Numerical revision of the Fagion illyricum alliance

Cluster analysis and multidimensional scaling are used to revise the syntaxonomy of the Fagion illyricum alliance based on presence/absence data. The operational syntaxonomical units are associations and subassociations as suggested in the literature. The results of principal coordinates analysis and nonmetric multidimensional scaling are fairly congruent, whereas some differences occur between the dendrograms obtained by complete linkage and incremental sum of squares clustering. However, a joint evaluation of ordinations and the consensus classification derived from the cluster analysis results facilitates a meaningful revision of the formerly accepted division of the alliance. New low-level syntaxa, and some new names, including Aremonio-Fagion to replace the invalid alliance name of Fagion illyricum, are proposed and the removal of four associations from the alliance is suggested.     

Pre-climax epiphyte communities of bryophytes and lichens in Mediterranean forests from the Central Plateau (Spain)

The pre-climax epiphytic communities of forests from the Spanish Mediterranean region (Central Plateau) were studied by numerical and traditional floristic methods. One hundred phytosociological relevés were analyzed through a classical numerical approach based on hard partitions improved by PCoA — Principal Coordinates Analysis — ordinations. Two groups easily related to two different suballiances included in Frullanion dilatatae Lecointe 1975, Ulotenion crispae (Barkman 1958) Lecointe 1975 and Fabronienion pusillae Barkman 1958 were detected. Two new syntaxa within the ass. Ortotrichetum lyellii (Allorge 1922) Lecointe 1975 are proposed. Phytogeography, syntaxonomy and ecology of these communities are discussed.     

Gradients in dry grassland and heath vegetation on rock outcrops in eastern Germany — An analysis of a large phytosociological data set

The following study presents a statistical analysis of 595 relevés gathered during a survey of isolated grasslands and dwarf shrub heaths in the region of Halle, eastern Germany. Relevés were classified with UPGMA clustering based on a Bray-Curtis distance matrix; the resulting classification was compared with a previously published phytosociological classification. Most of the 14 target communities were supported by both approaches, but in the case of communities on heavily disturbed sites cluster analysis corresponded to units on higher phytosociological levels (alliances). DCA ordinations clearly revealed that nutrient and moisture availability controlled the community differentiation. Both factors were, however, highly correlated with the distance to the outcrop edge. Thus the outcrop size also influenced differentiation of communities, making larger outcrops richer in xerophytic and endangered species. This appears to be largely due to edge effects since the relationships diminished sharply when we controlled for progressively increasing distances from the edge in partial ordinations. Thus, microtopography of outcrops was the most important factor for community differentiation. It is therefore suggested that future research and conservation management should concentrate on the consequences of nutrient influx and changing land use on larger outcrops.     

The impact of water-level regulation on littoral macroinvertebrate assemblages in boreal lakes

Regulation of lake water level for power production and flood control is among the major anthropogenic disturbances in boreal aquatic ecosystems. In Finland, over 300 lakes, representing one third of the total inland water area of the country, are artificially regulated. To study the effects of regulation on lake littoral macroinvertebrate communities, samples were taken from upper stony littoral and from lower soft bottom littoral habitats of 11 lakes with different regulation amplitudes (wintertime fall in water level 1.19–6.75 m). Twelve unregulated (wintertime fall in water level 0.11–0.55 m) lakes with otherwise similar characteristics were used as a reference. Non-metric Multidimensional Scaling ordinations showed that the composition of macroinvertebrate assemblages was strongly associated with the amplitude of water level regulation. Taxon richness also decreased with increasing intensity of regulation. Freezing and flushing of sediments in late winter are probably the most important factors leading to the impoverished littoral macroinvertebrate fauna. Invertebrates with long life cycle seem to be particularly vulnerable to unnatural water level fluctuation. Our results show that regulation of water level has a major impact on functionally significant lake littoral macroinvertebrates.     

A numerical classification of European Spartina communities

Summary The classical syntaxonomical treatment of the European Spartina communities as published in the series Prodrome of the the European plant communities, is compared with the results of a numerical treatment, based on largely the same set of relevés. 576 relevés, selected from the total salt marsh data set were subjected to agglomerative clustering with relocation with the similarity ratio as similarity measure. The resulting numerical system was compared with the syntaxonomical hierarchy. The correlation between both systems is close. The numerical units are slightly more heterogeneous because no purification occurred, which implies relevés to be left out of consideration. One new syntaxon, Spartinetum townsendii asteretosum tripolii, could be suggested from the results of the numerical treatment. Perspectives for the development of a numerical syntaxonomy are stressed.Communication number 40.     

Die Siedlungsvegetation des Böhmischen Karsts. 1. Syntaxonomie

The paper deals with the vegetation of village settlements at the territory of the Bohemian Karst. In the first part of this study, syntaxonomy of ruderal communities is presented. Deductive method of syntaxonomical classification was applied. An attempt for numerical evaluation of a species diagnostic value in phytosociology is presented. Discussion remarks on the current state of ruderal phytosociology are included.     

Phytosociological research on the montane coniferous forests of Greece: Mount Killini (NE peloponnisos—S Greece)

The montane coniferous forests and their degraded syntaxa included either in theQuercetalia ilicis or in theQuercetalia pubescenti-petraeae of the Meso- up to the Mountain-Mediterranean vegetation belts of Mount Killini, have been studied using the Braun-Blanquet method with 69 phytosociological relevés. The application of classification and ordination methods resulted in the recognition of seven forest and two scrub plant communities. These communities could be arranged along an altitudinal gradient. Their syntaxonomy and structure are described and the present horizontal and vertical arrangement of the coniferous syntaxa is mapped. From these syntaxa, 3 new associations and 1 new subassociation are described. The main factors influencing the differences in floristic composition, are altitude and human impact resulting in degradation of the coniferous forest associations. In addition, differences in soil parameters like pH, the presence of organic matter and nutrients appear to be important. Information on the site characteristics, structure and syndynamical position of the communities is given.     

Influences of the individualistic concept of vegetation on syntaxonomy

The individualistic concept of vegetation is based on three principles: (1) vegetation continuum, (2) ecological and chorological individuality of species and (3) multidimensional variability of vegetation. All principles reflect phenomena existing in nature. The conclusions arising from these principles are these: (1) plant communities (phytocoenoses) are not natural objects (wholes) as such but merely mixtures of plant individuals coexisting on the same site as the result of migration and environmental selection, (2) the classification of vegetation is quite arbitrary if not pseudoscientific, and (3) vegetation phenomena can be reduced to phenomena of plant individuals.The integrated concept of vegetation considers the phytocoenoses as real functional systems (wholes) where plant populations are integrated both by the environment and by interactions among and within plant populations. The principles of the individualistic concept, but not the above conclusions arising from them, are compatible with the integrated concept. Phytocoenoses limit the individualistic performance of species through restriction of ecological amplitudes and shifting of ecological optima (as compared with physiological amplitudes and optima). The individualistic behaviour of species does not exclude the formation of coenological groups of species which form a basis for the classification of vegetation according to floristic-coenological criteria. Under natural conditions, plant communities are usually interconnected by transition zones to form a vegetation continuum. Phenomena of the vegetation continuum do not cause greater difficulties in syntaxonomy than those of polymorphic taxonomic groups in plant taxonomy.     

Studies of a vegetation transect through brigalow (Acacia harpophylla) forest in central Queensland

Vegetation and environmental data were collected in 182 contiguous plots along a belt transect, 3.7 km long, in central Queensland through a relatively undisturbed forest dominated by brigalow (Acacia harpophylla). A subset of eighty-nine plots using percentage cover of 128 species was classified using a polythetic agglomerative approach. Dual stand and species ordinations by principal component analysis and reciprocal averaging were also undertaken. The cluster analysis and ordination of unstandardized cover data, grouped stands on the basis of abundance of the predominant canopy species, but only where these species were true dominants such as Macropteranthes leichhardtii did these same groupings appear in the ordination of standardized data. The latter ordination was ecologically more satisfying, but the complementary species ordination was unsatisfactory. The vegetation-species complex was best explained by dual species and stand ordinations using presence-absence data. Reciprocal averaging appeared to produce a marginally better ordination than principal component analysis. An ordination of eleven environmental factors indicated soil profile and presence of gilgai were the most important environmental variables. The ordination was enhanced by varimax rotation which focused on a more homogeneous environmental gradient and coincided more closely with the vegetation ordinations. An ordination using both species and environmental factors substantiated the explanation of the vegetation-environmental complex derived from separate ordinations. The main gradient revealed from the ordinations appeared to be a mesic-xeric gradient stretching from Macropteranthes leichhardtii semi-evergreen vine thicket at the mesic end diverging through various A. harpophylla - dominant communities to A. harpophylla - Eucalyptus melanophloia woodland on duplex soils and Dichanthium affine grassland on clay soils. Six plant communities are defined and described and each related to a particular set of environmental conditions. These communities are bonewood (Macropteranthes leichhardtii) - semi-evergreen vine thicket, brigalow (Acacia harpophylla) - semi-evergreen vine thicket, brigalow (A. harpophylla) continuum (clay soils), Dichanthium affine grassland, brigalow (A. harpophylla) continuum (duplex soils) and brigalow (A. harpophylla) - silver-leaved ironbark (Eucalyptus melanophloia) woodland.     

桂林岩溶石山青冈群落数量分类与排序

植物群落的数量分类和排序可以客观地揭示植物群落与环境之间的关系,从而能为植被恢复与重建、森林经营与管理和生物多样性保护等提供理论依据。基于群落学调查和环境因子测定数据,采用Ward聚类、双向指示种分析(TWINSPAN)和多元回归树(MRT)对桂林岩溶石山青冈群落进行数量分类,选用冗余分析(RDA)进行排序,分析其与环境因子之间的关系。结果表明:(1)3种分类方法所得结果基本一致,可将桂林岩溶石山青冈群落划分为3个群丛类型,分别为青冈-粗糠柴+龙须藤+红背山麻杆-三穗薹草群丛(Ass.Cyclobalanopsis glauca-Mallotus philippensis+Bauhinia championi+Alchornea trewioides-Carex tristachya)、青冈-龙须藤+红背山麻杆+干花豆-宽叶沿阶草+三穗薹草群丛(Ass.Cyclobalanopsis glauca-Bauhinia championi+Alchornea trewioides+Fordia cauliflora-Ophiopogon platyphyllus+Carex tristachya)、青冈-粗糠柴+干花豆-三穗薹草群丛(Ass.Cyclobalanopsis glauca-Mallotus philippensis+Fordia cauliflora-Carex tristachya);(2)冗余分析结果较好地反映出各群丛类型的分布格局及其与环境梯度的相互关系,在10个环境因子中,岩石裸露率、土壤含水量、pH值、全氮、全磷、全钾、速效钾这7个环境因子对群落的分布影响显著。土壤含水量和全钾含量可能是影响该植物群落物种组成与分布的重要生态因子。     

高营养级捕食者在浅水湖泊沿岸带与敞水区能量耦合的维持作用

研究利用保安湖沿岸带与敞水区两种生境中高营养级捕食者(达氏鲌与红鳍原鲌)的碳(δ13C)、氮(δ15N)稳定同位素数据,通过稳定同位素质量平衡混合模型、非度量多维尺度分析(NMDS)等方法,分析了两种生境中鲌类食物来源的差异.结果表明,两种生境中鲌类食物来源基本一致,且食物来源较为广泛,包括沿岸带饵料鱼类、敞水区饵料鱼...     

A mangrove community in the New Hebrides, south-west Pacific

A general survey of the mangal at Port Stanley, Malekula, New Hebrides, the most extensive mangal in the archipelago, was conducted over an 11-day period in September/October 1971. Seventeen species of true mangrove tree and mangrove associates were recorded. As is characteristic of mangal, this flora was distributed in a zonal pattern, four zones being recognized. Certain anomalies in zonation were attributed to a recent episode of crustal uplift. The aquatic component of the fauna was dominated by molluscs (26 species) and Crustacea (20 species). The terrestrial vertebrate fauna consisted of 4 species of reptiles, 21 birds and 5 mammals.
The mangrove community at Port Stanley is an integral part of that of the Indo-West Pacific region. However it is much restricted in number of species, and reasons for this are suggested: distance from Malesia, lack of fresh water, and shallow soils with little silt deposition. Faunal impoverishment is clearly associated with floral impoverishment.     

Modelling Environmental Responses of Plant Associations: A Review of Some Critical Concepts in Vegetation Study

The definition of vegetation types at different hierarchical levels, both to study the vegetation processes and for practical cartographic representation, is still considered a critical issue in many circles of plant ecologists. The problems are mainly related to the misleading idea that classification of the vegetation system, as developed by European phytosociologists during the last century within the discipline called syntaxonomy, would imply the assumption of the organismic concept of the plant community. After a short discussion on the role of Braun-Blanquet approach in plant ecology and in landscape ecology, the methods to detect multispecies responses along environmental gradients are briefly reviewed. In the main part of this article, we intend to stress that concepts considered critical, such as plant association and its ecological niche, are just operational tools that have nothing to do with the individualistic or organismic interpretation of plant communities in vegetation studies. Important to our views on vegetation, we believe that plant associations as well as the higher syntaxa can be regarded as fuzzy sets in an operational context for describing vegetation along ecological gradients in synthetic ways and can further the understanding of vegetation variation.     

Numerical classification and ordination of ruderal plant communities (Sisymbrietalia,Onopordetalia) in the western part of Slovakia

The ruderal communities of the orders Sisymbrietalia and Onopordetalia from the western part of Slovakia have been subjected to numerical classification and ordination. The ordination techniques proved to be a useful tool in the elucidation of the cluster pattern as well as in the detection of the main environmental variation underlying the floristic variation within the data. Results obtained with numerical techniques and traditional syntaxonomical classification have been compared. The similarity between these results is low at the level of the orders. This incompatability is explained by the differences in the weighting of the species in the course of the classification process and by the addition of non-floristical criteria that often occurs in syntaxonomical classification according to Braun-Blanquet. The highest value has been observed at the 3-clusters level (both orders and the Malvion neglectae). High similarity among the results of the numerical techniques have been observed, particularly in the group of space-dilating clusterings (Ward's method, Complete linkage clustering and MeQuitty's similarity analysis). Average linkage clustering produces the most diverse result. The Malvion neglectae appeared as a separate group in all numerical techniques adopted. This suggests the upranking of its syntaxonomical position. The Bromo-Hordeion murini turned out to be a very heterotoneous syntaxon.     

Epigeic lichen communities of taiga and tundra regions

The major physiognomic and ecological categories of the lichen-rich, epigeic communities in the boreal (taiga) and arctic (tundra) zones are defined and their syntaxonomy and ecology in Europe, Asia and North America is reviewed. In the boreal and hemiarctic areas open, dry, acidophytic lichen woodlands are widespread, especially on sandy habitats. Their epigeic lichen synusiae are usually dominated by four fruticoseCladina species, being extremely homogeneous in species composition and structure throughout the boreal zone, while the dominant trees and the other vascular plant flora of the woodlands are geographically more variable. No phytosociological classification system exists that would cover most of these communities over the circumpolar regions. Very similar communities, though much more poorly known, are found on thin soils over Precambrian rock outcrops. Other sites to produce epigeic lichen communities include open sand dunes, treeless heathlands, drier bogs and many seral stages, like those on road banks. Boreal lichen-rich communities on eutrophic soils may be developed in semiarid regions, in particular. In the Arctic, lichens are common in most communities, and the driest ones are regularly lichen-dominated, whether acidophytic or eutrophytic, chionophytic or achionophytic. Detailed syntaxonomic systems for their classification have been developed, especially in Greenland and Scandinavian mountains (in oroarctic zones in the latter regions). The richest fruticose lichen areas are in continental, hemiarctic timberline regions in northern Siberia and Canada. The southern and middle arctic subzones are also characterized by many macrolichens, such asCetraria cucullata, C. nivalis, Alectoria ochroleuca, andThamnolia vermicularis, but everywhere also small, crustose lichens are common on soil, such asRinodina turfacea andLopadium pezizoideum, which are often overlooked in vegetation analyses. The presence of microlichens and the formation of mosaic micropatterns of soil lichen communities is particularly typical of the northern arctic subzone. The conservation problems of the boreal and arctic lichen communities include overgrazing by reindeer or caribou, which has caused delichenization in some regions, extensive forest and tundra fires, use of heavy transport vehicles in forestry and tundra operations, and, locally, heavy industrial air pollution.     

Syntaxonomical study of Italian wall vegetation

A syntaxonomical study of Italian wall vegetation based on classification and ordination of a large phytosociological data set from various authors (using the IAHOPA program) has confirmed the alliances Centrantho-Parietarion and Galio-Parietarion (order Parietarietalia judaicae, class Parietarietea judaicae), as already proposed by traditional syntaxonomy. The variation in humidity and the north-south geographical gradient are shown to be the most significant factors for the differentiation of this vegetation in Italy. The presence of some associations belonging to the class Asplenietea trichomanis (alliance Cystopteridion, Potentillion caulescentis and Centaureo-Campanulion) shows a strong connection with natural rock vegetation.     

A critique for phytosociology

Abstract. Phytosociology is a subdiscipline of plant ecology that describes the co‐occurrence of plant species in communities. Gradient analysis and classification are its complementary tools. Various peculiarities and anachronisms of Central European phytosociology conceal its similarity with Anglo‐American approaches. Phytosociology deserves to be updated as a part of modern vegetation science that can build on a vast heritage of high‐quality data and the tools to store and analyse them in ways that go beyond syntaxonomy. By providing a context to more specialized pure and applied research, it has a crucial role to play in understanding community structure, ecosystem functioning and biological evolution.     

Succession in the southern part of the Canadian boreal forest

Forest succession following fire in a forest mosaic of northwestern Quebec has been studied in order to: (1) describe the successional pathways using communities of different ages and (2) evaluate convergence of successional pathways and possible effect of fire suppression on the establishment of steady-state communities. As a first step, ordination and classification techniques were used in order to remove changes in forest composition which are related to abiotic conditions. Then, ordinations based on tree diameter distributions were used to study shifts in species composition in relation to time since the last fire.Even under similar abiotic conditions, successional pathways are numerous. However, regardless of forest composition after fire, most stands show convergence toward dominance of Thuja occidentalis and Picea mariana on xeric sites and dominance of Abies balsamea and Thuja occidentalis on more mesic sites. Stable communities of >300 yr occur on xeric sites while on mesic sites directional succession still occurs after 224 yr. Nearly all species involved in succession are present in the first 50 yr following fire. Only Abies balsamea and Thuja occidentalis increase significantly in frequency during succession. Following initial establishment, successional processes can generally be explained by species longevity and shade tolerance. Early successional species may be abundant in the canopy for more than 200 yr while the rapid decrease of Picea glauca, a late successional species could be related to spruce budworm outbreaks. Considering the short fire rotation observed (about 150 yr), a steady-state forest is unlikely to occur under natural conditions, though it may be possible if fire is controlled.