半荒漠藻结皮中藻类的种类组成和分布

对宁夏沙坡头半荒漠藻结皮中22种藻(其中蓝藻10种,绿藻4种,硅藻6种,裸藻2种)进行了分离、鉴定;利用土壤磨片和电子探针揭示了藻体与基质间的结合方式;通过光镜、扫描电镜观察,从8个层次研究了藻类在结皮中的分布,并发现它们在微米间也呈"层片"分布规律,藻结皮由表及里依次为无机矿物质保护层(ca.0.02mm)、富藻层(ca.0.02～2.5mm)及疏藻层(2.5～5.0mm);藻丝通过胶鞘中多糖、蛋白质与粘土矿物质直接结合,或直接伸入矿物质内而网络、粘结着砂粒和土粒.

Species composition and distribution of algae in semi desert algal crusts

Twenty-two species of algae, including 10 Cyanophyta,4 Chlorophyta,6 Bacillariophyta and 2 Euglenophyta,were isolated and identified from the semi-desert algal crusts in Shapotou,Ningxia Autonomous Region.The relationship between algae and soil matrix was studied by grinding and superprobe,and the distribution of algal species in eight layers of crusts was examined under light and scanning electron microscopes.It was found that the algae exhibited a layer typed distribution in intermicron, and the layers of algal crust from surface to inner were in order of inorganic mineral protection layer(ca.0.02mm),alga enriched layer(0.02～2.5mm)and sparse algae layer(2.5～5.0mm).The filaments of algae were united with clay mineral by the polysaccharides and protein of their sheath,or extended directly into mineral granules to network and band sand and soil particles.