CALIBRATING CERRADO PHYSIOGNOMIES USING SAR AND OPTICAL IMAGES IN 
BRAZIL. 
Marisa D. Bitencourt', Humberto N. de Mesquita Jr. 
U tencourt@ib.usp. br id beto@ib.usp.br 
Ecology Department, University of Säo Paulo — 
Phone # 55-11-30917603 - Rua do Matäo, trav. 14, #321 
Sao Paulo - SP, Brazil, CEP 05508-900. 
, 
Commission IV, WG IV/6 
KEY WORDS: JERS-1/SAR, TERRA-MODIS, CERRADO PHYSIOGNOMIES, NDVI 
The objective of this study is to evaluate the potential use of L-band SAR images, comparing to optical images, to separate the 
physiognomic gradient of the Cerrado biome. The field data come from a project from the BIOTA/FAPESP Program which visited 
several remnants between 1999 and 2002. That project studied 206 Cerrado polygons within the state of Sáo Paulo — Brazil, in order 
to discriminate their physiognomies and their conservation stages. This study started in one pilot area located in a Conservation Unit 
(CU) which presents all Cerrado physiognomies. Thus, the vegetation classes within the CU were analyzed using Landsat 
TM/ETM+ and Terra-MODIS images, and then compared with the JERS-1/SAR images. After the classification of the 
physiognomies found in the pilot area the same procedure were done for 206 polygons all over the Sáo Paulo state. Thus, the NDVI 
LANDSAT images were obtained from 1999 to 2002 (combined with field trip) and the NDVI MODIS images were obtained 2000 
to 2002. Through those NDVI classes, the backscattering (o) of JERS-1 images from 1995 to 1997, were analyzed and showed the 
predominance of dense type of vegetation in most of the remnants. This images observations corroborated the information found in 
the field by a botany team, who also found predominantly forest type physiognomies. The results obtained for JERS-1image analyses 
were: campo cerrado around —13 dB; cerrado s.s. from —12 dB to —10 dB; cerradáo from —9 dB to —8 dB; and rainforest from —8 dB 
to —7 dB, are similar to those obtained for Cerrado and tropical rainforests according to the literature. 
1. INTRODUCTION. where cerradäo is spectrally similar to the seasonal 
semideciduous forest (SSforest). 
1.1 General Instructions 
Originally the Cerrado biome occupied 23% of the a 
Brazilian territory (200 million hectare). In 1997, the NGO 7 Wu. j 
Conservation International indicated this biome as one of the 18 ; v : Lad 4 
Hot Spots because more than 70% of it has been surrogated by b T 
agriculture, especially soy bean. The State of Sào Paulo used to N £L. 
À : : ; . a i 
have 14% of its area occupied by the biome, whilst today less TN US 
than 1% remains preserved (SMA-SP, 1999). The Figure 1 bo 
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shows the location of the Cerrado biome in Brazil and in Sào 
Paulo State. 
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To monitor such a huge area it is absolutely necessary to M. r3 
make use of satellite images even with some uncertainties. \ a = Ef 
Optical images for example, are widely considered as a good 8 EX M 241 
mean to describe the green leave structure of the vegetation, NONSE 
although they may saturate in forest physiognomies. Studies Sow 1 
with optical images in Cerrado physiognomies began in early 
80's with excellent results if seasonal conditions were taken 
into account (Biigncout stek, 1997, Mesquita Tr., 1998,2003). Figure 1 — South America map overlaid with the Cerrado 
Domain area. The small map on the bottom, shows the 
Domain in the State of Säo Paulo (IBGE, 1993). 
The SAR L-band radiation however, can penetrate more 
deeply through the canopy of the forest physiognomies and 
provide more information about the vegetation structure. 
  
Several authors have described the good potential of that band 
to study Cerrado physiognomies (Santos et al, 1998; Santos et 
al, 2000; Sano et al, 2001). It is possible to hypothesise that the 
combination of SAR image, specially from JERS-1satellite, and 
optical images together could provide better describe those 
physiognomies. By merging both data could improve the forest 
physiognomies discrimination, especially in the Cerrado biome, 
544 
The objective of this paper is to analyse the potential use 
of JERS-1 and optical images (Landsat TM/ETM+ and Terra- 
MODIS NDVI), to discriminate different physiognomies within 
the Cerrado Domain in the State of Sdo Paulo-Brazil. The 
database comprises the remnants studied in project of the 
BIOTA Program (http://eco.ib.usp.br/lepac/biota-cerrado) and 
the JERS-1 2" Research Investigation Program (NASDA). 
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