Land use dynamics in the Brazilian Cerrado in the period from 2002 to 2013

– The objective of this work was to analyze land use dynamics in the Brazilian Cerrado region from 2002 to 2013. This analysis was based on the interpretation of Landsat satellite images carried out by the projects Projeto de Conservação e Utilização Sustentável da Diversidade Biológica Brasileira (Probio) and TerraClass Cerrado 2013, both coordinated by Ministério do Meio Ambiente. In 2002, 38.9% of the Cerrado was covered by some type of anthropic activity. In 2013, this percentage increased to 43.4%. One of the main highlights is the emergence of a new agricultural frontier in the northern region of the study area, known as Matopiba.

Pesq. agropec. bras., Brasília, v.54, e00138, 2019 DOI: 10.1590/S1678-3921.pab2019.v54.00138 some areas, highly sensitive climatic seasonality, and high dynamics within land use classes (Silva & Sano, 2016). However, producing accurate land use maps of the biome is important, for example, to monitor biomass changes and related CO 2 emissions due to habitat conversion and degradation, as well as to define public policies either to prevent deforestation and degradation or to define the best strategies and priorities for biodiversity conservation.
Up to now, land use mapping in the Cerrado biome has focused on the use of medium spatial resolution (30 m) and optical satellite images. The first "wall-to-wall" land use map, encompassing the entire Cerrado, was prepared in 2002 based on the interpretation of more than 120 Landsat images by Projeto de Conservação e Utilização Sustentável da Diversidade Biológica Brasileira (Probio) (Sano et al., 2008(Sano et al., , 2010 under the coordination of Ministério do Meio Ambiente (MMA). More recently, Beuchle et al. (2015)  It should be noted that the studies carried out by PMDBBS and Beuchle et al. (2015) do not allow the long term (> 10 years) analysis of land use dynamics. In addition, the usability and consistency of the results obtained by GLAD have been questioned by some authors, such as Tropek et al. (2014), especially in the seasonal tropical domains. Because they are quite recent, the annual land use maps from MapBiomas have not yet been evaluated by the scientific community. In this context, Probio and the TerraClass are currently the best options for the long-term analysis of land use dynamics in the Cerrado. Such analysis is important to estimate the rate of loss of natural vegetation in the biome, as well as to estimate the ongoing conversion between different land use types, particularly the level of conversion of pasturelands into croplands.
The objective of this work was to analyze land use dynamics in the Brazilian Cerrado region from 2002 to 2013.
Although the mapping projects Probio and TerraClass Cerrado both used images obtained by the Landsat satellite series, i.e., Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-8 Operational Land Imager (OLI), respectively, it is important to point out the main differences and similarities between them when comparing results. In Probio, the minimum mapping area was defined as 40 ha and, in TerraClass Cerrado, as 6.25 ha, which resulted in a finer detail map for 2013. Moreover, non-identified areas (burned and cloud covered), bare soil, and mosaic of occupation (areas composed of a mixture of varying land use classes, such as houses, orchards, native vegetation, and relatively small pastures that cannot be defined as specific polygons) were only included in the TerraClass Cerrado legend. The final product of TerraClass Cerrado also received an independent validation, which showed a high overall accuracy of 80.2% (Mapeamento…, 2015). However, in the two developed products, the areas mapped as pasture refer only to the cultivated pastures, whereas natural vegetation represents the areas covered with native vegetation species, regardless of the presence of some type of land use, as cattle on natural grasslands (native pastures).
In the present study, the vector-based maps of Probio and TerraClass Cerrado, in shapefile format, were used to calculate the areas, in hectares, occupied by the major land use classes in the Cerrado biome; for this, the Calculate Geometry tool available in the ArcGIS software, version 10.2 (Environmental Systems Research Institute, Redlands, CA, USA), was adopted. A transition matrix was also used to determine the magnitude of changes in the major land cover types. In the experimental period, land use in the Cerrado increased from 38.9% (about 80 million hectares), in 2002, to 43.4% (about 88.5 million hectares) in 2013 (Figure 1). This corresponds to an average increase of 0.41% per year, i.e., to 772 thousand hectares per   The confusion matrix between Probio and Terra Class Cerrado data indicated that 5.3 million hectares of cultivated pasture in 2002 were converted into croplands in 2013 and that another 1.1 million hectares were converted into reforestation, especially with Eucalyptus. Approximately 19.1 and 3.7 million hectares of natural vegetation in 2002 were converted into cultivated pastures and into croplands, respectively, in 2013. Table 1 shows the areas occupied by pasturelands and croplands in 2002 and 2013 at the state level. The increase in areas occupied by croplands and cultivated pasturelands was 11% for both types of land use. However, the most noticeable feature is the significant increase in croplands of 128, 328, 286, and 41% in the states of Maranhão, Tocantins, Piauí, and Bahia, respectively. Estimates from the survey on agricultural production, Produção Agrícola Municipal , showed similar increases for soybean [Glycine max (L.) Merr.] planted area in the region: 136% for Maranhão, 400% for Tocantins, 533% for Piauí, and 51% for Bahia. Despite the different methodologies and uncertainties related to each project, the high magnitude of crop expansion in these states was captured by both datasets. This highlights the importance of the region encompassing these states, known as Matopiba (Miranda et al., 2014), the new agricultural frontier of the Cerrado. Matopiba covers approximately 45 million hectares and 151 municipalities and is already responsible for 10 and 15% of the national production of soybean and corn (Zea mays L.), respectively (Esquerdo et al., 2015).
The analysis of the maps produced by the Probio and TerraClass Cerrado projects showed that, from 2002-2013, the Cerrado biome lost its natural vegetation at a rate of 0.41% per year. This is much higher than the deforestation rate of 0.29% per year reported for Amazônia Legal during the same time period (INPE, 2018). The major changes in land use and cover were related to the conversion of natural vegetation into cultivated pastures and croplands, as well as of cultivated pastures into croplands.