Brazil has a monitoring system to track annual forest conversion in the Amazon and most recently to monitor the Cerrado biome. However, there is still a gap of annual land use and land cover (LULC) information in all Brazilian biomes in the country. Existing countrywide efforts to map land use and land cover lack regularly updates and high spatial resolution time-series data to better understand historical land use and land cover dynamics, and the subsequent impacts in the country biomes. In this study, we described a novel approach and the results achieved by a multi-disciplinary network called MapBiomas to reconstruct annual land use and land cover information between 1985 and 2017 for Brazil, based on random forest applied to Landsat archive using Google Earth Engine. We mapped five major classes: forest, non-forest natural formation, farming, non-vegetated areas, and water. These classes were broken into two sub-classification levels leading to the most comprehensive and detailed mapping for the country at a 30 m pixel resolution. The average overall accuracy of the land use and land cover time-series, based on a stratified random sample of 75,000 pixel locations, was 89% ranging from 73 to 95% in the biomes. The 33 years of LULC change data series revealed that Brazil lost 71 Mha of natural vegetation, mostly to cattle ranching and agriculture activities. Pasture expanded by 46% from 1985 to 2017, and agriculture by 172%, mostly replacing old pasture fields. We also identified that 86 Mha of the converted native vegetation was undergoing some level of regrowth. Several applications of the MapBiomas dataset are underway, suggesting that reconstructing historical land use and land cover change maps is useful for advancing the science and to guide social, economic and environmental policy decision-making processes in Brazil.
Widespread in the subtropics and tropics of the Southern Hemisphere, savannas are highly heterogeneous and seasonal natural vegetation types, which makes change detection (natural vs. anthropogenic) a challenging task. The Brazilian Cerrado represents the largest savanna in South America, and the most threatened biome in Brazil owing to agricultural expansion. To assess the native Cerrado vegetation (NV) areas most susceptible to natural and anthropogenic change over time, we classified 33 years (1985–2017) of Landsat imagery available in the Google Earth Engine (GEE) platform. The classification strategy used combined empirical and statistical decision trees to generate reference maps for machine learning classification and a novel annual dataset of the predominant Cerrado NV types (forest, savanna, and grassland). We obtained annual NV maps with an average overall accuracy ranging from 87% (at level 1 NV classification) to 71% over the time series, distinguishing the three main NV types. This time series was then used to generate probability maps for each NV class. The native vegetation in the Cerrado biome declined at an average rate of 0.5% per year (748,687 ha yr−1), mostly affecting forests and savannas. From 1985 to 2017, 24.7 million hectares of NV were lost, and now only 55% of the NV original distribution remains. Of the remnant NV in 2017 (112.6 million hectares), 65% has been stable over the years, while 12% changed among NV types, and 23% was converted to other land uses but is now in some level of secondary NV. Our results were fundamental in indicating areas with higher rates of change in a long time series in the Brazilian Cerrado and to highlight the challenges of mapping distinct NV types in a highly seasonal and heterogeneous savanna biome.
Limited funding is a major barrier to implementing ambitious global restoration commitments, so reducing restoration costs is essential to upscale restoration. The lack of rigorous analyses about the major components and drivers of restoration costs limit the development of alternatives to reduce costs and the selection of the most cost-effective methods to achieve restoration goals. We conducted detailed restoration cost assessments for the three most widespread biomes in Brazil (Amazon, Cerrado, and Atlantic Forest) and estimated the restoration costs associated with implementing Brazil's National Plan for Native Vegetation Recovery (12M hectares). Most surveys (60-90%) reported using the costly methods of planting seedlings or sowing seeds throughout the site, regardless of the biome. Natural regeneration and assisted regeneration approaches were an order of magnitude cheaper but were reported in < 15% of projects. The vast majority of tree planting and direct seeding costs were incurred during the implementation phase, and nearly 80% of projects ended maintenance within 30 months. We estimated a price tag of US$0.7-1.2 billion per year until 2030 to implement Brazil's restoration plan depending on the area that recovers through natural regeneration. Our results offer valuable insights for developing strategies to make restoration cheaper and to increase its cost-effectiveness for achieving diverse benefits in Brazilian ecosystems. Our survey also provides a starting point for sound assessments of restoration costs and their drivers in other biomes, which are needed to reduce the financial barriers to scaling up restoration at a global scale.
<p>Wildfire effects on riparian zones and stream water can be significant, particularly in the vegetation recovery and flow of nutrients between the terrestrial and aquatic ecosystem. However, the integrated knowledge about the impacts of fire on terrestrial and aquatic ecosystems in the Brazilian Cerrado is poorly known. In Brazilian Cerrado, wildfire is one of the main vectors of degradation of riparian vegetation, because the forest formation in riparian zones can be more sensitive to fire than the other savanna formation due to a less evident vegetation fire-adaptations. Our main objective was to understand the effects of fire on the resilience of riparian vegetation and their consequences to nutrient fluxes between terrestrial and aquatic ecosystem. This study was conducted in the Environmental Protection Area (APA) located in the Federal District - Brazil, which is one of Brazil&#8217;s Long-Term Ecological Research Site, after a wildfire (September 2011) that burned an area of about 140 km<sup>2</sup>. We analyzed the riparian vegetation resilience (for forests and surrounding savannas formations) and nutrients fluxes (in surface runoff and stream water) in five streams. We estimated the fire severity with Delta Normalized Burn Ratio index and the riparian vegetation resilience with the Normalized Vegetation Index and evaluated the changes in nutrient concentrations for nitrite + nitrate ([NO<sup>2-</sup> + NO<sup>3-</sup>]), ammonium (NH<sub>4</sub><sup>+</sup>), and phosphate (PO<sub>4</sub><sup>3-</sup>) during 16 months on stream water and surface runoff solution in burned and unburned areas using the Generalized Linear Models. Our results show that fire severity was similar between forests and savannas formations, but in savannas we observed higher vegetation resilience, with faster vegetation regrowth and recovery after three weeks. The concentration of nutrients on both surface runoff and inside the stream have changed in burned areas regarding unburned areas, with an increase of PO<sub>4</sub><sup>3- </sup>and [NO<sup>2-</sup> + NO<sup>3-</sup>] and a decreased of NH<sub>4</sub><sup>+</sup>. After 16 months of the fire event, the concentration of PO<sub>4</sub><sup>3-</sup>, [NO<sup>2-</sup> + NO<sup>3-</sup>] and NH<sub>4</sub><sup>+</sup> increased in surface runoff, while [NO<sup>2-</sup> + NO<sup>3-</sup>] decreased inside the streams in burned areas. Precipitation was a factor that caused the increase of concentrations of [NO<sup>2-</sup> + NO<sup>3-</sup>] and NH<sub>4</sub><sup>+</sup> and, the high precipitation on rainy season (October &#8211; March), that started after the fire, could have contributed to the input of these nutrients and particulate materials from ashes to streams. Our results showed that the occurrence of fire in riparian environments reduces the biomass of riparian forests and increases the concentration of nutrients on streams. &#160;These elevated postfire nitrogen and phosphate loading can influence streams ecosystem health, especially in oligotrophic streams like those found in Brazilian Cerrado. It is known that phosphorus and nitrogen are limited nutrients for algal and cyanobacterial growth in freshwater ecosystem and an increase of these organisms can disrupt the ecosystem integrity. Fire is a pulsed disturbance and its effect on freshwater ecosystem depends on terrestrial ecosystem recovery, in this way, it is necessary to integrate the knowledge about the impacts of fire on terrestrial and aquatic ecosystems to better understand the effects on the entire ecosystem.</p>
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