| Desert soil microbiotic crust was a kind of organic complex that consisted of bacteria, fungi, soil algae, lichens, moss, spore plants and so on. The physical, chemical and biological characteristics of soil microbiotic crust were significantly different from the loose sandy soil.It has more anti-wind and water erosion capacity than sandy soil. As a pioneer of semi-desert or desert ecosyste, desert algae played a key role in soil formation. Desert algae can increased the carbon, nitrogen and phosphorus content of desert soil.It was also a biological basis of vegetation succession in arid-desert areas when algae crust changed into lichen and moss crust even the implantation of vascular plants. There were no systematic researchs on desert crust algae of eastern margin of QingZang Plateau. Therefore, it had important theoretical and practical value that research on desert algae of eastern margin desert region of QingZang Plateau.Algal composition, ecological distribution, seasonal changes characteristic of eastern margin desert region of QingZang Plateau were researched by field studies, sampling, laboratory culture, species identification and physiological experiments. The results were showed as follows:1 According to morphological features, the algae species of eastern margin desert region of QingZang Plateau were 17 by separated and purificated preliminarily. But algae identification need further work.2. In sampling area, the algal one and four are dominant species. They arised in every sampling areas and season. they can grow very good in three growth media. These phenomenons indicated that the adaptability of the two algae were strong. the frequency of other algae was different in different seasons.3. The number and the composition of the algae were different in the different sampling areas of eastern margin desert region of QingZang Plateau. According to the species number, sampling area two and three was more than sampling area one. Sampling area four was the. Species number was more relation with the habitat.4.The vertical distribution of algal biomass eastern margin desert region of QingZang Plateau were asymmetry. Algal biomass dropped drastically from the surface to the centre. The algal species and number were the largest at 0～0.5cm soillayer. It decreased at 0.5～1cm soillayer. The algal species and number of 1～2cm soillayer was less than 0.5～1cm. There was no algal existing at 5cm soillayer.5. The number and the composition of the algae were different in the different season.There was 15 species in spring,14 species in summer,12 species in autumn. Biomass distribution of algae accorded with the 3,4-article law in spring. Biomass declined in summer. Only sampling area three had more algae in summer. Sampling area two and three had more algae in autumn.6. BBM, BG11 and Bristal media was used to culture the algae of eastern margin desert region of QingZang Plateau. The results showed that BG11 medium was fit for the algae. Algal species ten was found only in BG11 medium. Moreover, algal colony number was different among different sampling areas, soillayer and medium.7.Based on culturing in the room, the effects of pH, salt and Mg2+ on the algae species one and seven were researched. The results showed that the impact of the pH on the two algae were significant. Algae species one was more alkali than species seven. the two algae can growed in pH 11 solution. salt and Mg2+ was negative correlation with growth of the two algae.In summary, results of this study provided the basic datas for further researching works on algal species composition and distribution features of the desert region of the eastern margin of QingZang Plateau.It was a basic work for selecting algal species which was suitable for this area. It provided the first follow-up information for future biological crust algae study. These works also laid the foundation for artificial desert algae cultivation and field implant technology. |
PDF Full Text Request