Biomassa da vegetação arbórea, rasteira e necromassa em formações florestais e savânica em Goiás
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2020-11-25
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Universidade Federal de Goiás
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The Cerrado is the second largest biome in Brazil. It plays an important role in carbon balance and has already lost half of its original vegetation. However, uncertainties about its vegetation-biomass stocks are high. The present study aims to contribute to reduce such uncertainties regarding the distribution of tree biomass and different vegetation compartments in the biome. The objectives were to a) perform systematic review on the aboveground biomass estimates in the Cerrado and in savanna-vegetation strips outside the biome; b) estimate tree aboveground biomass, by the indirect method, in four phytophysiognomies in Niquelândia, Goiás: wooded savanna (Sa), forested savanna (Sd), semideciduous seasonal forest (Fa) and montane deciduous forest (Cm); c) estimate the dry biomass, by the direct method, and develop biomass expansion factors for the following compartments: undergrowth, natural regeneration, herbaceous, woody necromass, and litter. It was expected that the distribution of biomass between compartments would be different in Sa compared to other formations, with a higher proportion of undergrowth and herbaceous compartiments. The study was carried out at the Legados Verdes do Cerrado Reserve in Niquelândia, Goiás. Signs of disturbance were observed in Sa, Sd and Fa. Tree sampling consisted of 20 plots of 100 m² in each phytophysiognomy and included trees with a base diameter (taken at 0.30 cm from the ground) ≥ 5 cm for Sa and diameter at breast height > 5 cm for the other formations. Tree biomass was estimated with pre-selected allometric equations applied to height and diameter data. In each plot, biomass samples were collected from the following compartments in five sub-plots of 1 m2: natural regeneration, undergrowth, woody necromass and litter. For herbaceous samples were collected in a subplot with dimensions 0.4 x 0.6 m. Fresh biomass recorded in the field and a representative sample was taken to determine its dry mass in the laboratory. The difference in biomass distribution between phytophysiognomies was tested using the Kolmogorov-Smirnov (p <0.05). In the review, 65 publications were found, in 415 locations, most of them in Tocantins and Minas Gerais, for the Sa phytophysiognomy and covered the tree component. The largest study gaps are concentrated in the north, northeast and southwest of the biome and in Sd formations and seasonal deciduous forests. Total aboveground biomass density (Mg ha-1) followed the decreasing order of 118.84 (Cm), 81.52 (Fa), 40.48 (Sd), and 19.09 (Sa). Although in Sa the amount and proportion of biomass in the sub-shrub compartment (herbaceous and undergrowth) was numerically greater than in forest formations, the Kolmogorov-Smirnov test showed no significant difference (p > 0.05) in biomass distributions between phytophysiognomies. In general, the expansion factors produced in this study are lower than the ones found in the literature. We recommend the use of the biomass expansion factors produced in this study for vegetations with similar physiographic and environmental conditions, tree structure and disturbance regime.
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Guimarães, L. E. Biomassa da vegetação arbórea, rasteira e necromassa em formações florestais e savânica em Goiás. 2020. 116 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2020.