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利用水平土柱吸渗法对科尔沁沙地的沙质草地、固定沙丘和流动沙丘等3种生境0~100 cm土层土壤水分扩散率(D(θ))与土壤水分(θ)之间的关系进行了测定,研究了不同生境D(θ)及Boltzmann参数(λ)与θ的定量关系,并分析了D(θ)随生境及土壤剖面的变化规律。结果表明:(1)3种生境0~100 cm土层的土壤湿润峰迁移速率差异显著(P<0.05),且以沙质草地的最小,其次为固定沙丘,而流动沙丘的最大,平均值分别为0.38、0.97和1.60 cm·min-1;3种生境土壤湿润峰迁移速率随入渗距离均呈对数形式递减;(2)沙质草地、固定沙丘和流动沙丘0~100 cm土层的Boltzmann参数λ平均值分别为4.22、6.58和8.59 cm·min-1/2,且λ随θ的增加而减小;(3)沙质草地、固定沙丘和流动沙丘的D(θ)依次增大,0~100 cm的平均值分别为1.21、4.51和12.75 cm2·min-1;3种生境D(θ)随θ的变化规律都可以用经验公式D(θ)=aebθ拟合;D(θ)随土壤剖面的变化规律因生境不同而有较大差异,说明科尔沁沙地不同生境及同一生境不同土层的土壤水分扩散率差异较大,且具有较高的空间异质性;(4)土壤有机质含量和粘粉粒含量对D(θ)的影响较大,且D(θ)随这2个因素的增加而减小。此外,生境类型及植物根系对D(θ)也有较大影响。
Soil water diffusivity (D (θ)) and soil moisture (θ) in 0-100 cm soil layer of sandy grassland, fixed sand dune and mobile sand dune in Horqin sandy land were measured by horizontal soil column suction method The relationship between D (θ) and Boltzmann parameters (λ) and θ in different habitats was studied. The variation of D (θ) with habitat and soil profile was analyzed. The results showed that: (1) The wetting peak migration rates of 0-100 cm soil layer in 3 habitats were significantly different (P <0.05), and were the lowest in sandy grassland, followed by the fixed sand dunes, while the maximum and average moving sand dunes (0.38,0.97 and 1.60 cm · min-1, respectively). The migration rates of soil wetting peak in all three habitats decreased logarithmically with infiltration distance. (2) The soil layers of sandy grassland, fixed sand dune and mobile dune at 0 ~ 100 cm The Boltzmann parameters λ are respectively 4.22, 6.58 and 8.59 cm · min-1/2, and λ decreases with the increase of θ. (3) D (θ) of sandy grassland, The average values of 0 ~ 100 cm were 1.21, 4.51 and 12.75 cm2 · min-1, respectively. The change rule of D (θ) with θ was fitted by the empirical formula D (θ) = aebθ. θ) varies greatly with the soil profile due to different habitats, indicating that the differences of soil moisture diffusivities in different habitats and the same habitats in Horqin sandy land are quite different and have high spatial heterogeneity. (4) Soil organic matter content and sticky grain content had a greater effect on D (θ), and D (θ) decreased with the increase of these two factors. In addition, habitat types and plant roots have a greater impact on D (θ).