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）；藻丝皮由表及里依次为

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. 0.02 mm), alga-enriched layer(0.02-2.5 mm) and sparse algae layer(2.5-5.0 mm). 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.