Forest regeneration and seed rain in the conversion of a stand of Pinus sp. into native forest

In Southern Brazil, the National Forests (NF) are protected areas of sustainable use; however, most of them present a significant cover with old plantations of Pinus spp. established to foster commercial forestry. Nowadays, the NF management plans propose the conversion of Pinus stands into native forests. Pinus spp. are worrisome invasive plants whose spontaneous recruitment is a challenge to forest restoration. This paper aims to analyze seed rain and woody community composition in a stand where Pinus trees were eliminated to drive spontaneous regeneration (REG) in an NF in the Southern Atlantic Forest. The seed rain was measured in the restoring area and inside an adjacent Pinus stand (PIN). The tree community structure was analyzed comparatively in REG, PIN, and in a Native Araucaria Forest (NAT). One year after Pinus cutting, the seed rain of woody species was 1,802 and 1,502 seeds m-2.year-1 in REG and PIN, respectively. REG’s seed rain had higher diversity than PIN and absence of Pinus seeds. REG and NAT presented higher diversity of tree species than PIN, although REG had the lowest basal area and tree density. Nevertheless, 188 Pinus seedlings.ha-1 were observed in REG, which indicates that complementary restoration actions are needed.