Estrutura populacional, distribuição espacial e efeito de Leucaena leucocephala (Lam.) de Wit sobre espécies nativas em uma área de Cerrado

Abstract

Leucaena leucocephala (Lam.) de Wit is a Fabaceae species native to Central America and invasive in the Brazilian Cerrado. Its presence potentially negatively impacts the structure and diversity of native vegetation. In this study, we aimed to understand the invasive potential of the species and its implications for local biodiversity. The study was conducted at the Reserva Particular do Patrimônio Natural (RPPN) of the Federal University of Mato Grosso do Sul (UFMS). The population structure and spatial distribution of L. leucocephala were evaluated in 20 plots of 25 m². In these plots, the presence and abundance of individuals of this species at different ontogenetic stages (seedlings, juveniles, and adults) were recorded. Additionally, the effect of L. leucocephala presence on the diversity and abundance of seedlings and juvenile native species was assessed, investigating whether the recruitment pattern of the invasive species aligns with the Janzen-Connell hypothesis. This hypothesis predicts a reduction in recruitment rates near adult individuals due to the action of predators and pathogens. The results indicate that L. leucocephala is expanding in the study area, as it exhibits a reversed "J" population structure, along with aggregated spatial distribution, with dense juvenile clusters near adult individuals. The presence of this invasive species significantly reduced the diversity of juvenile native plants. Regarding the Janzen-Connell hypothesis, high mortality was observed during the transition from seedling to juvenile stages, and although seed and seedling abundance were high, juvenile abundance was not, indicating competition and resource limitation, partially supporting the hypothesis.