Day One part 3

Demonstration #1: Building a basic natural disturbance model in SELES

 * Objective: Develop an age class distribution for a hypothetical natural landscape based on disturbance dynamics.
 * Assumptions:
 * Fire is major disturbance agent
 * The disturbance regime is independent of space and time
 * All forests have equal probability of initiating and burning in forest age 10+ years
 * Conceptual model




 * Implementation – Requires two landscape events
 * Fire
 * Stand Aging
 * Data Requirements
 * Initial Age, Fire Cycle, Mean Fire Size
 * Output and Analysis
 * Age class distribution

Spatial data formats

 * SELES currently supports GRASS, ERDAS and ARC ASCII formats
 * A model has one resolution and extent, so all rasters must have the same dimensions and represent the same landscape
 * SELES has support for resizing and aligning rasters
 * SELES (V3.2) has support for rescaling rasters

Working with Rasters - Raster overlays




Procedural vs. Declarative Languages

 * Procedural languages
 * Specifies the steps the program must take to reach the desired state
 * Advantages: possibly faster
 * Disadavantages: black boxes
 * Declarative languages
 * describes a problem rather than defining a solution
 * simply state the desired result
 * Classic example: logic.
 * Advantages: closer to domain of thinking than domain of execution (more transparent)

Introduction to structure of SELES models

 * SELES model structure
 * Scenario specification file (.scn)
 * Controls the model
 * Procedural
 * Model definition file (.sel)
 * Specifies which landscape events to include
 * Specifies input/output layers, constants and variables
 * Declarative
 * Landscape Event Definition (.lse)