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Large-scale species and genetic metacommunity patterns are influenced by variation in environmental factors and distance between communities, according to previous studies. However, these studies often used different measures to assess patterns of metacommunity diversity, distances between communities and grain sizes at which environmental variables are measured. This hinders interpretations and generalizations of the underlying process that drive metacommunity diversity. We applied a synthetic and multi-analytical approach to identify general factors structuring the diversity of a large riverine metacommunity. Using complementing approaches we analyzed how distance, measured as Euclidean or topological distance, and environmental factors, assessed at different grain sizes, influenced different measures of metacommunity diversity (species richness, functional richness and phylogenetic diversity) of mayfly, stonefly and caddisfly species in a large river network (river Rhine, Switzerland). We found the amount of explained variation in species diversity was generally unaffected by grain size, but improved with the use of topological distance, compared to Euclidean distance. Variation in functional diversity was best explained by environmental factors at small grain sizes and topological distance. Variation in phylogenetic diversity was best explained when environmental variables were assessed at larger grain sizes and Euclidean distance was used. Overall, our results indicate that processes structuring metacommunity diversity may differ at the species, functional or phylogenetic level of the community, as recently postulated in the metacommunity–phylogenetics approach. While such differences may hinder comparisons across studies using different methodologies, it offers opportunities to disentangle the structuring factors within metacommunities by applying multiple analytical approaches to the same dataset.

Seymour, M., Deiner, K., & Altermatt, F. (2016). Scale and scope matter when explaining varying patterns of community diversity in riverine metacommunities. Basic and Applied Ecology, 17(2), 134–144. https://doi.org/10.1016/j.baae.2015.10.007

Cryptic species are phylogenetically diverged taxa that are morphologically indistinguishable and may differ in their ecological and behavioral requirements. This may have important implications for ecosystem services and conservation of biodiversity. We investigated whether two ecologically important cryptic species of the freshwater amphipod Gammarus fossarum (types A and B) are associated with different habitats. We collected data on their occurrence at both the landscape scale (large watersheds) and at the local scale (river reach) to compare macro- and microscale environmental parameters associated with their presence. Analysis of the landscape scale data showed that occurrence of types A and B differ with respect to watershed and river size and, interestingly, human impact on river ecomorphology. Whereas type B was mainly found in less forested areas with higher human impact, type A showed the opposite occurrence pattern. Analyses of the local scale data suggested that habitats occupied by type A were characterized by larger gravel, larger stones and less macrophytes than habitats occupied by type B. The landscape and local data set showed contradicting patterns with regard to stream size. Overall, the observed differences between the two types of G. fossarum most likely reflect ecological differences between them, but alternative explanations (e.g., historical colonization processes) cannot be completely ruled out. Our study underlines that common cryptic species can differ in their ecology and response to anthropogenic influence. Such differences in habitat requirements among difficult-to-identify taxa present a challenge for biodiversity and ecosystem management. Our results emphasize the importance of conservative and precautionary approaches in maintenance of habitat diversity and environmental heterogeneity.

Eisenring, M., Altermatt, F., Westram, A. M., & Jokela, J. (2016). Habitat requirements and ecological niche of two cryptic amphipod species at landscape and local scales. Ecosphere, 7(5). https://doi.org/10.1002/ecs2.1319

Setting up effective survey strategies for biodiversity monitoring in agro-ecosystems is a major task in order to detect adverse effects on biodiversity before negative changes will manifest. Here, we studied the relative costs required for the monitoring of butterflies and selected diurnal moths (Papilionoidea et Hesperioidea; Zygaenoidea: Zygaenidae) in farmland. Analysing data from a well-established Lepidoptera monitoring system in Switzerland, we assessed the influence of inspection periods, inspection frequency and transect length on counts of diurnal Lepidoptera. Furthermore, we estimated the number of transects in relation to sampling effort necessary to detect changes of a given effect size for recorded species number (and abundance). Reducing the counting frequency from seven to four inspections per season still yielded 80–90 % of the species, as long as peak abundances in summer months were included. The variation in observed species number was mostly independent of inspection frequency, but strongly increased when transect length was reduced to less than 1 km. Sedentary Lepidoptera species are especially valuable indicators as their occurrences are directly linked to local effects on biodiversity, and the proportion of recorded sedentary species was not substantially affected by reduced inspection frequency. Transects of 1–1.5 km length were generally the most cost-efficient to detect an effect on total species number of diurnal Lepidoptera in arable landscapes, given that travelling distances between transects were short. Studying effects on rare species or selected species groups would involve higher sampling intensity and costs. Surveying schemes with reduced inspection frequency and transect lengths can detect changes in species richness and total abundance of diurnal Lepidoptera cost-effectively. Facing expected changes in agricultural policy and management, the results and recommendations presented here will help to implement and improve cost-efficient Lepidoptera schemes to monitor changes in arable landscapes.

Lang, A., Bühler, C., Dolek, M., Roth, T., & Züghart, W. (2016). Estimating sampling efficiency of diurnal Lepidoptera in farmland. Journal of Insect Conservation, 20(1), 35–48. https://doi.org/10.1007/s10841-015-9837-7

To protect ecosystems and their services, the critical load concept has been implemented under the framework of the Convention on Long-range Transboundary Air Pollution (UNECE) to develop effectsoriented air pollution abatement strategies. Critical loads are thresholds below which damaging effects on sensitive habitats do not occur according to current knowledge. Here we use change-point models applied in a Bayesian context to overcome some of the difficulties when estimating empirical critical loads for nitrogen (N) from empirical data. We tested the method using simulated data with varying sample sizes, varying effects of confounding variables, and with varying negative effects of N deposition on species richness. The method was applied to the national-scale plant species richness data from mountain hay meadows and (sub)alpine scrubs sites in Switzerland. Seven confounding factors (elevation, inclination, precipitation, calcareous conte nt, aspect as well as indicator values for humidity and light) were selected based on earlier studies examining numerous environmental factors to explain Swiss vascular plant diversity. The estimated critical load confirmed the existing empirical critical load of 5e15 kgNha⁻¹yr⁻¹ for (sub)alpine scrubs, while for mountain hay meadows the estimated critical load was at the lower end of the current empirical critical load range. Based on these results, we suggest to narrow down the critical load range for mountain hay meadows to 10-15 kgNha⁻¹yr⁻¹.

Roth, T., Kohli, L., Rihm, B., Meier, R., & Achermann, B. (2017). Using change-point models to estimate empirical critical loads for nitrogen in mountain ecosystems. Environmental Pollution, 220, 1480–1487. https://doi.org/10.1016/j.envpol.2016.10.083