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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2025

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Abstract

Aim Species coexistence is based on resource partitioning and modulates biodiversity patterns across climates, latitudes and altitudes. Resource partitioning can occur via niche size or separation in the geographic range or ecological niche. While resource partitioning promotes biodiversity, the impact of different partitioning strategies on species richness remains largely unexplored. Location Two ecosystems with similar climates and ages are the species‐rich tropical alpine ecosystem in the South American Andes and the more species‐poor tropical alpine ecosystem in the eastern African mountains. Time Period Present‐day distribution and climatic conditions, integrating phylogenetic information extending back to the last 7 million years maximum. Major Taxa Studied Six lineages from the Asterales; three in each ecosystem, respectively. Methods We test whether geographic range and climatic niche partitioning strategies may explain differences in species richness between two ecosystems. We combine phylogenomic data with occurrence records and estimate metrics of size and overlap for climatic niche and geographic range. Results We show that the Andean species have larger climatic niches than the African species, suggesting that niche size is not explaining higher species richness in the Andes. Instead, a striking pattern for species with overlapping geographic ranges emerged: the Andean species show less climatic niche overlap than the African species, indicating more effective niche separation among Andean species. Main Conclusions We hypothesise that differences in resource partitioning, specifically increased niche separation among geographically overlapping species in the Andes compared to the eastern African mountains, contribute to the species richness difference between these tropical alpine biodiversity hotspots.

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Abstract

Pollinator conservation schemes typically focus on conserving existing, restoring degraded, or creating new wild bee habitats. Their effectiveness depends on dispersal corridors enabling habitat colonization by bees. However, the role of seminatural linear landscape structures (LLS) in connecting pollinator communities across intensively managed landscapes remains poorly understood. We analyzed 953 occurrences of wild bees comprising 79 nonparasitic species sampled at 68 study sites across a Norwegian and a Danish landscape. We first tested whether bee species richness was positively associated with the lengths of seminatural LLS in bee foraging ranges of study sites while controlling for local plant species richness. We then combined maps identifying seminatural LLS with least‐cost path (LCP) analysis to determine whether bee species compositional similarity, a proxy for connectivity, decreased as LCP length increased. The length of seminatural LLS, such as forest edges, was positively correlated with bee species richness and habitat connectivity. Specifically, wild bee species richness sampled along roadsides increased as the length of seminatural LLS increased in 1.5 km circles around the study sites, and increased as local plant species richness increased. The most likely dispersal routes between our bee communities tracked forest edges. The length of LCPs provided better models of bee species compositional similarity than geographic distance, suggesting that seminatural LLS, particularly forest edges, act as dispersal corridors in intensively managed landscapes. However, bee species compositional similarity among communities depended on site‐specific plant species richness and similarity in plant community composition, which highlights the importance of improving the habitat quality of seminatural LLS if they are to function as dispersal corridors. Our findings suggest that maps of LCPs can be used to identify important dispersal corridors between bee habitats and to direct wild bee habitat management actions along seminatural LLS to facilitate the dispersal of bees in intensively managed landscapes.

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Abstract

Hyperspectral imaging (HSI) captures rich spectral data across hundreds of contiguous bands for diverse applications. Dimension reduction (DR) techniques are commonly used to map the first three reduced dimensions to the red, green, and blue channels for RGB visualization of HSI data. In this study, we propose a novel approach, HSBDR-H, which defines pixel colors by first mapping the two reduced dimensions to hue and saturation gradients and then calculating per-pixel brightness based on band entropy so that pixels with high intensities in informative bands appear brighter. HSBDR-H can be applied on top of any DR technique, improving image visualization while preserving low computational cost and ease of implementation. Across all tested methods, HSBDR-H consistently outperformed standard RGB mappings in image contrast, structural detail, and informativeness, especially on highly detailed urban datasets. These results suggest that HSBDR-H can complement existing DR-based visualization techniques and enhance the interpretation of complex hyperspectral data in practical applications. Tested in remote sensing applications involving urban and agricultural datasets, the method shows potential for broader use in other disciplines requiring high-dimensional data visualization.