Resiliência e sequestro de carbono por floresta manejada na Amazônia Oriental

Abstract

Monitoring the Amazon Forest for carbon retention studies is of great importance in climate issues, such as the greenhouse effect. In the Amazon, forest management can contribute to avoided deforestation, preventing the emission of high amounts of gases, such as the CO2 that cause the studied effect (GHG). In permanent plots installed by the Jari Florestal company in its management area in the Jari valley and, subsequently, monitored by Embrapa, the dynamics of forest recovery (mortality; inclusion and growth of trees in this period) have been carried out since 2001) after the reduced impact extraction performed by the company. With this information, it is possible to infer whether the forest has already recovered the biomass lost during and after the activity of collecting and transporting trees, and what is the growth rate of the species studied in the period already monitored. The aim of the study was to evaluate the relationships of wood density and diametric variation with the population dynamics of 4 important commercial species: Vouacapoua americana Aubl. - acapu, Manilkara spp. - maçaranduba, Qualea ssp. - mandioqueira, Erisma uncinatum Warm - quaruba, to estimate the capacity for biomass recovery and maintenance of carbon stock in these species after handling. Data from 15 permanent plots of 1 ha each were analyzed, where all trees were measured before and after logging, with at least three remeasurements over 20 years of monitoring. The diameter at breast height (DBH) was calculated by measuring the circumference of the tree trunk at 1,30 m from the ground. Different wood densities have a strong influence on forest carbon recovery, especially species with intermediate density (cassava and quaruba). In these species, the balance was positive and there was accumulation and sequestration of carbon in the trees, while for those with higher density, the balance was negative. In the case of mandioqueira, the carbon accumulation rate was 251kg ha-1 year 1 . Trees with an intermediate diameter are the ones with the greatest growth, while mortality is concentrated in the smaller trees. This shows that the dynamics of recovery resilience after intermediate management disturbance is less dependent on thinner and thicker trees. Thus, it can be seen that the association of the management of native forests in the Amazon with the emission/sequestration of carbon is dependent on the diameter of the trees and the species. Therefore, it is recommended that more species with intermediate wood density be included in the cutting planning, avoiding the overexploitation of those with high density, such as maçaranduba. Cutting should also be concentrated on trees with intermediate diameters, avoiding cutting thicker ones, which, despite contributing less to carbon sequestration, are very important for stock maintenance and have an irreplaceable role, as "mother trees" of the forest.