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

José Frédson Bezerra Lopes,Diego Antunes Campos,Deodato Do Nascimento Aquino,Erich Celestino Braga Pereira,Eunice Maia De Andrade

doi:10.1590/1983-21252020v33n317rc

José Frédson Bezerra Lopes, Diego Antunes Campos + Show 3 more

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https://doi.org/10.1590/1983-21252020v33n317rc

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Abstract

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.

Highlights

The area of dry ecosystems is estimated in 41.5% of Earth's surface (SORENSEN, 2009) and, according to the recent simulation models, climatic changes can increase them in 11% to 23% up to the end of the 21st century (HUANG et al, 2015)
The Brazilian one is covered with Tropical dry forests (TDF) known as Caatinga phytogeographic domain (CPD); it covers an area of approximately 844,453 km2 and is home to a population of 27 million people
The explorable shrubby-arboreous biomass (ESAB) found after eight years of regeneration (30.03±7.13 Mg ha-1) was not significantly different than that after 5, and 11 years (39.17±13.12 Mg ha-1), expressing an ESAB accumulation over the evaluation periods

Summary

Introduction

The area of dry ecosystems is estimated in 41.5% of Earth's surface (SORENSEN, 2009) and, according to the recent simulation models, climatic changes can increase them in 11% to 23% up to the end of the 21st century (HUANG et al, 2015). Tropical dry forests (TDF) are part of these ecosystems and are found in all continents, covering an area of 1.056 km. Forest exploration has increased in this region through management projects, since this activity is less susceptible to the local climatic adversities. These managements include the discarding of residues (not used plant parts); little information about quantity of residues produced is found, only one study was found, which is based on secondary data (LOPES; ANDRADE, 2017). Information on possible benefits of these residues and how they affect soil geochemical properties in managed areas of TDF-CPD is not found. The use of forest residues such as branches for energetic purposes have been studied for other natural and planted forests (BRAZ et al, 2014; CRUZ FILHO, SILVA, 2009), and benefits to soil have been found for pine plantations (WEBSTER et al, 2016)

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