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Nitrogen (N) deposition is a major threat to biodiversity of many habitats in the lowlands. In mountain habitats, however, the effect of N deposition on biodiversity is not well understood. Here, data from the biodiversity monitoring of Switzerland were used to investigate whether high N deposition is negatively related to species richness and community uniqueness of vascular plants and bryophytes in mountain grassland. The total species diversity, as well as the diversity of three subsets of species (i.e. oligotrophic species, eutrophic species and targeted grassland species according to conservation objectives of the Swiss authorities) were analyzed. Overall, the empirical data from the present study indicate that the currently expert-based range of the critical load of N deposition below which harmful effects on sensitive ecosystems should not occur (upper bound is currently at 20 kg N ha −1 yr −1 ) is set too large for mountain hay meadows. Negative relations between N deposition and species richness and community uniqueness in mountain grassland were found already at 10–15 kg N ha −1 yr −1. The results suggest that the negative effect of N deposition on plant diversity is mainly due to a decrease of oligotrophic plant species and to a lesser extent to an increase in eutrophic plant species. While for bryophytes, the decrease of community uniqueness is related to changes in both oligotrophic and eutrophic species. Furthermore, because plant species richness of target species for conservation was negatively related to N deposition, airborne N deposition is likely to defeat conservation efforts in mountain grassland.
Roth, T., Kohli, L., Rihm, B., & Achermann, B. (2013). Nitrogen deposition is negatively related to species richness and species composition of vascular plants and bryophytes in Swiss mountain grassland. Agriculture, Ecosystems & Environment, 178, 121–126. https://doi.org/10.1016/j.agee.2013.07.002
Trait variation across species plays a fundamental role in ecology and evolution, but quantitative analyses of key life-history traits under natural conditions generally do not include a large number of species. In a comparative study, we analyzed interspecific variation in adult age as a minimum estimate of the lifespan of 708 vascular plant species along elevational gradients from 263–3175 m a.s.l. and compared this variation with predictions from r-K selection theory and the metabolic theory of ecology (MTE). Age data based on annual ring counts of root collars and rhizomes were combined with a systematic sample of current species distributions in Switzerland (453 plots, each 1 km2). Elevation and temperature trends were investigated by regression analyses of the variation in adult age across species and species assemblages (median adult age) at the landscape level. We included climate, land use and geology as environmental predictors in multiple regressions and considered phylogeny by eigenvector filtering. We found a general increase in adult age towards higher elevations at the level of overall interspecific variation, and this trend was also detectable within individual plant families. Species generally had a shorter lifespan under warmer climates and, in agreement with r-K prediction, in lowland agricultural landscapes. We found an exponential adult age–temperature relationship that is consistent with MTE. The estimate of the MTE parameter ‘activation energy’ for median adult age in multiple regression was 0.65 eV (95% CI 0.62–0.69 eV) which coincided with the predicted range of 0.60–0.70 eV. Our results imply that climate warming could accelerate species turnover rates by favoring short-lived species over the whole range of life histories and species assemblages. Besides the strong temperature relationship, residual variability and confounding factors demonstrate the need for additional research about interactions between broad-scale constraints and more local drivers of life-history variation.
Nobis, M. P., & Schweingruber, F. H. (2013). Adult age of vascular plant species along an elevational land‐use and climate gradient. Ecography, 36(10), 1076–1085. https://doi.org/10.1111/j.1600-0587.2013.00158.x
Imperfect detection can seriously bias conventional estimators of species distributions and species richness. Plant traits, survey-specific conditions and site-specific characteristics may influence plant detection probability. However, the generality of the problems induced by imperfect detection in plants and the magnitude of this challenge for plant distribution studies are currently unknown.
We address this question based on data from the Swiss Biodiversity Monitoring, in which vascular plants are surveyed twice in the same year along a 2.5-km transect in 451 1-km2 quadrats. Overall, 1700 species were recorded. We chose a random sample of 100 species from the 1700 species to determine general detection levels. To examine the relationship of covariates on detection, we chose a stratified random sample of 100 species from 886 species that were detected in at least 18 locations, with 25 each from four life-forms (LF): grass, forb, shrub and tree. Using a Bayesian multispecies site-occupancy model, we estimated occurrence and detection probability of these species and their relation to covariates.
Based on the random sample of 100 species, detection probability during the first survey ranged 0.03–0.99 (median 0.74) and during the second survey, 0.03–0.99 (median 0.82). Based on the stratified random sample of 100 species, detection probability during the first survey ranged 0.02–0.99 (median 0.87) and during the second survey, 0.01–1 (median 0.89). Detection probability differed slightly among the four LFs. In 60 species, survey season or elevation had significant effects on detection. We illustrated detection probability maps for Switzerland based on the modelled relationships with environmental covariates.
Synthesis. Our findings suggest that even in a standardized monitoring program, imperfect detection of plants may be common. With the absence of a correction for detection errors, maps in plant distribution studies will be confounded with spatial patterns in detection probability. We presume that these problems will be much more widespread in the data sets that are used for conventional plant species distribution modelling. Imperfect detection should be estimated, even in distribution studies of plants and other sessile organisms, to better control detection errors that may compromise the results of species distribution studies.
Chen, G., Kéry, M., Plattner, M., Ma, K., & Gardner, B. (2013). Imperfect detection is the rule rather than the exception in plant distribution studies. Journal of Ecology, 101(1), 183–191. https://doi.org/10.1111/1365-2745.12021
Extensively cultivated permanent grassland with a high species diversity has strongly decreased in Switzerland over the last decades owing to agricultural intensification and abandonment. The question arises which diversity of species can still be found in the current ‘usual’ cultural landscape of Switzerland and how it differs from extensively cultivated permanent grasslands.
The study presented analyses the species diversity and species composition in select extensively cultivated permanent grasslands, and it compares the findings with average values of the species diversity of vascular plants, mosses and snails according to the ‘Biodiversity Monitoring Switzerland’.
Currently cultivated permanent grasslands in the Swiss average still show a high species diversity in the three species groups compared to traditional land use forms. Whilst for vascular plants the average number of species in extensively used grasslands is higher than the national average on comparable sites, the analysis showed no difference for mosses and snails. Additionally, the vascular plants included more indicator and character species and more plant species of the Red List on extensively cultivated grassland. The differences of the species composition of vascular plants between extensively cultivated permanent grassland and the nationwide average values can be ascribed to nutrient gradients.
Schlup, B., Stalling, T., Plattner, M., & Weber, D. (2013). Die Artenvielfalt des durchschnittlichen Dauergrünlands der Schweiz. Ein Vergleich zu naturschutzfachlich wertvollen Wiesen und Weiden. Naturschutz und Landschaftsplanung 45: 013-020.
Aim
Spatial dynamics and habitat connectivity affect community composition and diversity in many ecosystems. For many decades, diversity patterns in riverine ecosystems were thought to be related to local environmental conditions. Recent theoretical work, however, suggests that diversity in rivers is strongly affected by dispersal along the dendritic landscape structure and that environmental conditions are intrinsically linked to the network position. In this study we tested hypotheses on network position by relating river network geometry and connectivity to multi-level biodiversity patterns across large scales.
Location
Three major alpine drainage basins in Switzerland were studied (Rhine, Rhone, Ticino), extending over an elevational gradient of > 2500 m and covering a total area of 41,285 km2km2.
Methods
We sampled all may-, stone- and caddisfly species at 217 sites which representatively cover the three river networks. Using generalized additive models, we related diversity patterns in aquatic insects to centrality within the network as a direct river network property, and to catchment area and elevation , which are related to network position.
Results
Centrality within the river network, and catchment area and elevation had significant and interacting effects on α-diversity and community similarity. Alpha diversity was lowest in peripheral headwaters and at high elevations. Species richness generally increased with increasing catchment area. Well-connected, central communities within the river network had greater α-diversity than more peripheral communities did. Elevation was a strong predictor of α-diversity, with the most diverse communities found at mid-elevation sites. Community similarity decreased with increasing along-stream distance between sites.
Main conclusions
Our results highlight the fact that diversity patterns of aquatic insects in river systems are related to local factors such as elevation, but interact with network properties and connectivity along waterways, and differ among insect orders. These findings are consistent with dispersal-limited processes and indicate that riverine diversity should be addressed and protected taking the river network structure into account.
Altermatt, F., Seymour, M., & Martinez, N. (2013). River network properties shape α-diversity and community similarity patterns of aquatic insect communities across major drainage basins. Journal of Biogeography, 40(12), 2249–2260. https://doi.org/10.1111/jbi.12178
- Thermal niches are more conserved at cold than warm limits in arctic-alpine plant species: Thermal limits in arctic-alpine plants.
- Land use impacts on biodiversity in LCA: A global approach.
- Plants, Birds and Butterflies: Short-Term Responses of Species Communities to Climate Warming Vary by Taxon and with Altitude.
- Host plant availability potentially limits butterfly distributions under cold environmental conditions.
Sonderheft Hotspot
Das Hotspot Sonderheft zu 20 Jahren BDM zeigt, wer hinter den Daten steckt und beleuchtet aktuelle Entwicklungen der Biodiversität.
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