J.H.J. Schaminee

European Vegetation Survey: Current state of some national programmes

Vegetation survey programmes in Austria, Great Britain, the Netherlands and Germany are described. The aims of these programmes are discussed and their origin and motivation elucidated against the historical background of the development of phytosociology (as part of vegetation science) in particular countries. The Austrian, British and Dutch national vegetation surveys have been logistically supported by either basic-research (Austria) or nature-conservation (Great Britain and the Netherlands) funding organisations. They are either being published (British Plant Communities) or heading for publication of their first volumes within the next two years. The German vegetation survey is a voluntarily-based enterprise expected to complete its work by the end of this century. The experience gained by the management of these national surveys is of fundamental importance in launching the European Vegetation Survey (a project under preparation)

Assessing the relative importance of dispersal in plant communities using an ecoinformatics approach

Increased insight into the factors that determine the importance of dispersal limitation on species richness and species composition is of paramount importance for conservation and restoration ecology. One way to explore the importance of dispersal limitation is to use seed-sowing experiments, but these do not enable the screening of large sets of species and habitats. In the present paper we present a complementary approach based on comparing small plots with larger regions with regard to species composition and distribution of functional traits. We developed a GIS tool based on ecological and geographical criteria to quantify species pools at various spatial scales. In this GIS tool, containing floristic, large databases, phytosociological and functional information are exploited. Our premise is that differences in the nature of the species in local and regional species pools with regard to functional traits can give important clues to the processes at work in the assembly of communities.We illustrate the approach with a case study for mesotrophic hay meadows (Calthion palustris). We tested the effects of differences in frequency in the local Habitat Species Pool and differences in dispersal and persistence traits of species on local species composition. Our results show that both species pool effects and functional traits affect the probability of occurrence in small plots. Species with a high propagule weight have, given the frequency in the Local Habitat Species Pool, a lower probability of occurrence in small plots. The probability of local occurrence, however, is increased by the ability to form a persistent soil seed bank and by adult longevity. This provides support for the view that the degree of dispersal limitation is dependent on the degree of spatial isolation of the focal site relative to source populations and moreover that species inherently differ in the degree to which dispersal limitation is a limiting factor for local occurrence.

Large vegetation databases and information systems: New instruments for ecological research, nature conservation, and policy making

Abstract Almost a century ago, Josias Braun-Blanquet developed his phytosociological approach for vegetation field study. At that time, nobody could foresee what the impact of this methodology would be for vegetation science as well as for its application in nature conservation. Hundreds of thousands of so-called relevés (vegetation plot records) have been made, collected in field books, and many of them have been published afterward. Some 20 years ago, the software package Turboveg was developed for the input, storage, and handling of vegetation data. Since then, many national and regional vegetation databases have been compiled, providing the basis for national and international classification overviews and other scientific studies. It is estimated that currently there have been more than 4.2 million relevés made throughout Europe, including 1.8 million relevés already available in electronic dabatases and about 45% of these available in Turboveg format. The computerized vegetation data have been shown to offer new possibilities for ecological research (a new branch of study, called eco-informatics), of which a number of examples will be discussed. Furthermore, the electronic data form a fundament for the compilation of ecological information systems. As an example of these, the information system SynBioSys will be discussed as a new tool for nature conservation and policy making, including Natura 2000.

The analysis of long-term changes in plant communities: case studies from the Netherlands

The nature of the plant community has been a long-standing point of discussion in vegetation science. Already in the early decades of the last century, debate focused on whether plant communities existed as discrete, intra-dependent entities or merelyas loose assemblages of species each responding individualistically to local environmental conditions. Despite the fundamental nature of this question, the issue is generally ignored in many studies. For example, within the study of succession, a major topic in vegetation science, the question of stability within vegetation types is rarely addressed. Generally, succession research investigates vegetation development in terms of communities passing through a series of vegetation types, without considering the nature of these types; they are implicitly regarded to be constant. To some extent, this idea is a misconception, as can be concluded from studies within the framework of the national vegetation classification of the Netherlands. During this programme, a large data set has been built up, comprising more than 350 000 vegetation releves, made in the period 1929-2001. Comparison of sets of releves from different decades revealed that in most ecosystems the floristic composition of the vegetation types involved has changed, although the appearance of the vegetation and the presence and abundance of (most of) the diagnostic species have remained the same. In the present study, three examples were elucidated: an aquatic vegetation type dominated by Stratiotes aloides (Stratiotetum), a species-rich grassland type on river dunes (Medicagini falcatae-Avenetum pubescentis), and a forest community (Betulo-Quercetum roboris).

European Red List of Habitats : Part 2. Terrestrial and freshwater habitats

The first ever European Red List of Habitats reviews thencurrent status of all natural and semi-natural terrestrial,nfreshwater and marine habitats and highlights the pressuresnthey face. Using a modified version of the IUCN Red List ofnEcosystems categories and criteria, it covers the EU28, plusnIceland, Norway, Switzerland and the Balkan countries and theirnneighbouring seas. Over 230 terrestrial and freshwater habitatsnwere assessed. The European Red List of Habitats provides annentirely new and all embracing tool to review commitments fornenvironmental protection and restoration within the EU2020nBiodiversity Strategy. In addition to the assessment of threat,na unique set of information underlies the Red List for everynhabitat: from a full description to distribution maps, images,nlinks to other classification systems, details of occurrencenand trends in each country and lists of threats withninformation on restoration potential. All of this is publiclynavailable in PDF and database format (see links below), so thenRed List can be used for a wide range of analysis. The Red Listncomplements the data collected on Annex I habitat types throughnArticle 17 reporting as it covers a much wider set of habitatsnthan those legally protected under the Habitats Directive.

Formalized classification of European fen vegetation at the alliance level

Phytosociological classification of fen vegetation (Scheuchzerio palustris-Caricetea fuscae class) differs among European countries. Here we propose a unified vegetation classification of European fens at the alliance level, provide unequivocal assignment rules for individual vegetation plots, identify diagnostic species of fen alliances, and map their distribution. 29 049 vegetation-plot records of fenswere selected fromdatabases using a list of specialist fen species. Formal definitions of alliances were created using the presence, absence and abundance of Cocktail-based species groups and indicator species. DCA visualized the similarities among the alliances in an ordination space. The ISOPAM classification algorithm was applied to regional subsets with homogeneous plot size to check whether the classification based on formal definitions matches the results of unsupervised classifications. The following alliances were defined: Caricion viridulo-trinervis (sub-halophytic Atlantic dune-slack fens), Caricion davallianae (temperate calcareous fens), Caricion atrofusco-saxatilis (arcto-alpine calcareous fens), Stygio-Caricion limosae (boreal topogenic brown-moss fens), Sphagno warnstorfii-Tomentypnion nitentis (Sphagnumbrown-moss rich fens), Saxifrago-Tomentypnion (continental to boreo-continental nitrogen-limited brown-moss rich fens), Narthecion scardici (alpine fens with Balkan endemics), Caricion stantis (arctic brown-moss rich fens), Anagallido tenellae-Juncion bulbosi (Ibero-Atlantic moderately rich fens), Drepanocladion exannulati (arcto-borealalpine non-calcareous fens), Caricion fuscae (temperate moderately rich fens), Sphagno-Caricion canescentis (poor fens) and Scheuchzerion palustris (dystrophic hollows). The main variation in the species composition of European fens reflected site chemistry (pH, mineral richness) and sorted the plots from calcareous and extremely rich fens, through rich andmoderately rich fens, to poor fens and dystrophic hollows.

Classification of European beech forests: a Gordian knot?

Questions: What are the main floristic patterns in European beech forests? Which classification at the alliance and suballiance level is the most convincing? - Location: Europe and Asia Minor. - Methods: We applied a TWINSPAN classification to a data set of 24605 releves covering the whole range of Fagus sylvatica forests and the western part of Fagus orientalis forests. We identified 24 operational phytosociological units (OPUs), which were used for further analysis. The position of each OPU along the soil pH and temperature gradient was evaluated using Ellenberg Indicator Values. Fidelity of species to OPUs was calculated using the phi coefficient and constancy ratio. We compared alternative alliance concepts, corresponding to groups of OPUs, in terms of number and frequency of diagnostic species. We also established formal definitions for the various alliance concepts based on comparison of the total cover of the diagnostic species groups, and evaluated alternative geographical subdivisions of beech forests. - Results: The first and second division levels of TWINSPAN followed the temperature and soil pH gradients, while lower divisions were mainly geographical. We grouped the 22 OPUs of Fagus sylvatica forests into acidophytic, meso-basiphytic and thermo-basiphytic beech forests, and separated two OPUs of F.orientalis forests. However, a solution with only two ecologically defined alliances of F.sylvatica forests (acidophytic vs basiphytic) was clearly superior with regard to number and frequency of diagnostic species. In contrast, when comparing groupings with three to six geographical alliances of basiphytic beech forests, respectively, we did not find a strongly superior solution. - Conclusions: We propose to classify F.sylvatica forests into 15 suballiances - three acidophytic and 12 basiphytic ones. Separating these two groups at alliance or order level was clearly supported by our results. Concerning the grouping of the 12 basiphytic suballiances into ecological or geographical alliances, as advocated by many authors, we failed to find an optimal solution. Therefore, we propose a multi-dimensional classification of basiphytic beech forests, including both ecological and geographical groups as equally valid concepts which may be used alternatively depending on the purpose and context of the classification.

Large-scale ordination and gradient analysis of salt-marsh communities in the Netherlands in the light of the Dutch National Vegetation Classification

In the development of the Dutch National Vegetation Classification, little emphasis was placed on ordination or gradient analysis. The current study provides a national-scale ordination analysis of salt-marsh communities in the Netherlands and presents it in the context of the National Classification. A series of 4 DCA ordinations derived from synoptic tables of 21 salt-marsh communities, each varying in their emphasis on dominant species, showed that the importance of dominance vs. overall assemblages of species in classifying communities varies with the communities in question: for species-poor communities such as the Spartinetea, T hero-Salicornietea, and portions of the Asteretea tripollii (Puccinellion maritimae and Puccinellio-Spergularion salinae), dominant species were critical in distinguishing communities while for more diverse communities (the Armerion maritimae and the Saginetea maritima of the Astereteae tripolii), total floristic composition was important and over-emphasis on dominant species obscured differences between several communities. Ordination scores were strongly correlated with mean Ellenberg indicator values for salinity and pH, but only weakly with moisture values. In this respect, Ellenberg values do not appear to reflect the critical conditions of duration and timing of flooding in Dutch salt-marsh vegetation. Ordinations based on both synoptic tables and on individual releves were carried out to study the validity of previously-reported classifications of several related associations. The analysis resolved the question of whether the Suaedetum maritimae is best placed in the Thero-Salicornietea or in the Cakiletea maritimae; it was clearly associated with the Thero-Salicornietea. As for the question of whether certain related associations better belong within the Lolio-Potentillion or within the saltmarsh alliance Armerion maritimae, both options are possible from the point of view of this study. The approach used here of ordinating synoptic tables to locate possible overlap between syntaxa and then using ordinations of individual releves within these to examine the problem areas further provides a useful method for verifying and revising classifications at the national level.

Climate and land use change impacts on Mediterranean high-mountain vegetation in the Apennines since the 1950s

Background: High-mountain ecosystems are centres of plant diversity that are particularly sensitive to land-use and climate change. Aims: We investigated the ecological trends associated with land use and climate change since the 1950s in different vegetation types in high-mountain habitats in the central Apennines. Methods: We analysed temporal changes in: Pinus mugo scrub, calcareous subalpine grasslands and alpine scree vegetation, comparing historical and recent vegetation records from vegetation plots from two periods (1955–1980 and 1990–2014) for their ecological indicator values (Landolt temperature and nutrient indicators) and structural traits (growth forms) over time using generalised linear models (GLMs). Results: We observed significant temporal differences in the ecology and structure of the analysed habitats. In the Pinus mugo scrub we detected a reduction of subalpine and herbaceous species and in calcareous alpine screes we observed an increment of the lower montane, montane and subalpine species and of dwarf shrubs. Conversely, subalpine grasslands were stable over time. Conclusions: Ecological changes that have occurred in the Central Apennines, following changes in type and intensity of land use and recent warming are consistent with those observed in other European mountains, for which climate and land-use changes are claimed as the main driving forces.

A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies.