**2.1 Uruçui-Una ecological station**

The Uruçuí-Una Ecological Station (UUES), with a total area exceeding 1,300 square kilometers, was established in 1981 with the purpose of protecting and preserving fragments of Cerrado ecosystems and promoting the development of scientific research.

Identification and Analysis of Burned Areas in Ecological Stations of Brazilian Cerrado 189

In Brazil, the causes of forest fires in the Cerrado were mostly associated to incorrect use of firefighting equipment: lack of fire lines, climate conditions and lack of fire control equipment. Also, illegal burning is one important cause of these fires. Recent studies have shown that 67% of the burned areas in Brazil (in 2000) were in Cerrado (Tansey et al. 2004). According to Vicentini (1993) and Silva et al. (2009) the Cerrado has been increasingly occupied and converted into agricultural land. The author affirms that the Conservation Units located in this biome have been constantly impacted by the action of frequent forest fires. Intensive agriculture is one of the factors that contribute to the generation of Conservation Units of small areas, which presents one or more vulnerable characteristics

Besides releasing carbon dioxide (CO2) into the atmosphere, burning can release other gases that cause global warming, and high frequency of fire affects the establishment of trees and

The scanner Thematic Mapper (TM), coupled in Landsat 5, sense data in seven spectral bands simultaneously. Band 6 senses thermal infrared radiation and can only acquire night scenes. The resolution on the ground (spatial) in bands 1-5 and 7 are 30 square meters and in

Bands 1 (blue, 0.45-0.52m), 2 (green, 0.52-0.60m) and 3 (red, 0.63-0.69m) are obtained in the waves lengths of the visible in the electromagnetic spectrum; while the bands 4-7 are collected in infrared region (4 - infrared near, 0.76-0.90m; 5 – infrared medium, 1.55- 1.75m; 6 – infrared thermal, 10.4-12.5m; and 7 – infrared medium, 2.08-2.35m).

Only bands 3 and 4 were used in the experiments conducted in this paper. Band 2 was only used in the generation of the color composition (Fig. 3). An image was obtained in the quarter ASO (August, September and October) of every studied year, which corresponding to the drought periods. This study comprises the years 1985, 1987, 1989, 1996, 1998, 2000, 2007, 2008 and 2010, in agreement with the readiness of TM data and with the occurrence of

Additional information on program Landsat can be seen in NASA (2011).

the climatic phenomena El-Niño and La-Niña. Fig. 3 shows the UUES in 1989.

due to the occurrence of fires, as previously mentioned.

shrubs (Hoffmann & Moreira, 2002, Krug et al., 2002).

**4. Used data** 

band 6 is 120 square meters.

Fig. 3. Image of the UUES area in 1989

The vegetation cover consists predominantly of UUES *cerrado stricto sensu*, but other types of vegetation, e.g. *campo cerrado* are also found. The *cerrado sensu stricto* in this area is composed of grasslands, with dense cover of grass and low trees.

The UUES located in the plateaux sub-region (scarps that resulted from the erosive action of waters) in the Cerrado of the Southwest of Piauí, within the boundaries of the cities of Baixa Grande do Ribeiro and Santa Filomena, about 730 km from Teresina, the State capital. Fig. 2 shows the location and boundaries of UUES.

Fig. 2. Location of the Uruçuí-Una Ecological Station

The average altitude of the plateau in the UUES is 620 meters. With a typically tropical climate, this area has high average temperatures, varying between 24 and 26 ºC, with absolute maximum annual reaching 40 °C. The relative humidity of air oscillates between 60 and 84% and the average annual precipitation levels are below 800mm. Regarding its physiography Piaui is a typical zone of transition, i. e., a mixture of biomes such as the *Caatinga*, the *Closed Deciduous Forest* and *Cerradão*. Finally, the aforementioned economies of the two municipal districts are predominantly agricultural, particularly grain production, such as soybean and corn (Medeiros & Cunha, 2006).
