Global Journal of Human-Social Science, B: Geography, Environmental Science and Disaster Management, Volume 23 Issue 6

© 2023 Global Journals Volume XXIII Issue VI Version I 13 ( ) Global Journal of Human Social Science - Year 2023 B Evaluating Soil Carbon Efflux Responses to Soil Moisture and Temperature Variations in Brazilian Biomes Subsequently, the collections from the five monitored points were averaged. The soil carbon efflux measurements were performed using a portable infrared gas analyzer (EGM- 4, PP systems, Amesbury, MA, USA) connected to a soil CO 2 flow chamber (SRC-1, PP Systems, Amesbury, MA, USA). Air temperature and relative humidity measurements were made using a portable microclimate station (Kestrel 4500 Weather Tracker, NK Company, Boothwyn, PA, USA), and at a soil depth of 5 cm, soil temperatures were measured using a digital thermometer (Instrutherm TE-300, São Paulo, SP, Brazil) and soil moisture measurements were made monthly using the gravimetric method. Precipitation data was obtained from the National Meteorological Institute (INMET, 2018). Except for Pantanal, that leaf area index (LAI) was not collected, in the other study areas was measured using a linear ceptometer (AccuPar-LP 80, Decagon Devices, Washington, USA), and monthly averages were taken for all variables. A collector with an area of 1 m² placed at a height of 1.20 m was used to obtain litter. The litter produced was collected monthly, then stored for subsequent drying in a circulating oven for 72 hours. Afterward, it was weighed using a semi-analytical balance (Scoriza, 2012). e) Statistical analyses Soil moisture, litterfall, and leaf area index (LAI) were subjected to regression analyses to explore the interdependence of these variables, which play crucial roles in soil CO2 efflux. The aim was to identify models that accurately describe the field experimental data gathered at the three sites. Furthermore, an examination of the impact of soil temperature and moisture on effluxes was conducted, with sensitivity analysis providing insights into potential scenarios related to climate change. After conducting normality and homo- scedasticity tests, Spearman correlation tests ( ρ ) were employed to explore potential correlations among the variables. The Tukey test was then utilized to compare groups. Additionally, p values ≤ 0.05 were deemed statistically significant. Consequently, these datasets will facilitate the analysis of soil CO2 efflux, enabling the establishment of regression models. III. R esults and D iscussion a) Characterization of variables The analysis of the monthly litterfall (S), soil carbon efflux, precipitation (Ppt), leaf area index (LAI), soil temperature (T s ), and soil humidity ( ) variations corresponding to the Cerrado, the Cerrado-Amazonian Ecotone, and the Pantanal forests are shown in Figure 1.