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 17 ( ) Global Journal of Human Social Science - Year 2023 B Evaluating Soil Carbon Efflux Responses to Soil Moisture and Temperature Variations in Brazilian Biomes Table 2: Analysis of sensitivity of soil carbon efflux for soil temperature (Ts) and soil moisture ( ) for Cerrado-Amazonian Ecotone, Pantanal and Cerrado. Effect on soil carbon efflux for each model Variables Cerrado Cerrado-Amazonian Ecotone Pantanal Ts+2ºC 0.6% 17.4% 19% Ts+2ºC and -10% - 2.7% 19.7% 9.7% Ts+2ºC and +10% 4.0% 15.2% 26% The soil carbon efflux at the Cerrado site appeared to be unaffected by Ts or since the positive and negative changes in the magnitude of the efflux were considerably smaller than those corresponding to the Ecotone and Pantanal. This is an interesting finding because it showed that the observed efflux increased in response to a local increase in S (February), meaning that litter supply plays an important role in litter decomposition and CO 2 emission. Moreover, the regression model for Cerrado may be able to describe the local emission peak via the inclusion S I variable. The Ecotone and Pantanal sites appeared to be more sensitive to Ts and , even though the Ecotone site showed more sensitivity to Ts than . When the soil moisture content varies by 10%, the expected variation in efflux was not significant compared with the 17.4% increase in the efflux that resulted from an increase in Ts by 2 ºC. This observation confirmed the strong correlation between the efflux and Ts observed at this site ( ρ = 0.893 and p < 0.001). The model was sensitive to variations of 2ºC and 10% for Ts and U in the Pantanal, resulting in a 26% increase in soil carbon efflux. This value is 7% higher compared to the model that only changed the temperature, being similar to Wang et al. (2014), who reported an increase in emissions of approximately 21% owing to a 2 ºC rise in temperature. Even though these sites are located less than 215 km apart, their soil types, vegetation characteristics, and climates are considerably different, and these differences were responsible for the distinguishing results. Additionally, the results obtained in this study further confirmed that the Mato Grosso state presents a complex mosaic landscape that may respond differently to climate changes. Therefore, it may be necessary to consider specific solutions that seek to establish sustainability as well as preventive actions to mitigate soil CO 2 emissions. Once climate change is present, it is necessary to monitor carbon emissions in these biomes for a longer period to improve mathematical models and to advance the environmental management of the most sensitive areas. Given the fact that tropical ecosystems may be responsible for approximately 67% of the total annual global CO 2 efflux (Bond-Lamberty e Thomson, 2010b) changes in litter production and efflux due to climate and land-use change have important implications for global CO 2 cycling. This serves as an alert to government officials and highlights the need for preventive actions to mitigate soil CO 2 emissions (Pinto Jr. et al., 2018). IV. C onclusion In this study, a positive and significant correlation was observed between soil moisture content and the efflux in Cerrado and Pantanal. However, in the Ecotone, an opposite observation was made; a positive and significant correlation existed only between soil temperature and efflux. These correlations allow us to increase our understanding of which variables influence carbon emissions. Another important result is that combinations of leaf area index and litterfall can be used to facilitate the representation of efflux seasonality. Compared to other locations, the Cerrado forest was the least sensitive to changes in temperature and humidity. For the Ecotone and Pantanal, an increase in soil temperature by 2 ºC resulted in an increase in carbon emissions by 19.7 and 26%, being a worrying result, given that these regions are constantly being deforested. Additionally, the biomes analyzed in this study have a complex mosaic landscape with regions that respond differently to warming, being recommended that this type of experiment be applied in more locations in this Brazilian region, in order to understand how changing vegetation cover influences carbon emissions. Funding This work was supported by the Mato Grosso Research Support Foundation-FAPEMAT [grant number 0194288/ 2017]. R eferences R éférences R eferencias 1. Adachi, M.; Bekku, Ys.; Rashidah, W.; Okuda, T.; Koizumi, H. 2006. Differences in soil respiration between different tropical ecosystems. Applied soil ecology , 34(2-3), 258-265. https://doi.org/10.1016/j. apsoil.2006. 01.006 2. Alvares, C. A.; Stape, J. L.; Sentelhas, P. C.; Gonçalves, J. L. M; Sparovek, G. 2013. Köppen’s clim ate classification map for Brazil. Meteorologische Zeitschrift , Zurich, Vol. 22, No. 6, 711–728. https://doi.org/10.1127/0941-2948/2013/ 0507. 3. Andrade, L.P.; Novais, J. W. Z.; De Musis, C. R.; Sanches, L.; Pereira, S. P. 2016. Efeitos de borda sobre o microclima de um parque ecológico urbano