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Questions Zelený & Schaffers (Journal of Vegetation Science 23, 2012, 419) blame mean Ellenberg indicator values for producing ‘highly biased results’ that are ‘too good to be true,’ statements causing considerable confusion among plant ecologists. I ask if (1) the detrimental phenomena they observed can be reproduced in yet another real-world data set using the recently revised indicator values of Landolt et al. (Flora indicativa. Ecological indicator values and biological attributes of the flora of Switzerland and the Alps, 2010, Haupt, Bern, CH), (2) the issue of supposed bias also applies to species-based functional traits, and (3) the assumed ‘bias’ also concerns principal components analysis. Methods In a first step, I probe the effect of randomizing indicator values by verification of classifications through ANOVA and CCA using published data. Then, I repeat the same procedure replacing the matrix of indicator values with a species by traits matrix. In a third step I apply testing with ANOVA to an ordination of principal components. Finally, patterns of alternative vegetation descriptors (species, mean indicator values, traits frequency, site factors) are compared using Mantel correlation. Results The results at first glance confirm the failings of tests as found by Zelený & Schaffers (Journal of Vegetation Science 23, 2012, 419). However, when using traits data instead of mean indicator values, precisely the same happens, raising the possibility that mean species-based traits are also ‘biased’. The effect prevails when applied to PCA scores. I conclude that Zelený & Schaffers (Journal of Vegetation Science 23, 2012, 419) overlooked that unrealistic significances in ANOVA emerge from statistical dependence; they are artefacts of a non-valid null model. Conclusions Restrictions in the use of mean indicator values and species-based traits concern statistical tests only that assume statistical independence from species scores when there is none. I conclude that mean indicator values deserve rehabilitation as there is no bias involved in their use.

In an era of the availability of very large databases, the problem of efficient methods to analyze such datasets remains. In large scale forest and landscape monitoring projects for instance, appropriate data mining techniques that can summarize the overall status of landscapes are necessary for planning and implementing follow-up management strategies. We consider a vegetation data set consisting of species data from more than 120 mires spread across Switzerland with a total of 20,134 plots on 2658 vascular and non-vascular plant species. Using species indicator values as proxy for site conditions, we propose some simple strategies for data mining involving multidimensional scaling and nonparametric probability density function estimation, both of which are known in the classical statistical literature. We show how commonly known techniques can be adapted in a novel and effective approach for the specific purpose of analyzing plant species occurrence in the plots to identify site conditions that influence species configurations and species diversity, thus providing important information concerning aspects of large scale vegetation structure. Our results indicate high variations among the mires with respect to site conditions that affect species assemblage and species diversity. While species indicator values continue to be popular as well as subject of much debate and research in the ecological community, our experience shows that careful methods of analysis at large landscape scales can reveal some powerful results, which can be taken up as the starting point for the next level of investigation.

The identification of differentiating species, also termed indicator species, is a key issue in striving for group pattern in vegetation samples. With this objective in mind Jancey (1979) proposed species ranking on a variance ratio (F-ratio) criterion, the mechanism of analysis of variance. Almost 20 years later Dufrene and Legendre (1997) presented their indicator value analysis with the same objective in mind but based on different reasoning. This raises the question if (i) the results of the two approaches are equivalent or (ii), if one of the measures of performance is superior in predicting specific properties of ecosystems, such as site conditions, biodiversity, succession or other. Because the outcome of both methods strictly relies on the strength of vegetation pattern reflected by the data sets used as well as the quality of classifications, we compare results from a small and also a large real-world data set and we evaluate the effect of the number of groups involved when clustering sites. In a subsequent step, the ranking of indicator species identified by either of the methods is compared with a ranking obtained by correlating species with measured environmental factors. The results confirm that the outcome of ranking by maximum indicator value (IndVal) according to Dufrene and Legendre (1997) is very similar to the ranking devised by Jancey (1979). Rank correlation reaches a maximum of r > 0.95 when the data set is large and group number in clustering is low. In our examples Jancey’s method is generally more closely related to the environmental predictive power of species, outperforming IndVal when applied to continuous variables measured in the field. We conclude that the potential of Jancey’s method is generally underrated. As expected, the agreement of results between the two approaches depends on the strength of similarity patterns inherent in the data sets analysed. The method of Dufrene and Legendre (1997) is well adapted to issues of phytoso-ciology where classification is frequently based on expert knowledge. If the resolving power of species is used as a surrogate for patterns and processes of plant-environment systems, then ranking by variance ratio may be the more promising approach.

Questions: How does plant diversity (species richness, species abundance andrate of change) evolve in early succession on bare peat? Does successionconverge towards one equilibrium stage or end up in several stages? Is there aregular pattern in succession velocity?Location: A mire in the calcareous Jura Mountains of northwest Switzerland.Method:Twenty-one 1-m 2 permanent plots onbare peatwereused tomonitortemporal stages over a 21-year period (1988 to 2008) in a Swiss mire where aslide occurred in 1987. Species diversity and life forms were analysed based onShannon’s equitability index and cover. We used classification and metricordination techniques to investigate patterns of successional rates and trends.The high temporal resolution of the survey allowed the pattern of successionvelocity to be analysed.Results: Species richness increased continuously over the 21 years of succes-sion. The highest cover throughout the study period was the life form sedge.Time trajectories of the 21 plots revealed three alternative pathways towardsintermediate equilibrium stages in the first years, still not converging in thelater stages. Changes in succession velocity reached a first maximum about 6years after the slide had occurred and a second maximum 12 years later.IntroductionEarly successional stages in vegetation have long beenstudied in plant ecology (Van der Valk 1992). The classicalissue in succession is change in species composition,where the direction of change includes alternative path-ways towards one or several equilibrium stages.The literature contains numerous examples of earlysuccession on many types of bare substrate, includingriver sediments (Rejmanek et al. 1987), seashore mea-dows (Ecke & Rydin 2000), salt marsh sand (Roozen W Jun et al.2004), pumice (del Moral & Jones 2002; del Moral 2007),newly formed islands after the lowering of a lake watertable(Rydin B Salonen et al. 1992), Germany (Patzeltet al. 2001), Ireland (Wilson et al. 2007), the CzechRepublic (Konvalinkova & Prach 2010) and North´America (Ferland & Rochefort 1997; Robert et al. 1999;Campbell & Rochefort 2003; Poulin et al. 2005). Todate, few long-term studies of vegetation successionon bare peat have been carried out. This paper reportson the colonization and early succession of bare peatafter a bog burst in 1987 (Feldmeyer-Christe MColhoun et al. 1965; Tomlinson & Gardiner 1982; Alexan-der et al. 1986; Carling 1986; Large 1991; Feehan O Warburton et al. 2003; Caseldine G Warburton et al. 2004).

To assess whether short-term changes in mire vegetation can be detected using the phytosociological approach, paired vegetation releves from two surveys of 112 mire sites of Switzerland were assigned to phytosociological alliances through a numerical approach. About 30% of the plots were assigned to different alliances in the two surveys. These transitions were analysed based on species frequencies and interpreted ecologically using Landolt’s indicator values. Transitions between different alliances were more frequently related to the appearance of new species rather than to the disappearance of species. Transitions from and to peat bog communities were frequent. Many plots with fen vegetation were transformed into other wetland types. Fen-grassland increased in abundance, mainly at the cost of small-sedge fens. To re-establish the function of the Swiss mires as peat producers, we recommend to raise the mean summer water table to a maximum depth of 10 cm.

The mapping and monitoring of Swiss mires has so far relied on a classification system based on expert judgement, which was not supported by a quantitative vegetation analysis and which did not include all wetland vegetation types described in the country. Based on a spatially representative sample of 17,608 releves from 112 Swiss mires, we address the following questions: (1) How abundant are wetland vegetation types (phytosociological alliances) in Swiss mires? (2) How are they distributed across the country––is there a regional pattern? (3) How clearly are they separated from each other? (4) How clear and reliable is their ecological interpretation? Using published wetland vegetation releves and lists of diagnostic species for phytosociological units (associations and alliances) established by experts, we developed a numerical method for assigning releves to units through the calculation of similarity indices. We applied this method to our sample of 17,608 releves and estimated the total area covered by each vegetation type in Switzerland. We found that vegetation types not included in previous mapping were either rare in Switzerland (partly due to mire drainage) or poorly distinguished from other vegetation units. In an ordination, the Swiss mire vegetation formed a triangular gradient system with the Sphagnion medii, the Caricion davallianae and the Phragmition australis as extreme types. Phytosociological alliances were clearly separated in a subset of 2,265 releves, which had a strong similarity to one particular association, but poorly separated across all releves, of which many could not be unequivocally assigned to one association. However, ecological gradients were reflected equally well by the vegetation types in either case. Overall, phytosociological alliances distinguished until now proved suitable schemes to describe and interpret vegetation gradients. Nevertheless, we see the urgent need to establish a data base of Swiss wetland releves for a more reliable definition of some vegetation units.

Synthesizing genetic data at population level and vegetation data at community level may give insight into how ecological and evolutionary processes associated with different vegetation influence genetic diversity and differentiation of plant populations. We correlated population genetic patterns of Carex sempervirens with community vegetation patterns in abandoned subalpine grassland in the Swiss Alps. Within-population genetic diversity (percentage of polymorphic bands and Nei's gene diversity) of C. sempervirens was not significantly correlated with plant richness, evenness or Shannon's diversity index (Pearson correlation coefficient |r| 0.10). However, the genetic distance (FST) between C. sempervirens populations was significantly positively correlated with the vegetation dissimilarity between communities (Mantel's r=0.23, P

Vegetation changes following agricultural land abandonment at high elevation — which is frequent in Europe — could have a major impact on carbon (C) sequestration. However, most information on the effects of vegetation changes on ecosystem C stocks originates from low-elevation studies on reforestation or early successional forests, and little is known about how these stocks change during long-term secondary forest succession and at high elevation. We assessed aboveground, belowground, and ecosystem organic matter and C stocks in high-elevation ecosystems that represent the long-term development (centuries) following land abandonment: short- and tall-grass pastures, Swiss mountain pine (Pinus mugo Turra), mixed-conifer, and Swiss stone pine ( Pinus cembra L.) – European larch ( Larix decidua P. Mill.) forests. Aboveground C stocks were lowest in the short-grass pastures (0.1 Mg C·ha–1) and reached a maximum in the mixed-conifer and stone pine – larch forests (166 Mg C·ha–1). Belowground C stocks did not differ among the ecosystems studied. We only detected ecosystem C sequestration during reforestation; whereas no significant differences in ecosystem C stocks were found during long-term secondary forest development. Our calculations showed that only an additional 1733–3032 Mg C·year–1 would be sequestered owing to natural reforestation in high-elevation Switzerland, which likely can be considered negligible compared with total annual C sequestration calculated for Swiss forests in other studies.

Landscape research in Switzerland enjoys a high technological and intellectual standard. It is influenced by both region-independent stimuli (e.g. remote sensing, sociology, population biology or statistics), and stimuli that have a strong bounding to the regional context. Region-specific stimuli for Landscape Research in Switzerland are:- the highly heterogeneous topography of the mountains as prerequisite to develop and test landscape-related theories,- the contrasting individualistic lifestyles of a multi-ethnic society that generates contrasting notions towards landscapes and thus contrasting methods in landscape research,- the long tradition of environmental research, monitoring and education and the high public motivation to support landscape-related research, as well as- the direct democracy where Landscape Research finds an ideal experimental ground to test theories and research hypothesis about how public participation or diverse (public) value systems and stakeholder values affect landscapes.Landscape research in Switzerland developed under the institutional umbrella of several public universities and research Institutions, primarily in the disciplines of geography, botany, remote sensing, forestry, agriculture, ethnology and sociology.Modern landscape research in Switzerland is performed as basic as well as applied research. It is well-positioned in the following fields: (1) the interactions between stakeholder values (towards nature & landscapes) and landscape development, (2) integrating spatial aspects of population genetics with landscape ecology, (3) the impact of communications technology on landscape resources, exploring heterogeneity in ecosystem processes across landscapes, relating landscape indicators to ecological processes, landscape historical approaches, and communicating research to the public and to policy makers. Die Landschaftsforschung in der Schweiz ist sowohl technologisch als auch intellektuell hoch entwickelt. Sie wird geprägt von überregional wirkenden Forschungsstimuli, wie z.B. der Fernerkundung, der Soziologie, der Populationsbiologie oder der Statistik aber auch von Stimuli, die einen starken regionalen Bezug haben. Letztere sind:- die unterschiedliche Topographie des Gebirges als günstige Voraussetzung für das Entwickeln und Testen von landschaftsrelevanten Theorien,- die unterschiedlichen, individuellen Lebensstile einer multi-kulturellen Gesellschaft, welche bewirken, dass Landschaften ganz unterschiedlich wahrgenommen, und mit gegensätzlichen Methoden untersucht werden,- die langjährige Tradition im Erforschen und Beobachten der Umwelt sowie in der Umwelterziehung und die grosse Bereitschaft der Öffentlichkeit, landschaftsrelevante Forschung zu unterstützen, und- die direkte Demokratie, die für die Landschaftsforschung einen idealen experimentellen Raum zum Testen von Theorien und Hypothesen darstellt, z.B. darüber, wie die öffentliche Mitbeteiligung oder die unterschiedlichen Werthaltungen der Akteure die Landschaft beeinflussen.Die Landschaftsforschung in der Schweiz entwickelte sich an unterschiedlichen Institutionen und Universitäten, hauptsächlich in den Disziplinen Geographie, Botanik, Fernerkundung, Forst- und Agrarwissenschaften, Ethnologie und Soziologie.Die moderne Landschaftsforschung in der Schweiz versteht sich als grundlagen­ orientierte und angewandte Forschung. Sie ist auf folgenden Gebieten führend: (1) Analyse der Zusammenhänge zwischen den unterschiedlichen Werthaltungen der Akteure (gegenüber Natur & Landschaft) und der Landschaftsentwicklung, (2) Integration der räumlichen Aspekte der Populationsgenetik in die Landschaftsökologie, (3) Auswirkungen moderner Kommunikationstechnologien auf die Landschaft, (4) Analyse von ökologischen Prozessen in der realen Landschaft, (5) Indikatoren zur Beschreibung des Landschaftszustandes und ihre Verknüpfung mit ökologischen Prozessen, (6) Landschaftsgeschichte, und (7) Umsetzung von Wissen für die Öffentlichkeit und die Politik.

Forest mapping at the landscape scale for resource planning and monitoring usually applies a discrete forest definition based on the primary forest use. Forest uses, however, can change in space and time. Therefore, the dependent forest definition may no longer be appropriate. We analysed how the Swiss National Forest Inventory partitions the continuous landscape resources into discrete forest/non-forest classes of the Swiss Jura mountain range and how such a binary classification affects the representation of forest resources in space. Additionally, we performed a sensitivity analysis to assess the effect of different forest classification thresholds representing different forest definitions on the spatial estimates of the dependent forest area. Relevant landscape variables for forest area estimations were sampled from coloured aerial imagery in the Swiss Jura mountain range on a rectangular 500 m × 500 m spaced grid. Each sample plot of 50 m × 50 m dimension containing all measured landscape variables was then classified as forest or non-forest based on the Swiss National Forest Inventory definition, as well as other selected thresholds along the landscape variables’ range. The resulting forest area as defined by the Swiss National Forest Inventory covered 45.2% of the Jura mountain range containing 86.7% of the overall tree vegetation. In agreement with the original forest use, tree vegetation on forest sample plots was taller, denser and stands were larger than on non-forest plots. However, we identified considerable amounts of tree vegetation located outside of the forest dispersed all over the landscape. 73.3% of all the sample plots contained some fractions of tree vegetation, while only 18.0% were fully covered by trees. Among the different continuous landscape variables tree canopy cover had a large effect on forest area estimates, while the effects of tree canopy height and stand width were found to be moderate. This study confirmed that the applied forest definition of the Swiss National Forest Inventory extracted the spatial domain of forests appropriately if the original forest use is of interest. However, our results also indicate that a change in forest use and hence forest definition result in considerably different spatial pattern and forest area estimation. In the presented approach forest becomes a dependent variable, whereas the independent raw data is represented by continuous landscape variables. As a consequence, different forest definitions for different forest uses can be applied in a subsequent analysis step. By this, forest area estimates can be adapted easily and consistently to a range of new forest uses as applied in the third Swiss National Forest Inventory.

We address issues of investigations in plant ecology with a time span exceeding the range of ordinary research projects. According to the findings in the papers of this special issue of Community Ecology and other related publications, long-term monitoring is faced with specific methodological challenges: 1. Since the system to be monitored as well as the objectives of monitoring may change over time, the spatial, temporal and thematic scales should be changed considerably. 2. Experience shows that monitoring results are often used for different purposes. However, there exists no sampling design that would offer a true multi-purpose application. The selection of the sampling design will therefore restrict the future use of data. 3. While the selection of sampling units is random and therefore statistical, the selection of variables is usually preferential. This may seriously hamper the results thematically and statistically. It is concluded that combining precise ground measures with remote sensing data b...

Species composition in forest patches is influenced by distance-to-edge within an average range of 748 m. Pellissier et al., in this issue, assess the significance of this pattern using a very large data set, a well-defined target population and comprehensive logistic models. This is a recipe for overcoming the lack of general validity frequently observed in vegetation science.

A set of coupled logistic growth equations is used to simulate the temporal replacement of vegetation (species or groups). Simulation results approximately reproduce two time series of 415 to 585 years obtained from field investigations in the Swiss National Park (SNP). Although the shape and the fit of the simulated curves are convincing, the assumption that all species must be present at the beginning of the simulation and also the absence of movement in space are not realistic. To overcome this, the model is extended to include space and is used for simulating the succession in an abandoned pasture of the SNP. As long as only vegetation change in all individual quadrats is simulated separately, vegetation boundaries remain unchanged over the simulated period of 400 years. When species are allowed to move between quadrats, the spatial pattern changes over the simulated time, and field data can be taken as boundary conditions to realistically simulate change. It is concluded that spatial dynamics must be taken into account to model long-term succession.

Several non-parametric estimators have been proposed for estimating species richness from a spatial sample. While the label non-parametric may suggest that a method makes few assumptions,...

We used space-for-time substitution to obtain a directed successional sequence for subalpine meadow vegetation in the Swiss National Park. Since human impacts (e.g., domestic animal grazing) ceased in 1914, the successional processes documented are assumed to be autogenic in nature. The data consist of 59 permanent plots spanning almost 90 years, and include many spatial replications. An initial inspection of the individual time series revealed the existence of a variety of response patterns, which are described in the literature as representing different successional types. However, a closer inspection suggested that many of these series can be superimposed, as they are part of a much longer deterministic series. Linking the individual time series proved to be challenging. A heuristic approach produced results that differed depending on initial starting conditions. We therefore derived a deterministic algorithm to produce a unique solution. The resulting sequence largely confirmed the heuristic interpret...

In this paper, we quantify the effects of habitat variability and habitat heterogeneity based on the partitioning of landscape species diversity into additive components and link them to patch-specific diversity. The approach is illustrated with a case study from central Switzerland, where we recorded the presence of vascular plant species in a stratified random sample of 1'280 quadrats of 1 m2 within a total area of 0.23 km2. We derived components of within- and between-community diversity at four scale levels (quadrat, patch, habitat type, and landscape) for three diversity measures (species richness, Shannon index, and Simpson diversity). The model implies that what we measure as within-community diversity at a higher scale level is the combined effect of heterogeneity at various lower levels. The results suggest that the proportions of the individual diversity components depend on the habitat type and on the chosen diversity aspect. One habitat type may be more diverse than another at patch level, but less diverse at the level of habitat type. Landscape composition apparently is a key factor for explaining landscape species richness, but affects evenness only little. Before we can test the effect of landscape structure on landscape species richness, several problems will have to be solved. These include the incorporation of neighbourhood effects, the unbiased estimation of species richness components, and the quantification of the contribution of a landscape element to landscape species richness.

Die Geschichte des Naturschutzes in seinen ersten hundert Jahren gleicht einer endlosen Reihe von Feuerwehrübungen: Rettung von Tier- und Pflanzenarten vor dem Aussterben, Bewahren von Biotopen und Landschaften in Schutzgebieten, fast immer in Eile und als Reaktion auf Eingriffe der nutzsuchenden Menschen. Ist Naturschutz im großen und ganzen erfolgreich gewesen? Die Frage wird verschieden beantwortet und erinnert dabei an die Metapher vom halbvollen oder halbleeren Glas: Wer vor allem die Roten Listen, die Veränderung der europäischen Kulturlandschaften oder die Regenwaldzerstörung vor Augen hat, wird mit "Nein" antworten. Wer sich hingegen ausmalt, was ohne Naturschutz zusätzlich verschwunden wäre, wird positiver urteilen. Die Frage müßte denn auch eher in die Zukunft zielen: Wie hat Naturschutz morgen zu funktionieren, damit dem Artensterben Einhalt geboten und dem Bedürfnis der Menschen nach Naturerlebnis genügt werden kann? Zumindest beim Prinzip herrscht Einigkeit: Naturschutz darf nicht mehr bloß Reaktion sein, sondern muß als vorausgeplante Aktion mit einem umfassenden Zielsystem stattfinden. Die Ziele müssen definiert, quantifiziert und in einer nationalen Strategie verankert werden.

In this ecological risk assessment we evaluated potential climate-induced vegetation changes in mountain forests of Central Europe and possible impacts on species richness. The analysis was performed on all lkm grid points of the Swiss forest inventory (c. 11500 points) as well as on two subsets representing the forested points within the geographical limits of two inventories of legally protected reserve areas. The core of the approach is (a) a conceptual model of the movement of climatic ranges along altitudinal gradients as a result of global warming and (b) a spatially explicit forest community simulator that predicts a potential natural vegetation unit for any given 1 km grid point of the Swiss forest inventory for both current climate and for altered climate regimes. The model is derived from empirical data featuring the relationships between quasi-natural vegetation types and measured site variables. Species richness for any modelled forest community is estimated on the basis of phytosociological releves.

A spatially explicit, climate-sensitive vegetation model is presented to simulate both present and future distribution of potential natural vegetation types in Switzerland at the level of zonal forest communities. The model has two versions: (1) a ‘basic’ version using geographical region, aspect, bedrock (represented by soil pH), and elevation, and (2) a ‘climate-sensitive’ version obtained by replacing elevation (complex environmental gradient) with temperature (climatic factor). Version 2 is used to predict vegetation response under different (today's and projected) climatic conditions. Two regional climate scenarios are applied: (1) assuming an annual mean temperature increase of 1.1 — 1.4 °C, and (2) assuming an increase of 2.2 — 2.75 °C. Both scenarios result in significant changes of the spatial vegetation patterns as compared with today's climatic conditions. In scenario 1, ca. 33 % of the sample points remain unchanged in terms of the simulated zonal forest community; in scenario 2, virtually all sample points change. The most noticeable changes occur on the Swiss Plateau with Carpinion forests (zonal vegetation of present colline belt) expanding to areas that are occupied today by submontane and low-montane Fagus forests. To estimate the reliability of the simulation, quantitative (comparison with field mapping) and qualitative (comparison with climate types in the Alpine region) tests are performed and the main limitations of the approach are evaluated.

Tussocks of graminoids can induce spatial heterogeneity in soil properties in dry areas with discontinuous vegetation cover, but little is known about the situation in areas with continuous vegetation and no study has tested whether tussocks can induce spatial heterogeneity in litter decomposition. In a subalpine grassland in the Central Alps where vegetation cover is continuous, we measured soil properties [concentration of N, C, organic matter (OM) and pH] and monitored litter decomposition traits (dry mass loss, loss of C, N, P and K) inside and outside tussocks of Carex sempervirens. Soil C, N, OM concentrations or pH inside tussocks did not differ significantly from those outside tussocks. After 1 year of decomposition, litter dry mass loss, C and K loss were significantly smaller inside than outside tussocks. The slower litter decomposition inside tussocks was likely caused by the elevated tussock base, which made environmental conditions inside tussocks much dryer than those outside in early spring when snow melts. Our results suggest that in areas with continuous vegetation cover tussocks induce spatial heterogeneity in litter decomposition but not in soil properties.

Using empirical data (ca. 7500 phytosociological releves), a simple, probabilistic ‘vegetation-site’ model was developed, to simulate geographical distribution of 71 forest community types, representing the potential natural vegetation (PNV) of Switzerland. The model was interfaced to a geographic information system (GIS) and used to generate a numerical vegetation map, on the basis of digital maps of 12 environmental variables including climatic conditions (temperature and precipitation), topography (elevation, slope, aspect), and soil parameters (soil pH and physical soil parameters). The predicted distribution of forest communities was compared with several vegetation maps, prepared for some subregions of Switzerland by means of traditional field methods. Similarity ranged from 50 to 80 %, depending on the community type, level of vegetational hierarchy and the geographical region. The current resolution and accuracy of the simulated vegetation map allows us to study the vegetational patterns on the level of the entire country or its major geographical and climatic regions. The simulated vegetation map is potentially an important tool in ecological risk assessment studies concerning the possible impacts of climate change on the ecological potential of forest sites and biological diversity of forest communities.

The species–area relationship (SAR) has been extensively studied in a wide range of plant communities, but very few studies have directly addressed how plant communities affect the SAR and what are the underlying mechanisms. Many graminoids form distinct tussocks where many other plant species grow, but no study has investigated whether the SAR holds true for the vegetation on tussocks. In four plant communities on an abandoned subalpine pasture in the Swiss National Park, we made releves on 600 tussocks of Carex sempervirens and measured tussock basal area and other tussock traits. In all four communities, species richness on C. sempervirens tussocks was strongly positively related to tussock basal area ( R 2 ⩾0.74), while other tussock traits explained very little ( R 2 C. sempervirens tussocks differed significantly among the four communities. This was because plant communities affected richness in smaller tussocks (basal diameter C. sempervirens tussocks and changes with plant communities. Changes in the SAR on C. sempervirens tussocks are very likely because smaller tussocks are less independent of the plant communities than the larger ones, regarding disturbance or nutrients.

century has seen an astonishing development in information technology affecting almost every facet of the society. Easy and nearly unlimited access to computers, satellites and communications systems has also affected the way landscape research is done today. Data are obtained in massive amounts and data mining is now an issue. Also in the biological sciences, modern methods such as molecular genetics have revolutionized our understanding of ecology and evolution and how these interact with the environment. Following modern trends in science, landscape research has become computationally intensive, with strong theoretical components. Now, information is quantified, hypotheses are tested and scientific inference is formal. Landscape research is an interdisciplinary science. It deals with complex environmental processes at multiple spatial and temporal scales. While the interdisciplinary nature and the

Questions: How do species diversity, frequency and composition in tussocks differ from those in similar sized plots outside tussocks? Does the extent of the differences depend on community types or environmental conditions? Location: A sub-alpine grassland in the Swiss National Park. Methods: In each of the two communities (short grass and tall graminoid) differing in species composition, grazing intensity and soil nutrient availability, relevés were made in 40 pairs of small circular plots, with one plot located inside a randomly selected Carex sempervirens tussock and the other outside. Results: We found 92 vascular species, of which 46 had a frequency higher than 5%. Species richness (S), pooled cover, Shannon’s diversity (H) and cumulative species number (CS) were higher outside than inside the C. sempervirens tussocks, but evenness (J) was lower. S, H and CS differed more in the tall graminoid community than in the short grass community. However, dissimilarity between the paired relevés inside and outside tussocks did not differ between the two communities. Of the 46 most frequent species, 12 were statistically more and only one less frequent outside than inside the tussocks. Vegetation inside and outside tussocks could be clearly distinguished in the ordination space. Conclusion: Vegetation inside C. sempervirens tussocks is different from that in the surrounding area and represents an impoverished but homogenized version of the surrounding vegetation. Although tussocks of C. sempervirens were systematically avoided by grazers, there is little evidence that tussocks facilitate the species growing inside them.

Tentative evidence indicates that a discrete tussock may not be genetically uniform, especially if its vitality is reduced. Using molecular markers, we studied the genetic composition of eight vigorous and eight weak tussocks of Carex sempervirens (cover 75% and 35%, respectively) to elucidate the relationship between tussock vigor and genetic variability. Four C. sempervirens tussocks harbored more than one genotype. However, all four variable tussocks were weak, and the additional genotypes occurred only at the edge of the tussock base. The formation of a genetically variable tussock of C. sempervirens is best explained by a seedling or small tussock being incorporated by a large, expanding tussock that eventually surrounds it. The vitalityrelated pattern was most likely caused by the greater intraspecific competition both inside and around the vigorous tussocks. We conclude that the formation of a tussock may involve more than one seedling and that tussocks, therefore, may not a priori be treated as genetic individuals.

Plant Ecology, 172 (1), ISSN:1385-0237, ISSN:1573-5052

Succession theories and related methods for time series analysis are presented and illustrated by examples using published data. Starting from a rather general definition of succession which is understood as any directional change of vegetation in time, the phenomena can be distinguished at three different levels of perception: pattern, process and mechanism. Pattern is the phenomenon perceived and reflected in the sample data. Process is a grammar generating this pattern (Dale 1980). Both can be accessed by appropriate statistical analysis. Mechanisms are the causes of the changes. Whereas in some cases they can be inferred from patterns and processes, they cannot be observed or measured directly.