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The intensification of agricultural practices has led to an alarming decline in farmland biodiversity. With the aim of stopping and even reversing this trend, biodiversity promotion areas (BPA – formerly named «ecological compensation areas») were introduced in the 1990s. In this study, the influence of BPA on the biodiversity of butterflies and breeding birds was investigated in 46 landscape squares of 1 km². If the proportion of BPA in the landscape increased from 5 % to 15 %, the butterfly species richness increased by 22 % and that of birds by 10 %. In the case of birds, farmland and AEO (agriculture-related environmental objectives) priority species primarily benefited from BPA with high ecological quality, though these were rare in most landscapes. For both taxonomic groups, the proportion and quality of BPA habitats was more important than their spatial configuration, including the distances between them. Our study at the landscape scale illustrates the important role of biodiversity promotion areas and highlights their positive effect on biodiversity in the intensively farmed Swiss agricultural landscape.

Ritschard, E., Zingg, S., Arlettaz, R., & Humbert, J. Y. (2019). Biodiversitätsförderflächen: Vögel und Tagfalter profitieren von der Fläche und Qualität. Agrarforschung Schweiz 10 (5): 206–213, 2019

Moving beyond species count data is an essential step to better understand the effects of environmental perturbations on biodiversity and ecosystem functions, and to eventually better predict the strength and direction of those effects. Here, coupling an integrative path analysis approach with data from an extensive countrywide monitoring program, we tested the main spatial, environmental and anthropogenic drivers of change in the functional structure of aquatic macroinvertebrate communities along the entire Swiss Rhine river catchment. Functional structure was largely driven by inherent altitudinal variation influencing and cascading to regional scaled factors such as land use change and position in the riverine network, which, in turn, transformed local habitat structure variables. Those cascading effects across scales propagated through the biotic community, first affecting prey and, in turn, predators. Our results illustrate how seemingly less important local factors can act as essential transmission belts, propagating through direct and indirect pathways across scales to generate the specific context in which each functional group will strive or not, leading to characteristic landscape wide variations in functional community structure.

Harvey, E., & Altermatt, F. (2019). Regulation of the functional structure of aquatic communities across spatial scales in a major river network. Ecology, 100(4). https://doi.org/10.1002/ecy.2633

Aim

Species distribution models (SDMs) are widely used to study geographic distributions of taxa in response to natural and anthropogenic environmental conditions. For a community, common approaches include fitting individual SDMs (iSDMs) to all taxa or directly modelling community properties such as richness. However, the parameters of iSDMs are difficult to identify for rare taxa, and community properties do not reveal taxon-specific responses. Individual models can be combined into a hierarchical multispecies distribution model (mSDM) that constrains taxon-specific parameters according to overarching community parameters, or a joint model (jSDM) in which interdependencies between taxa are jointly inferred. We compare how individual, hierarchical multispecies and joint SDMs differ in quality of fit, explanatory power and predictive performance, and analyse how these properties depend on the prevalence of taxa.

Taxa

Presence–absence observations of 245 benthic macroinvertebrate taxa identified at a mixed taxonomic resolution.

Location

Four hundred and ninety-two sites in rivers throughout Switzerland.

Methods

Individual, hierarchical and joint hierarchical generalized linear models (GLM) were developed for all taxa. Parameters were estimated using maximum likelihood estimation or Bayesian inference with Hamiltonian Markov chain Monte Carlo simulations. Predictive performance was assessed with cross-validation. In addition, the predicted family and species richness of the models was compared with a GLM for richness.

Results

Individual models show a slightly higher quality of fit largely due to overfitting for rare taxa. The mSDM achieves a similar quality of fit and explanatory power, mitigates overfitting for rare taxa and considerably improves predictive performance over the whole community. The joint models further improve the quality of fit, but decrease predictive performance and increase predictive uncertainty.

Main conclusions

We show that even a relatively simple mSDM combines many of the analytical capabilities of iSDMs and improves predictive performance. Increasingly complex mSDMs and jSDMs provide additional analytical possibilities, but depending on the data and research questions, different levels of complexity may be appropriate.

Caradima, B., Schuwirth, N., & Reichert, P. (2019). From individual to joint species distribution models: A comparison of model complexity and predictive performance. Journal of Biogeography, 46(10), 2260–2274. https://doi.org/10.1111/jbi.13668

Seit 2010 werden Gewässerinvertebraten im Biodiversitätsmonitoring Schweiz (BDM) an etwa 500 regelmässig über die Schweiz verteilten Probenahmestellen erfasst. Sowohl hohe Insektizidanwendungsraten im Einzugsgebiet als auch geringe Naturnähe der Gewässer wirken sich negativ auf die Gewässerinvertebraten aus. Gegenwärtig scheint aber besonders die Erwärmung der Gewässer zu tief greifenden Veränderungen der Artgemeinschaften in den Schweizer Fliessgewässern zu führen.

Hutter, P., Roth, T., Martinez, N., Stucki, P., & Litsios, G. (2019). Fliessgewässer-Fauna unter Druck. Erste Trends aus dem Biodiversitätsmonitoring Schweiz (BDM). AQUA & GAS 7/8, 2019.