An Ecological Assessment of the Louisiana Tensas River Basin Chapter 3 
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31 
Figure 3.8 
Roads Crossing Streams. 
# of Crossings 
Ha 
Xings/Ha 
18 
5,601 
0.32 
159 
45,387 
0.35 
288 
92,471 
0.31 
116 
61,742 
0.19 
8 
11,126 
0.07 
20 
7,346 
0.27 
220 
79,713 
0.28 
238 
72,212 
0.33 
1067 
375,807 
0.28 
The forest cover map of the Tensas River Basin (Figure 
3.9) is based on the North America Landscape Charac¬ 
terization (NALC) satellite imagery data. NALC satellite 
data, available since the early 1970s, is a Federal effort to 
create similar data sets for the entire country. The resolu¬ 
tion of the NALC data is 60 meters; thus, each pixel 
(picture element) represents an area about the size of a 
football field. Compare the land cover map shown in 
Figure 3.4 (30-meter pixels) to the NALC data (Figure 
3.9) . 
Although individual pixels are far too small to be rendered 
accurately here, the visual impression of broad-scale 
regional patterns is readily apparent. Forest vegetation 
shows up on the NALC image as red in color, agriculture 
shows up as light red, grey, light blue and white. When the 
NALC Image is enlarged the agriculture almost always 
shows a pattern of rows or right angles typical of farm 
fields. 
