High plant species richness in monospecific tree plantations in the Central Amazon

Because forest plantations cover an extensive area worldwide, they play an important role shaping current biodiversity conservation policies. This study evaluated plant species richness in the regenerating forest community beneath five 35-year-old homogeneous forest stands consisting of indigenous terra-firme species (Simarouba amara, Dipteryx odorata, Bagassa guianensis, Jacaranda copaia and Dinizia excelsa). These data were compared to adjacent primary forests in the Manaus region, Amazonas state, Brazil. These plantations are among the oldest native tree plantations of the Brazilian Amazon. All studied stands showed species richness near that of the primary forest, with the single exception being J.copaia. The relationship between species composition and the environmental variables was studied by canonical correspondence analysis (CCA). The CCA yielded correlations that were validated by a permutation test between species composition and canopy openness, nitrogen content, pH, base saturation and soil aluminum content. Our results showed that long standing homogenous plantation stands can provide high levels of density and species richness of the understory, comparable to those found in the surrounding primary forest. This finding reinforces the value of anthropogenic landscapes for conserving biodiversity.

► Forest plantations have been advocated to maintain species richness and conservation.
► This study focuses on regeneration beneath five adult mono-specific tree plantations.
► Environmental data and vegetation surveyed were combined in the study.
► Comparisons were made between forest plantations and pristine terra-firme forests.
► All species played important role to recover species richness and site protection.