90 
remote sensing analysis to evaluate rangeland in an area protected from grazing 
for two years. The area is located inside INPE's test site in Cachoeira Paulis- 
ta, 200 kilometers from Sao Paulo. The vegetation cover is one main palatable 
plant, known in Brazil as Capim Gordura ( Melinis minutiflora ) and very few 
mixed areas of Capim Coloniao ( Panicum maximum) . The two main invaders are Sapé 
( Imperata brasiliensis ) and Vassourinha ( Baccharis rufescens) : Taboa ( Thyfa 
ap. ), an impalatable plant, indicates the presence of highly humid lowland 
soils, and a high water table. Some other species appear in some scattered 
plots because of the human use of this area before it was placed under pro 
tection. Napir elefente ( Pannisetum purpureum) Batatais ( Paspalum notatum) , 
Bambu and some bushes appear in the area also. During June-September, the dry 
season of Sao Paulo State, the palatable species such as( Melinis) are usually 
dry having lost their leaves after the flowering stage and the seed spreading 
stage. The invaders such as Sapé and Vassorinha stay fresh and strong extrac 
ting their needs from soil moisture but provide a less dense canopy cover. The 
dry season was choosen for the flight because of this contrast between 
palatable and nonpalatable plants. Laboratory spectrophotometer analysis was 
done to study the leaf reflectance along wavelength bands, using a Perkin-Elmer 
450 model, with integrated sphere. In the growing stage of both ( Melinis) and 
( Imperata) , the leaf reflectance curves (fig.l), show high chlorophyl absorption 
around 500 and 650 my wavelength. But ( Melinis) shows higher absorption than 
(Imperata). ( Imperata ), has the same reflectance curve pattern as ( Melinis) , but 
it is displaced about 10 my towards the shorter wavelength, in the all bands, 
comparing with ( Melinis ) curves —using this information an estimated leaf 
reflectance curve (fig. 2). It showed that there is high contrast between areas 
covered by ( Imperata ) and ( Melinis) in the spectral regions of: 500, 650 my and 
after 700 my. For this reason four filters have been chosen to be used with the 
selected films. (Table 1). The combination of filter transmissions and plant 
reflectance curves are also illustrated, (fig.2). 
The flight was on the 6th of July 1973, using a Hasselblad 500 EL/70mm 
system from an altitude of 1500 feet. Photos at a scale of 1:9144 were thus 
obtained. Four filters were used: yellow, orange, red and Kodak Wratten 89B. 
The primary purpose of the yellow filter is the correct rending of those color 
tones in the gray value. The orange filter is more a contrast filter and cover 
over corrects for the blue sky, so that, sky tones become darker than they 
appear to the eye and distant details appear stronger. The red filter goes 
further in over correction (4). Table-1, shows the flight parameters. The oper 
ation time was around 12:00 o'clock to avoid vegetation shade. 
Interpretation : The data was collected from four bands, each filter 
transmitting information about the ground cover. The summation of the data 
obtained from the four bands made accurate and efficient interpretation possi 
ble. The yellow filter transmits reflected radiation by the plant surfaces 
longer than .45y wave length. The red filter eliminates reflected radiation in 
wave length shorter than 0.575y. Thus the red filter gives information in a 
more contrasted format than the yellow by absorbing some information that 
appears with the other filters. This facilitates the interpretation by