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Butterfly monitoring and Red List programs in Switzerland rely on a combination of observations and collection records to document changes in species distributions through time. While most butterflies can be identified using morphology, some taxa remain challenging, making it difficult to accurately map their distributions and develop appropriate conservation measures. In this paper, we explore the use of the DNA barcode (a fragment of the mitochondrial gene COI) as a tool for the identification of Swiss butterflies and forester moths (Rhopalocera and Zygaenidae). We present a national DNA barcode reference library including 868 sequences representing 217 out of 224 resident species, or 96.9% of Swiss fauna. DNA barcodes were diagnostic for nearly 90% of Swiss species. The remaining 10% represent cases of para- and polyphyly likely involving introgression or incomplete lineage sorting among closely related taxa. We demonstrate that integrative taxonomic methods incorporating a combination of morphological and genetic techniques result in a rate of species identification of over 96% in females and over 98% in males, higher than either morphology or DNA barcodes alone. We explore the use of the DNA barcode for exploring boundaries among taxa, understanding the geographical distribution of cryptic diversity and evaluating the status of purportedly endemic taxa. Finally, we discuss how DNA barcodes may be used to improve field practices and ultimately enhance conservation strategies.

Litman, J., Chittaro, Y., Birrer, S., Praz, C., Wermeille, E., Fluri, M., Stalling, T., Schmid, S., Wyler, S., & Gonseth, Y. (2018). A DNA barcode reference library for Swiss butterflies and forester moths as a tool for species identification, systematics and conservation. PLOS ONE, 13(12), e0208639. https://doi.org/10.1371/journal.pone.0208639

Land use change strongly affects soil organic carbon (SOC), which is a critical driving force for soil quality and soil services. However, the influence of detailed land use dynamics on SOC remains an active research field. We investigated the impact of long-term grass-/cropland conversion dynamics on SOC for the Swiss agroecosystem (8‵500 km²). In Switzerland multi-temporal SOC observations are sparse, while the spatio-temporal resolution of available land use data is inadequate to capture small structured and dynamic land use. Thus, we stratified one-time SOC observations of two periods (n_{1995–1999​} = 1096; n_2011–2015​ = 502) into typical land use classes of grass-/cropland conversion regimes to analyze states and trends of SOC. First, based on spectral imagery and auxiliary variables, we established a Random Forest classifier to detect annual grass-/cropland distributions in a spatial resolution of 30 × 30 m for 2000–2015. Second, we used the annual land use maps to derive classes of typical land use dynamics based on a pattern description of conversion regimes. Third, we comparatively assessed the SOC covariate importance (IMP) and SOC sample representation of land use dynamics using terrain and climate covariates. Subsequently, we statistically analyzed SOC across land use dynamics and two periods. The land use classifier shows an Overall Accuracy of 86%, while the annual land use maps deviate by 6%–11% from census data. 46% of the farmland underlies frequent grass-/cropland conversions. The SOC covariate importance of land use dynamics is increased by at least 2.4 times compared to the SOC covariates. The SOC observations consistently represent land use dynamics across SOC covariates. In both periods, SOC increased as the grassland share within the land use regimes increased. The mean SOC for permanent grasslands is 35 g kg^-1 and 17 g kg^-1 for permanent croplands. Areas of land use conversions where grassland is dominant show increased SOC (29–30 g kg⁻¹) compared to areas where cropland was dominant (23–25 g kg⁻1). The mean differences of SOC between the periods and classes are statistically not significant except for permanent cropland, for which the SOC is decreased by 5.2 g kg^-1.

Stumpf, F., Keller, A., Schmidt, K., Mayr, A., Gubler, A., & Schaepman, M. (2018). Spatio-temporal land use dynamics and soil organic carbon in Swiss agroecosystems. Agriculture, Ecosystems & Environment, 258, 129–142. https://doi.org/10.1016/j.agee.2018.02.012

Functional traits are increasingly being used to understand the response of species to environmental change and their effects on ecosystem functioning. However, some ecologically important traits, such as plant height, influence the probability of species detection during field surveys. Imperfect detection of species could therefore bias measures of functional trait composition and diversity, leading to incorrect estimates of trait–environment relationships due to a process of “detection filtering.” The importance of detection filtering for functional ecological studies remains unknown.

We used hierarchical models that account for detection filtering to analyse data on 1,296 vascular plant species sampled in 362 1-km² plots, distributed along a 2,460-m elevational gradient in Central Europe. We examined how detection filtering altered measures of functional diversity (multivariate functional richness and packing) and composition (community means of three traits). We also determined whether the strength of detection filtering varied over the gradient, to determine whether detection filtering biased trait–environment relationships.

Species detectability was correlated with all three functional traits tested in this study, meaning that short species with small seeds and high specific leaf area values were less likely to be detected. This suggests that imperfect detection has the potential to bias measures of functional composition. Generally, measures of functional composition were not strongly affected by detection filtering, but functional packing was underestimated when detection filtering was not accounted for. In addition to the traits, distributional characteristics were important; rare species and species occurring mainly at low elevations tended to have lower detection probabilities.

Overall, detection filtering did not strongly bias trait–environment relationships because the effects of the environment on functional composition and diversity were larger than the effects of detection.

Our results suggest that many measures of functional composition and diversity are robust to detection filtering, but some are likely biased. Functional ecologists should consider correcting for imperfect detection, and our approach provides a simple method to do so for a wide range of datasets.

Roth, T., Allan, E., Pearman, P. B., & Amrhein, V. (2018). Functional ecology and imperfect detection of species. Methods in Ecology and Evolution, 9(4), 917–928. https://doi.org/10.1111/2041-210X.12950

Nitrogen (N) deposition is a major threat to biodiversity in many habitats. The recent introduction of cleaner technologies in Switzerland has led to a reduction in the emissions of nitrogen oxides, with a consequent decrease in N deposition. We examined different drivers of plant community change, that is, N deposition, climate warming, and land-use change, in Swiss mountain hay meadows, using data from the Swiss biodiversity monitoring program. We compared indicator values of species that disappeared from or colonized a site (species turnover) with the indicator values of randomly chosen species from the same site. While oligotrophic plant species were more likely to colonize, compared to random expectation, we found only weak shifts in plant community composition. In particular, the average nutrient value of plant communities remained stable over time (2003–2017). We found the largest deviations from random expectation in the nutrient values of colonizing species, suggesting that N deposition or other factors that change the nutrient content of soils were important drivers of the species composition change over the last 15 years in Swiss mountain hay meadows. In addition, we observed an overall replacement of species with lower indicator values for temperature with species with higher values. Apparently, the community effects of the replacement of eutrophic species with oligotrophic species was outweighed by climate warming. Our results add to the increasing evidence that plant communities in changing environments may be relatively stable regarding average species richness or average indicator values, but that this apparent stability is often accompanied by a marked turnover of species.

Roth, T., Kohli, L., Bühler, C., Rihm, B., Meuli, R. G., Meier, R., & Amrhein, V. (2019). Species turnover reveals hidden effects of decreasing nitrogen deposition in mountain hay meadows. PeerJ, 7, e6347. https://doi.org/10.7717/peerj.6347