Agradecimentos: This study was carried out as a collaborative effort of the ForestPlots.net meta-network, a cyber- initiative that unites contributing scientists and their permanent plot records from the world's tropical forests. This paper is an outcome of ForestPlots.net approved Research Project #40. We thank our colleagues who made this work possible by helping in the field and later with data management. We are thankful to Dr. Jean Carlo Gonçalves Ortega for his collaboration in interpreting the data and statistical analysis and to Dr. Oliver L. Phillips for revising the whole manuscript. We also want to express our appreciation to the editor and reviewer for their insightful comments, which have helped us to significantly improve the paper. Funding This work was funded by U.S. Agency for International Development under the Partnerships for Enhanced Engagement in Research (PEER) program of the National Academies of Science. This work was funded by U.S. Agency for International Development under the Partnerships for Enhanced Engagement in Research (PEER) program of the National Academies of Science Ver menos

Abstract: Tree mortality rates and the modes of tree death have recently been extensively investigated in the Amazon. However, efforts to describe these processes have not been well distributed across the basin. No study has yet investigated in depth tree mortality process in the unique low, open, bamboo-dominated forests of southwestern Amazonia, a region with a distinct climate and the epicenter of recent severe drought events. Here, we investigated the leading ways that trees die in the terra-firme forests of the southwestern Brazilian Amazon, to understand whether the dynamics of mortality differ from those recorded in other parts of the basin. Using data from six permanent plots located in southwestern Amazonia, we calculated the mortality rate for three main modes of tree death: standing, broken and uprooted. We thus identified the predominant mode of death over a 14 year period (2002–2016). We found that trees in the southwestern Amazon died mainly standing (325 trees, 0.8% year-1) and broken (362 trees, 0.8% year-1); significantly fewer trees died uprooted (156 trees, 0.4% year-1, equivalent to less than one in five of all trees dying). During the study period, the tree mode of death with the greatest proportion in the region alternated between standing and broken trees. Forest characteristics of the southwestern Amazon, like presence and high density of bamboo culms, and the fact that the region was subject to severe droughts in 2005 and 2010, may be affecting how trees die in southwestern Amazon. The presence of these factors makes the forest dynamics of the southwestern Amazon different from other regions of the Amazon basin Ver menos