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The use of surrogates to identify protected areas is a common practice in conservation biology. The use of top predators as surrogates has been criticized but recently a strong positive relationship was found between the presence of top predators and species diversity of several taxa. As mentioned by the authors, these striking results need to be assessed on a larger scale.
We used data from the Swiss Biodiversity Monitoring Programme and the Swiss breeding bird survey to analyse the use of raptor species as a surrogate for plant, butterfly and bird species richness. For each raptor species, we compared species richness in sites where a raptor species was recorded and compared these sites with the remaining sites in which the raptor species was not recorded. For comparison we conducted the same analyses using tits Parus spp. Tits are common prey species of some raptor species and were the most species-rich generalist genus in our data.
We found little justification for a focus on top predators when identifying conservation areas. For bird and plant species richness, raptors were reasonable surrogates for high species richness but no raptor species predicted sites with above-average butterfly species richness.
The presence of tit species performed equally as well as the presence of raptor species to predict sites with high species richness of birds and plants, and performed even better for predicting high butterfly species richness.
Synthesis and applications. Conservation planners using indicator species should be aware that relationships among higher taxa are complex and depend on the species group and the scale of analysis. As shown with the case of raptors, the usefulness of a biodiversity indicator can vary between adjacent areas even if the same species groups are analysed. We recommend the use of more than one indicator species from different taxonomic groups when identifying areas of high biodiversity.
Roth, T., & Weber, D. (2007). Top predators as indicators for species richness? Prey species are just as useful: Predators and biodiversity. Journal of Applied Ecology, 45(3), 987–991. https://doi.org/10.1111/j.1365-2664.2007.01435.x
We present a method that permits the retrospective assessment of frequency changes in species, based on the evaluation of specimens in biological collections. The method assumes that the increase and decrease in the frequency of a species is reflected in the number of collected specimens. A comparison of the specimen numbers from different time periods allows for an evaluation of the frequency changes of a particular species, provided that the specimen numbers are corrected for the general collecting activity of each time period. We used a reference data set consisting of 10 521 specimens of 85 species to reflect general collecting activity. For 42 species of bryophytes in Switzerland, we calculated the 'relative collecting activity', i.e. the number of specimens of an individual species as a percentage of the number of specimens from the reference data set. We examined changes in the relative collecting activity between the periods 1850-1939 and 1940-1999, using a permutation test. The calculated results were further assessed, taking all background information on each single species into account. In seven cases, the resulting assessments differed from the test results. According to the assessments, 16 species showed a decline and four had increased. The frequency of seven species was considered stable. For the remaining 15, mainly rare species, reliable assessments depend on further study of their former and actual frequencies. When species analysed were arranged into three classes of rare, medium and high frequency, the results showed that the rare and medium frequency species underwent significant decline, whereas the common species were stable. The fact that 12 species of medium or high frequency have most probably declined is of particular interest.
Hofmann, H., Urmi, E., Bisang, I., Müller, N., Küchler, M., & Schubiger, C. (2007). Retrospective assessment of frequency changes in Swiss bryophytes over the last two centuries. Lindbergia, 32, 18–32.
In der 69. Folge der Forschritte (Bäumler et al. 2005) wurden die ersten Daten 2001-2003 des Biodiversitäts-Monitoring Schweiz (BDM) mit dem Verbreitungsatlas der Schweizer Flora verglichen (Welten und Sutter 1982, Nachträge 1984, 1994). Die Erfassung der gesamten Schweiz (vgl. Messnetze in Abb. 1) ist beim BDM auf 5 Jahre angesetzt. Im vorliegenden Beitrag werden nun die mit dem vollständigen Datensatz 2001-2005 aktualisierten Resultate und Grafiken der Folge 69 erneut publiziert.
Latour, C., & Bäumler, B. (2007). Fortschritte in der Floristik der Schweizer Flora (Gefässpflanzen). 74. Folge: Aktualisierte Resultate (Daten 2001-2005) zum Vergleich des Verbreitungsatlas mit den ersten Daten 2001-2003 des Biodiversitäts-Monitoring Schweiz (69. Folge). Botanica Helvetica.
Habitat fragmentation, patch quality and landscape structure are important predictors for species richness. However, conservation strategies targeting single species mainly focus on habitat patches and neglect possible effects of the surrounding landscape. This project assesses the impact of management, habitat fragmentation and landscape structure at different spatial scales on the distribution of three endangered butterfly species, Boloria selene, Boloria titania and Brenthis ino. We selected 36 study sites in the Swiss Alps differing in (1) the proportion of suitable habitat (i.e., wetlands); (2) the proportion of potential dispersal barriers (forest) in the surrounding landscape; (3) altitude; (4) habitat area and (5) management (mowing versus grazing). Three surveys per study site were conducted during the adult flight period to estimate occurrence and density of each species. For the best disperser B. selene the probability of occurrence was positively related to increasing proportion of wetland on a large spatial scale (radius: 4,000 m), for the medium disperser B. ino on an intermediate spatial scale (2,000 m) and for the poorest disperser B. titania on a small spatial scale (1,000 m). Nearby forest did not negatively affect butterfly species distribution but instead enhanced the probability of occurrence and the population density of B. titania. The fen-specialist B. selene had a higher probability of occurrence and higher population densities on grazed compared to mown fens. The altitude of the habitat patches affected the occurrence of the three species and increasing habitat area enhanced the probability of occurrence of B. selene and B. ino. We conclude that, the surrounding landscape is of relevance for species distribution, but management and habitat fragmentation are often more important. We suggest that butterfly conservation should not focus only on a patch scale, but also on a landscape scale, taking into account species-specific dispersal abilities.
Cozzi, G., Müller, C. B., & Krauss, J. (2008). How do local habitat management and landscape structure at different spatial scales affect fritillary butterfly distribution on fragmented wetlands? Landscape Ecology, 23(3), 269–283. https://doi.org/10.1007/s10980-007-9178-3
Aim We predict fine-scale species richness patterns at large spatial extents by linking a systematic sample of vascular plants with a multitude of independent environmental descriptors.
Location Switzerland, covering 41,244 km2 in central Europe.
Methods Vascular plant species data were collected along transects of 2500-m length within 1-km2 quadrats on a systematic national grid (n = 354), using a standardized assessment method. Generalized linear models (GLM) were used to correlate species richness of vascular plants per transect (SRt) with three sets of variables: topography, environment and land cover. Regression models were constructed by the following process: reduction of collinearity among variables, model selection based on Akaike’s information criterion (AIC), and the percentage of deviance explained (D2). A synthetic model was then built using the best variables from all three sets of variables. Finally, the best models were used in a predictive mode to generate maps of species richness (SRt) at the landscape scale using the moving window approach based on 1-km2 moving windows with a resolution of 1 ha.
Results The best explanatory model consisted of seven variables including 14 linear and quadratic parameters, and explained 74% of the deviance (D2 = 0.742). Used in a predictive mode, the model generated maps with distinctive horizontal belts of highest species richness at intermediate altitudes along valley slopes. Belts of higher richness were also present along rivers and around large forest patches and larger villages, as well as on mountains.
Main conclusions The approach involved using consistent samples of species linked to information on the environment at a fine scale enabled landscapes to be compared in terms of predicted species richness. The results can therefore be applied to support the development of national nature conservation strategies. At the landscape scale, belts of high species richness correspond to steep environmental gradients and associated increases in local habitat diversity. In the mountains, the belts of increased species richness are at intermediate altitudes. These general belt-like patterns at mid-elevation are found in all model parameterizations. Other patterns, such as belts along rivers, are visible in specific parameterizations only. Thus we recommend using several sets of parameters in such modelling studies in order to capture the underlying spatial complexity of biodiversity.
Wohlgemuth, T., Nobis, M. P., Kienast, F., & Plattner, M. (2008). Modelling vascular plant diversity at the landscape scale using systematic samples. Journal of Biogeography, 35(7), 1226–1240. https://doi.org/10.1111/j.1365-2699.2008.01884.x
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Das Hotspot Sonderheft zu 20 Jahren BDM zeigt, wer hinter den Daten steckt und beleuchtet aktuelle Entwicklungen der Biodiversität.
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