Variabilidade espacial da emissão de CO2 e atributos do solo no Cerrado da região do Mato Grosso do Sul

Abstract

Soil CO2 emission (FCO2) is the result of the interaction between the physical, chemical and biological attributes of the soil and such interactions sometimes make the FCO2 understanding complex because they carry the aspects inherent to spatial correlations at different scales. In this sense, multifractal analysis was adopted to better understand the patterns of spatial variability between FCO2 and other soil attributes. The values of total CO2 emission (ET), temperature (Ts) and soil moisture (Us) were collected for eight weeks in transects containing 128 points in degraded pasture areas (PDr) and silvopastoral system (SSP) in the Brazilian Cerrado. The variables analyzed were: magnetic susceptibility (SM), soil Bulk density (Bd), macroporosity (macro), microporosity (micro), water-free porosity (WFP), carbon stock (Cs), humification of the organic matter index(HLIFS), soil clay content (clay) and carbon stability in the soil ( factor k). The joint multifractal analysis was adopted to study the possible relationships between ET and soil attributes at different scales. The highest emission rates were observed in the SSP (2.91 Mg C-CO2 ha-1), as well as the highest EC (40.11 Mg ha-1), clay content (623.69 g kg-1) and SM (54.95 10-8 m3 kg-1) when compared to PDr, whose values were, respectively, 2.17 Mg C-CO2 ha-1, 18.80 Mg ha-1 121.92 g kg-1 and 0.02 10-8 m3 kg-1). However, Ts (23.80°C), factor k (0.11 day -1) and HLIFS (3949.17 ua) were higher in PDr when compared to SSP values (Ts = 19.05°C; factor k = 0.07 day-1; HLIFS = 1166.23 water). The attributes Ds (1.59 g dm-3) and macro (0.18 m3 m-3) were higher in the PDr, while in the SSP the micro (0.43 m3 m-3) and PLA (16.76%) were higher in relation to PDr (0.17 m3 m-3 and 11.51%). The spectrum of the generalized dimension showed that both in the SSP and in the PDr the study variables presented low multifractality. On the other hand, the singularity spectrum demonstrated that the variability of soil attributes is concentrated in the lowest values of these, since in the study areas the branch of the respective spectrum was longer to the right. The results of the joint multifractal analysis showed that both in the PDr and in the SSP the correlations between ET and soil attributes were significant (p <0.01). The multifractal analysis showed that the variability of ET and soil attributes are represented by the lowest values of these except for the macroporosity in the SSP and that for the present study the behavior of ET and soil attributes show low multifractality. The relationship between soil CO2 emission and the attributes of the soil responsible for its production and transport in both the PDr and the SSP occur at different scales.