Disentangling the effects of disturbances-driven tree mortality on seed dispersal networks in the Amazon

• Grant number: 25/09905-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: September 01, 2025
• End date: February 28, 2026
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Mathias Mistretta Pires
• Grantee: Rubia Ferreira dos Santos Morini
• Supervisor: Paulo Monteiro Brando
• Host Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: Yale School Of The Environment, United States
• Associated to the scholarship: 24/06458-3 - Effects of fragmentation and forest fires on seed-dispersal networks and the feedbacks on plant functional diversity, BP.DD

Abstract

Deforestation in the Amazon extends beyond vegetation loss, leading to forest degradation through increased exposure to fire, extreme climate events, and edge effects. These disturbances elevate tree mortality and disrupt ecological processes such as seed dispersal, compromising forest resilience. Here, I aim to investigate how tree mortality driven by different disturbances-fire, drought, windstorms, and edge effects-affects seed-dispersal interactions in the Amazon-Cerrado ecotone, a region undergoing rapid forest loss within the "arc of deforestation." I test two hypotheses: (1) that the loss of plant-frugivore interactions occurs proportionally to tree mortality, regardless of species identity, and (2) that the loss is not proportional but depends on the identity and functional importance of the species lost. To test these hypotheses, I will construct seasonal seed-dispersal networks using long-term data on plant mortality, fruit availability, and frugivore presence. Tree mortality records will allow me to identify species most affected by each disturbance, enabling simulations of species extinctions under disturbance-specific scenarios. I will then assess how the resulting changes in plant composition alter network structure and affect frugivore communities. By integrating phenological data with interaction models and applying statistical tools including network metrics, beta-diversity, PCA, and GAMs, this study aims to quantify the cascading impacts of tree mortality on ecological interactions and forest regeneration. I expect to provide critical insights into the mechanisms driving forest regeneration in disturbed landscapes, offering a scientific basis for conservation strategies aimed at preserving ecological interactions and maintaining biodiversity in the Amazon. (AU)