为明晰烤烟连作是否对根际细菌群落结构产生影响,采集不同生育时期的轮作和连作烤烟根际土壤,运用454焦磷酸测序技术,对根际土壤细菌16S r DNA V1-V3片段序列结构组成进行分析。结果表明,与轮作处理相比,连作处理烤烟根际酸杆菌门丰度...为明晰烤烟连作是否对根际细菌群落结构产生影响,采集不同生育时期的轮作和连作烤烟根际土壤,运用454焦磷酸测序技术,对根际土壤细菌16S r DNA V1-V3片段序列结构组成进行分析。结果表明,与轮作处理相比,连作处理烤烟根际酸杆菌门丰度在生育前期低而在后期高,但α-变形菌门和放线菌门表现出相反的变化趋势;烤烟连作降低了表征菌群丰度的Chao指数和物种丰富度的Shannon指数,表明烤烟连作降低了根际土壤细菌多样性。主成分分析和NMDS(non-metric multidimensional scaling)的聚类分析结果显示不同处理烤烟根际细菌群落结构随生育期而迁移,轮作与连作烤烟根际土壤细菌群落结构差异在生育前期体现明显,生育后期不明显,表明生育期是影响烤烟根际细菌群落结构变化的主要因素,而连作与轮作是次要因素。展开更多
Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an inc...Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates （mammals, birds, reptiles, and amphibians） at both regional （biogeographic realm） and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa （birds and mammals） than for the two ectothermic taxa （reptiles and amphibians） in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000-99,999 km^2 than for ecoregions of 100,000-5,000,000 km^2.展开更多
A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 20...A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.展开更多
文摘为明晰烤烟连作是否对根际细菌群落结构产生影响,采集不同生育时期的轮作和连作烤烟根际土壤,运用454焦磷酸测序技术,对根际土壤细菌16S r DNA V1-V3片段序列结构组成进行分析。结果表明,与轮作处理相比,连作处理烤烟根际酸杆菌门丰度在生育前期低而在后期高,但α-变形菌门和放线菌门表现出相反的变化趋势;烤烟连作降低了表征菌群丰度的Chao指数和物种丰富度的Shannon指数,表明烤烟连作降低了根际土壤细菌多样性。主成分分析和NMDS(non-metric multidimensional scaling)的聚类分析结果显示不同处理烤烟根际细菌群落结构随生育期而迁移,轮作与连作烤烟根际土壤细菌群落结构差异在生育前期体现明显,生育后期不明显,表明生育期是影响烤烟根际细菌群落结构变化的主要因素,而连作与轮作是次要因素。
文摘Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates （mammals, birds, reptiles, and amphibians） at both regional （biogeographic realm） and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa （birds and mammals） than for the two ectothermic taxa （reptiles and amphibians） in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000-99,999 km^2 than for ecoregions of 100,000-5,000,000 km^2.
基金Under the auspices of Major State Basic Research Development Program of China (973 Progrom) (No 2007CB106801)National Key Technology R&D Program of China (No 2006BAD16B06)National Natural Science Foundation of China (No 30470180,30770397)
文摘A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.
