Understorey wildfires harm tropical forests by affecting natural regeneration, but the trajectories of fire-disturbed forests after disturbance are poorly understood. To fill this gap, we conducted experimental burns in a transitional forest between the Amazon forests and the Brazilian Savanna (Cerrado) and investigated their effects on plant community diversity of regeneration. The experiment consisted of three 50-ha plots that between 2004 and 2010 were burned either annually (six times), every three years (thrice) or not at all (Control). To evaluate early post-fire recovery, we recorded grass occurrence and regenerating stems (≤1 cm in diameter at breast height). We noted that high fire-frequency plots had a reduction of species richness (62%) and abundance (84%) and were associated with floristic and structural changes, dominance of few species and increase of grass colonization when compared with low fire-frequency. We observed that resprouts were the main pathway for forest restoration in both burned regimes, particularly in low fire-frequency. However, the forest can recover from fires by means of resprouting, until a threshold in fire frequency is reached, when resprouts and seedlings declined for most of the species, with a few fire-tolerant species becoming dominant.

中文翻译：

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亚马逊东南部森林中较高的火灾频率损害了木本物种的再生

林下野火通过影响自然更新来危害热带森林，但对受火灾干扰的森林在干扰后的轨迹知之甚少。为了填补这一空白，我们在亚马逊森林和巴西稀树草原 (Cerrado) 之间的过渡森林中进行了实验性焚烧，并研究了它们对植物群落再生多样性的影响。该实验由三个 50 公顷的地块组成，在 2004 年至 2010 年期间，每年（六次）、每三年（三次）或根本不燃烧（对照）。为了评估火灾后的早期恢复，我们记录了草的出现和再生茎（胸高直径≤1 cm）。我们注意到，高火灾频率地块降低了物种丰富度（62%）和丰度（84%），并与植物区系和结构变化有关，与低火频相比，少数物种占优势，草定殖增加。我们观察到，在两种燃烧状态下，新芽都是森林恢复的主要途径，尤其是在低火灾频率下。然而，森林可以通过重新发芽从火灾中恢复，直到达到火灾频率的阈值，此时大多数物种的重新发芽和幼苗下降，少数耐火物种占主导地位。