Quantificação do estoque de carbono em espécies arbóreas nativas e no solo em Sistema Integrado

Abstract

Over time, interest in adopting sustainable production systems has grown due to the challenges of producing food, fiber, energy, timber and non-timber products in a manner compatible with existing natural resources. Efforts have been made to integrate agricultural, livestock, and forestry activities in order to increase the efficiency of land, energy, nutrient, and labor use. Therefore, this study aims to evaluate: the development over the years of five Cerrado tree species (Angico vermelho – Anadenanthera macrocarpa (Benth) Brenan, Amburana – Amburana cearensis A.C. Smith, Vinhático – Plathymenia reticulata Benth, Baru – Dipteryx alata Vogel, and Jatobá-da-Mata – Hymenaea courbaril L.) under an integrated crop–forest (ICF) system, as well as to estimate the volume, biomass, and carbon stock of these trees at the experimental area of the School of Agronomy of the Federal University of Goiás; the light incidence in relation to the developing tree structure of these five Cerrado species over the months; and the soil fertility and soil carbon stock in the same experimental area. The tree component was established with 3 m spacing between trees and 24 m between rows. The total experimental area is 1.7 hectares and planting took place in December 2019. Twice a year (from 2022 to 2025), during the rainy and dry seasons, two variables of the tree species in the study were measured: total plant height (Ht), in meters (m), and basal stem diameter (D0), in centimeters (cm). Considering the data obtained through the forest inventory (height and diameter), the volume, wood biomass, and carbon of the studied trees were determined. The results showed that A. macrocarpa was the species with the greatest development in diameter and height, while A. cearensis showed the lowest development. A. macrocarpa presented the highest accumulated biomass (21.918 Mg ha⁻¹) and, consequently, the highest accumulated carbon stock (10.959 Mg ha⁻¹), whereas A. cearensis showed the lowest accumulated biomass (0.144 Mg ha⁻¹) and the lowest carbon stock (0.072 Mg ha⁻¹) among the species. Light measurements were collected between 11:00 a.m. and 1:00 p.m., and the light sampling points were located at the center of each plot and at distances of 2.8 m, 4.5 m, and 7.5 m from the central point on the east (E) and west (W) sides. This procedure was carried out twice a year from 2022 to 2025. Light values from the seven sampling points were compared with full-sun light values (13.5 m) and among the studied tree species. The results indicated that, for A. macrocarpa, D. alata, and H. courbaril at sampling point 0, light incidence was lower when compared to A. cearensis and P. reticulata. In contrast, A. cearensis and P. reticulata were under full-sun conditions at all sampling points. H. courbaril stood out as the species with the lowest light incidence at point 0. Regarding soil fertility, soil samples were collected in April 2024 under four treatments, namely: treatment 1, tree rows of the integrated crop–forest (ICF) area; treatment 2, inter-rows of the tree species in the ICF area; treatment 3, cropland area; and treatment 4, permanent preservation area (PPA). To evaluate soil fertility aspects, soil samples were collected from the 0–20 cm depth using a Dutch auger and subsequently identified and sent to a laboratory for soil texture and fertility analyses. For soil bulk density and soil organic carbon (SOC) analyses, trenches 50 cm deep were opened at each sampling point in each treatment, allowing the stratification of sampling into the 0–10, 10–20, 20–30, and 30–40 cm layers. Soil organic carbon (SOC) analysis was carried out as described in the protocols of the ILPF Rede (2023), using an elemental analyzer (CHNS) to determine soil organic carbon content. Soil carbon stock was calculated using a formula that includes soil organic carbon content, soil bulk density, and the thickness of the sampled soil layer. The results showed that the cropland treatment had the highest soil carbon content among the studied areas, while the PPA had the highest soil carbon stock. Soil texture, predominantly sandy, was similar among the studied systems. The ICF areas showed good soil chemical quality, indicating that ICF systems are a good alternative for improving soil fertility while also generating income throughout the year. In the literature, no scientific studies are found addressing these native Cerrado tree species under this experimental arrangement in an integrated crop-livestock-forest (ICLF) system, therefore, this study is novel on the subject.