The Amazon Basin is undergoing extensive environmental degradation as a result of deforestation and the rising occurrence of fires. The degradation caused by fires is exacerbated by the occurrence of anomalously dry periods in the Amazon Basin. The objectives of this study were: (i) to quantify the extent of areas that burned between 2001 and 2019 and relate them to extreme drought events in a 20-year time series; (ii) to identify the proportion of countries comprising the Amazon Basin in which environmental degradation was strongly observed, relating the spatial patterns of fires; and (iii) examine the Amazon Basin carbon balance following the occurrence of fires. To this end, the following variables were evaluated by remote sensing between 2001 and 2019: gross primary production, standardized precipitation index, burned areas, fire foci, and carbon emissions. During the examined period, fires affected 23.78% of the total Amazon Basin. Brazil had the largest affected area (220,087 fire foci, 773,360 km2 burned area, 54.7% of the total burned in the Amazon Basin), followed by Bolivia (102,499 fire foci, 571,250 km2 burned area, 40.4%). Overall, these fires have not only affected forests in agricultural frontier areas (76.91%), but also those in indigenous lands (17.16%) and conservation units (5.93%), which are recognized as biodiversity conservation areas. During the study period, the forest absorbed 1,092,037 Mg of C, but emitted 2908 Tg of C, which is 2.66-fold greater than the C absorbed, thereby compromising the role of the forest in acting as a C sink. Our findings show that environmental degradation caused by fires is related to the occurrence of dry periods in the Amazon Basin.
The southern region of the Amazon stands out for the growing agricultural development and installation of large hydroelectric projects. Given this scenario, the objective of this study was to quantify the Áreas de Preservação Permanente (APPs), Permanent Preservation Areas, of the water bodies of the Teles Pires river basin according to the current legislation, checking whether there is conflict regarding the use and occupation of these areas, and then check for the occurrence of degradation and identify the environmental fragility of the area. Using the Modified Normalized Difference Water Index (MNDWI), the water bodies located in the study area were delineated and the APPs were delimited according to Law 12,651/2012. To identify the existence of conflicts within these areas, a map of land use and occupation was generated through Maximum Likelihood supervised classification, which was compared with the limits of the APPs, considering conflict areas whose land use is related to anthropic activities. Lastly, the potential and emerging fragility of the area were calculated, considering data of the slope, soil type and land cover/land use. The delimited APP comprised 3.96% of the total area of the basin and it showed a state of low degradation, with 83.83% of the area conserved under native vegetation cover and 15.93% showing conflicting type of use, with the occupation by pastures standing out, and among the APP categories mapped the headwaters were the most impacted. The spatialization of conflicts within the basin indicated that it has a very different conservation pattern, with the most critical areas concentrated in the center-east, where municipalities that have more than 40% of the APP occupied by anthropic activities are located. The north of the basin has areas with higher potential fragility, which is attenuated by the great soil protection.
The Teles Pires River basin in Brazil’s center-west has recently expanded agricultural economic development at the expense of both the Amazon rainforest and Cerrado savannah. We evaluated these changes occurring in this basin over the last 34 years. Maps were generated to determine changes in land use classifications between 1986, 1991, 1996, 2000, 2005, 2011, 2015, and 2020. The supervised classification of Landsat 5 and 8 images used the maximum likelihood algorithm. Satellite spatial data on land use downloaded from the United States Geological Survey were validated according to 1477 locations, where our research team categorized land use in the field during 2020. The growth in agricultural crops (+643%) and pasture (+250%) from 1986 to 2020 were detrimental to natural areas, such as the rainforest and savannah. The percentage increase in the agricultural areas between the evaluated years peaked around 1996 and stabilized in 2020 at 40% of the Teles Pires River basin’s land area. Land use change patterns were related to political/economic events in Brazil, forest/pasture conversions until 2011, and the change from pasture to crops from 2011 to 2020. There was greater intensity in the changes in the upper Teles Pires River basin toward the south, which expanded northward over time. Sustainable agricultural intensification is needed in such stabilized, frontier areas.
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