渭北黄土高原不同立地上刺槐根系分布特征研究

Researches on Root Distribution Characters of Robinia Pseudoacacia on Different Sites in Weibei Loess Plateau

采用土钻法对渭北黄土高原地区的主要造林树种刺槐的根系分布特征进行了调查研究。结果表明 ,不同立地上的刺槐根系分布特征具有明显的差异 ,阳坡立地上的根系密度和生物量均小于阴坡立地 ;不同林龄根系分布在深度上没有明显的差异 ,但是其根系的生物量和根系密度具有明显的差异。不同立地上刺槐的根系消弱系数 (root extinction coefficient)β值之间也存在明显的差异。阴坡立地的β值均在0 .982以上 ,而阳坡立地上的β值则一般小于 0 .982 ,说明阴坡立地上的刺槐根系分布深度要大于阳坡立地。其细根 (Φ <1mm )的分布深度大于较粗根系 (Φ <3mm )的分布深度 ,有利于刺槐对深层土壤中水分、养分的吸收 ,适应干旱环境 。

Soil drilling method is applied for root distribution characters investigation of the main forestation tree species on the loess plateau. The results indicate that there is obvious difference in the root distribution characters on different sites, both root density and root biomass on southern slope are smaller than that on northern slope. There are no obvious differences in root distribution depth on stand of different age, but root biomass and root density increased with age. Root extinction coefficient β, is one of the most important parameters in determining the vertical distribution depth of tree species. In this study, results showe that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicates that the vertical root distribution depth of Robinia pseudoacacia on southern exposition is deeper than that on southren exposition. And the distribution depth of fine roots (Φ<1 mm) is deeper than that of thicker roots(Φ<3 mm), which is in favor of the uptake of water and nutrients from deeper layers, helps the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree.