Themethods of vegetation ecology were used to analyze the community structure of Hefei Ring Park, andspecies composition, distribution patternoftree heightand DBH weredescribed.Through calculation of tree growth index...Themethods of vegetation ecology were used to analyze the community structure of Hefei Ring Park, andspecies composition, distribution patternoftree heightand DBH weredescribed.Through calculation of tree growth index and association correlation of component species, the community structures were analyzed. The results showed that community structures are complex, there are 22 pairs of species with positive association, and tree individual in the following communities grow well and are more stable, the majorarePlatycladus orientalis-Prunuscerasifera f.atropurpurea-Osmanthusfragrans, Robinia pseduacacia- Ligustrum lucidum,Robinia pseudoacacia-Ginkgobiloba-Photinia serrulata,Populuscadadensis-Ligustrum lucidum-Osmanthusfragrans, Sophora japonica-Ligustrum lucidum-Buxussinica, Cyclobalanopsis glauca- Distylium racemosum.展开更多
This study aims to examine spatial and temporal variations of zooplankton species composition,density and biomass distribution and community structure, based on the data obtained from three separate cruises carried ou...This study aims to examine spatial and temporal variations of zooplankton species composition,density and biomass distribution and community structure, based on the data obtained from three separate cruises carried out in November 1997, April and July 1999. Results show that 244 species of zooplankton and 8 groups of planktonic larvae were identified, which were dominated by copepods, followed by amphipods, ostracods and medusae. The total species were 201 and 198 for the cruises of November 1997 and July 1999, respectively, and no obvious seasonal variation of species richness was observed. The distribution of zooplankton species richness decreased from pelagic to coastal waters. Average richness of species in each station was higher in the cruises of November 1997(62) and April 1999(61) than in the cruise in July 1999 (56), which was mainly a result from the pelagic or coastal water mass movement made by the monsoon. Zooplankton in the upper waters (0―100 m) around Nansha Islands belonged to the typical tropic pelagic fauna, most of them were pelagic warm-water species, followed by coastal warm-water species and euryhaline warm-water species. The number of dominant species ranged from 5 to 7 in each cruise. No obvious seasonal succession of dominant species was observed. Sagitta enflata, Cypridina nami, Cosmocalanus darwinii, Pleuromamma gracilis and Echinopluteus larva were the main dominant species. The average of zooplankton biomass and density in three cruises were 31, 32, 28 mg·m 3 and 31, 39, 35 ind·m 3, respectively. Copepods were the most abundant, followed by chaetognaths. Zooplankton high biomass distributed mainly in the northwestern waters around Nansha Islands, and generally occurred in the areas of oceanic front and upwelling. The main reason for zooplankton quantity without obvious seasonal variation was the relative steady temperature dynamics in the waters around Nansha Islands.展开更多
The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversi...The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04–2.953 and 64.2%–74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.展开更多
In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-specie...In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-species analysis programs(TWINSPAN)classifies plots and species into different groups.De-trended correspondence analysis(DCA)and canonical correspondence analysis(CCA)reflects the relationship between community and site conditions.Afforestation with Larix olgensis Herry.Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains.The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process.Twenty-eight L.olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method.Species composition,community structure attributes of diversity,and site conditions were analyzed.Communities were classified by TWINSPAN into five successional stages:immature,juvenile,mid-aged,nearmature and mature.Classifications were validated by DCA and CCA analysis.Site conditions such as soil and litter thickness,soil organic matter,soil density,and pH were measured.Successional stages varied in community composition and species population,accompanied by time from afforestation and a gradient of site conditions.This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions.The study showed that L.olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.展开更多
This study aims to analyze the spatial and temporal variations of the abundance and biodiversity of pelagic copepods and their relationships with the environmental factors in the North Yellow Sea(NYS). These variation...This study aims to analyze the spatial and temporal variations of the abundance and biodiversity of pelagic copepods and their relationships with the environmental factors in the North Yellow Sea(NYS). These variations were analyzed on the basis of the survey data of the NYS in four seasons from 2006 to 2007. A total of 31 copepod species that belong to 17 genera, 13 families and 4 orders were identified in the four seasons. Of these copepods, the species belonging to Calanoida is the most abundant component. The dominant species include Calanus sinicus, Centropages abdominalis, Paracalanus parvus, Acartia bifilosa, Oithona plumifera, and Corycaeus affinis. C. sinicus is the most important and widely distributed dominant species in all of the seasons. The dominant species have not shown any significant variation for the past 50 years. However, the richness of warm-water species increased. The abundance of copepods significantly varied among different seasons: the average abundance was higher in spring(608.2 ind m^(-3)) and summer(385.1 ind m^(-3)) than in winter(186.5 ind m^(-3)) and autumn(128.0 ind m^(-3)). Factor analyses showed a high correlation between the spatial distributions of dominant copepods and environmental parameters, and Chl-a was the most important factor that influenced the distribution of copepods. This research can provide the fundamental information related to zooplankton, especially pelagic copepods. This research is also beneficial for the long-term monitoring of zooplankton ecology in the NYS.展开更多
文摘Themethods of vegetation ecology were used to analyze the community structure of Hefei Ring Park, andspecies composition, distribution patternoftree heightand DBH weredescribed.Through calculation of tree growth index and association correlation of component species, the community structures were analyzed. The results showed that community structures are complex, there are 22 pairs of species with positive association, and tree individual in the following communities grow well and are more stable, the majorarePlatycladus orientalis-Prunuscerasifera f.atropurpurea-Osmanthusfragrans, Robinia pseduacacia- Ligustrum lucidum,Robinia pseudoacacia-Ginkgobiloba-Photinia serrulata,Populuscadadensis-Ligustrum lucidum-Osmanthusfragrans, Sophora japonica-Ligustrum lucidum-Buxussinica, Cyclobalanopsis glauca- Distylium racemosum.
文摘This study aims to examine spatial and temporal variations of zooplankton species composition,density and biomass distribution and community structure, based on the data obtained from three separate cruises carried out in November 1997, April and July 1999. Results show that 244 species of zooplankton and 8 groups of planktonic larvae were identified, which were dominated by copepods, followed by amphipods, ostracods and medusae. The total species were 201 and 198 for the cruises of November 1997 and July 1999, respectively, and no obvious seasonal variation of species richness was observed. The distribution of zooplankton species richness decreased from pelagic to coastal waters. Average richness of species in each station was higher in the cruises of November 1997(62) and April 1999(61) than in the cruise in July 1999 (56), which was mainly a result from the pelagic or coastal water mass movement made by the monsoon. Zooplankton in the upper waters (0―100 m) around Nansha Islands belonged to the typical tropic pelagic fauna, most of them were pelagic warm-water species, followed by coastal warm-water species and euryhaline warm-water species. The number of dominant species ranged from 5 to 7 in each cruise. No obvious seasonal succession of dominant species was observed. Sagitta enflata, Cypridina nami, Cosmocalanus darwinii, Pleuromamma gracilis and Echinopluteus larva were the main dominant species. The average of zooplankton biomass and density in three cruises were 31, 32, 28 mg·m 3 and 31, 39, 35 ind·m 3, respectively. Copepods were the most abundant, followed by chaetognaths. Zooplankton high biomass distributed mainly in the northwestern waters around Nansha Islands, and generally occurred in the areas of oceanic front and upwelling. The main reason for zooplankton quantity without obvious seasonal variation was the relative steady temperature dynamics in the waters around Nansha Islands.
基金the National Natural Science Foundation of China (Grant No.30270282 30170147)
文摘The composition and structure of five natural secondary forests in Shenzhen were studied based on data of plots and were compared with Hong Kong zonal forest, so as to detect their succession stage and species diversity level. According to succession process of subtropical forest and ecological characteristics of dominant species, the authors speculate that five communities are at different stages. Sinosideroxylon community dominated by heliophilous evergreen broad-leaved tree (Sinosideroxylon wightianum) and conifer tree (Pinus massoniana) is at the third stage. Itea + Acronychia community dominated by two evergreen broad-leaved heliophytes (Itea chinensis and Acronychia pedunculata) is at the fourth stage. The others, i.e., Schefflera, Sterculia and Cleistocalyx + Sterculia community are at the fifth stage where some mesophytes are dominant but heliophytes have a weighed percentage of importance value. Due to succession stage and different forest management and conservation models, the species diversity of five communities is significantly lower than that of Endospermum community in Hong Kong. The values of Shannon-Wiener index and Pielous evenness index of five communities are 2.04–2.953 and 64.2%–74% respectively, but those of the Endospermum community are 4.74 and 79% respectively. The current situation of these communities suggests that the necessary measures should be taken to protect and restore the communities.
基金We express our sincere appreciation to Xiao-Yu Guo,Yao Fu,Yu Dong,Tian-Bo Wang,Yi-Fu Wang for their fieldwork assistance,and to the members of Langxiang Forestry Bureau for their friendship and assistance.
文摘In order to understand the management of regional vegetation,numerical classification and ordination are widely used to investigate community distribution and vegetation features.In particular,two-way indicator-species analysis programs(TWINSPAN)classifies plots and species into different groups.De-trended correspondence analysis(DCA)and canonical correspondence analysis(CCA)reflects the relationship between community and site conditions.Afforestation with Larix olgensis Herry.Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains.The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process.Twenty-eight L.olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method.Species composition,community structure attributes of diversity,and site conditions were analyzed.Communities were classified by TWINSPAN into five successional stages:immature,juvenile,mid-aged,nearmature and mature.Classifications were validated by DCA and CCA analysis.Site conditions such as soil and litter thickness,soil organic matter,soil density,and pH were measured.Successional stages varied in community composition and species population,accompanied by time from afforestation and a gradient of site conditions.This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions.The study showed that L.olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.
基金supported by the National Natural Science Foundation of China(31101875,41210008)
文摘This study aims to analyze the spatial and temporal variations of the abundance and biodiversity of pelagic copepods and their relationships with the environmental factors in the North Yellow Sea(NYS). These variations were analyzed on the basis of the survey data of the NYS in four seasons from 2006 to 2007. A total of 31 copepod species that belong to 17 genera, 13 families and 4 orders were identified in the four seasons. Of these copepods, the species belonging to Calanoida is the most abundant component. The dominant species include Calanus sinicus, Centropages abdominalis, Paracalanus parvus, Acartia bifilosa, Oithona plumifera, and Corycaeus affinis. C. sinicus is the most important and widely distributed dominant species in all of the seasons. The dominant species have not shown any significant variation for the past 50 years. However, the richness of warm-water species increased. The abundance of copepods significantly varied among different seasons: the average abundance was higher in spring(608.2 ind m^(-3)) and summer(385.1 ind m^(-3)) than in winter(186.5 ind m^(-3)) and autumn(128.0 ind m^(-3)). Factor analyses showed a high correlation between the spatial distributions of dominant copepods and environmental parameters, and Chl-a was the most important factor that influenced the distribution of copepods. This research can provide the fundamental information related to zooplankton, especially pelagic copepods. This research is also beneficial for the long-term monitoring of zooplankton ecology in the NYS.
