Vertical distribution of algae in semi-desert soil of Shapotou area,Ningxia Hui Autonomous Region
历山自然保护区猪尾沟森林群落植被格局及环境解释

Quantitative research on ecological relationships at landscape and re gion scales between vegetation and the environment has been developing rapidly, and became one of the focuses of vegetation science. In this paper, pattern of f orest vegetation in Zhuweigou of Lishan Mountain Nature Reserve, in relation to the environmental factors, was investigated using TWINSPAN, DCA and DCCA. By TWINSPAN, the forest communities were classified into 9 types. In general, th e distribution of plant communities could comprehensively reflect the influence of climate, altitude, topography, edaphic conditions and so on. These patterns c ould be considered a combination of factors operating at different scales. The r esults of DCA ordination indicate that the main factors that restricted distribu tion of the communities were temperature and humidity in Lishan Mountain. That i s to say, altitude and disturbance appeared to override the effect of soil nutri ents. At the same time, the ordination of species and the ordination of quadrats were compared. It was shown that the ordination plot of the dominant species in plant community was similar to that of the plant community type. To some extent , the distribution of the former determined that of the latter. The species-environment correlation was more obvious using DCCA than DCA ordina tion, It was in favor of interpreting the ecological meaning of the ordination a xes. The first axis expressed the gradient of altitude among the communities, an d the second axis represented the gradient in aspect and slope among the communi ties. Generally using DCCA, the quadrats with similar composition and environmen ts and the species with similar habitat located closer to the center of the ordi nation plot.