For the second part of the lab assignment, I explored least-cost path and corridor analysis. Focusing on the corridor analysis, I was asked to determine corridors between two separate sections of the Coronado National Forest to model potential areas that black bears could use to move between the two sections of forest.
I started with a landcover raster, DEM raster, and a roads shapefile. From there, I converted the DEM into a slope raster and created a euclidean distance raster for the roads. Then, I reclassified the rasters and assigned suitability values for certain ranges or values. For instance, Sections closer to roads had lower suitability values than areas further from roads since bears do not like the noise pollution coming from roads.
Once they were all reclassified, I used the weighted overlay tool to create an overall suitability raster output. In order to generate a corridor, I needed to create a cost raster. I then “inverted” the overall suitability raster using the following raster formula: 11- overall suitability raster= cost raster. I had to subtract by 11 because I received a warning in the next step when I initially used 10.
From there, I used the cost distance tool twice. I ran it once with Coronado1 (section of Coronado National Forest) as the source and once with Coronado2 (other section of Coronado National Forest)as the source. The cost raster was used as an input for the cost distance tool. Next, I used the cost distance output in the corridor tool and generated a raster that could be used to determine potential corridors. To determine the threshold for the corridor I looked at the output with varying thresholds from 1.05 times the minimum value to 1.10 times the minimum value. Eventually, I settled on a threshold of 1.075 times the minimum value for the corridor output. This identified two potential corridors that bears may be using to travel between the two sections of Coronado National Forest. See the corridors in the map below.
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