Plant Functional Type Diversity of High Andean Vegetation Across Biomes and Elevations

Questions: Plant functional types (PFTs) represent distinct evolutionary solutions to environmental filtering. Although previous studies in specific sites/countries in the high Andes have examined changes in PFT structure along environmental gradients, a comprehensive analysis spanning the entire mountain range is lacking. We asked: (1) How do regional PFT pools and spectra vary among the Páramo, Puna and high Andean Patagonia biomes and across alpine to nival elevation belts? (2) Do PFT richness, diversity and abundance show consistent latitudinal and elevation trends, linked to climate and substrate conditions?. Location: High Andes of South America. Methods: We developed a PFT classification system based on their general morphological plan, applicable across the entire latitudinal and elevational range of the high Andes. Using this framework, we classified 716 species/morphospecies into 14 PFTs and analysed PFT cover, spectra and diversity for 65 summits in 17 study sites within the GLORIA-Andes network. Results: PFT richness and diversity declined with increasing latitude and elevation. At higher elevations, tussock graminoids decreased in relative cover, whereas shorter PFTs such as cushions, rosette herbs and prostrate shrubs became more important. When cover was weighted by PFT species richness, some groups including erect herbs in the Páramo and rosette herbs in the Puna increased their importance. Convergence in PFT composition and abundance was higher in alpine and subnival belts, whereas nival summits showed greater between-region heterogeneity. These patterns were linked to abiotic factors, with lower PFT richness and diversity associated with higher scree and rock cover and colder air temperatures, and with regional differences in precipitation seasonality. Conclusions: High Andean summits exhibit distinct PFT spectra across latitude and elevation. Functional diversity diminishes under more limiting conditions: higher elevations and further away from the equator, while short-stature, cold-tolerant PFTs gain relative importance. Erect shrubs and erect, rosette and prostrate herbs were the PFTs with the highest number of species, increasing their relative importance in most communities when weighting PFT cover by richness. This study provides a functional baseline for understanding and comparing community responses to climate change across the high Andes.