Database diagram

Database diagram


The smallest unit of analysis is the pixel. At the landscape level, pixel size is often set to 30 x 30 m, or 0.09 HA. However, pixels can easily be re-sized for any purpose. Each pixel will contain a number of attributes (below). These attributes are stored as GIS rasters.

Pixel properties (i.e. raster data sets):

  • Habitat
    • Habitat: habitat = 1, non-habitat = NoData
    • Binary Habitat: habitat = 1, non-habitat = 0
    • Future Habitat: habitat in year [X] =1, non-habitat = NoData
    • Distance to habitat edge
  • Core habitat: Habitat beyond [X] m from edge = 1, all other areas = NoData
  • Habitat patches: Patch ID*
  • Patch sub-network: Sub-network ID*
  • Distance to habitat: Euclidean or cost-weighted distance
  • Distance to protected area: Euclidean or cost-weighted distance
  • Threat level
  • NHD+ catchment COMID
  • Upstream characteristics (% forested, %impervious, etc.)
  • Downstream characteristics (e.g., distance to stream)


A patch is set of contiguous habitat cells. Each patch is assigned a unique ID and several attributes which can be used to assess its overall value in protecting the species in question. These attributes are listed below:

  • Size/geometry
  • Minimum distance to neighboring patches (Euclidean or cost weighted)
  • Minimum distance to nearest protected area (Euclidean or cost weighted)
  • Shortest path betweenness (contribution to keeping the sub-network intact)
  • Overall threat level


In cases where habitat patches are larger than the typical area that can be conserved at one time, the patches are divided into sub-patches. Divisions can be based parcels, catchments, blocks, hexagons, or any other areal unit that makes sense. Each sub-patch contains the following attributes:

  • Size
  • Patch to which the sub-patch belongs
  • Mean distance to edge

Patch sub-network

A patch sub-network includes areas within which individuals can successfully travel between patches.

  • Total habitat area
  • Number of patches