Department Aquatic Ecology

Conserving natural ecosystems requires consistent and standardized biodiversity data to advance scientific research and ecological understanding. Despite several national initiatives to develop databases of species habitat suitability maps, even well-studied countries often lack comprehensive, standardized databases that cover a wide range of taxonomic groups modelled using a consistent framework. Using Switzerland as a case study, we demonstrate how these gaps can be addressed by introducing SDMapCH (v1.3), a nationwide raster database of species habitat suitability maps at 25-meter resolution. SDMapCH provides maps for about 7,500 species under both present conditions and future climate scenarios. SDMapCH was developed using the N-SDM software, an end-to-end platform based on a spatially-nested hierarchical framework. N-SDM allows multi-level integration of species and covariate data, helping to address niche truncation. SDMapCH outputs were evaluated using a state-of-the-art cross-validation procedure, and all layers passed a systematic data integrity check. By providing standardized, high-resolution habitat suitability maps for diverse species across various taxonomic and functional groups, SDMapCH stands as a key resource for scientific research and biodiversity assessments.

Climate projections for continental Europe indicate drier summers, increased annual precipitation, and less snowy winters, which are expected to cause shifts in species' distributions. Yet, most regions/countries currently lack comprehensive climate-driven biodiversity projections across taxonomic groups, challenging effective conservation efforts. To address this gap, our study evaluated the potential effects of climate change on the biodiversity of an alpine country of Europe, Switzerland. We used a state-of-the art species distribution modeling approach and species occurrence data that covered the climatic conditions encountered across the full species' ranges to help limiting niche truncation. We quantified the relationship between baseline climate and the spatial distribution of 7291 species from 12 main taxonomic groups and projected future climate suitability for three 30-year periods and two greenhouse gas concentration scenarios (RCP4.5 and 8.5). Our results indicated important effects of projected climate changes on species' climate suitability, with responses varying by the taxonomic and conservation status group. The percentage of species facing major changes in climate suitability was higher under RCP8.5 (68%) compared to RCP4.5 (66%). By the end of the century, decreases in climate suitability were projected for 3000 species under RCP8.5 and 1758 species under RCP4.5. The most affected groups under RCP8.5 were molluscs, algae, and amphibians, while it was molluscs, birds, and vascular plants under RCP4.5. Spatially, by 2070–2099, we projected an overall decrease in climate suitability for 39% of the cells in the study area under RCP8.5 and 10% under RCP4.5, while projecting an increase for 50% of the cells under RCP8.5 and 73% under RCP4.5. The most consistent geographical shifts were upward, southward, and eastward. We found that the coverage of high climate suitability cells by protected areas was expected to increase. Our models and maps provide guidance for spatial conservation planning by pointing out future climate-suitable areas for biodiversity.

Choosing the appropriate scale for measuring environmental predictors is needed for accurately modelling species distributions. This need is becoming increasingly important with the use of high-resolution species distribution models (SDMs), emphasizing the challenge of aligning predictors with the spatial and ecological scales at which species interact with their environments. Focal predictors, which summarize landscape information within a spatially moving window, are powerful to account for neighboring information and scale dependency but have remained overlooked in SDMs. Using an automated selection procedure to identify the best predictors and measurement scales from a high-dimensional pool of candidates, including 13 nested circular focal sizes from 25 m to 5 km radius for each landscape feature, this study evaluated the use of focal predictors through a set of national-scale, high-resolution SDMs for more than 7000 species across 17 major taxonomic groups. It further examined whether focal selection depended on species' mobility or body size. Among all species, focal predictors were selected at least once in ≥ 94% of the SDMs, highlighting their important role. For mobile species, larger focal windows were selected for the land use and land cover category, whereas sessile species were associated with larger focal windows for topographic predictors. For small species, predictors with smaller focal windows were more often selected. Given the importance of focal predictors across all studied taxa, adjusting the optimal scale for each predictor and species is of utmost importance to improve model performance and account for species' scale dependency.