Browsing by Author "Chiarucci, Alessandro"
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- Fine‐grain beta diversity of Palaearctic grassland vegetationPublication . Dembicz, Iwona; Dengler, Jürgen; Steinbauer, Manuel J.; Matthews, Thomas J.; Bartha, Sándor; Burrascano, Sabina; Chiarucci, Alessandro; Filibeck, Goffredo; Gillet, François; Janišová, Monika; Palpurina, Salza; Storch, David; Ulrich, Werner; Aćić, Svetlana; Boch, Steffen; Campos, Juan Antonio; Cancellieri, Laura; Carboni, Marta; Ciaschetti, Giampiero; Conradi, Timo; De Frenne, Pieter; Dolezal, Jiri; Dolnik, Christian; Essl, Franz; Fantinato, Edy; García‐Mijangos, Itziar; Giusso del Galdo, Gian Pietro; Grytnes, John‐Arvid; Guarino, Riccardo; Güler, Behlül; Kapfer, Jutta; Klichowska, Ewelina; Kozub, Łukasz; Kuzemko, Anna; Löbel, Swantje; Manthey, Michael; Marcenò, Corrado; Mimet, Anne; Naqinezhad, Alireza; Noroozi, Jalil; Nowak, Arkadiusz; Pauli, Harald; Peet, Robert K.; Pellissier, Vincent; Pielech, Remigiusz; Terzi, Massimo; Uğurlu, Emin; Valkó, Orsolya; Vasheniak, Iuliia; Vassilev, Kiril; Vynokurov, Denys; White, Hannah J.; Willner, Wolfgang; Winkler, Manuela; Wolfrum, Sebastian; Zhang, Jinghui; Biurrun, IdoiaQUESTIONS: Which environmental factors influence fine-grain beta diversity of vegetation and do they vary among taxonomic groups? LOCATION: Palaearctic biogeographic realm. METHODS: We extracted 4,654 nested-plot series with at least four different grain sizes between 0.0001 m² and 1,024 m² from the GrassPlot database, covering a wide range of different grassland and other open habitat types. We derived extensive environmental and structural information for these series. For each series and four taxonomic groups (vascular plants, bryophytes, lichens, all), we calculated the slope parameter (z-value) of the power law species–area relationship (SAR), as a beta diversity measure. We tested whether z-values differed among taxonomic groups and with respect to biogeographic gradients (latitude, elevation, macroclimate), ecological (site) characteristics (several stress–productivity, disturbance and heterogeneity measures, including land use) and alpha diversity (c-value of the power law SAR). RESULTS: Mean z-values were highest for lichens, intermediate for vascular plants and lowest for bryophytes. Bivariate regressions of z-values against environmental variables had rather low predictive power (mean R² = 0.07 for vascular plants, less for other taxa). For vascular plants, the strongest predictors of z-values were herb layer cover (negative), elevation (positive), rock and stone cover (positive) and the c-value (U-shaped). All tested metrics related to land use (fertilization, livestock grazing, mowing, burning, decrease in naturalness) led to a decrease in z-values. Other predictors had little or no impact on z-values. The patterns for bryophytes, lichens and all taxa combined were similar but weaker than those for vascular plants. CONCLUSIONS: We conclude that productivity has negative and heterogeneity positive effects on z-values, while the effect of disturbance varies depending on type and intensity. These patterns and the differences among taxonomic groups can be explained via the effects of these drivers on the mean occupancy of species, which is mathematically linked to beta diversity.
- Species–area relationships in continuous vegetation : Evidence from Palaearctic grasslandsPublication . Dengler, Jürgen; Matthews, Thomas J.; Steinbauer, Manuel J.; Wolfrum, Sebastian; Boch, Steffen; Chiarucci, Alessandro; Conradi, Timo; Dembicz, Iwona; Marcenò, Corrado; García‐Mijangos, Itziar; Nowak, Arkadiusz; Storch, David; Ulrich, Werner; Campos, Juan Antonio; Cancellieri, Laura; Carboni, Marta; Ciaschetti, Giampiero; De Frenne, Pieter; Dolezal, Jiri; Dolnik, Christian; Essl, Franz; Fantinato, Edy; Filibeck, Goffredo; Grytnes, John‐Arvid; Guarino, Riccardo; Güler, Behlül; Janišová, Monika; Klichowska, Ewelina; Kozub, Łukasz; Kuzemko, Anna; Manthey, Michael; Mimet, Anne; Naqinezhad, Alireza; Pedersen, Christian; Peet, Robert K.; Pellissier, Vincent; Pielech, Remigiusz; Potenza, Giovanna; Rosati, Leonardo; Terzi, Massimo; Valkó, Orsolya; Vynokurov, Denys; White, Hannah; Winkler, Manuela; Biurrun, IdoiaAIM: Species-area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location Palaearctic grasslands and other non-forested habitats. TAXA: Vascular plants, bryophytes and lichens. METHODS: We used the GrassPlot database, containing standardized vegetation-plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested-plot series with at least seven grain sizes ranging from 1 cm(2) to 1,024 m(2). Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis-Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types. RESULTS: The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law. MAIN CONCLUSIONS: We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis-Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.