The long-term dynamics of regeneration in tropical forests dominated by single tree species remains largely undocumented, yet is key to understanding the mechanisms by which one species can gain dominance and resist environmental change. We report here on the long-term regeneration dynamics in a monodominant stand of Brosimum rubescens Taub. (Moraceae) at the southern border of the Amazon forest. Here the climate has warmed and dried since the mid-1990′s. Twenty-one years of tree and liana regeneration were evaluated in four censuses in 30 plots by assessing species abundance, dominance, and diversity in all regeneration classes up to 5 cm diameter. The density of B. rubescens seedlings declined markedly, from 85% in 1997 to 29% in 2018 after the most intense El Niño-driven drought. While the fraction contributed by other tree species changed little, the relative density of liana seedlings increased from just 1 to 54% and three-quarters of liana species underwent a ten-fold or greater increase in abundance. The regeneration community experienced a high rate of species turnover, with changes in the overall richness and species diversity determined principally by lianas, not trees. Long-term maintenance of monodominance in this tropical forest is threatened by a sharp decline in the regeneration of the monodominant species and the increase in liana density, suggesting that monodominance will prove to be a transitory condition. The close association of these rapid changes with drying indicates that monodominant B. rubescens forests are impacted by drought-driven changes in regeneration, and therefore are particularly sensitive to climatic change.

单树种为主的热带森林再生的长期动态在很大程度上尚无记载，但对于了解一种树种获得优势并抵御环境变化的机制而言，这是关键。我们在这里报告了红景天（Romosim rubescens Taub）单一优势林中的长期再生动态。（桑科）在亚马逊森林的南部边界。自1990年代中期以来，这里的气候变暖和干燥。在30个地块的四次普查中，通过评估所有直径不超过5 cm的物种的丰度，优势度和多样性，对21年的树木和藤本植物进行了评估。冬凌草的密度厄尔尼诺现象最严重的干旱导致幼苗从1997年的85％明显下降到2018年的29％。虽然其他树种贡献的比例变化不大，但藤本植物幼苗的相对密度仅从1％增至54％，四分之三的藤本植物的丰度增加了10倍或更多。再生群落的物种周转率很高，总体丰富度和物种多样性的变化主要由藤本植物而不是树木决定。在这种热带森林中，长期保持单一优势受到单一优势物种再生的急剧下降和藤本植物密度增加的威胁，这表明单一优势将被证明是暂时的。这些快速变化与干燥的紧密联系表明风信子森林受到干旱驱动的再生变化的影响，因此对气候变化特别敏感。