Facilitative effects of tree species on natural regeneration in an endangered biodiversity hotspot

Canopy species can act changing abundance, survival and spatial distribution of other species below. The present study investigated the potential of four native species from the Atlantic Forest (Bixa arborea Huber, Inga laurina (Sw.) Willd., Joannesia princeps Vell. and Senna multijuga var. verrucosa (Vogel) H.S. Irwin & R.C. Barneby) at two spacings (2 × 2 and 3 × 3 m) in facilitating natural regeneration in areas undergoing forest restoration in southeastern Brazil. Circular plots were established under the canopies of each individual of these species and in open areas. All regenerating tree species were counted and identified. Joannesia princeps and S. multijuga var. verrucosa supported a greater richness of species under their canopy compared to the control area, but did not differ from the other species. The richness of regenerating trees under Bixa arborea and Inga laurina canopy did not differ from the control area. A greater abundance of regenerating trees was found below Inga laurina, Joannesia princeps and S. multijuga var. verrucosa. Trees planted at 2 × 2 m spacing sheltered a greater richness of regenerating tree species than at 3 × 3 m spacing. The species Joannesia princeps and S. multijuga var. verrucosa and the use of 2 × 2 m spacing are therefore recommended for accelerating the natural succession of degraded areas. Knowledge of the best combinations of species and spacing schemes to use to restore Atlantic rain forest is valuable because this design can guide the structuring and composition of regenerated forests.