多枝柽柳和疏叶骆驼刺幼苗生物量分配及根系分布特征

以塔克拉玛干沙漠南缘荒漠-绿洲过渡带上两种主要建群种植物多枝柽柳(Tamarix ramosissima)和疏叶骆驼刺(Alhagi.sparsifolia SHAP.)的一年生幼苗为研究对象,采用人工壕沟全根挖掘法,研究同一生境条件下两种植物幼苗在生物量分配、根冠比、根系分布特征对极端干旱环境的适应特征.结果表明:(1)两种植物幼苗生物量分配策略明显不同.多枝柽柳幼苗把更多的生物量分配到地上,其根冠比为0.75;而疏叶骆驼刺幼苗把更多的生物量分配到地下,其根冠比为1.73.(2)两种植物幼苗地上/地下生物量属于典型的幂函数异速生长关系,异速生长模型的相关系数都在0.83以上.(3)两种植物幼苗根系分布各异.多枝柽柳幼苗根系多由垂直的主根和水平扩展的侧根组成,根长在垂直剖面上近似"丰"字形分布;骆驼刺幼苗根系在土壤中呈网状分布,根长在垂直剖面上近"古"字形分布.

Characteristics of biomass allocation and root distribution of Tamarix ramosissima Ledeb. and Alhagi sparsifolia Shap. seedlings

The study took juveniles of T. Ramosissima and A. Sparsifolia as study objects, which are the key species of desert - oasis transition zone in the south fringe of the Taklimakan Desert. The trench method and root tracing method were used to excavate their whole root system. The aim of the experiment is to study the features of the biomass allo-cation, root / shoot ratio and root distribution of two plant juveniles under the same extra-arid habitant condition with comparing their differences. The results shows as follows: (1) Biomass allocation of two plant juveniles are obviously different. T. Ramosissima allocates more biomass into shoots, whose root / shoot ratio is 0. 75. On the contrary, A. Sparsifolia allocates more biomass into roots with root / shoot ratio of 1.73. (2) Relationships between the root and the shoot of two plant juveniles are characterized by the allometry model, their correlation coefficients are larger than 0.83. (3) Root distribution of two plant juveniles is also significantly different. The root system of T. Ramosissima is composed by a vertical main root and some horizontal lateral roots, whose root system distribution is like a Chinese character of "feng" (丰) in its soil vertical profiles. The root system of A. Sparsifolia is composed of the tillers which are net-shaped, whose root system distribution in its soil vertical profiles is like a Chinese character of "gu"(古).