毛乌素沙地不同植被类型的土壤颗粒分形与土壤碳氮变化特征

为了探讨不同植被类型的土壤碳氮特征,测定了毛乌素沙地不同植被群落土壤0~10、10~20和20~60 cm土层土壤有机质、全氮及土壤颗粒组成的动态变化,并分析了土壤颗粒组成中沙粒、极细沙和黏粉粒质量分数变化与土壤有机质和全氮质量分数间的关系。结果表明,固沙植被的建植显著提高土壤有机质和全氮质量分数,而不同植被类型对土壤有机质和全氮质量分数的影响差异主要发生在土壤表层(0~10 cm),深层差异不显著。而同一植被类型土壤有机质和全氮质量分数随土层加深呈下降趋势,表现出垂直方向的变异。其中樟子松样地对表层土壤有机质和全氮质量分数含量影响最大,具有明显表聚性,随土层加深土壤有机质和全氮质量分数含量下降最为显著,而沙柳+油蒿+杨柴样地和沙地柏+油蒿样地土壤有机质、全氮质量分数随土层加深无显著变化。固沙植被的建植显著提高土壤黏粉粒(0.05 mm)和极细沙(0.05~0.10 mm)质量分数,而显著降低了沙粒质量分数(0.1~1.0 mm),不同植被类型样地各层土壤极细沙和黏粉粒质量分数由大到小依次为樟子松样地、沙地柏油蒿样地、沙柳油蒿杨柴样地,而沙粒质量分数与之相反。同一植被类型样地,随土层加深沙粒平均质量分数均呈增加趋势,极细沙和黏粉粒质量分数则呈降低趋势。土壤颗粒组成与土壤有机质、全氮质量分数间相关性表明,土壤中黏粉粒和极细沙粒质量分数分别与土壤有机质和全氮质量分数呈显著正相关,而沙粒质量分数却与土壤有机质和全氮质量分数呈显著负相关(p0.01)。

Characteristic of Soil Particle Size Distribution and Soil Organic Carbon and Nitrogen Dynamics of Different Veg- etation Typesi n the Mu Us Sandy Land

In order to study the characteristic of soil particle size distribution and soil organic carbon and nitrogen dynamics of different vegetation types , we measured the distributions of particle size fractions , organic matter and total nitrogen content in soils profile of 0-10 cm, 10-20 cm, and 20-40 cm at different vegetation types in the Mu Us Sandy Land , and analyzed the relationships among the content of silt clay (<0.05 mm), fine sand( 0.05-0.1), sand (0.1-1 mm), and the content of soil organic matter and total nitrogen .The planted sand fixing vegetation significantly increased soil organic matter and total nitrogen content , the influence of different vegetation types on soil organic matter and total nitrogen content mainly ap -peared in the surface layer (0-10 cm), but there was no significant difference in the deep soil layers .But in the same veg-etation type, soil organic matter and total nitrogen content were decreased with soil depth with vertical variation .The Pinus sylvestris sample had the greatest influence on the soil organic matter and total nitrogen content of surface with the obvious table cohesion , the most significantly decreased with soil depth .But the content of soil organic matter , total nitrogen in the other two pieces of sample had no significant change with the soil depth .Planted sand fixing vegetation significantly in-creased the content of silt clay and fine sand , but significantly reduced the content of sand , and the content of silt clay and fine sand of the different sample in the order of Pinus sylvestris>Salix psammophila+Artemisia odr osica+Hedysaur m frutico-sum>Aret misia ordosica+Junpi erus Sabina, but contrary to the content of sand .However, the content of sand in the same vegetation type sample was increased with soil depth , while the contents of silt clay and fine sand were decreased with soil depth.The relationships between the particle size fraction and the content of soil organic matter and total nitrogen showed that the content of soil organic matter and total nitrogen had significantly positive correlation with the content of silt clay and fine sand, but significantly negative correlation with the content of sand (p<0.01).