Predições de carbono em uma floresta secundária em recuperação na Amazônia oriental.

Abstract

This study aimed to assess the total carbon stock and to identify the main species responsible for this stock under different restoration techniques. Three restoration strategies were analyzed, passive, assisted and active, over three years, 2018, 2020 and 2022. Data were collected at Fazenda Piave, located in Igarapé-Açu (PA), which is predominantly composed of secondary forest under regeneration for more than 20 years, with a history of abandoned pasture. The treatments were defined according to the level of intervention within each plot: Passive Restoration (PR), characterized by the absence of human intervention since abandonment; Directed Restoration (DR), involving low-impact management practices, such as selective logging and enrichment planting with species of commercial interest; and Active Restoration (AR), which consisted of planting native and exotic species combined with the implementation of a silvopastoral system. Each treatment consisted of a 100 × 100 m plot subdivided into 10 × 10 m subplots. Carbon stock prediction was based on an allometric model developed for secondary forests, with a conversion factor of 47% for carbon. The results indicated that AR exhibited the highest carbon stock in all years analyzed, mainly due to the contribution of the exotic species Acacia mangium, widely used for its rapid biomass accumulation but considered invasive. In PR and DR, Lacistema pubescens was the species with the highest carbon stock in the assessed years. However, DR showed considerably lower total carbon stocks compared to PR, less than half, possibly due to the removal of individuals through management. Another distinction observed among the restoration strategies concerned carbon stocks by diameter class, in DR the highest carbon stock was concentrated in smaller classes, 0–20 cm, whereas in PR and AR, it was concentrated in intermediate classes, 10–40 cm. Therefore, the restoration method influences not only total carbon stocks, but also the species contributing to them and the diameter classes in which they accumulate. In the context of secondary forests, this finding highlights the importance of further studies on the subject and the careful selection of restoration strategies to achieve the desired outcomes.