Impacts of climate, soil and biotic interactions on the interplay of the different facets of alpine plant diversity

• Published in: The Science of the total environment 2020-01, Vol.698, p.133960-133960, Article 133960
• Main Authors: López-Angulo, Jesús, Pescador, David S., Sánchez, Ana M., Luzuriaga, Arantzazu L., Cavieres, Lohengrin A., Escudero, Adrián
• Format: Article
• Language: English
• Subjects: Altitude; Biodiversity; Biotic and abiotic factors; Chile; Climate; Climate Change; Community assembly; Ecological gradients; Ecology; Environmental Monitoring; Facets of alpine plant diversity; Phylogeny; Plants; Soil; Spain; Species interactions; Structural equation models
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.133960

Disentangling the processes that drive plant community assembly is critical for understanding the patterns of plant diversity. We studied how different abiotic and biotic factors shape the interplay between the facets of alpine plant diversity, functional (FD), phylogenetic (PD) and taxonomic diversity (TD), in three different mountain ranges with contrasting evolutionary histories and climate conditions (Pyrenees and Mediterranean-type mountains in central Spain and Chilean Andes). We hypothesized that the causal links vary in strength and sign across regions. We used species inventories, functional trait data, and a phylogeny from 84 plant communities spread throughout three high-mountain alpine grasslands. Structural equation models were used to test our causal hypotheses on the relationships observed between the three diversity facets, and the abiotic (elevation, potential solar radiation and soil total nitrogen) and biotic factors (C-score). Despite our causal model presented a high variability in each mountain range, TD always decreased with increasing elevation (sum of direct and indirect effects). We also found some patterns suggesting that assembly processes could be climatically/biogeographically structured such as the negative relationship between FD and elevation found in Mediterranean mountains and the negative relationship between FD and TD found in both Spanish mountain ranges (independently of their different climates). A remarkable finding of this study is that ecological factors such as soil total nitrogen and elevation indirectly alter the relationships between the diversity facets. Our results suggest that diversity facets are simultaneously affected by different ecological and biogeographical/evolutionary processes, resulting in some general trends but also in parallel idiosyncratic patterns. Our findings highlight that although FD stand out by its explanatory power of community processes, TD and PD provide a complementary and necessary view that should not be disregarded in the attempt to globally explain community assembly processes. [Display omitted] •Links among ecological factors and alpine plant diversity facets are idiosyncratic.•Elevation does not always negatively affect diversity facets in plant communities.•Indirect effects of elevation can modify direct links between two diversity facets.•FD is a cornerstone of community assembly, but it is not the panacea.