蛇麻黄和沙蒿两种典型灌丛对藻类分布的影响

为了解生物结皮中藻类植物与维管植物的关系,通过野外采样和室内固体培养法,研究了古尔班通古特沙漠中蛇麻黄和沙蒿灌丛对藻类分布的影响。结果表明：在两种灌丛内外,藻类种类组成主要表现在优势物种和优势度的变化。藻类物种多样性在两种灌丛内外有一定的差异,蛇麻黄灌丛内藻类物种数及多样性指数显著低于灌丛外（P＜0.05）,而沙蒿内藻类物种数显著高于灌丛外,多样性指数无明显差异。在群落结构中,蛇麻黄灌丛内蓝藻和丝状藻类物种数及优势度显著低于灌丛外（P＜0.05）,但单细胞和球形种类的优势度变化趋势相反且变化极显著（P＜0.01）。沙蒿灌丛内蓝藻、单细胞和球形种类的物种数显著高于灌丛外;蓝藻和丝状藻类的优势度由灌丛内至灌丛外显著升高（P＜0.01）,而绿藻、单细胞和球形种类则相反。在两种灌丛内外,藻类不同类群优势度的变化主要由一些关键物种引起,藻类在这两种灌丛中的不同分布特征可能是由于调节机制不同所致。

Effects of Shrubs of Ephedra distachyaand Artemisia arenariaon Algal Distribution

The effects of shrubs of Ephedra distachya and Artemisia arenaria on the distribution, species composition, species diversity and community structure of algae were investigated within and out of the shrubs of Ephedra distachya  and Artemisia arenaria . The results showed that there was no obvious difference in species composition of algae within and out of the shrubs of E. distachya and A. arenaria. The difference was mainly represented by the change of dominant species of algae. There was a difference of species diversity for the two semi shrub plants. Species diversity in the shrubs of E. distachya was lower significantly than that out of the semi shrubs. However, number of algal taxa in the semi shrubs of A. arenaria was higher significantly than that out of the shrubs, and there was no difference in Shannon Weaver index. In community structure, number of taxa and dominance degree of cyanobacteria and filamentous algae in the semi shrubs of E. distachya were significant lower than those out of the shrubs (P<0.05). An opposite change trend was observed for unicellular and coccoid algae. However, for A. arenaria, numbers of taxa of cyanobacteria, green algae, diatom, filamentous algae, unicellular and coccoid algae in the semi shrubs were higher significantly than those out of the shrubs. The dominance degree of cyanobacteria and filamentous algae increased significantly from the internal area to the external area of the shrubs (P<0.01). An opposite trend was observed for green algae, unicellular and coccoid algae. The change of dominance degree of different communities within and out of the two semi shrubs was mainly caused by some key taxa. Different distribution of algae in the semi shrubs of E. distachya  andA. arenaria  was possibly caused by different regulative mechanisms.