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.     

Mitteleuropäische Waldschlagrasen

Plant communities of forest clearings dominated by grass and grass-like species are analyzed. Their system is based on the coenological species groups. Each association is characterised from the view point of synecology, synchrology and syntaxonomy.     

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.     

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.     

The scope of culture in chimpanzees, humans and ancestral apes

More studies have focused on aspects of chimpanzee behaviour and cognition relevant to the evolution of culture than on any other species except our own. Accordingly, analysis of the features shared by chimpanzees and humans is here used to infer the scope of cultural phenomena in our last common ancestor, at the same time clarifying the nature of the special characteristics that advanced further in the hominin line. To do this, culture is broken down into three major aspects: the large scale, population-level patterning of traditions; social learning mechanisms; and the behavioural and cognitive contents of culture. Each of these is further dissected into subcomponents. Shared features, as well as differences, are identified in as many as a dozen of these, offering a case study for the comparative analysis of culture across animal taxa and a deeper understanding of the roots of our own cultural capacities.     

AN INQUIRY INTO THE PRINCIPLES OF NEEDS‐BASED ALLOCATION OF HEALTH CARE

The concept of need is often proposed as providing an additional or alternative criterion to cost‐effectiveness in making allocation decisions in health care. If it is to be of practical value it must be sufficiently precisely characterized to be useful to decision makers. This will require both an account of how degree of need for an intervention is to be determined and a prioritization rule that clarifies how degree of need and the cost of the intervention interact in determining the relative priority of the intervention. Three common features of health care interventions must be accommodated in a comprehensive theory of need: the probabilistic nature of prognosis (with and without the intervention); the time course of effects; and the fact that the most effective treatments often combine more than one intervention. These common features are problematic for the concept of need. We outline various approaches to prioritization on the basis of need and argue that some approaches are more promising than others.     

Theoretical vegetation science on the way

Some historical notes are presented on the start and early development of the Working-Group for Data-Processing, now Working-Group for Theoretical Vegetation Science, of the International Association for Vegetation Science. One of the major outcomes of the first period of activities in the Working-Group has been the creation of a phytosociological coding and retrieval system to be used in combination with multivariate methods. One branch of classical phytosociology which could have profited much from the Working-Group's achievements, i.e. syntaxonomy, never developed fully into a numerical syntaxonomy and, in fact, it did not develop much at all over the last 20 yr.The next phase in the development of the Working Group is characterized by a strong emphasis on vegetation dynamics. First, these dynamical studies concentrated on real sequences of data from permanent plots, which were treated with the numerical methods available. Later, dynamical models started to be developed in order to predict succession and other forms of long-term vegetation dynamics, for which real data are not available.The third phase, which has been entered only recently, is characterized by an overall emphasis on vegetation theory, from which both the most appropriate choice of numerical methods in any particular case, and dynamical phenomena can be approached. Moreover, vegetation theory is of fundamental importance for the development of the plant community concept and of vegetation typology.In addition, some remarks are made on the growing need for vegetation ecology to cooperate with experimental ecophysiology and population ecology.     

甘肃小陇山华山松群落灌木层优势种种间关联性分析

通过野外大量调查,选取小陇山华山松林55个样方中的20个常见物种,运用多物种复合关联VR,χ2检验,Pearson相关系数和Spearman秩相关系数和关联测度等测算和综合分析群落的种间联接关系,结果表明:(1)多物种关联性(VR)的分析表明华山松林主要组成成员间的关系以正关联为主,说明华山松群落主要种群对生存环境的需求是一致的;(2)20个常见种种对中以华山松-锐齿栎、华山松-栓皮栎、华山松-辽东栎等种对之间呈正关联;锐齿栎-栓皮栎、锐齿栎-盐肤木等呈现负关联;黑刺菝葜、多毛樱桃等为独立关系等,是群落内环境的体现,是群落内环境异质性的表征;(3)依据华山松林种间关系的不同性质把组成群落的20个常见种归纳为3个生态种组,即正关联组、负关联组和独立组;(4)种间关联的研究结果对华山松群落的生境监测、营林管理、林区道路景观再造中的树种选择和配置有一定的实际指导意义。     

Alnus glutinosa – dominated wetland forests of the Baltic Region: community structure,syntaxonomy and conservation

Community structure, syntaxonomy and conservation aspects of Alnus glutinosa-dominated forests in the Baltic States, Central Europe, southern Fennoscandinavia and north-western part of the Commonwealth of Independent States are surveyed. Communities of the black alder wetlands, subjected to cluster analysis (TWINSPAN, GROUPAGE) and correspondence analysis (CANOCO) and synsystematically treated following the Braun-Blanquet approach, belong to Alnion (Carici elongatae-Alnetum Schwick. 33 with two subassociations, Sphagno squarrosi-Alnetum Sol.-Gorn. ex Pried. 96) and Alno-Ulmion (mainly Circaeo-Alnetum Oberd. 53) forests in the Baltic Region. The indicator values sensu Ellenberg, site ecology, floristic assemblages and the phytogeographical features point at a high affinity of these forests in a wide geographical area. Eleven syntaxonomical approaches by classifying central and north-eastern European alderwoods have been analysed. These differ in Alnion classification and distinguish from 2 to more than 10 syntaxa at the level of association. The actual distribution of less disturbed black alder wetlands and areas under these forests in Europe suggests that the SE part of the Baltic Region could be the key area for Alnus glutinosa-dominated wetlands. Thus, it deserves an establishment of an international network of standard protected areas so as to maintain the diverse community samples and elaborate the principles of sustainable management. Abbreviations: In figures CLT PALU means Caltha palustris, CAL PALU – Calla palustris. Abbreviations of all other species follow first 3 and 4 letters of the genus and species name, respectively. Nomenclature: Tabaka et al. (1988) for vascular plants, Abolina et al. (1984) for mosses.     

The feeding behaviour of some common lotic insect species in two streams of differing detrital content

The trophic relationships of the benthic invertebrates at two places of differing detrital content in an oligotrophic stream system were examined during a 12 month period.
The sites are described and their detrital contents and other abiotic features compared.
The faunal list at each site is fairly similar but certain species are more common at or restricted to one or other site. The reasons for this are briefly discussed.
The predators and omnivores are in two groups: the first feed only on certain prey and are thus limited by the distribution of their prey. The others consume a wide range of prey and have wider distributions.
The predator species are non-selective in their choice of prey which are devoured in an intensity which cannot however be related to their density in the benthos.
In poorer trophic conditions predators adapt by consuming a greater quantity of algae and detritus; cannibalism and interpredator-predation occur. The prey species are more intensely consumed under poor trophic conditions.
The ecology of two species of predatory Plecoptera is examined and the results indicate that competition probably occurs between them.     

Is there a general theory of community ecology?

Community ecology entered the 1970s with the belief that niche theory would supply a general theory of community structure. The lack of wide-spread empirical support for niche theory led to a focus on models specific to classes of communities such as lakes, intertidal communities, and forests. Today, the needs of conservation biology for metrics of “ecological health” that can be applied across types of communities prompts a renewed interest in the possibility of general theory for community ecology. Disputes about the existence of general patterns in community structure trace at least to the 1920s and continue today almost unchanged in concept, although now expressed through mathematical modeling. Yet, a new framework emerged in the 1980s from findings that community composition and structure depend as much on the processes that bring species to the boundaries of a community as by processes internal to a community, such as species interactions and co-evolution. This perspective, termed “supply-side ecology”, argued that community ecology was to be viewed as an “organic earth science” more than as a biological science. The absence of a general theory of the earth would then imply a corresponding absence of any general theory for the communities on the earth, and imply that the logical structure of theoretical community ecology would consist of an atlas of models special to place and geologic time. Nonetheless, a general theory of community ecology is possible similar in form to the general theory for evolution if the processes that bring species to the boundary of a community are analogized to mutation, and the processes that act on the species that arrive at a community are analogized to selection. All communities then share some version of this common narrative, permitting general theorems to be developed pertaining to all ecological communities. Still, the desirability of a general theory of community ecology is debatable because the existence of a general theory suppresses diversity of thought even as it allows generalizations to be derived. The pros and cons of a general theory need further discussion.     

Reworked carboniferous spores: An example from the lower jurassic of northeast Scotland

An association of contemporaneous Jurassic mega- and miospores with reworked Carboniferous mega- and miospores is described from the Lower Lias rocks of northeast Scotland. The assemblage is compared with other accounts of reworked spores in Jurassic sediments. It is suggested that such reworking was particularly common in the Lower Jurassic of northern Europe and that four situations exist in the literature concerning probable cases of reworking: (1) the spores are recognised as reworked; (2) the identity of the spores as Carboniferous species is recognised and the “range” of these species is extended into the Jurassic; (3) the reworked spores are not recognised as such, and are incorrectly assigned to Jurassic genera and species; (4) the spores are recognised as Carboniferous, but their origin is attributed to contamination rather than reworking. In conclusion, the contrasting preservational features exhibited by the reworking and contemporaneous megaspores are discussed and interpreted as the result of differing depositional and postdepositional histories.     

The associationBlechno serrulati-Acoeloraphetum wrightii in the remates de Guane,W. Cuba,and its ecology

A new association:Blechno serrulati-Acoeloraphetum Wrightii, endemic in W. Cuba, is described and the syntaxonomy and synecology discussed.     

Mayr's view of Darwin: was Darwin wrong about speciation?

We commonly read or hear that Charles Darwin successfully convinced the world about evolution and natural selection, but did not answer the question posed by his most famous book, ‘On the Origin of Species …’. Since the 1940s, Ernst Mayr has been one of the people who argued for this point of view, claiming that Darwin was not able to answer the question of speciation because he failed to define species properly. Mayr undoubtedly had an important and largely positive influence on the study of evolution by stimulating much evolutionary work, and also by promoting a ‘polytypic species concept’ in which multiple, geographically separated forms may be considered as subspecies within a larger species entity. However, Mayr became seduced by the symmetry of a pair of interlocking ideas: (1) that coexistence of divergent populations was not possible without reproductive isolation and (2) reproductive isolation could not evolve in populations that coexist. These beliefs led Mayr in 1942 to reject evidence of the importance of intermediate stages in speciation, particularly introgression between hybridizing species, which demonstrates that complete reproductive isolation is not necessary, and the existence of ecological races, which shows that ecological divergence can be maintained below the level of species, in the face of gene flow. Mayr's train of thought led him to the view that Darwin misunderstood species, and that species were fundamentally different from subspecific varieties in nature. Julian Huxley, reviewing similar data at the same time, came to the opposite conclusion, and argued that these were the intermediate stages of speciation expected under Darwinism. Mayr's arguments were, however, more convincing than Huxley's, and this caused a delay in the acceptance of a more balanced view of speciation for many decades. It is only now, with new molecular evidence, that we are beginning to appreciate more fully the expected Darwinian intermediates between coexisting species. © The Author. Journal compilation © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 3–16.     

Relationships between syntaxonomy ofThero-Salicornietea and taxonomy of the generaSalicornia andSuaeda in the Iberian Peninsula

This paper deals with the syntaxonomy of the classThero-Salicornietea in the Iberian Peninsula, falling particularly upon the significance that taxonomy of the generaSalicornia andSuaeda has on it. Three alliances were differentiated, two Atlantic and one Mediterranean. The Atlantic ones wereSalicornion dolichostachyo-fragilis, with four associations grouping slikke communities with tetraploid glasswort (Salicornia) species, andSalicornion europaeo-ramosissimae, with three associations of schorre with generally diploid glasswort species. The Mediterranean allianceSalicornion patulae had six associations distributed both in coastal (southern and eastern coasts) and inland salt marshes. A complete syntaxonomy of the class, maps of the distribution of its associations and tables summarizing their floristic composition are also provided.     

The concept of stcucture in phytosociology with references to classification of plant communities

Summary The concept of structure in phytosociology has been analysed. Three families of structure characteristics have been distinguished: (1) qualitative constituent, (2) quantitative constituent and (3) relational characteristics. Selected structural features are illustrated in some detail and completed by references. The key role of spatial structure has been emphasized and a simple method for the introduction of the parameters of spatial structure in data processing has been proposed. Some remarks to the present syntaxonomy have been added from the spatial structure point of view.Contribution from the Working Group for Data-Processing, International Society for Vegetation Science.Thanks are due to Drs. J. Jenik and J. Kvt for advice and to the Editors for linguistic help.     

Statistical evidence for ancestral correlation patterns

Statistical correlations in DNA sequences are an important source of information for processes of genome evolution. As a special case of such correlations and building up on our previous work, here we study, how short-range correlations in Eukaryotic genomes change under elimination of various classes of repetitive DNA. Our main result is that a residual correlation pattern, common to most mammalian species, emerges under elimination of all repetitive DNA, suggesting features of an ancestral correlation signature. Furthermore, using this general framework, we find classes of repeats, which upon deletion move the correlation pattern towards this residual pattern (simple repeats and SINEs) or away from this residual pattern (LINEs). These findings suggest that the common correlation pattern visible in the mammalian species after repeat elimination can be associated with a common mammalian ancestor.     

Fifty years of co‐evolution and beyond: integrating co‐evolution from molecules to species

Fifty years after Ehrlich and Raven's seminal paper, the idea of co‐evolution continues to grow as a key concept in our understanding of organic evolution. This concept has not only provided a compelling synthesis between evolutionary biology and community ecology, but has also inspired research that extends beyond its original scope. In this article, we identify unresolved questions about the co‐evolutionary process and advocate for the integration of co‐evolutionary research from molecular to interspecific interactions. We address two basic questions: (i) What is co‐evolution and how common is it? (ii) What is the unit of co‐evolution? Both questions aim to explore the heart of the co‐evolutionary process. Despite the claim that co‐evolution is ubiquitous, we argue that there is in fact little evidence to support the view that reciprocal natural selection and coadaptation are common in nature. We also challenge the traditional view that co‐evolution only occurs between traits of interacting species. Co‐evolution has the potential to explain evolutionary processes and patterns that result from intra‐ and intermolecular biochemical interactions within cells, intergenomic interactions (e.g. nuclear‐cytoplasmic) within species, as well as intergenomic interactions mediated by phenotypic traits between species. Research that bridges across these levels of organization will help to advance our understanding of the importance of the co‐evolutionary processes in shaping the diversity of life on Earth.     

Host-dependent association and its implications on the relative abundance of blue alfalfa aphid and pea aphid (Homoptera: Aphididae) on alfalfa in Oklahoma

Field populations of blue alfalfa aphid and pea aphid on alfalfa were sampled during 1985 and 1986 to determine the association of co-occurrence, interspecific interactions and comparative temporal variations in the spatial dispersion patterns of these species in Oklahoma. Relative abundance of these species is discussed in the light of above analyses.Cole' s coefficient revealed a high degree of association between these species in terms of their occurrence on the same alfalfa stems in the field. Regression analyses indicated that the species populations tended to increase in concert on the same stems without evidence of competitive displacement. Spatial dispersion patterns of both species were highly aggregated at low population densities early in the season. Over time, both species tended to disperse and became less aggregated as numbers increased. It was concluded that magnitude of interspecific interactions between the blue alfalfa aphid and the pea aphid were not of a nature that they could be termed as competing species. On the contrary, a concept of an “ecospecies” is proposed for practical applications such as sampling plans and economic threshold determinations.