Estoque de carbono e nutrientes na serapilheira em diferentes fitofisionomias do Bioma Cerrado dependente da classe textural do solo

Abstract

The Brazilian Cerrado is characterized by different types of vegetation, or different phytophysiognomies, in the same region, and the differences between them may be associated to the edaphic character and to the carbon and nutrient stock in the organic matter represented by the litter. The clay content of the soil can be one of the main determining factors in the production and stocking of carbon and nutrients of litter in Cerrado environments. However, studies associated with soil characteristics, litter and phytophysiognomies have been little discussed in the literature, and may be of great relevance in the functioning of ecosystems in the Cerrado Biome. The objective of the present work was to evaluate the carbon and nutrient stocks in different litter fractions in nine sites of the Cerrado Biome in soils with different textural class patterns. The study was done in nine natural sites in the municipalities of Uberlândia (6 sites), Iraí de Minas (1 site), Santa Vitória (1 site) and Ituiutaba (1 site) in the Triângulo Mineiro-MG. In the previously selected areas, soil samples were collected in two periods (November 2017 and April 2018) of the rainy season. At the sites, litter collection at the selected sites was done in an area of 50 x 50 cm (2,500 cm2), the plant material was dried at 60°C and passed through sieves of two diameters (6 and 2 mm), constituting the leaf fractions (F1), coarse (F2) and fine (F3), respectively. Soil texture analysis was done by determining clay, silt and sand contents. Soil chemical analyzes (organic carbon, nitrogen, phosphorus, potassium, calcium, magnesium, aluminum and pH) and litter (organic carbon, nitrogen, phosphorus, potassium, calcium and magnesium) were done. The number of forest individuals and the stem circunference (≥ 10) cm of the the plant species were determined within each site, counting in ten (10) plots with an area of 4 x 4 meters (160 m²) within each site and the circunference at ground level measured with a tape measure. Soil and litter attributes data were statistically analyzed by correlation and multivariate analysis to measure the degree of association between attributes and similarity among the nine sites studied. The results of the physical-chemical analyzes of the soils indicated a predominance of soils of clayey to very clayey texture, following the sequence S2 > S1 > S4 > S9 > S3 > S5 > S6 > S7 > S8. The largest deposition of litter (dry matter) in g.m-2 was the following sequence S3 > S4 > S5 > S1 > S9 > S2 > S6 > S7 > S8. It was concluded in this research that the soil clay content strongly influences the dry matter yield and the number of trees per hectare, since the highest levels of litter deposition and number of trees are related to the sites with higher levels of clay in the soil. Phytophysiognomies do not depend on the textural class of the soil.