沙棘—侧柏混交林生物量、林地土壤特性及其根系分布特征的研究

Biomass and Soil Characteristics of Hippophae Rhamnoides and Platycladus Orientalis Mixed Forest and Its Root System Distribution

选择黄土高原17a生的侧柏纯林作为对照，对沙棘-侧柏混交林中的侧柏生长、林地土壤特性及根系分布特征进行了系统研究。研究结果表明，混交林中侧柏平均树高比纯林的高25．80％，平均胸径大36．88％，林分生物量高128．23％，地上各部分生物量都明显高于侧柏纯林；混交林地与侧柏纯林地相比，土壤各层容重减小，而总孔隙度、毛管空隙度、非毛管空隙度、自然含水量、最大含水量、毛管含水量、最小含水量均有不同程度的增大；根系分布特征研究表明，侧柏纯林中根径≤1mm和1～3mm的根系主要集中分布在0—60nm土层内，而混交林在0—180cm的范围内分布相对更深，更均匀；根径≥3mm的根系侧柏纯林与混交林具有较为相似的垂直分布特征。混交林中根径≤1mm和1～3mm的根系水平分布范围相对纯林的更大，而根径≥3mm的根系的分布范围较小。

The biomass, soil characteristics and root distribution of 17-year-old pure Platycladus orientalis stand and Hippophae rhamnoides × Platycladus orientalis mixed stand were studied in Yongshou County, Shaanxi Province on the Loess Plateau. Results showed that mean height, diameter of breast hight and stand biorrmss in the mixed stand were 25.80%, 36.88% and 128：23 % higher than those in the pure stand, respectively. Total biomass of each part in the mixed stand was higher than that in the pure stand. Compared with the pure stand, soil bulk density in the mixed stand was reduced. On the contrary, soil porosity, water capacity and moisture capacity were increased to a certain extent. Platycladus orientalis root system （diameter≤1mm and 1- 3 mm ） in the pure stand was mainly distributed in the upper 60 cm of soil, yet those in the mixed stand were distributed more deeply and evenly. Distribution of Platydadus orientalis root system （diameter≥3 mm） in the mixed stand was close to that in the pure stand. Horizontal distribution area of Platycladus orientalis root （diameter≤1 mm and 1 -3 mm） in the mixed stand was broader than that in the pure stand, while for root diameter greater than 3 mm, the distribution in the mixed stand was narrower than that in the pure stand.