCO 3,thus there is a positive correlation between the content of SOM and CaCO 3.Due to the climate change and anthropogenic activities in Hulun Buir Sandy Land in the north China,desertification there tends to be inexorable and more severe than before.[Methods]The study was conducted in the Hulun Buir Sandy Land.Total 93 sampling sites relating to mobile,semi-fixed and fixed sand dunes were located by GPS.Three sample plots nearby each sampling site were set up randomly.Aeolian topsoil(0~5 cm)were selected.SOM was determined using potassium dichromate volumetric method,while CaCO 3 was measured using a calcium ion concentration meter.Spatial variations of SOM and CaCO 3 were calculated and analyzed based on the theory of semi-variogram.Significant differences and correlation of data in different type of sand dunes were identified by SPSS16.0 statistical software,while spatial variation of that was analyzed by ArcGIS10.2 and GS+win10 software.[Results]1)The average content of SOM and CaCO 3 in the topsoil of Hulun Buir Sandy Land were 31.05 and 2.73 g/kg,respectively.During sand dune fixation,the content of SOM and CaCO 3 continuously increased.SOM content in mobile sand dunes was significantly lower than that in semi-fixed and fixed sand dunes,but CaCO 3 content in mobile sand dunes was just significantly lower than that in fixed sand dunes.2)The content of CaCO 3 was positively correlative with the content of SOM by power function(R^2=0.539,P<0.01).While the content of CaCO 3 in mobile,semi-fixed and fixed sand dunes were also positively correlative with the content of SOM,with R 2 were 0.580,0.630 and 0.245 respectively.With the increasing content of CaCO 3,the growth rate of SOM in fixed sand dunes was lower than that in mobile and semi-fixed sand dunes.3)During sand dune fixation,the spatial variation of SOM and CaCO 3 were increasing,the distribution of SOM and CaCO 3 tended to be homogeneous,and the influence of random factors on the spatial variability of organic matter was getting more important.Structural factors of soil were the main cause of the spatial variation of SOM and CaCO 3 in Hulun Buir Sandy Land.[Conclusions]During sand dune fixation,the decreasing intensity of soil erosion may influence the content,correlation and spatial variation of SOM and CaCO 3.The results of this study may provide theoretical reference for regional desertification combating and ecological restore.