Estrutura, diversidade e quantificação de carbono da comunidade arbórea de um fragmento de Mata Atlântica no NIASSA-UFJF

Abstract

The Atlantic Rainforest, located in Brazil's most densely populated region, has undergone increasingly intense transformations, especially in the last century. One of its most affected phytophysiognomies is the semideciduous seasonal forest (SSF), which has been reduced to 7.1% of its original cover. For these SSF fragments to thrive, we need studies to support environmental policies, such as studies on their floristic composition, structure, and ecosystem services, such as carbon stocks. We are also in the UN Decade of Restoration, which aims to stop the degradation of ecosystems worldwide, concluding that only healthy ecosystems can combat climate change and halt biodiversity collapse. Reference ecosystems (REs) serve as a benchmark for the success of restoration projects. A RE should, among others, be a shelter for the region's native species, have normal community development functions, and be protected from direct human disturbances. With this in mind, we aimed to carry out a forest inventory in the Atlantic Forest remnant of NIASSA-UFJF, Ewbank da Câmara – state of Minas Gerais, where important forest restoration projects are underway, in order to understand and elucidate its conservation status, its successional stage, its forest structure, species composition and floristic diversity, describing its viability as a reference ecosystem, as well as quantifying the aboveground carbon stock (AGC) of the tree component. To do this, we set up 30 permanent 15 x 12 m plots in the remnant, totalling a sample area of 0.54 ha, where all living or dead trees with a CAP ≥ 15.7 were measured, identified, and had their height estimated. We then calculated phytosociological parameters and generated diameter distribution histograms of the species with the highest importance value (VI). We calculated the Shannon index value (H' - 4. 19 nats.ind-1) and equability (J - 0.81). To quantify the AGC, we obtained the wood density values of the individuals of the species with the largest basal area and the highest VI, as phytosociological analysis showed and applied them together with the DBH and height values in global equations to estimate biomass. We found 175 morphospecies distributed in 51 families and 87 genera. The species with the highest VI were Lacistema pubescens Mart., Sorocea guilleminiana Gaudich., Xylopia brasiliensis Spreng., and Ocotea bicolor Vattimo-Gil. The total carbon stock in the remnant is 58.08 t.ha-1. This value was similar to other studies on secondary regeneration SSF in Minas Gerais and represents secondary forests in the mid-succession phase. Considering its structural parameters, land use background, and general comparison with other studies in the SSF of Minas Gerais, we conclude that the NIASSA forest remnant is in a medium-advanced regeneration stage and shelters at least eight threatened species populations. We consider the remnant to be a good ER for comparison with studies carried out at NIASSA and throughout the region, and it provides a relevant ecosystem service expressed in stored carbon.