m 
An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 
How to Read the Maps and Charts in this Report 
Figure 2.3 illustrates the types of maps and charts that 
appear in Chapter 2. 
The map of mid-Atlantic watersheds is color-coded 
to show relative conditions among watersheds. The 
colors range from red to green, indicating relatively 
“less desirable” and “more desirable” conditions, 
respectively. 
A quintile 
contains 1/5 of 
the watersheds. 
Quintiles are 
formed after 
ranking 
watersheds for 
the indicator. 
The Data Range 
shows the 
indicator values 
for watersheds 
contained in each 
quintile. 
Quintile 
1 
2 
3 
4 
5 
Data Range (Percent) 
<70.600 
70.600- 76.869 
76.870- 84.579 
84.580- 89.889 
>89.890 
The value shown on the X axis is the upper limit of a data 
range. For example, this bar shows the number of 
watersheds with data values between 60-70. 
A brief explanation of the essential methods is given. 
40 50 60 70 
Indicator Value 
Woody landcover along streams was calculated as the percent 
of streamlength with forest landcover types. By intersecting a 
buffer zone around each stream with the landcover, a data set is 
created which records all landcover types within a specified 
distance to stream center. 
Sources: USGS 1:100,000 River Reach 3 stream data, and 
MRLC 30 meter Landsat land-cover data. 
Figure 2.3 
How to read the maps and charts in this report. 
