“Regeneração florestal após a retirada de pinus na mata atlântica subtropical e transposição de solo como alternativa de restauração nucleadora”

Abstract

The National Forests (FLONAs) in southern Brazil are Conservation Units (UCs) and often have extensive areas dominated by invasive exotic species, especially species of the Pinus genus. The FLONA de Chapecó (FNC) is a UC for sustainable use that has a considerable proportion of forest cover made up of P. taeda and P. elliottii plantations, with the conversion of these areas to native forests being one of the challenges for the conservation of genetic diversity on site. Exotic species have a recognized capacity for spontaneous regeneration and invasion of areas subjected to forest cutting. This study quantified the presence and density of species based on a phytosociological survey in the upper woody forest strata of individuals with PAP ≥ 15 cm, and the recruitment and regeneration of woody species in the lower stratum with a height ≥ 50 cm of three areas of the FLONA Chapecó with different forest vegetation coverage: area undergoing forest regeneration in which a population of Pinus spp. was suppressed ten years ago (REG); native forest undisturbed in the last sixty years (NAT); and a plot of Pinus spp. of similar age (PIN). It also evaluated the viability of litter and soil transposition as a core forest restoration strategy in degraded areas, quantifying the recruitment of woody species from samples collected in the same areas. The results regarding the composition of the woody community show that the upper stratum does not present a statistical difference in terms of richness between the three treatments (χ2 = 6.038 and p = 0.04842, according to the Kruskal-Wallis test), but concerning to the number of individuals per hectare, the area under regeneration was lower than the other two areas (according to the Mann-Whitney test); the lower stratum presents a statistical difference between the “PIN” treatment, with a higher value, and the other two treatments, however there was no difference between the “NAT” and “REG” treatments (χ2 = 10.32 and p = 0.005597) . Regarding to the number of individuals per hectare, the lower stratum of “REG” was lesser than of “PIN”. Litter and soil samples from the regeneration area did not show ex situ germination, while the native forest area had a low recruitment of native tree species. The Pinus spp. Originated from samples of litter and soil had high germination of Pinus spp. and few individuals of native species. The suppression of Pinus spp. allowed satisfactory diversity for the upper stratum of the “REG” area, at levels comparable to the natural area (NAT), however the species richness of the lower stratum was low in both “REG” and “NAT”. In the “REG” area, due to the low diversity of species in the lower stratum, additional management actions must be considered for ecological restoration objectives, such as the removal of lianas, aiming to improve the recruitment of new individuals and native species.