Refine
Document Type
- Article (3)
Has Fulltext
- yes (3)
Is part of the Bibliography
- no (3)
Keywords
- community ecology (2)
- Karakachan (1)
- Succulent Karoo (1)
- beta diversity (1)
- boundary dynamics (1)
- central Europe (1)
- change detection (1)
- data exchange (1)
- database (1)
- diversity indices (1)
- ecotone (1)
- edge effects (1)
- habitat island (1)
- image segmentation (1)
- land management (1)
- macroecology (1)
- metadata (1)
- nestedness (1)
- phytosociology (1)
- plot (1)
- quartz fields (1)
- relevé (1)
- scientific reward (1)
- shrub encroachment (1)
- soil diversity (1)
- species composition (1)
- species turnover (1)
- transhumance (1)
- transition zone (1)
Institute
The historical transition from the Bulgarian Kingdom through the Soviet period to the present state of Bulgaria has affected humans and their land use preferences, leading to repeated transformations of the vegetation. We analysed the proportional change of vegetation types in the Tsentralen Balkan National Park in Bulgaria using aerial imagery over the last 65 years and object based image segmentation. Segments were classified into three land cover classes (vegetation types): shrubland, grassland, and shrub-grassland mosaic. In order to interpret the observed proportional changes of these vegetation types we collated livestock numbers over the same period. The shrub-grassland mosaic constantly decreased over the first 20 years, whereas shrublands and grasslands both increased. During the period 1969–1989, the trend continued and areas covered by the shrub-grassland mosaic decreased by 82%, while shrublands increased by 56% and grasslands increased by 18%. The species rich shrub-grassland mosaics were most affected by the land use changes. The overall land cover diversity pattern reduced to two classes. The period with the least changes was 1989–2012, when changes in landscape cover stabilized after the area was designated a National Park. Livestock numbers varied throughout the study period due to the transformation processes. This probably also affected the change in the vegetation patterns analyzed, as few other drivers are known from the Stara Planina Mts. The aerial imagery time series was helpful to reconstruct the changes in the vegetation of the study area, however, extending the time series would allow for a better correlation with livestock numbers.
Questions: Habitat islands are often characterized by the presence of more or less sharp boundaries to adjacent matrix habitats. However, knowledge on boundaries of natural habitat islands is scarce, especially regarding patterns of beta diversity and its two underlying components: species turnover and nestedness. We therefore aim to quantify the effects of fine-scaled and sharp boundaries of quartz islands (quartz gravel-covered soils) on the different components of plant beta diversity and how they are linked to different soil environmental drivers. Location: Knersvlakte, Western Cape, South Africa. Methods: We sampled plant species richness in 56 fine-scale transects of 6 m × 1 m plots across eight different boundary types (four quartz island to matrix, four between habitats on quartz islands). Soil depth and chemistry (pH, electrical conductivity) were analyzed for each 1 m2 plot. Differences in the two beta diversity components (turnover and nestedness) for each boundary type were tested by t tests. We used linear models to test relationships between species and environmental dissimilarity. Results: All boundary types showed high beta diversity. Species turnover was the prevailing component for six boundary types, the nestedness component was only important for two boundary types. We found a significant linear increase of species dissimilarity with increasing dissimilarity in soil pH and distinct plant communities for the habitat types, but no significant increase for electrical conductivity or soil depth. Conclusions: The spatial distinctiveness of the quartz islands leads to sharp boundaries, which result in high beta diversity, mainly through species turnover. This reflects the high levels of diversification and adaptation of the local plant communities. Nestedness occurred at two boundaries to the matrix, indicating that the latter does not necessarily represent an impermeable boundary for all species of the respective ecosystem. Studying diversity patterns across boundaries contributes to the question of applicability of island biogeography theory to habitat islands.
Der Global Index of Vegetation-Plot Databases (GIVD) ist eine Metadatenbank von Vegetations - datenbanken weltweit, die im Jahr 2010 von einem internationalen Leitungsgremium ins Leben gerufen wurde und auf einem Server in Greifswald beheimatet ist. Ziel von GIVD ist es, einen besseren Überblick über die zunehmende Zahl von Vegetationsdatenbanken zu geben und ihren Inhalt für übergreifende vegetationsökologische Analysen zu erschließen. Im vorliegenden Beitrag analysieren wir, welche Daten aus Mitteleuropa (incl. Benelux-Länder) in GIVD derzeit registriert sind. Am 20. März 2011 stammten 1,35 Millionen der insgesamt registrierten 2,45 Millionen Vegetationsaufnahmen aus den 12 betrachteten Ländern. Mit über 600.000 digital verfügbaren Vegetationsaufnahmen entsprechend einer Dichte von 18 km–2 sind die Niederlande weltweit führend.