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Organized Oral Session

Hybrid Session

Session: : A System Understanding of Plant Roots and Their Global Consequences

OOS 49-4 - Contributions of subtropical and tropical species to belowground plant ecological strategies

Thursday, August 10, 2023
8:45 AM – 9:00 AM PDT
Location: 252
Elucidating patterns of species-level root trait variation at global scales contributes to our understanding of the ecological and evolutionary processes that shape biodiversity patterns. Yet, our current perspective has been largely informed by species in the temperate biome, questioning our understanding of species-level root trait variation at a global scale and the contributions and variability within some of the most diverse biomes on earth. Here, we aim to strengthen our global understanding of plant functional strategies - that in turn structure biodiversity - by assessing the contributions of subtropical and tropical regions to global diversity in root trait strategies. Specifically, we investigated the degree of, and interspecific (co)variation in traits related to the belowground collaboration and conservation axes among biomes, using the Global Root Trait (GRooT) database v2.0. We determined root functional diversity of subtropical and tropical biomes and their contribution to the global root trait space. Finally, we explored the drivers underlying subtropical and tropical of inter-specific root trait variation. Our results show that global comparisons among biomes is only possible for woody species, with data related to the collaboration and conservation axes for non-woody species coming mostly from temperate biomes. Tropical woody species had significantly lower specific root length and greater diameter, suggesting a shift among biomes along the collaboration axis. Yet, root nitrogen-root tissue density responses differed, resulting in contrasting interpretations when analyzing the conservation axis. Despite the greater biodiversity of the tropics and subtropics, when accounting for species richness, neither functional richness, evenness and dispersion differ between the tropical, subtropical, and temperate biomes. Nonetheless, subtropical and tropical biomes still account for 40% of the unique functional space relative to the global trait space. Our results suggest that inter-specific root trait variation within subtropical and tropical biomes is largely due to differences in evolutionary history, and not environmental factors. Yet, due to the asymmetric distribution of root trait data across subtropical and tropical biomes, our understanding of root trait variation largely comes from subtropical Asia and tropical America.