Environmental Drivers of Taxonomic, Functional, and Phylogenetic Diversity in Temperate Forest Ecosystems

Abstract

Accelerated global biodiversity loss critically threatens forest ecosystem multifunctionality and service provision. Understanding environmental drivers across taxonomic (TD), functional (FD), and phylogenetic (PD) biodiversity facets is essential for effective conservation. However, the multi-dimensional nature of biodiversity is difficult to assess, and many studies overlook the interplay between functional traits and evolutionary history within a community. Here, we use Hill numbers to integrate TD, FD, and PD across five ecologically distinct taxa (birds, butterflies, snails, vascular plants, and mosses) to better understand environmental factors driving forest biodiversity in Switzerland. We included micro- and macroclimatic conditions, soil properties, topography, and vegetation structure and diversity. Our results highlight the intricate, taxon-specific nature of environmental effects on biodiversity. Across taxa, vegetation structure and diversity, and climatic factors emerged as key drivers of biodiversity facets, while soil characteristics mostly influenced less-mobile taxa. Vegetation structure and diversity acted as strong ecological filters shaping species richness and traits, reflecting responsiveness to short-term dynamics like disturbance or management, but were weak predictors of PD. Conversely, more temporally stable abiotic factors such as climate and soil conditions were consistent drivers across all facets, highlighting their broad impact on biodiversity. We show that FD and PD metrics complement TD by revealing additional insights into ecosystem functionality and evolutionary history. Given the differential responses of biodiversity indicators to environmental drivers, especially climate, maintaining ecosystem functionality and resilience under climate change requires assessments that go beyond taxonomic diversity and include the functional and phylogenetic dimensions.

Keywords: biodiversity, environmental drivers, forest ecosystems, functional diversity, multi-taxon, Phylogenetic diversity, taxonomic diversity