To utilize the various geoprocessing tools available in ArcGIS for vector analysis and to run script commands using Python to perform geoprocessing operations
Background
The DNR of Michigan wanted help determining where the most suitable bear habitats are located in Marquette County. This was found using these specific criteria: proximity to streams, the most common type of land cover in which bears are found, all within DNR management areas, and at least 5 km away from urban or built up lands.
Methods
Objective 1: Mapping an Excel file
Black bear locations of Marquette County, Michigan, were downloaded in an excel file containing XY coordinates. Since these data are in a non-spatial database, the coordinates were added as an "event theme" and after they were mapped on the NAD 1983 HARN Michigan GeoRef (Meters) coordinate system. They were then exported as a feature class to be brought into the geodatabase properly.
Objective 2: Determining preferred forest type of black bears
All feature classes from the bear management geodatabase were added to the map. A spatial join was performed between the bear locations layer and the land cover type layer. The MINOR_TYPE field was then summarized in order to find the three land cover types which contained the largest count of bears. These 3 forest types were considered the suitable bear habitats and therefore a criteria in determining the most suitable bear habitats. Using "select by attributes", these 3 forest types were selected and made into a new layer.
Objective 3: Determining correlation between streams and black bear habitation
In order to determine if distance to streams is an important factor in bear habitat selection, a buffer of 500 feet was created around all streams in Marquette County, and then the dissolve tool was used to connect the buffers. Next, the clip tool was used on the streams buffer layer with the bear locations layer to discover if most bears (at least 30%) were located near streams.
Objective 4: Finding suitable habitat (near streams in top 3 forest types)
An intersect was performed to find habitats near streams within the top 3 forest types. This provides the best suitable habitat for bears.
Objective 5: Finding suitable habitat within DNR management land
Once the best suitable habitat was determined, the DNR management land needed to be added to the criterion. A clip was performed to limit the DNR land to the study area being researched. The clip was then dissolved to eliminate the individual divisions inside of the DNR management lands. After this, the intersect tool was used to determine where the best suitable habitats were found within DNR management lands in the study area.
Objective 6: Eliminating areas near urban or built up areas
Urban and built up areas are hazardous to bears, so those needed to be eliminated from the possible study locations. To accomplish this, a spatial query was used in the land cover layer to create a new layer containing only urban and built up areas. In this new layer, a buffer of 5 km was created around all urban and built up areas, and then an erase was performed to eliminate these areas from the most suitable habitat on DNR management land layer. This provided the most suitable study area for bears in Marquette County, Michigan (Figure B).
Objective 7: Generating a data flow model
A data flow model was created including each step that was taken and the tools which were used to accomplish each task (Figure A)
Objective 8: Using Python
A few simple command scripts for geoprocessing tools were run using Python to demonstrate a more efficient way of running tools in ArcGIS (Figure C).
Results
The top 3 suitable forest types for bears were Mixed Forest Land, Forested Wetlands, and Evergreen Forest Land. It was also found that approx. 72% of bears lived within 500 meters of a stream, so streams were designated an important criterion in selecting suitable bear habitats. Figure B shows the most suitable bear habitat locations in Marquette County based on these two criterion, as well as the limitations of being within DNR management land and at least 5 km away from urban or built up lands.
Figures
Figure A. Data Flow Model
Figure B. Map of Suitable Bear Habitat in Marquette County, Michigan
Figure C. Python script
Sources
State of Michigan Open GIS Data:
http://gis.michigan.opendata.arcgis.com/
Landcover is from USGS NLCD:
http://www.mcgi.state.mi.us/mgdl/nlcd/metadata/nlcdshp.html
DNR management units:
http://www.dnr.state.mi.us/spatialdatalibrary/metadata/wildlife_mgmt_units.htm
Streams from:
http://www.mcgi.state.mi.us/mgdl/framework/metadata/Marquette.html
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