Significance: The Amazonian tropical forests have been disappearing at a fast rate in the last 50 y due to deforestation to open areas for agriculture, posing high risks of irreversible changes to biodiversity and ecosystems. Climate change poses additional risks to the stability of the forests. Studies suggest “tipping points” not to be transgressed: 4° C of global warming or 40% of total deforested area. The regional development debate has focused on attempting to reconcile maximizing conservation with intensification of traditional agriculture. Large reductions of deforestation in the last decade open up opportunities for an alternative model based on seeing the Amazon as a global public good of biological assets for the creation of high-value products and ecosystem services.

Amazonian environments are being degraded by modern industrial and agricultural activities at a pace far above anything previously known, imperiling its vast biodiversity reserves and globally important ecosystem services. The most substantial threats come from regional deforestation, because of export market demands, and global climate change. The Amazon is currently perched to transition rapidly from a largely forested to a nonforested landscape. These changes are happening much too rapidly for Amazonian species, peoples, and ecosystems to respond adaptively. Policies to prevent the worst outcomes are known and must be enacted immediately. We now need political will and leadership to act on this information. To fail the Amazon is to fail the biosphere, and we fail to act at our peril.

Tropical forests are recognized for their role in providing diverse ecosystem services (ESs), with carbon uptake the best recognized. The capacity of tropical forests to provide ESs is strongly linked to their enormous biodiversity. However, causal relationships between biodiversity and ESs are poorly understood. This may be because biodiversity is often translated into species richness. Here, we argue that focusing on multiple attributes of biodiversity—structure, composition, and function—will make relationships between biodiversity and ESs clearer. In this review, we discuss the ecological processes behind ESs from tropical humid and subhumid forests of South America. Our main goal is to understand the links between the ESs and those three biodiversity attributes. While supporting and regulating services relate more closely to forest structure and function, provisioning services relate more closely to forest composition and function, and cultural services are more related to structure and composition attributes. In this sense, ESs from subhumid forests (savannas) differ from those provided by the Amazon Forest, although both ecosystems are recognized as harboring tremendous biodiversity. Given this, if anthropogenic drivers of change promote a shift in the Amazon Forest toward savanna—the savannization hypothesis—the types of services provided will change, especially climate regulating services. This review emphasizes the importance of deeply understanding ecosystem structure, composition, and function to better understand the services ecosystems provide. Understanding that anthropogenic impacts on biodiversity occur through these three main attributes, it becomes easier to anticipate how humans will impact ESs.

RESUMO As inundações sem precedentes de abril a maio de 2024 no Rio Grande do Sul afetaram mais de 90% do estado, deslocando centenas de milhares de pessoas e causando 172 mortes. O fenômeno El Niño Oscilação Sul foi considerado importante para explicar a variabilidade nas chuvas observadas, consistente com pesquisas anteriores que mostram que eventos anteriores de fortes chuvas na área ocorreram durante anos de El Niño. As frentes frias que trazem chuvas permaneceram estacionadas no sul do Brasil, uma vez que não puderam se mover para o centro do Brasil devido ao bloqueio atmosférico com ar quente e seco e às temperaturas mais altas naquela região. A inundação em Porto Alegre foi desencadeada por fortes chuvas na Bacia do Guaíba, com acumulações superiores a 500 mm em 5 dias, levando a níveis recordes de 5,35 m em 5 de maio, valores mais altos que a enchente anterior, em 1941. Além do caráter extremo deste evento, isso contribuiu para os impactos significativos de enchentes em áreas vulneráveis da Região Metropolitana de Porto Alegre e municípios próximos. Isso mostra a necessidade de avaliar objetivamente o risco e reforçar a infraestrutura para inundações para aumentar a resiliente a esta e futuras enchentes, ainda mais extremas.