Cut Cycles and Soil Carbon Potential Stocks in a Managed Forest in the Caatinga Domain in Brazil

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.

Structural dynamics in a seasonally dry tropical forest under different silvicultural systems

“…In the SC2 treatment, the results for 2021 exceed the 1996 data by an average of 1.4 times. This confirms the finding by Lopes et al (2020) that the original stocks of woody biomass do not correspond to the maximum potential exploitable shrub and tree biomass. In this regard, Riegelhaupt, Pareyn, and Bacalini (2010) had already questioned the exclusive use of this criterion, given, for example, the lack of parameters to certify that the initial average stock found in a certain area corresponds to the maximum stock that the site can reach.…”

“…Evaluating an area of SDTF under management with clearcutting in Ceará, Lopes et al (2020) found that the vegetation reached the average stock of original biomass at 8 years of regeneration in a location with a hot semi-arid climate and average annual rainfall of 744 mm. However, although the initial stock was recovered seven years before the cutting cycle, the vegetation cover was still quite young, with most of the biomass occupying the first diameter class (2 -5.99 cm).…”

“…From an economic point of view, the annual yield would be based on a flawed criterion. Because of this, Lopes et al (2020) suggest that the definition of cutting cycles should also be supported by an assessment of biodiversity and the occurrence of biomass in the upper diameter classes.…”

The influence of clear-cut area size on forest regrowth: a case study in the dry tropical forests of Pernambuco, Brazil

“…In sustainable forest management of the Caatinga (and other forests in Brazil), regulation by area is advocated based on the division of the forest area into annual productive units, and with a minimum harvest cycle of 15 years (Araújo Filho and Carvalho, 1997;Drumond et al, 2004;Riegelhaupt et al, 2010;Matos et al, 2019, Lopes et al, 2020. The commonly adopted cutting cycle for Caatinga forests is established by federal and state legislation, still lacking solid scientific basis.…”

“…Management of tropical dry forests in Brazil expanded 450% in the last two decades; but little is known about the ideal recovery time of the harvested stock after clear cut as well as the growth dynamics of these areas (Lopes et al, 2020). Many aspects regarding sustainability need further investigation, especially potential for recovery of productive capacity and ways to minimize anthropic impacts on vegetation.…”