毛乌素沙地天然臭柏灌丛地的土壤特性

Distribution Patterns of Soil Properties Under Natural Sabina Vulgaris Shrub in MU-US Sandy Land

采用样方调查法对毛乌素沙地天然臭柏灌丛地土壤特性调查结果表明 :臭柏灌丛地土壤水分、有机质、全氮、速效钾和碱解氮等养分资源分布具有空间异质性。在臭柏灌丛地(覆盖度 70 %～ 85 % ) 0～ 5 cm的土层 ,聚集了较多的中细粒子 ( 0 .2 5～ 0 .0 2 cm) ,平均含量为68.9% ,比油蒿覆盖区 (覆盖度 40 %～ 5 5 % )高 9% ,并随土层深度的加深 ,其含量降低。水分、有机质、全氮、速效钾和碱解氮等养分含量的分布 ,存在明显的“沃岛”现象。在 0～ 1 0 0 cm的土层范围内 ,臭柏灌丛地 60 %以上的土样含水率为 1 %～ 2 % ,变异系数高达 1 1 3%。土层深度 <2 0 cm时 ,臭柏灌丛土壤含水率由灌丛内向灌丛外逐渐减少 ,当土层 >2 0 cm时 ,则正好相反。70 %的土样速效磷含量 <2 mg/kg,除速效磷之外 ,土壤中的有机质、全氮、速效钾、碱解氮等在臭柏灌丛下 0～ 2 0 cm的土层内相对富集。在 0～ 1 0 0 cm的土层内 ,有机质的变异系数为 96.3% ,全氮为 1 0 1 .4% ,碱解氮为 80 .6% ,速效钾为 88.4%。臭柏灌丛地土壤特性的空间异质性 ,是生物和物理过程共同作用的结果。

The soil properties under natural Sabina vulgaris shrub in Mu-us sandy land were reserched with plot investigation. The result showed that distribution patterns of soil moisture, organic matter, total N, available K and hydrolytic N presented spatial heterogeneity. The average content of middle and fine soil particles(0.25～0.02mm) in layer of 0～5cm under Sabina vulgaris shrub(70%～85% cover)which was 9% higher than that under Artemisia ordosica shrub(40%～55% cover) ,was 68.9%, and it dropped down with increasing deep. The soil nutrients, such as organic matter, total N, available K and hydrolytic N, and the soil moisture showed an evident phenomenon of “island of fertility” under Sabina vulgaris shrub. The soil samples with 1%～2% of moisture was over 60%, and variation coefficient of soil moisture was 113% in layer of 0～100cm. The soil moisture decreased gradually from the center of shrubs to its edge in layer of 0～20cm but it showed opposite trend under layer of 20cm. The content of available P was less than 2mg/kg. The organic matter, total N, available K and hydrolytic N of soil massed over layer of 20cm. The variation coefficient of organic matter was 96.3%, of total N was 101.4%, of hydrolytic N was 80.6% ,and of available K was 88.4% in layer of 0～100cm. The spatial heterogeneity of soil resources resulted from the process of the biology and the physics.