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Changes in species composition is an important process in many ecosystems but rarely considered in systematic reserve site selection. To test the influence of temporal variability in species composition on the establishment of a reserve network, we compared network configurations based on species data of small mammals and frogs sampled during two consecutive years in a fragmented Atlantic Forest landscape (SE Brazil). Site selection with simulated annealing was carried out with the datasets of each single year and after merging the datasets of both years. Site selection resulted in remarkably divergent network configurations. Differences are reflected in both the identity of the selected fragments and in the amount of flexibility and irreplaceability in network configuration. Networks selected when data for both years were merged did not include all sites that were irreplaceable in one of the 2 years. Results of species number estimation revealed that significant changes in the composition of the species community occurred. Hence, temporal variability of community composition should be routinely tested and considered in systematic reserve site selection in dynamic systems.

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Questions: 1. Does random colonization predominate in early stages of primary succession? 2. Do pioneer species facilitate the establishment of later arriving species? 3. Does an initially random distribution change to an aggregated pattern with ongoing succession?Location: Lignite mining region of Lower Lusatia, eastern Germany.Methods: Individual plants were mapped along a 2 m × 28 m transect during three successive years and classified into two groups (1) the pioneer Corynephorus canescens and (2) 'all other species'. Using the pair-correlation function, univariate point pattern analysis was carried out by applying a heterogeneous Poisson process as null model. Bivariate analysis and a toroidal shift null model were applied to test for independence between the spatial patterns of the two groups separately for each year, as well by exploring spatiotemporal patterns from different years. Results: In the first year Corynephorus and 'all other species' showed an aggregated pattern on a spatial scale > 40 cm and in the second and third years a significant attraction for distances between 4 and 12 cm, with an increasing radius in the third year. The analyses of interspecific spatiotemporal dynamics revealed a change from independence to attraction between distances of 4 cm and 16 cm when using Corynephorus as focal species. However, applying 'all other species' as focal points results in a significant attraction at distances up to 60 cm in the first year and a diminishing attraction in the second and third years with distances = 6 cm. Conclusions: Facilitative species-species interactions are present in early stages of primary succession, resulting mainly from pioneer species acting as physical barriers and their ability to capture diaspores being drifted by secondary dispersal along the substrate surface. However, due to gradual establishment of perennial species and their ability of lateral extension by vegetative dispersal, facilitation may influence spatial patt

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Former lignite mining sites harbour an important potential for nature conservation. In order toprotect these conservation values, strategies and measures have been developed that should preventnature conservation from being restricted to the »land that nobody wants«. Though up to now it hasbeen possible to ensure the long-term protection of some priority sites, an establishment of aconservation network that covers representatively the characteristic biodiversity of these areas is notyet foreseeable. Thus a standardised systematic conservation planning based on regional conservationgoals and accounts as well for the complementarity of the individual sites as for the requirement ofcertain species should be given more emphasis.

Based on a comprehensive 4-year survey the spontaneous vegetation of the Lusatian post-mining landscape is described. Thirteen vegetation types are distinguished and characterized with respect to characteristic species, dominant growth form, and frequency of occurrence. Indirect gradient analysis showed that there is a broad overlap of vegetation types, and that no successional trends can be inferred on the basis of floristic composition alone. The species composition was related to environmental variables by means of direct gradient analysis and canonical correspondence analysis. The multivariate approach showed that variables like pH, organic carbon, phosphate and water capacities have an obvious influence on species composition. However, in some cases it is not clear whether this is cause or consequence of the respective vegetation colonization. The age of the stands can be identified as an important variable, but cannot be distinguished from spatial autocorrelation effects. The univariate approach showed that no threshold values can be detected in important parameters, such as pH. Autocorrelation effects hamper the interpretation of the complex data set. All successional sequences observed or inferred so far are combined to a conceptual model of spontaneous vegetation development. According to the local circumstances, various types of initial vegetation are possible. Initial vegetation is subsequently followed by a large number of stages and types which form a complex network. Some of these stages are stabilized by a dense vegetation layer or competitive power of the dominant species. The direction of succession is influenced to varying portions by neighborhood effects, facilitation, disturbance, and other mechanisms. The duration of the stages and the transition probabilities cannot be exactly predicted in the present state of knowledge. Besides its scientific importance, primary succession is regarded as an adequate means of restoration leading to areas likewi

The predictability of early primary succession in post-mining landscapes of eastern Germany was studied at sites 5-70 yr following dumping. This chronosequence was investigated using indirect ordination methods. The position of the vegetation types in the ordination diagram was found not to infer any temporal sequence. Independent observations show that the change of vegetation type is slow and does not necessarily occur among types adjacent in the ordination diagram. Furthermore, direct ordination revealed that environmental parameters such as pH, the levels of available phosphate and organic carbon as well as the age of the study sites do not significantly account for the variance. Instead, attention needs to be paid to the influence of spatial aspects and also what recultivation measures have been carried out. A detailed account of the vegetation dynamics of individual sample plots showed - depending on the respective vegetation type - divergence, convergence, and fluctuation at the smallest spatial scale. While the species richness of the sample plots remained more or less constant after initial colonization, mean vegetation cover continuously increases with age, although some sites still remain free of vegetation after as long as 70 yr. No general trend in dominant life forms was indicated. A conceptual model of early succession mechanisms is outlined and Five basic mechanisms are identified (i.e. site availability, site suitability, availability of diaspores, strategies of colonizing species and biotic interactions). Their respective importance in three different stages of early succession is estimated and compared. The predictability of vegetation dynamics at each stage is rated differently.

An Beispielen von Datensätzen aus der Bergbaufolgelandschaft (BFL) werden Methoden der Generalisierung für vegetationskundliche und zoologische Datensätze vorgestellt, deren Ergebnisse durch Validierungsdaten überprüft wurden. Als Basis dienen u. a. mittels fernerkundlicher Methoden erstellte digitale Karten und GIS. Unter vegetationskundlichem Aspekt zeigt sich bei Übergang von einer höheren auf eine niedrigere Beobachtungssebene ein Anstieg im Informationsgehalt. Als Werkzeug der vegetationskundlichen Generalisierung ist die Anwendung der CASI Methode in Kombination mit der kleinräumigen vegetationskundlichen Erfassung erfolgversprechend und effektiv. Der Einsatz von LANDSAT-TM-Daten ist bei größeren, zusammenhängenden und in der Vegetationsstruktur homogenen Bereichen sinnvoll. Die Biotoptypenkartierung eignet sich nur eingeschränkt zur räumlichen Generalisierung. Zoologische Daten und Satellitendaten können erfolgreich zur flächendeckenden artgenauen Generalisierung verschnitten werden. Als Methodik der artenzahlspezifischen Generalisierung wird das Biotophybrid-Verfahren diskutiert. Die vorgestellten Methoden sind als Module eines umfassenderen landschaftsökologischen Modells zu denken, das mit Hinzunahme und Verschneidung weiterer Parameter der Landschaft weitergehende Analysen und Entwicklungsprognosen von Artverbreitung und Arten-diversität ermöglicht.

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Silbergrasfluren, Sandtrockenrasen, bergbauspezifische Ansaaten und krautreiche Pionierfluren, Calamagrostis epigejos-Bestände sowie vegetationsarme Sandflächen und Rohkippen sind die dominierenden Vegetationseinheiten in den terrestrischen Offenlandbereichen. Diese Vegetationstypen sind keine Einheiten im pflanzensoziologischen Sinn und weisen sowohl räumlich als auch zeitlich breite floristische Übergangsbereiche auf. Der Sukzessionsverlauf auf diesen Flächen ist durch verschiedene Mechanismen gekennzeichnet, die zu unterschiedlichen Zeitpunkten zur Ausprägung gelangen. Zu Beginn der Besiedlung ist in erster Linie die Verfügbarkeit von Diasporen ausschlaggebend In den sich etablierenden Initialbeständen dominieren Mechanismen wie Facilitation, Inhibition und Tolerance. In einer dritten Phase sind darüber hinaus Störungen als ein weiterer Faktor für den Sukzessionsverlauf ausschlaggebend. Diese große Bandbreite verschiedener Mechanismen erfordert es, sich einerseits von der Vorstellung eines linearen Sukzessionsverlaufs zugunsten sogenannter Sukzessionsnetze zu lösen. Andererseits ist ein naturschutzfachliches Konzept notwendig, welches den tatsächlich ablaufenden Prozessen Rechnung trägt. Am ehesten ist dazu das Patch-Dynamik-Konzept geeignet, welches es ermöglicht, die in vielen Richtungen offene Entwicklung einer kleinräumigen Heterogenität sowie die zeitliche Dynamik in den Mittelpunkt der Betrachtung zu stellen.

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