Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the...Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities （ANOSIM）, fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis （NMS）, assemblages were separated into three groups at a Bray-Curtis similarity value of 42%： the upper, middle and lower groups. Following analysis of similarity percentages of species contributions （SIM- PER）, shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis （RDA） suggested that habitat structure （such as elevation, substrate, and flow velocity） contributed to the spatial and temporal pattem of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams [Current Zoology 56 （6）： 670-677, 2010].展开更多
Two new bird records for China of the Himalayan Black-lored Tit (Parus xanthogenys) and the Nepal Wren-Babbler (Pnoepyga immaculata) were established at Zhangmu,a small town in Tibet bordering on Nepal,in two birding ...Two new bird records for China of the Himalayan Black-lored Tit (Parus xanthogenys) and the Nepal Wren-Babbler (Pnoepyga immaculata) were established at Zhangmu,a small town in Tibet bordering on Nepal,in two birding trips in 2010,respectively.展开更多
Pinus taiwanensis is a species endemic to China.This study selected four typical plots of Pinus taiwanensis in the natural secondary forest around Macheng City,in order to reveal the characteristics of and the relatio...Pinus taiwanensis is a species endemic to China.This study selected four typical plots of Pinus taiwanensis in the natural secondary forest around Macheng City,in order to reveal the characteristics of and the relationships between different diameter classes(determined based on the diameter at breast height or DBH),forest densities and species diversity,as well as the similarities of species diversity of different plots within the community.The result showed that Pinus taiwanensis was the dominant species in the community.The ratio of Pinus taiwanensis trees of diameter class IV reached a peak of 19.46%of the total followed by diameter class VII at 18.92%.The study recorded 156 species of vascular plants from 130 genera of 71 families;Pinus taiwanensis was the dominant species in the community.When the forest density was 1200 trees ha-1 with the largest average diameter of DBH=36.779±4.444 cm,the diversity(Shannon index H'=1.6716)and the evenness(Pielou index E=0.6727)of the tree layer was the highest.When the forest density reached 1525 trees ha-1 with the lowest average diameter of DBH=18.957±5.141 cm,the richness(Dma=5.4308),the diversity(H'=2.9612)and the evenness(E=0.8985)of all shrub layers climbed to the maximum.When the forest density was 1325 trees ha-1,the richness(Dma=5.8132),the diversity(H'=3.0697)and the evenness(E=0.9025)of all herb layers peaked.In terms of vertical structure,the average diversity indexes were herb layer>shrub layer>tree layer.High canopy density weakened light intensity in the community,causing a reduction in the species diversities of herbs and shrubs.The average similarity coefficient between the sample plots was 0.3356,which was at the medium dissimilarity level.External disturbances and improper management were major contributors to the low species diversity of the community.The implementation of scientific management measures is urgently needed to optimize the forest structures of Pinus taiwanensis,create a benign community environment,and promote species diversities and establish a stable forest community structure.展开更多
基金supported by the National Basic Research Program of China (2009CB119200)Anhui Provincial Natural Science Foundation (090413080)Natural Science Foundation of Anhui Education Bureau (KJ2008B211,KJ2009A110)
文摘Spatial and temporal variation of fish assemblages were investigated seasonally from May 2007 to February 2008 across 11 study sites in a subtropical small stream, the Puxi Stream, of the Huangshan Mountain. Along the longitudinal gradient from headwater to downstream, fish species richness and abundance increased gradually, but then decreased significantly at the lower reaches. The highest species richness and abundance were observed in August and the lowest in February. Based on analysis of similarities （ANOSIM）, fish assemblages were significantly different in spatial variation but not in temporal variation. Although differences were observed both among sites and among stream orders, the lower R value in order-variation suggested stream order was not the optimal factor explaining the spatial variation of fish assemblages. In addition, dam construction did not significantly alter fish assemblages in the sites adjacent to and immediately downstream to dams. Using cluster analysis and non-metric Multi Dimensional Scaling analysis （NMS）, assemblages were separated into three groups at a Bray-Curtis similarity value of 42%： the upper, middle and lower groups. Following analysis of similarity percentages of species contributions （SIM- PER）, shifts in occurrence or abundance of S. curriculus, Z. platypus, R. bitterling and A. fasciatus contributed most to the differences amongst the three groups. Standard Deviation Redundancy Analysis （RDA） suggested that habitat structure （such as elevation, substrate, and flow velocity） contributed to the spatial and temporal pattem of fish assemblages in the Puxi Stream. In conclusion, the fish assemblages in Puxi Stream presented significant spatial but not temporal variation. Human disturbance has perhaps induced the decrease in species diversity in the lower reaches. However, no significant change was observed for fish assemblages in sites far from and immediately downstream from low-head dams [Current Zoology 56 （6）： 670-677, 2010].
文摘Two new bird records for China of the Himalayan Black-lored Tit (Parus xanthogenys) and the Nepal Wren-Babbler (Pnoepyga immaculata) were established at Zhangmu,a small town in Tibet bordering on Nepal,in two birding trips in 2010,respectively.
基金Scientific Research Project of Education Department of Hubei Province (B2018481,B2018482)
文摘Pinus taiwanensis is a species endemic to China.This study selected four typical plots of Pinus taiwanensis in the natural secondary forest around Macheng City,in order to reveal the characteristics of and the relationships between different diameter classes(determined based on the diameter at breast height or DBH),forest densities and species diversity,as well as the similarities of species diversity of different plots within the community.The result showed that Pinus taiwanensis was the dominant species in the community.The ratio of Pinus taiwanensis trees of diameter class IV reached a peak of 19.46%of the total followed by diameter class VII at 18.92%.The study recorded 156 species of vascular plants from 130 genera of 71 families;Pinus taiwanensis was the dominant species in the community.When the forest density was 1200 trees ha-1 with the largest average diameter of DBH=36.779±4.444 cm,the diversity(Shannon index H'=1.6716)and the evenness(Pielou index E=0.6727)of the tree layer was the highest.When the forest density reached 1525 trees ha-1 with the lowest average diameter of DBH=18.957±5.141 cm,the richness(Dma=5.4308),the diversity(H'=2.9612)and the evenness(E=0.8985)of all shrub layers climbed to the maximum.When the forest density was 1325 trees ha-1,the richness(Dma=5.8132),the diversity(H'=3.0697)and the evenness(E=0.9025)of all herb layers peaked.In terms of vertical structure,the average diversity indexes were herb layer>shrub layer>tree layer.High canopy density weakened light intensity in the community,causing a reduction in the species diversities of herbs and shrubs.The average similarity coefficient between the sample plots was 0.3356,which was at the medium dissimilarity level.External disturbances and improper management were major contributors to the low species diversity of the community.The implementation of scientific management measures is urgently needed to optimize the forest structures of Pinus taiwanensis,create a benign community environment,and promote species diversities and establish a stable forest community structure.
