CUT CYCLES AND SOIL CARBON POTENTIAL STOCKS IN A MANAGED FOREST IN THE CAATINGA DOMAIN IN BRAZIL

CICLOS DE CORTE E POTENCIAL APORTE DE CARBONO AO SOLO EM MANEJO FLORESTAL DA CAATINGA

ABSTRACT

Management of tropical dry forests in Brazil expanded 450% in the two latest decades; but little is known about the dynamics of these areas. Thus, the objective of this work was to evaluate if the recovery of mean original biomass stocks (MOBS) is a consistent criterion to define cut cycles in a managed forest for charcoal production, and determine the remaining biomass and its contribution to soil carbon stocks. The study was conducted at the Ramalhete Settlement, in General Sampaio, CE, Brazil, in 2018. The explorable shrubby-arboreous biomass (ESAB) and the ESAB mean annual increases (ESAB -MAI) were determined in five areas subjected to clearcutting after 3, 5, 8, 11, and 15 years, and in a preservation area with 40 years of regeneration. Each area was divided into seven plots (20 × 20 m), totaling 42 plots. The ESAB of the plots were compared and the remaining biomass (branches, stumps, and litterfall) in a recently explored area was calculated and converted into organic carbon. The remaining biomass of branches had higher contribution to soil carbon stocks, followed by the litterfall, and stumps. The carbon stocks of the branch component were 3.4-fold higher than those of the litterfall. The recovery of the MOBS of an area after clearcutting should not be used as a criterion to define the cut cycle, since these original carbon stocks do not represent the maximum ESAB production possible in the area; the biodiversity and amount of ESAB in the classes of larger diameter are more adequate criteria.

Keywords:
Tropical dry forest; Caatinga phytogeographic domain; Plant biomass; Regeneration; Forest residues