汾河河口湿地植被数量分类与排序

在群落样方调查基础上,采用双向指示种分析（TWINSPAN）和除趋势对应分析（DCA）对汾河入河口湿地植被群落进行了数量分类和排序。TWINSPAN将78个样方分为18个群丛,并论述了各群丛的群落学特征。DCA排序结果反映了植物群落类型与环境梯度水分之间的关系,表明影响群丛分布格局的主导生态因子为土壤水分。     

桂林岩溶石山青冈栎群落的数量分析

应用双向指示种分析(TWINSPAN)和除趋势对应分析(DCA)方法对桂林岩溶石山青冈栎群落进行数量分类与排序。通过TWINSPAN分类,将青冈栎群落60个样方划分为8个群丛类型,探讨了各群丛类型的基本特征。结果表明:DCA排序与TWINSPAN分类结果较一致,DCA排序较好地体现了各群丛类型与环境因子的相互关系,DCA第一排序轴主要反映了坡度的变化梯度;DCA排序图的对角线基本体现了坡向的变化梯度。坡度的变化是影响岩溶石山青冈栎群落物种组成与分布的重要生态因子。     

山西北部地区沙棘群落的数量分类和排序研究

采用双向指示种分析法对山西北部地区沙棘群落进行分类和排序研究,结果将山西北部地区沙棘群落划分为14个群系,并论述了各群系的特征。DCA排序进一步说明了群系的分布格局与水分和土壤的密切关系,结果表明组成沙棘灌丛的种群对群落生境具有指示作用,能客观反映群落的生境特征．     

Ordination methods and chironomid species in stony bottom streams

Stony bottom streams in Italy were sampled in 369 sites in different years, and 174 chironomid species (or species groups) were identified.The species by sites matrix was submitted to different ordination methods, with the aim of outlining the major factors that are responsible of the observed species composition.The methods considered were principal component analysis (PCA), detrended correspondence analysis (DCA) and non-metric multidimensional scaling (MDSCAL). These methods assume different models describing the species-responses to the environmental gradients.PCA gave poor results, the best species ordination was given by MDSCAL. DCA gave results in agreement with MDSCAL. DCA results were useful as a starting point to perform MDSCAL. MDSCAL was performed with different options. At last Procrustean analysis was carried out to have a single fitted configuration, that summarized the results given by the different MDSCAL methods.All multivariate analyses emphasized that the first ordination axis can be interpreted as a crenonrithron-potamon gradient, probably an oxygen availability and/or a water temperature gradient, whereas the second axis can be considered a water speed gradient, separating lotic from lentic sites.The 3rd and 4th ordination axes had apparently no ecological meaning.Separated clusters of species were never evident, so well defined chironomid species assemblages could not be outlined in this analysis.     

Response of epilithic diatom assemblages to water pollution in rivers in the Tokyo Metropolitan area, Japan

1. During the spring of 1992, fifty-two quantitative diatom samples were collected from twenty-eight rivers located in the Tokyo Metropolitan area, Japan, to study the response of the diatom assemblages to water pollution (assessed using physical and chemical data determined monthly from April 1987 to March 1992). 2. Species composition was analysed by means of biotic indices (Pantle and Buck's saprobic index) and multivariate analyses [two-way indicator species analysis (TWINSPAN) for classification and canonical correspondence analysis (CCA) for ordination]. Species-abundance relationships were analysed using diversity indices (species richness, Shannon's diversity index and Pielou's evenness index) and rank-abundance patterns (rank-abundance curves). 3. CCA revealed two major gradients. The first corresponded to organic pollution and eutrophication. The second corresponded to variables related to geographical location. Four main station groups were determined by TWINSPAN. The location of the indicator species of groups 1–3 along the CCA axis 1 is consistent with their known pollution tolerance characteristics. Indicator species for group 4 had larger scores on CCA axis 2, and are representative of brackish water environments. 4. Species richness tended to be higher in the intermediate range of water pollution. Pielou's evenness index and Shannon's diversity index followed the same tendency but only weakly. 5. The rank-abundance patterns of diatom assemblages were more or less constant in all stations. The curves were very similar in shape, differing only in length and gradient (directly related to species richness and evenness, respectively). 6. The results of this study indicate that the response of diatom assemblages to environmental change can be observed in species compositional variation. Multivariate analyses and pollution indices revealed this response and are to be preferred to species diversity measures.     

中条山中段植物群落数量分类与排序研究

在群落样方调查基础上,采用双向指示种分析法（TWINSPAN）和除趋势对应分析（DCA）对中条山中段植物群落进行了数量分类和排序。TWINSPAN将53个样方分为14组,根据植被分类的原则划分为14个群丛,论述了各群丛的群落学特征。53个样方的DCA排序结果反映了植物群落类型与环境梯度之间的关系,表明影响群丛分布格局的主导生态因子为海拔高度、水分和热量。DCA排序将65个种分为5个种组,各种组在排序轴上的位置反映了种组成员的生态适应性及其在群落中的重要性和更新生态位。     

Spatial Structure of the Insect Community of a Small Dimictic Lake in the Laurentians (Québec)

The distribution of merolimnic benthic insects was studied in Lake Cromwell, a small (9 ha) and shallow (max. depth 9 m) dimictic lake with a summer hypolimnetic warming on the Laurentian highlands of Québec. Communities were described from 22 sets of emergence data. Two hundred and twelve species were recognized of which 153 were Chironomidae (Diptera). Through clustering and ordination techniques, five communities were recognized: one in the flooded shrub zone along the shore, two littoral, one sublittoral and one profundal. Differences between the communities were more quantitative than qualitative. The majority of species inhabited the shore and littoral stations, and only the hardiest reached the deepest zone. There were few species characteristic of the profundal, none of them abundant. Discriminating, dominant, and characteristic species were determined for each community, as were the ubiquitous species. There is a general decrease in species richness, species diversity and population density, and a change in community structure along the depth gradient. A discontinuity at 1–2 m is related to a sharp increase in Chaoboridae in the deeper waters.     

草海国家级自然保护区水生植物群落的数量分类与排序分析

在群落样方调查的基础之上,采用双向指示种分析法（TW INSPAN）和除趋势对应分析（DCA）对草海国家级自然保护区水生植物群落进行分类和排序。TW INSPAN将50个样方分为17组,根据植被分类的原则划分为17个群丛,论述了各个群丛的群落学特征。50个样方的DCA排序结果反映了植物群落类型与环境梯度之间的关系,表明影响群落分布格局的主导生态因子为水分条件,第一轴反映了各个群落类型所在的水分条件梯度。排序结果与分类结果较吻合,反映出植物群落类型和物种分布随环境因子梯度变化的趋势。     

The role of chironomids (Diptera) in the profundal macrozoobenthos in Finnish reservoirs

The proundal macrozoobenthos of 12 Finnish inland polyhumic reservoirs was studied by quantitative sampling in 1984 and 1986. Additionally, the succession of the macrozoobenthos in one young reservoir (Lake Kyrkösjärvi) was studied during its first six years. The zoobenthos material was analyzed using the DCA (detrended correspondence analysis) method, and the ordination of sites (i.e. reservoirs), was related to associated environmental data. The role of chironomids was, in general, important in the profundal of the reservoirs. Because of the coarse bottom quality at many sampling sites, many littoral taxa were found in the profundal zone. The genusChironomus dominated (>50% of the total zoobenthic biomass) especially in the acidic, upper-reach reservoirs.Chironomus larvae also dominated in the zoobenthos of Lake Kyrkösjärvi during its first three years. Some of the reservoirs showed similarities with the dystrophic lake type of the lake typology system (Brundin, 1956). Because of the initially eutrophic character of the bottom, many reservoirs belonged to eutrophic lake types. Finnish reservoirs appear to contain a zoobenthic fauna intermediate between natural lakes and bog pools. This theme was discussed from the ecological and evolutionary point of view ofChironomus species.     

A comparative study of the impact of species composition on a freshwater phytoplankton community using two contrasting biotic indices

Biodiversity index based on species richness and evenness has been a frequently used measure to describe phytoplankton community composition and the impact of water pollution on biotic components, despite it could not reflect clearly the impact of a particular species on the structure and function of phytoplankton community. On the contrary, an index based on the niche theory has been developed and used to elucidate the changes of phytoplankton community with the alteration of species composition under various levels of water quality. Through comparison on the Shannon–Wiener biodiversity index (H′) and the community pollution value (CPV), this paper depicted the algal species composition change along the gradation of water quality and quantified the impact of species composition on the structure and function of a freshwater phytoplankton community in four urban lakes in central China. This study found that not only CPV could indicate water pollution status but also the fluctuation of CPV along water pollution gradient could show the influence of dominant species composition on community function. The comparison between Shannon–Wiener biodiversity index and CPV shows that the presence of dominant species sustains the stability and the succession of phytoplankton community under the changing water environments. The results of this study indicate that the combination of biodiversity index and CPV can provide a systematic way to understand biotic interactions and species responses to altered habitats at the community level. Most importantly, these indicators will provide valuable information for lake management and restoration practices.     

山西五台山蓝花棘豆群落的数量分类和排序

应用双向指示种分析法(TWINSPAN)和除趋势对应分析法(DCA)对山西五台山蓝花棘豆群落[Oxytropis coerulea (Pall.) DC.]进行了分类和排序.TWINSPAN分类结果将26个样方划分为8个群丛,即,蓝花棘豆 披针叶苔草 垂穗鹅观草群丛、蓝花棘豆 披针叶苔草群丛、蓝花棘豆 披针叶苔草 地榆群丛、蓝花棘豆群丛、蓝花棘豆 披针叶苔草 莓叶委陵菜群丛、蓝花棘豆 无芒雀麦群丛、蓝花棘豆 地榆群丛、蓝花棘豆 山蒿群丛,并分别对每个群丛生境进行了论述. DCA二维排序图较好地验证了TWINSPAN的分类结果,其纵、横坐标均反映了群丛所在环境的海拔等生态因子的梯度变化.种的DCA排序结果表明,群落中的建群种对海拔等生态因子有明显的指示作用,随海拔升高群落中的建群种由喜温耐旱植物演变为喜湿耐寒植物.     

长江三峡地区干流河岸植物群落的初步研究

以长江三峡干流河岸植物群落为研究对象,对群落的物种组成、物种多样性进行了分析,并利用ＴＷＩＮＳＰＡＮ方法对植物群落进行高等级式划分。结果表明：河岸植物区系组成较为复杂,以温带成分为主,有着较高比率的世界分布成分。植物生活性方面,草本种类的比率略高于木本种类,藤本种类较少。藻、草丛群落之间的物种多样性差异不显著。ＴＷＩＮＳＰＡＮ和ＤＣＡ分析显示,河岸植物群藻可分为６大类群,这些类群呈现沿湿度梯度方向     

滹沱河流域湿地植被的数量分类和排序

应用TWINSPAN和DCA相结合的方法,对滹沱河流域湿地植被74个样方进行分类和排序,将湿地植被分为16个群丛。DCA排序第一轴反映土壤含水量梯度,第二轴反映土壤类型的变化。主要优势种的DCA排序图与样方的DCA排序图有很大的相似性,优势种的分布格局在很大程度上决定着植物群丛的分布格局。     

Assessment methodology for southern siliceous basins in Portugal

A sampling programme was developed in three stream types, of siliceous geology, from the south of Portugal (small and mid-sized lowland streams and small-sized median altitude streams). The samples were taken according to the AQEM site protocol procedure, keeping transport and depositional habitats samples separated. In each stream type, at least 13 sites were studied over a gradient of organic pollution (pre-classification). The benthic macroinvertebrates were identified to the lowest possible taxonomic level. A Detrended Correspondence Analysis of macroinvertebrate communities identified a gradient of organic pollution strongly related to the first axis. This ordination allowed the establishment of classes of organic pollution using the Kmeans software (post-classification). Metrics based on the macroinvertebrate communities (tolerance, richness, composition and trophic structure) were computed and tested for correlation with the gradient of organic pollution (first axis of DCA). Most of the selected metrics were able to discriminate the four quality classes (high, good, moderate and poor) of ecological status. A multimetric index, integrating ASPT′ index, Trichoptera families and percentage of Gasteropoda, Oligochaeta and Diptera, is proposed to assess the ecological status of Portuguese southern siliceous basins.     

Spatial distribution pattern of the riparian vegetation in a basin in the NW Spain

The riparian vegetation of a basin in the NW Spain was studied to establish its spatial variation pattern and to relate floristic and structural differences in the community to environmental factors. Eighty-seven sampling units in 43 sampling stations were used. Samples were classified in 5 groups using Two Way Indicator Species Analysis (TWINSPAN). Three groups represented reaches with riparian wood along their banks: Mediterranean alderwoods and shrubby willow woods. The remaining two corresponded to floodplains with vegetation colonizing moderately eutrophicated deposits of gravel. Structural characteristics of richness and diversity differentiated the alder woods. In these, the shaded environment created by the woody species limited herbaceous vegetation development. This was dominated by Carex acuta subsp. broteriana. Classification and CCA ordination results were compared. The TWINSPAN groups could be recognized in the CCA graph. The ordination was related to a pollution gradient associated with altitude. This pollution gradient involved bank ruderalization, incorporation of nitrophilous species and a decrease in the vegetation quality. The influence of the lithological features on vegetation was also evident.     

云南大山包黑颈鹤自然保护区草甸植被的数量分类和排序

在法瑞学派样地调查法的基础上,采用双向指示种分析（TWINSPAN）和趋势对应分析（DCA）对大山包黑颈鹤自然保护区草甸植被进行数量分类和排序研究。调查样地包含114个物种,分属31科72属,其中禾本科（14种）、菊科（13种）、蓼科（8种）、石竹科（6种）、玄参科（6种）等科所含物种较多。经TWINSPAN分类,106个样地分为20个聚组,根据其指示种确定为20个群丛。样地DCA和物种DCA排序结果反映了植物群丛与指示种之间的一致关系,排序轴的生态学意义说明水分和海拔两个环境因子同时影响该区草甸植被的分布。     

Quantitative classification and ordination of forest communities in Pangquangou National Nature Reserve

Quantitative analysis of ecological relationships between vegetation and the environment has become an essential means in the field of research of modern vegetation ecology. In this article, based on data from 84 quadrates, forest communities in this reserve were investigated using TWINSPAN, DCA and DCCA. The results will be helpful in the construction and development of Pangquangou National Nature Reserve. Using TWINSPAN, the forest communities were classified into seven types. The distribution pattern of vegetation reflects the comprehensive influence of environments. The results of DCA and DCCA clearly reflect the relationship between the pattern of forest communities and environmental gradients. The ordination result of DCCA indicates that altitude is more important than other environmental factors because the change of altitude gradient will lead to changes in the temperature and humidity gradients. The first of the DCA ordination axes indicates the humidity gradient, and the second indicates the temperature gradient. All these results show that the main factors restricting the distribution of communities in this reserve are temperature and humidity. The ecological meaning of the ordination axis in DCCA is much clearer than that in DCA, and the species-environment correlation of DCCA is more obvious than DCA. The first DCCA axis indicates the altitude gradient among the communities, while the second is the gradient in aspect and slope among the communities. DCCA ordination can simultaneously express similarities of species and environment. Therefore, the quadrat location in the DCCA ordination figure is much closer than in the DCA.     

Quantitative classification and ordination of forest communities in Pangquangou National Nature Reserve

Quantitative analysis of ecological relationships between vegetation and the environment has become an essential means in the field of research of modern vegetation ecology. In this article, based on data from 84 quadrates, forest communities in this reserve were investigated using TWINSPAN, DCA and DCCA. The results will be helpful in the construction and development of Pangquangou National Nature Reserve. Using TWINSPAN, the forest communities were classified into seven types. The distribution pattern of vegetation reflects the comprehensive influence of environments. The results of DCA and DCCA clearly reflect the relationship between the pattern of forest communities and environmental gradients. The ordination result of DCCA indicates that altitude is more important than other environmental factors because the change of altitude gradient will lead to changes in the temperature and humidity gradients. The first of the DCA ordination axes indicates the humidity gradient, and the second indicates the temperature gradient. All these results show that the main factors restricting the distribution of communities in this reserve are temperature and humidity. The ecological meaning of the ordination axis in DCCA is much clearer than that in DCA, and the species-environment correlation of DCCA is more obvious than DCA. The first DCCA axis indicates the altitude gradient among the communities, while the second is the gradient in aspect and slope among the communities. DCCA ordination can simultaneously express similarities of species and environment. Therefore, the quadrat location in the DCCA ordination figure is much closer than in the DCA.     

Can we trust gradients extracted by Detrended Correspondence Analysis?

Abstract. In this study, data from dry temperate grassland vegetation in Denmark are used to compare the predictive power of gradients obtained by ordination. One of the problems of ordination methods based on weighted averaging, namely the assumption of symmetric, unimodal response curves, is investigated by smoothing species responses to simple and complex gradients respectively. It was found that species response types to a pH gradient are diverse and often deviate from a unimodal, symmetrical shape. Bimodal responses were also found, but they disappeared when more influential gradients were considered. Many species showed truncated responses with optima near gradient ends. In order to assess the impact of unrealistic response assumptions and reported problems with instability on the performance of DCA, the predictive potentials of measured variables and coenoclines extracted by DCA were compared. Despite field data violating the assumption of unimodal response, DCA was found to extract gradients predicting species abundance better than the environmental variables available. Shortcomings and advantages of indirect and direct methods in plant ecology are discussed.     

文峪河上游河岸林群落环境梯度格局和演替过程

以文峪河上游河岸林为研究对象,通过对群落建群种的DCA排序和物种关联分析进行生态种组划分,阐明了河岸林群落建群种各生态种组之间的生态演替功能差异,结合对样地和生态适应性功能组的DCA排序结果,分析了河岸林群落空间分布的环境梯度格局及其影响因素,基于以上分析,构建了研究地区河岸林群落演替过程,揭示了环境梯度格局对河岸林群落演替的控制作用。通过研究,文峪河上游河岸林群落生态适应性功能组比群落在排序空间上具有更好的分异性,采用生态适应性功能组更有利于分析群落的时空关系;研究地区河岸林群落9个建群种划分为阳性喜湿先锋型、阳性中生演替型、耐阴喜湿演替后期型和阳性中生逃避型4个生态种组;研究地区海拔梯度、河岸带坡度和河谷型共同决定了河岸林群落的分布格局,河岸带坡度和河谷型实际反映的是河岸带水文状况对河岸林群落时空格局的控制作用;根据生态适应性功能组和生态种组构建了研究地区河岸林群落演替模型,不同的海拔及其相应的河谷型具有明显不同的演替过程。