An Ecological Assessment of the Louisiana Tensas River Basin: Chapter 2 
For each watershed, the nine indicators (Table 2.1) included 
in this chapter were calculated from land cover and from the 
spatial relationships among roads, streams, and land cover. 
Figure 2.2 
National maps of (a) roads, (b) rivers, 
and (c) watershed boundaries. The 
maps are from the ArcLISA distribu¬ 
tion of the U.S. Geological Survey 
Digital Line Graph maps of rivers 
(1973) and roads (1980), and the 
U.S. Geological Survey map of 8- 
digit hydrologic accounting units. 
Table 2.1 List of landscape indicators used for the national context. 
U-Index (proportion of watershed area with anthropogenic land cover) 
Agriculture Index (proportion of watershed area with agriculture land cover) 
Number of natural land cover types per unit area 
Proportion of watershed that has forest land cover 
Average forest patch size as a percentage of watershed area 
Index of forest connectivity 
Proportion of total stream length with forest land cover 
Proportion of total stream length with anthropogenic land cover 
Number of roads crossing streams per unit stream length 
