The Oregon BLM State Office developed a semi-automated technique to map juniper distribution for specific project areas. The technique uses 0.5 meter color infra-red NAIP imagery to identify juniper vegetation and map individual trees. The maps are used to plan for field activities such as fuel treatments and habitat restoration.
The first step in the technique identifies juniper vegetation from other vegetation such as grasses. Tree shadows are digitally classified and only vegetation within a specified distance is presumed to be juniper vegetation. The second step delineates individual juniper trees. Juniper vegetation is buffered inward so that the center of each vegetation patch has the lowest value. A GIS function is used to designate these lowest values as tree centers. The tree centers are then buffered out by the distance from the edge of the patch to the lowest value. The buffers are then used to mask out the juniper vegetation and identify patches of vegetation as individual trees.
Juniper Mapping using Color Infrared NAIP imagery