An Ecological Assessment of the Louisiana Tensas River Basin Chapter 1 
Figure 1.3 shows an example of measuring spatial pat¬ 
terns as an indicator of stream conditions. The distribution 
of streamside land cover has been mapped for the same 
subwatershed that is shown in Figure 1.2. Stream seg¬ 
ments that are green have adjacent forest; orange indi¬ 
cates that streams are next to agriculture or urban land 
covers. The pattern of streams in relation to land cover is 
an indicator of conditions within the stream. Forests often 
filter pollutants, preventing them from reaching the water, 
whereas agricultural and urban landuse often contribute 
pollutants to streams. They also dissipate energy associ¬ 
ated with major precipitation events; this reduces nutrient 
loading and the severity of flooding. A simple summary 
indicator might be the percentage of stream length in the 
parish that is adjacent to forest land cover. To refine this 
indicator, a model might help to account for “natural” 
conditions, for example whether or not forest was the 
natural land cover for the parish. 
Figure 1.3 
Spatial patterns of land cover in 
relation to streams for a 
subwatershed in the Tensas River 
region. Stream segments are colored 
green or orange, depending on 
whether the segments are adjacent to 
forest or agriculture/ urban land cover. 
