In order to research the population distribution pattern of endangered species Toona ciliata Roem., the sampling quadrats of 5 mx5 m and 3 m×3 m in size, accurate to 1 mxl m, were established in 2 newly-found onl...In order to research the population distribution pattern of endangered species Toona ciliata Roem., the sampling quadrats of 5 mx5 m and 3 m×3 m in size, accurate to 1 mxl m, were established in 2 newly-found only existing T. cili- ata Roem. communities （T1 and T2） with contiguous grid quadrate method, in the Nanhe River valley, Gucheng County. By X2 test, t-test of distribution coefficient Cx method, and F test of Morisita pattern index Iδ whether the distribution patterns of the T. ciliata Roem. populations conformed to Poisson distribution were checked. The results indicated that, population T1 was in Poisson distribution under 5 m×5 m and 3 m×3 m in size by Cx and 16 methods, but in clumped distribution pattern un- der 5 m×5 m in size by the Chi-square test; however, the population was in Pois- son distribution under the dimension of 3 m×3 m. Population T2 under human dis- turbance had higher population density, indicating clumped distribution under 3 above-mentioned tests. If Chi-square test is satisfied, a distribution pattern is in Poisson distribution, and size and quantity of sampling quadrats should be given pri- ority to; and if df is greater, both theoretical values and observed values tend to- wards normal distribution more probably, and the test of distribution pattern, there- fore will be more dependable.展开更多
The distribution pattern of Isoetes sinensis populations was investigated in relation to its biological characteristics such as age structure and regeneration mode, and the microenvironment. Contagious distribution pa...The distribution pattern of Isoetes sinensis populations was investigated in relation to its biological characteristics such as age structure and regeneration mode, and the microenvironment. Contagious distribution pattern was found in populations of all sizes. Under the same climatic and site conditions, the heterogeneity of mieroenvironment resulting from the different depths of water and soil erosion significantly affecred the type and scale of distribution patterns of Isoetes sinensis populations. Even at the same site, the center and the edges of the water body had different effects on the distribution pattern of the plants. As one of the co-dominants, the distribution of Isoetes sinensis in communities was affected by other dominant species, especially by the evergreen grass species. Water is the major factor determining the distribution pattern of lsoetes sinensis in various communities. The pattern of contagious distribution was observed in different size of populations of I.sinensis, however the Lloyd indices obtained for the populations of various sizes differed significantly.展开更多
基金Supported by Public Welfare Research Project of Science and Technology Agency of Hubei Province(402012DBA40001)~~
文摘In order to research the population distribution pattern of endangered species Toona ciliata Roem., the sampling quadrats of 5 mx5 m and 3 m×3 m in size, accurate to 1 mxl m, were established in 2 newly-found only existing T. cili- ata Roem. communities （T1 and T2） with contiguous grid quadrate method, in the Nanhe River valley, Gucheng County. By X2 test, t-test of distribution coefficient Cx method, and F test of Morisita pattern index Iδ whether the distribution patterns of the T. ciliata Roem. populations conformed to Poisson distribution were checked. The results indicated that, population T1 was in Poisson distribution under 5 m×5 m and 3 m×3 m in size by Cx and 16 methods, but in clumped distribution pattern un- der 5 m×5 m in size by the Chi-square test; however, the population was in Pois- son distribution under the dimension of 3 m×3 m. Population T2 under human dis- turbance had higher population density, indicating clumped distribution under 3 above-mentioned tests. If Chi-square test is satisfied, a distribution pattern is in Poisson distribution, and size and quantity of sampling quadrats should be given pri- ority to; and if df is greater, both theoretical values and observed values tend to- wards normal distribution more probably, and the test of distribution pattern, there- fore will be more dependable.
基金Supported by the State Key Basic Research and DevelopmentProgram(G2000046805) .
文摘The distribution pattern of Isoetes sinensis populations was investigated in relation to its biological characteristics such as age structure and regeneration mode, and the microenvironment. Contagious distribution pattern was found in populations of all sizes. Under the same climatic and site conditions, the heterogeneity of mieroenvironment resulting from the different depths of water and soil erosion significantly affecred the type and scale of distribution patterns of Isoetes sinensis populations. Even at the same site, the center and the edges of the water body had different effects on the distribution pattern of the plants. As one of the co-dominants, the distribution of Isoetes sinensis in communities was affected by other dominant species, especially by the evergreen grass species. Water is the major factor determining the distribution pattern of lsoetes sinensis in various communities. The pattern of contagious distribution was observed in different size of populations of I.sinensis, however the Lloyd indices obtained for the populations of various sizes differed significantly.
