A better understanding of the natural regeneration in tropical forests could help develop more effective restoration strategies. This study examined relationships in structural and diversity attributes of natural regeneration in five forest fallow ages after slash-and-burn agriculture (6 months, 2 years, 5 years, 10 years, and 15 years) in the Republic of Congo. For each fallow age, all stems with a diameter ≥1 cm and below 5 cm (height ≥ 130 cm), corresponding to natural forest regeneration, were identified to the species level, and measured (diameter and height) in 12 plots (10 m × 10 m). Three structural attributes (stem density, maximum diameter, and maximum height) and five diversity indices (species richness, Shannon diversity, Simpson diversity, Fisher's alpha and Pielou's evenness) were estimated at the plot level. Our results revealed an increase in structural and diversity attributes with fallow ages, except stem density. The young fallow (6 months, 2 years and 5 years) had greater stem density (61 ± 48 stems), while the old fallow (10 years and 15 years) had higher maximum height (5.39 ± 2.36 m) and Shannon's index (0.94 ± 0.18). These results provided new insights into natural regeneration between young and old secondary forests.

中文翻译：

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中非潮湿森林休耕期天然林再生

更好地了解热带森林的自然更新有助于制定更有效的恢复策略。本研究考察了刚果共和国刀耕火种农业后五个森林休耕期（6 个月、2 年、5 年、10 年和 15 年）自然更新的结构和多样性属性之间的关系。对于每个休耕年龄，所有与天然林更新相对应的直径≥1 cm且低于5 cm（高度≥ 130 cm）的茎均按物种水平进行鉴定，并在12个样地（10 m）中进行测量（直径和高度） × 10 m）。在样地水平上估计了三个结构属性（茎密度、最大直径和最大高度）和五个多样性指数（物种丰富度、香农多样性、辛普森多样性、费舍尔阿尔法和皮卢均匀度）。我们的结果显示，除了茎密度外，休耕期的结构和多样性属性有所增加。年轻休耕（6个月、2年和5年）的茎密度较大（61±48茎），而老休耕（10年和15年）具有较高的最大高度（5.39±2.36 m）和香农指数（0.94） ±0.18）。这些结果为年轻和老的次生林之间的自然更新提供了新的见解。