ROCKY MOUNTAIN LANDSCAPE SIMULATOR (RMLANDS)
Spatial Data
This section provides a brief description of the spatial data base compiled for this application. Each required and optional spatial data layer is described in detail, including the data sources and processes used to derive the grid, its use in RMLANDS, and definitions of the grid attribute values.
In order to simulate natural succession and disturbance processes (i.e., excluding anthropogenic disturbances), RMLANDS requires at a minimum 8 separate, single-attribute input grids; 8 additional optional grids can be specified as well. Each grid is discussed in detail below, including the data sources and processes (i.e., ESRI's AML routines) used to derive the grid, its use in RMLANDS, and definitions of the grid attribute values.
RMLANDS uses the grid data structure. Grids are based on uniform square units called cells (or pixels). Each cell represents an actual portion of geographic space where each cell has a defined X and Y value that corresponds to the coordinates defined by the projection. For example, in the Universal Transverse Mercator (UTM) projection, the grid that covers the entire UPL project area is in UTM zone 13 and covers an area defined by a range of X and Y values (minimum and maximum). In the UPL application each grid cell is 25 meters on a side (i.e., 625 m2 or .0625 ha).
RMLANDS requires that all grids are perfectly aligned. This means that not only must they have the same cell size and the same numbers of rows and columns, but the cells need to occupy the exact same geographic space (out to six decimal places) and have the same number of total cells. RMLANDS does a check of this when it first executes to insure that these requirements are met. If one grid is not aligned, the program will not run. The cell size or numbers of rows or columns can be defined by the user when the project first begins, but it needs to be consistent among grids. The loopshift.aml program was written to make sure that these grid properties are consistent and should be run as a safeguard before running RMLANDS.
The spatial data used to create these grids can take various forms. Some of the input data is already in grid format and simply needs to be altered slightly to conform to our grid template. For example, to create the elevation grid, we started with an existing grid with elevation values. The only processing required was to resample it to a different cell size (if necessary) and shift it slightly to conform to the grid template. Other input data might be in vector format (such as points, lines or polygons) that need to be manipulated in such a way as to extract some subset of the original data based on one or more attributes contained within this data source. We then extract the data that we want and convert it to a grid, again using the same grid template. An example of this would be the streams grid. This grid was derived from a line coverage (RGSTREAMS) that contained that contain a stream order attribute used to assign a stream size class to each stream cell. Finally, some of the input grids can be derived from other required grids. For example, from the elevation grid, we derived the slope and aspect grids; from the cover, age and elevation grids, we derived the condition-age and condition grids.
Click on the links below for a description of each input grid, including the data sources and processes used to derive the grid, its use in RMLANDS, and definitions of the grid attribute values.
Required Input Grids:
1. Cover
2. Condition
3. Age
4. Elevation
5. Slope
6. Aspect
7. Streams
Optional Input Grids:
9. Buffer
10. Wildfire zones
11. Pinyon decline zones (not used in UPL application)
12. Pine beetle zones (not used in UPL application)
13. Fir beetle zones (not used in UPL application)
14. Spruce beetle zones (not used in UPL application)
15. Spruce budworm zones (not used in UPL application)
16. Prairie dog zones (not used in UPL application)