Integrating FACE experiment and vegetation model to unravel the effects of increased CO2 on tropical forest phenology

• Grant number: 24/02277-4
• Support Opportunities: Regular Research Grants
• Duration: July 01, 2024 - June 30, 2026
• Field of knowledge: Biological Sciences - Ecology - Ecosystems Ecology
• Convênio/Acordo: CNPq
• Principal Investigator: Tomas Ferreira Domingues
• Grantee: Tomas Ferreira Domingues
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 22/07735-5 - The impact of climate variability and weather extremes on plant phenology and its implications on biodiversity, AP.PFPMCG.TEM

Abstract

The evaluation of how phenological strategies, particularly those linked to water use, influence the response of plants and ecosystems to elevated CO2 (eCO2), remains a crucial endeavor. Furthermore, the assessment of how the coordination between phenology and functional traits could restrict the occurrence of diverse phenological patterns and modulate these responses is still to be assessed. To address these questions, we propose, for the first time in the Amazon forest, a data-model integration involving a Free Air CO2 Enrichment (FACE) experiment (AmazonFACE) and the individual-based vegetation model TROLL. With TROLL, we will simulate ecosystem functioning at the AmazonFACE plots calibrated with climatic and functional traits data collected in a pre-experimental phase. We will evaluate the model's performance in representing vegetation structure, carbon and water cycles using statistical goodness-of-fit techniques. We will also evaluate, through analyses of trait distribution and positioning within functional space, model's ability to represent observed phenological strategies (evergreen, semi-deciduous and deciduous) and diversity of functional traits linked to phenology (e.g., leaf flush, longevity and senescence) and its coordination with other essential traits linked to the plant economics spectrum (e.g., stem diameter increment rates, wood density, leaf N and P, stomatal conductance and photosynthetic capacity). A virtual experiment will be conducted to simulate the application of increased CO2 levels (+200 ppmv), mirroring the AmazonFACE target. With this experiment we aim to investigate whether eCO2 induces shifts in the occupation of functional space, changing the occurrence of phenological strategies and their coordination with other traits. We will also conduct simulations incorporating varying levels of phenological diversity by adjusting the occupancy of functional spaces to represent different phenological strategies. It will enable us to assess the impact of these variations on ecosystem functioning (carbon and water cycle) under typical climate conditions and eCO2 levels. This integrated approach holds substantial potential to advance our comprehension of how tropical ecosystems respond to eCO2, contributing to more accurate predictions of climate change impacts on biodiversity and the Amazon's capacity to deliver crucial processes and functions. (AU)