Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Funder: Brazilian Program for Biodiversity ResearchFunder: Fundação de Amparo à Pesquisa do Estado do Amazonas; Id: http://dx.doi.org/10.13039/501100004916Funder: National Institute for Amazonian BiodiversityAbstract: Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser‐availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource‐availability hypothesis). Time period: Tree‐inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree‐inventory plots across terra‐firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance‐weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra‐firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser‐availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

More than 10,000 pre-Columbian earthworks are still hidden throughout Amazonia.

This is the author accepted manuscript. The final version is available from the American Association for the Advancement of Science via the DOI in this recordData and materials availability: Data from publicly available sources are cited in the supplementary materials. Other data and computer codes used in the analysis are publicly available at Zenodo repositoryIndigenous societies are known to have occupied the Amazon basin for more than 12,000 years, but the scale of their influence on Amazonian forests remains uncertain. We report the discovery, using LIDAR (light detection and ranging) information from across the basin, of 24 previously undetected pre-Columbian earthworks beneath the forest canopy. Modeled distribution and abundance of large-scale archaeological sites across Amazonia suggest that between 10,272 and 23,648 sites remain to be discovered and that most will be found in the southwest. We also identified 53 domesticated tree species significantly associated with earthwork occurrence probability, likely suggesting past management practices. Closed-canopy forests across Amazonia are likely to contain thousands of undiscovered archaeological sites around which pre-Columbian societies actively modified forests, a discovery that opens opportunities for better understanding the magnitude of ancient human influence on Amazonia and its current state.Coordination of Superior Level Staff Improvement under the Academic Excellence Program (CAPES/PROEX)Coordination of Superior Level Staff Improvement under the Academic Excellence Program (CAPES/PROEX)Coordination of Superior Level Staff Improvement under the Academic Excellence Program (CAPES/PROEX)National Council for Scientific and Technological Development (CNPQ)National Council for Scientific and Technological Development (CNPQ)National Council for Scientific and Technological Development (CNPQ)European Research CouncilSão Paulo Research Foundation (FAPESP)Amazon FundSão Paulo Research Foundation (FAPESP)PVEMEC/MCTI/CAPES/CNPq/FAPEuropean Union’s Horizon 2020European Union’s Horizon 2020CAPESANRMCT/CNPq/CT-INFRA/GEOMAMCT/CNPq/CT-INFRA/GEOMACAPES/PDSECAPES/FapespaCNPqFAPESPCNPq/CAPES/FAPS/BC-NewtonFAPEMATRoyal Society GCRF International Collaboration AwardNSF/DEBCNPQ/PQNatural Environment Research Council (NERC)Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Natural Environment Research Council (NERC)Gordon and Betty Moore Foundatio