Testate Amoeba (Arcellinida,Euglyphida) Ecology along a Poor‐Rich Gradient in Fens of Western Poland

We investigated the relationships between testate amoebae (Arcellinida, Euglyphida), vegetation and water chemistry along environmental gradients in minerotrophic peatlands (fens) in western Poland. We hypothesized that: a) hydrochemistry significantly influences structure of testate amoeba communities, and b) testate amoeba communities are more closely correlated with the hydrochemical variables (environment) than with the vegetation data. Testate amoeba communities and vegetation from 71 sample plots were investigated together with the hydro‐chemistry and hydrology based on 16 environmental variables and vegetation composition. Testate amoeba communities revealed a distinctive poor‐rich gradient in analysed fens. Mineral‐rich habitats, which were dominated by brown mosses, were preferred by a higher number of taxa than acidic habitats, which were dominated by Sphagnum. We recorded a total of 107 testate amoebae taxa. The average species richness of testate amoebae for brown mosses was higher (20) than for Sphagnum (13). We found that testate amoebae communities were similarly correlated with vascular plants, mosses and environmental parameters. Results of direct ordination demonstrate that hydrology, pH, Mg²⁺ and sodium remain the most important environmental control for the entire data set. CCA showed that in case of brown mosses hydrology, sodium and oxygen affect testate amoeba communities significantly whereas in Sphagnum only sodium emerge as most significant determining testate amoeba assemblages. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Differences in habitat quality explain nestedness in a land snail meta-community

We set up two alternative hypotheses on how environmental variables could foster nestedness; one of “nested habitats” and another of “nested habitat quality”. The former hypothesis refers to situations where the nestedness of species depends on a nestedness of discrete habitats. The latter considers situations where all species in an assemblage increase in abundance along the same environmental gradient, but differ in specialisation or tolerance. We tested whether litter‐dwelling land snails (terrestrial gastropods) in boreal riparian forest exhibited a nested community structure, whether such a pattern was related to differences in environmental variables among sites, and which of the two hypotheses that best could account for the found pattern. We sampled litter from 100 m² plots in 29 mature riparian forest sites along small streams in the boreal zone of Sweden. The number of snail species varied between 3 and 14 per site. Ranking the species‐by‐site matrix by PCA scores of the first ordination axis revealed a similarly significant nested pattern as when the matrix was sorted by number of species, showing that the species composition in this meta‐community can be properly described as nested. Several environmental variables, most notably pH index, were correlated with the first PCA axis. All but two species had positive eigenvectors in the PCA ordination and the abundance increased considerably along the gradient for most of the species implying that the hypothesis of “nested habitats” was rejected in favour of the “nested habitat quality” hypothesis. Analyses of nestedness have seldom been performed on equal sized plots, and our study shows the importance of understanding that variation in environmental variables among sites can result in nested communities. The conservation implications are different depending on which of our two hypotheses is supported; a conservation focus on species “hotspots” is more appropriate if the communities are nested because of “nested habitat quality”.     

珠海鹤洲水道沿岸红树林湿地大型底栖动物群落特征

对珠海鹤洲水道沿岸的4个红树人工林(包括老鼠簕Acanthus ilicifolius、木榄Bruguiera gymnorrhiza、秋茄Kandelia candel和无瓣海桑Sonneratia apetala)样地和2个挺水植被(短叶茳芏Cyperus malaccensis和芦苇Phragmites australis)样地的大型底栖动物群落进行为期一年(2010年12月、2011年3、6、9月共4次野外采样)的生物调查。研究与分析了大型底栖动物的种类、生活型及功能群、栖息密度、平均生物量、多样性指数等群落特征,并结合等级聚类和非参数多变量标序(MDS)方法对大型底栖动物的群落结构进行深入探讨。本调查共采集大型底栖动物35种,包括环节动物(7种)、软体动物(10种)、甲壳动物(10种)、鱼类(1种)和其他无脊椎动物(7种)。优势种包括谭氏泥蟹(Ilyrplax deschampsi)(占总个体数的34%)、麦克碟尾虫(Discapseudes mackiei)(占总个体数的25%)、羽须鳃沙蚕(Dendronereis prinnaticirris)(占总个体数的12%)。在6种生境类型中,老鼠簕站位大型底栖动物物种数量最多,为19种,均匀度和多样性指数均较高;短叶茳芏样地大型底栖动物栖息密度最高,为254.7 ind/m2,但是多样性指数(H"=1.25)最低;无瓣海桑站位平均生物量最高,为32.0613 g/m2。研究结果表明：(1)不同生境下大型底栖动物群落结构存在显著差异,尤其是无瓣海桑站位,无论群落结构、优势种还是生活型等都与其它站位有明显不同;(2)围垦区人工湿地与自然滩涂大型底栖动物群落结构差异显著;(3)潮汐作用对大型底栖动物群落结构影响显著。     

Multivariate approach to the classification and ordination of the forest ecosystem of Nandiar valley western Himalayas

QuestionsDoes the vegetation composition of the forests of Nandiar Valley correlate with climatic, topographic and edaphic variables? Is it possible to identify plant communities through indicator species in relation to environmental gradients? Can this approach of classification and ordination will be helpful for conservation planning?LocationForests of Nandiar Valley, Moist temperate Western Himalayas Pakistan.MethodsEighty stands were selected for quantitative and qualitative characteristic of vegetation between an elevations of 525–3817 m. Species composition was recorded by using 400 m long transects. GPS, climatic, edaphic and topographic data were recorded for each sampling site. The relationship between habitat types, species composition and distribution along with climatic, edaphic and topographic variables were analyzed using TWINSPAN, Cluster analysis and DCA ordination.ResultsSum 325 vascular plants species belonging to 97 families were recorded. Diversity index and species richness was maximum in the moist temperate zone. Classification and ordination showed that the variance in species data was 7.07. Two-ways indicator species analysis classified the vegetation into eight plant communities. Indicator species analysis revealed that slope aspect, wind speed, temperature, dew point, wet bulb, pH, organic matter and phosphorous were the strongest parameters (p ≤ 0.05) determining plant community composition and indicator species in each habitat. The results also show the strength of the environment – species relationship using Monte Carlo procedures. DCA ordination grouped different species having similar habitat and habitats having common species.ConclusionsThe multivariate analysis of the vegetation along with environmental variables of Nandiar valley confirmed the indicators of each sort of vegetation communities/microclimatic zones which could further be used in conservation planning and management not only in studied area but also in the adjacent regions as well as in the areas exhibit similar sort of climatic, edaphic and topographic conditions.     

上海地区早春非耕地杂草分布与环境因子关系的统计生态学研究

野外调查发现上海地区早春非耕地杂草共106种,隶属于29科88属．计测了261个样地1305个样方中杂草的生态重要值和6种主要环境因子,应用典范对应分析作出了反映106种杂草与6种环境因子关系的二维排序图,应用双向指示种分析对106种杂草进行了有生态学意义的定量分类．根据6种环境因子与前两个排序轴相关系数的大小,发现土壤水分、土壤翻耕程度、人迹出没程度、交通影响程度是影响上海地区早春非耕地杂草分布的主要环境因素;根据双向指示种分析,结合典范对应分析的结果,可以从106种早春中分出五个生态类群,即类群Ⅰ：湿生淤泥海边滩涂杂草类群,类群Ⅱ：相对干燥海边滩涂杂草类群,类群Ⅲ：干扰相对较小的人工林地杂草类群;类群Ⅳ：干旱、开阔、干扰较重环境中的杂草类群;类群Ⅴ：湿润、开阔、干扰较重的弃耕农田环境中的杂草类群．     

Relationships between environmental variables and vegetation across mountain wetland sites,N. Iran

The mountain wetlands studied represent a unique habitat on the southern slopes of the Alborz mountain range, the second largest range in Iran. In comparison with other parts of this range the western section is ecologically and botanically unknown. Floristic and vegetation variation were assessed using diverse environmental variables along a broad altitudinal span (350 m to 3200 m a.s.l.). Using both statistical and ordination analyses floristic variation was assessed on three defined altitudinal belts which were delimited based on Alborz macro-climatic boundaries. The distribution of individual wetland plant species, of phytogeographic elements and of life-forms all differ among altitudinal belts. This result is also shown in both direct and indirect analyses of ordinations. The proportion of geophytes significantly increases with altitude and geophytes are very well represented in the upper altitudinal belt. The number of species of a narrow phytogeographical distribution (e.g. endemics) increases with altitude, soil pH and EC declined with altitude. The first axis of DCA ordination with passively projected environmental variables indicates that, organic matter and concentration of Fe²⁺ are increased toward higher altitude. The second axis of ordination is related to both soil texture and slope inclination. The distribution of species in the CCA species plot is also close to the distribution of those in the DCA ordination. This study indicates that altitude and slope together with other dependent environmental variables (pH, EC, Ca²⁺ and soil texture) are the main ecological factors controlling species distribution across the Western Alborz wetland sites.     

Ecological characteristics of the freshwater Ostracoda in Bolu Region (Turkey)

Total of 40 ostracod taxa obtained from 141 different sampling locations in Bolu were examined to determine relationships between habitat preferences of species and their ecological characteristics from June to August 2006. According to the first axis of Canonical Correspondence Analysis (CCA), 52% of the relationships between species and five most influential environmental variables with 36.2% of variances were explained. Although the first four variables, air temperature, water temperature, pH, and electrical conductivity had significant influence (P?P?=?0.47) was relatively low. Spearman correlation analyses indicated that some species had weak to strong positive correlation with electrical conductivity, whereas some others had a significant negative correlation with pH and redox potential. Only two species (Herpetocypris chevreuxi and Ilyocypris inermis) had strong correlation to the habitat type (P?Heterocypris incongruens, I. bradyi, Candona neglecta, and C. candida) had high Environmental Tolerance Index (ETI) values for at least six different environmental variables. Thus, cosmopolitans are highly adaptable within a wide range of environmental conditions and geographical distribution.     

Relationships between macroinvertebrate communities and environmental variables in metal-contaminated streams in south-west England

1. Macroinvertebrate species and information on thirty-nine variables were recorded at forty-six sites on twelve Cornish streams affected to varying extents by past metalliferous mining. 2. Relationships between macroinvertebrate communities and environmental variables were examined using canonical correspondence analysis (CCA). Copper was the strongest correlate with Axis 1 of the analysis, suggesting that it may have a major role in determining community structure. There were also strong correlations between Axis 1 and aluminium, alkalinity, pH, dissolved organic matter and algal cover, and between Axis 2 and discharge. 3. CCA distinguished four site groupings. In spite of seasonal changes in position on the ordination, as revealed through CCA and detrended correspondence analysis (DCA), sites retained their group membership. There were differences in the proportions of the major taxa within the four CCA-derived groups. In the group with the highest copper concentration, Ephemeroptera were absent, but triclads and chironomids were abundant, with Orthocladiinae the dominant group. 4. Changes in the occurrence of species along the metal gradient reflected changes in sensitivity. Tolerance' plots of selected species based on the CCA site ordination diagram were used to identify environmental thresholds. 5. As well as direct toxic effects of copper and aluminium on invertebrate communities, co-precipitation of these two metals could be an important physical factor. Further modifying influences resulting from interactions between toxic metals and pH, alkalinity, hardness and dissolved organic matter contributed to the complexity of conditions affecting the faunal community in metal-contaminated streams. 6. The most severely contaminated sites, with mean copper concentration exceeding 500 μgl^?1, were all characterized by a reduced community dominated by the flatworm Phagocata vitta, the chironomids Chaetodadius melaleucus and Eukiefferiella claripennis and the net-spinning caddis Plectrocnemia conspersa. The necessity for species identification is demonstrated in relation to variation in metal tolerance.     

Distribution, ecological tolerance and optimum levels of freshwater Ostracoda (Crustacea) from Diyarbak?r, Turkey

A total of 23 ostracod taxa were found in 48 of 90 different water bodies (wetlands, springs, lakes, creeks, etc.) located at moderate to high elevation (530–1,095 m) in Diyarbakır province. The ecological tolerances and optimum values for environmental variables of 15 species were analyzed. Accordingly, maximum numbers of species were found between 700 and 800 m. Ostracod species and sampling sites along with seven environmental variables were ordinated with canonical correspondence analysis (CCA). The first axis of CCA explained 72% of the relationship between species and environmental variables. Of these, water temperature, redox potential and altitude were the most influential (P < 0.05) factors for species. Based on habitat similarities, an unweighted pair group mean average dendrogram divided species into four clustering groups. Among the species, Potamocypris arcuata, Candona neglecta and Psychrodromus fontinalis had the highest optimum estimates for altitude, whereas P. arcuata, Herpetocypris brevicaudata and P. fontinalis exhibited the highest tolerances to altitude. While most species revealed unique tolerances and optimum values for different ecological variables, species with cosmopolitan characteristics had wider ranges of ecological tolerances and distribution amid the variety of habitats along elevational gradients.     

Weed vegetation ecology of arable land in Salalah,Southern Oman

This paper applies multivariate statistical methods to a data set of weed relevés from arable fields in two different habitat types of coastal and mountainous escarpments in Southern Oman. The objectives were to test the effect of environmental gradients, crop plants and time on weed species composition, to rank the importance of these particular factors, and to describe the patterns of species composition and diversity associated with these factors. Through the application of TWINSPAN, DCA and CCA programs on data relating to 102 species recorded in 28 plots and farms distributed in the study area, six plant communities were identified: I- Dichanthium micranthum, II- Cynodon dactylon–D. micranthum, III- Convolvulus arvensis, IV- C. dactylon–Sonchus oleraceus, V- Amaranthus viridis and VI- Suaeda aegyptiaca–Achyranthes aspera. The ordination process (CCA) provided a sequence of plant communities and species diversity that correlated with some anthropogenic factors, physiographic variables and crop types. Therefore, length of time since farm construction, disturbance levels and altitude are the most important factors related to the occurrence of the species. The perennial species correlated with the more degraded mountain areas of new farm stands, whereas most of the annuals correlated with old lowland and less disturbed farms.     

秦岭山地天然次生林群落MRT数量分类、CCA排序及多样性垂直格局

采用多元回归树(MRT)对秦岭山地天然次生林群落进行数量分类,采用典范对应分析(CCA)进行排序,分析了秦岭山地天然次生林群落物种多样性沿海拔梯度的变化规律。结果表明:(1) 275个样方共有种子植物195种,隶属61科128属。乔、灌、草3个层次物种多样性变化沿海拔梯度的变化趋势基本一致,呈单峰模型;(2)经交叉验证认为秦岭山地天然次生林群落可分为2类,Ⅰ冬瓜杨(Populus purdomii)+陇东海棠(Malus kansuensis)+蛇莓(Duchesnea indica)群落,Ⅱ锐齿槲栎(Quercus aliena var. acuteserrata)+黄栌(Cotinus coggygria)+茜草(Rubia cordifolia)群落;(3) CCA排序结果揭示了群落生境的分布范围,反映出生态轴的排序意义,较好地反映秦岭山地天然次生林群落与环境因子的关系,其结果表明,海拔、坡向、凋落层厚度和干扰情况4个变量对该地区次生林群落的分布有较大的影响。     

协惯量分析与典范对应分析在植物群落排序中的应用比较

采用协惯量分析(PCA-CA COIA)和典范对应分析(CCA)两种排序方法, 对北京小龙门林场的黄檗 (Phellodendron amurense)群落进行了分析, 并用Spearman秩相关系数检验了对应排序轴的相关性。两种排序方法得出的结果基本一致, 两者的第一排序轴都反映了海拔高度和坡向对群落分布的影响, 而各自第二、第三排序轴所代表的环境意义有所差异, 并出现了交叉, 但是两者的前3个排序轴均反映了海拔、坡位、土壤厚度和凋落物层厚度的变化趋势, 说明在环境因子个数较少或共线性效应不明显的情况下, 协惯量分析也能达到CCA的分析效果, 并且在排序轴特征值解释量上高于典范对应分析。     

Longitudinal structure of fish assemblages in a minimally disrupted stream

The longitudinal distribution patterns of fish species are affected by both natural and anthropogenic variables. The role of these factors on the formation of species assemblages is well documented in North America and Western Europe, but detailed information is lacking from Central and Eastern Europe, and the Carpathian region especially. Therefore, we examined the structure of fish assemblages in response to six key environmental parameters in a natural stream system (Udava stream basin, Slovakia). We used the indirect ordination method of gradient analysis (Detrended Correspondence Analysis, DCA) to analyse the species groups and their connections to the sampled sites and to recognize the strongest gradient of assemblage composition. Subsequently, we used the direct ordination method (Canonical Correspondence Analysis, CCA) to identify the strongest gradients in relation to selected variables. Two major gradients were identified that follow the upstream-downstream pattern of fish communities and three variables (distance from source, depth and site slope) are correlated with the first CCA axis (P < 0.05) and two variables (depth and vegetation cover) are correlated with the second CCA axis (P < 0.05). We assume that these factors influence the temperature and the amount of dissolved oxygen that can cause oxygen and temperature stress to intolerant species (e.g., salmonids). Based on these results, we assume that the economically important species, brown trout and grayling, are not native to the stream basin and this status is only the consequence of natural factors. Furthermore, the results suggest that the Udava stream offers favourable conditions for fish species distribution — a view supported by the high variability of particular variables within the proposed model.     

Structure of chironomid assemblages along environmental and geographical gradients in the Bohemian Forest lakes (Central Europe): An exploratory analysis

Eight glacial lakes of the Bohemian Forest (Czech Republic and Germany) were characterised by the distribution of chironomids collected as pupal exuviae. Twenty-eight taxa were identified, including some faunistically interesting species of the region. Two-way indicator species analysis (TWINSPAN) was used to classify lakes according to their taxonomic composition. Canonical correspondence analysis (CCA) and multiple regression were used to relate the chironomid assemblages to two sets of explanatory variables: (i) local environmental variables, and (ii) broad-scale spatial variables. The TWINSPAN classified the lakes into four groups, whereas presence/absence of three taxa was indicative for this classification. The CCA of assemblage composition on environmental variables showed that chironomids respond significantly to altitude and alkalinity. The ordination of composition data on geographical variables revealed strong longitudinal gradient in chironomid distributions. Altitude and alkalinity accounted for 36.2% of the total variation, while the geographic gradient explained 20.5%. As revealed by the variation partitioning procedure, the significant effect of these variables was, in large part, independent of each other. Overall taxonomic richness appeared to be governed by altitude only. Causal ecological and historical factors underlying these results are discussed. This paper may provide a basis for hypothesis testing in future research of the Bohemian Forest lakes.     

Vegetation ecology of phytogenic hillocks (nabkhas) in coastal habitats of Jal Az-Zor National Park,Kuwait: Role of patches and edaphic factors

Phytogenic sandy hillocks (Arab. ‘nabkha’) are very frequently occurring aeolian deposits along the coastal plain of Kuwait. We investigated the vegetation of 42 nabkhas in a coastal habitat of Jal Az-Zor National Park, Kuwait. Sixty-two species were recorded (47 annuals and 15 perennials) in the studied nabkhas. Four vegetation types were recognized after classifying the vegetation of the nabkhas by TWINSPAN. They were named after their dominating host species which are Nitraria retusa, Zygophyllum qatarense, Haloxylon salicornicum and Panicum turgidum. Using Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA), we assessed the relationships between environmental gradients, floristic composition, species diversity, and geomorphology aspects of the studied habitats. Notable environmental variables affecting the distribution of the vegetation types in the study area were: geomorphological aspect, size of plants forming the core of the nabkha, moisture and nutrients contents, salinity, sand and silt components, and pH.     

藏北高原草地群落的数量分类与排序

采用TWINSPAN数量分类和DCA、CCA排序的方法,对藏北高原草地29个样点进行统计分析。结果显示:(1)TWINSPAN数量分类将藏北高寒草地群落划分成10种类型。(2)样点DCA排序第一轴基本反映了水分环境梯度,第二轴基本反映了热量梯度。(3)TWINSPAN分类所划分的各群落在DCA排序图上都有各自的分布范围和界限,说明DCA排序能较好的反应各优势群落与其环境资源之间的关系。(4)样点CCA排序表明,影响群落分布的首要环境因子是水分因子(年均降水量)和空间因子(经度),其次是热量因子(年均温度),CCA排序进一步阐明了群落分布决定于水分和温度等环境因子,并间接验证了TWINSPAN的分类结果。(5)物种CCA排序和TWINSPAN分类结果表明:植物群落中物种的分布格局与植物群落类型的分布格局存在一定的相似性。     

三峡库区澎溪河消落带植物群落分布格局及生境影响

三峡消落带是一条特殊的水—陆交错带,其生境的特殊性及对整个三峡库区的影响逐渐成为地学、环境科学、生态学等学科的研究热点。植被是消落带各项生态功能的载体。然而,三峡水库的运行使消落带原有植被遭到破坏。通过对澎溪河消落带植物群落及其生境的实地调查,采用双向指示种法(TWINSPAN)划分植物群落类型,并结合方差分解和CCA排序法研究4类生境影响因素组14个生境影响因子与植物群落空间分布的关系,探讨生境对消落带植物群落组成、结构及多样性的影响。结果表明:(1)消落带植物群落包括5种类型:狗牙根+雀稗群落、狗尾草+狗牙根群落、黄荆群落、白茅+鬼针草群落、苔草群落;(2)CCA排序中,第1排序轴对消落带植被空间变化的累计解释量为6.83%,占生境条件总解释量的44.73%,能很好地解释消落带植物群落与生境的相互关系,植物群落类型沿排序轴呈梯度分布;(3)土壤是影响消落带植被空间分布格局的主要影响因素组,各影响因素组间交互作用明显。淹水时间、海拔、土壤含水量是植物群落空间分布的主要影响因子,解释量分别为5.3%、3.0%、2.9%;(4)4类影响因素组共解释消落带植物群落空间格局变化的14.6%,未解释部分所占比例较大,可能是由于消落带内生境条件复杂,影响其群落组成及空间分布的潜在因素较多,如各种土地利用政策、人类活动干扰及景观组成等因素也可能对消落带植物群落构成有影响。研究消落带植物空间分布及其与生境的关系,以期为科学认识消落带、保护水库环境提供依据。     

Relationships between environment and mountain riparian plant communities associated with two rare tertiary-relict tree species, Euptelea pleiospermum (Eupteleaceae) and Cercidiphyllum japonicum (Cercidiphyllaceae)

Euptelea pleiospermum and Cercidiphyllum japonicum are dominant relictual tree species of the riparian plant communities in the subtropical region of Shennongjia Mountains, central China. Community survey and multivariate analysis were carried out to characterize their ecological ranges and regeneration characteristics, and further to explore the factors determining their present distribution boundaries and the barriers restricting their range expansion. We recorded 303 woody species, among which there were 14 relictual, rare and/or endemic woody species. Results obtained from cluster analysis corroborated the results from non-metric multidimensional scaling (NMS) ordination, classifying the 42 plots into three well-defined associations. Correlation analysis revealed that variation in species composition among associations was partly explained by some physical (altitude, slope, soil temperature) and chemical (available K, NH₄, pH) properties. Multiple regression analyses with data of adults and seedlings with physical and chemical variables revealed contrasting patterns of the two dominant relictual species. Both taxa have a high resprouting rate that keeps the stands stable irrespective of scarcity of seedlings. However, expansion of the distribution range is difficult in such a situation. E. pleiospermum prefers riparian habitats with poor nutrients in the south-facing slope of the Shennongjia Mountains, which may indicate that this species is light-demanding at some life stages and well adapted to a nutrient-poor habitat where competition from other species is limited. The Cercidiphyllum japonicum population was more scattered and fragmented, and preferred riparian habitats on gentle slopes. Both species are favored by the mild and moist microclimate, but the current conditions in these subtropical mountain riparian habitats probably do not really provide optimal ecological conditions for the two relictual species.     

On the relationship between ecology and phytoplankton composition in a karstic spring (Çepni,Bolu)

The phytoplankton assemblages and their relationship to physico-chemical environmental variables were studied in Akkaya spring, a limnocrene type of karstic spring pool, for 14 months from May 2003 to July 2004. A total of 63 taxa, belonging to Bacillariophyta (62%), Chlorophyta (29%), Cyanophyta (3%), Pyrrophyta (3%), Euglenophyta (2%), and Chrysophyta (2%), were found. According to CCA analysis, three environmental variables (conductivity, calcium, and sulphate) had the greatest influence on species composition. Based on their seasonal occurrence, most of the species found closer to the center of CCA diagram had cosmopolitan characteristics, while members of the genus Spirogyra were found together in the fall season. Similar seasonal patterns were also recorded in three other crustacean taxa including Cladocera (Daphnia sp.), Copepoda (Cyclops sp.), and Ostracoda (Fabaeformiscandona fabaeformis). Overall, the first two axes of CCA explained 97% of the relationship between species composition and environmental variables. This result was also supported by UPGMA analysis, where three main groups were clustered based on their binary data and ecological preferences. Although physico-chemical characteristics of the pool changed in the following months, after building of a concrete wall around the pool in October 2003, the long-term effect of such changes are not known at the moment.     

神农架川金丝猴栖息地森林群落的数量分类与排序

在神农架川金丝猴生境典型地段设立样方58块,根据样方资料对神农架川金丝猴栖息地的森林群落用组平均法分类和DCA排序.用组平均法将58块样地分为9个群系,依据《中国植被》的分类原则和系统将研究区植物群落划归为7个植被型.样地的DCA排序较好地揭示了该区森林群落的分布格局与环境梯度的关系;DCA第二轴明显地反映出森林群落的海拔梯度变化,沿DCA第二轴从右到左,海拔逐渐升高;第一轴表现了各植物群落或植物种所在环境的坡度、坡向,即水分和光照因素,沿第一轴从下到上,坡度渐缓、坡向渐向阳.其中海拔梯度是环境因子中对森林群落起决定性作用的因子.研究表明,巴山冷杉+糙皮桦-大齿槭+尾萼蔷薇-高原露珠草+星果草群系发育较好,高大树木占有较大的比例,是神农架川金丝猴最适宜栖息地.7个植被型物种丰富度指数在群落梯度上呈规律性波动.其中针叶林和针叶-阔叶混交林中,物种丰富度指数在群落梯度上的总体趋势表现为灌木层＞草木层＞乔木层;在常绿阔叶林和常绿-落叶阔叶混交林中,该趋势为灌木层＞乔木层＞草本层;在落叶阔叶林中,其丰富度指数的趋势为灌木层＞草本层和乔木层.不同植被类型川金丝猴食源植物种类在群落梯度上的变化趋势与物种丰富度指数相同,但地衣类植物作为川金丝猴冬季的重要食物只在针叶林和针叶-阔叶混交林中生长.本研究为制定栖息地保护计划,更好地保护神农架川金丝猴提供了科学理论依据.