Natural recovery of plant species diversity in secondary forests in Eastern Amazonia: contributions to passive forest restoration

Abstract

Natural regeneration is important in the context of the strategies to recover native vegetation in Brazil and of the international commitments of forest restoration undertaken by the country. However, trajectories of recovery can be highly variable and context-dependent, demanding studies to foster the use of secondary forests in restoration. Here, we describe the natural recovery of plant diversity in a chronosequence (5-21 years old) and how it is influenced by age of the regenerating forests. For this, we sampled the floristic composition and structure in 20 fragments of secondary forest in Southeast Pará in 2014 and 2015. Transects of either 10 × 250 m or 20 × 125 m (0.25 ha) were delimited in each forest fragment, and subdivided into 25 subplots of 10 × 10 m, where plants of the upper stratum (DBH ≥ 10 cm) were sampled. The lower stratum (DBH < 10 cm) was sampled in five 5 × 20 m subplots that were nested in the 0.25-ha transects. We recorded 5509 individuals of 282 species and 61 families in the 20 transects evaluated. The species diversity recovery occured rapidly in the first few decades of ecological succession. Floristic composition of the upper stratum was correlated with forest age. Species diversity metrics were predicted by the age and basal area of secondary forests, demonstrating their importance as indicators of successional stages in secondary forests. Our results reinforce the relevance of using secondary forest in restoration programmes across the Amazonian region. Keywords Biodiversity • Ecological restoration • Ecological succession • Forest resilience • Land-use change Resumo A regeneração natural é importante no âmbito das estratégias de recuperação da vegetação nativa do Brasil e dos compromissos internacionais de restauração florestal assumidos pelo país. Entretanto, as trajetórias da regeneração são muito variáveis e dependentes do contexto, tornando necessário mais estudos que contribuam para incentivar o uso de florestas secundárias na restauração. Neste trabalho, descrevemos a recuperação natural da diversidade de plantas em uma cronosequência (5-21 anos) e sua relação com o tempo de recuperação. Para tanto, coletamos dados estruturais e florísticos em 20 fragmentos de florestas secundárias no sudeste do Pará em 2014 e 2015. Delimitamos um transecto de 10 × 250 m ou de 20 × 125 m (0,25 ha) em cada fragmento, subdividido em 25 parcelas de 10 × 10 m, onde foi realizada a amostragem de plantas do estrato superior (DAP ≥ 10 cm). O estrato inferior (DAP < 10 cm) foi amostrado em cinco subparcelas de 5 × 20 m aninhadas no transecto de 0.25ha. Encontramos 282 espécies, 61 famílias e 5509 indivíduos nos 20 transectos avaliados. A recuperação diversidade de espécies foi rápida nas duas primeiras décadas de sucessão ecológica. A composição florística do estrato superior foi correlacionada Electronic supplementary material The online version of this article (

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