Community assembly across Subarctic landscapes

• Main Author: de La Peña Aguilera, Pablo
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2024
• Subjects: Ecology; Subarctic
• Online Access: https://pub.epsilon.slu.se/33538/; https://pub.epsilon.slu.se/33538/3/de-la-pena-aguilera-p-2024-05-06.pdf

This thesis delves into the mechanisms driving community assembly, focusing on the impacts of environmental filtering and dispersal limitation on species richness and composition. I explore diversity patterns in vascular plants, soil fungi, and arthropods across two subarctic landscapes and at different spatial scales. As a background, I characterize the similarity in conditions between the two study areas and quantify patterns of alpha, beta and gamma diversity among the target taxa. I then relate these patterns to variation in microclimate, in productivity, and in the dispersal capacity of each taxon. In particular, I examine the influence of microclimatic conditions on species richness and abundance of arthropods and plants, and the similarity in taxon-specific responses to similar drivers. To test for an association between productivity and diversity, I examine alpha and beta diversity patterns of arthropods across productivity gradients at the local, landscape and regional scales, and test for scaledependencies in the patterns observed. Finally, I assess how community dissimilarity varies among taxa across the landscape. Across the two subarctic regions, I found highly similar microclimatic conditions and productivity gradients. In both regions, species richness generally decreases with elevation and increases with soil temperature and moisture. The increase in arthropod richness along productivity gradients is consistent across scales, but plant richness shows weak relationships with arthropod richness. Higher species richness at lower elevations is attributable to species niche shapes, with a majority of “productivitygeneralist” species covering the entire productivity gradient, and a minority of “productivityspecialist” species occurring exclusively at either low- or high-productivity sites – with the latter group being more specious. Higher species richness in high-productive areas did not translate into any greater dissimilarity in community composition. Moreover, highly dispersive species exhibit ...