USDA Forest Service
 

Economic Aspects of Forest Management on Public Lands

 
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Software for Land Management Planning

[Photograph]: Forest Service employees reviewing paperwork.Multiple-resource Analysis and Geographic Information System

MAGIS is a robust modeling tool for analysis of multiple resource issues. One or two polygon coverages may be used (stands and treatment units) plus a  roads coverage.   Forest vegetation on the treatment unit polygons is represented using a 'vegetative state and pathway' paradigm.  Vegetative 'states' are the unique combination of dominant species, structure class and density (or crown closure) class.  These states can be stratified by habitat type (group).  Each vegetative state is a discrete unit, and forest stands move from one state to the next in well-defined 'pathways'.  The pathway could be succession, a disturbance process like insect infestation or fire, or some human-applied treatment.  Standing volume for forested stands is entered by polygon, and is modified with a simple annual growth percentage increment based on state; or volume may be determined by state characteristics.
       Land management treatments are allocated as options to treatment units through a set of rules; not all treatment units would necessarily have all defined management regime options available for MAGIS to select from.  For example, it wouldn't make sense for a treatment unit that consists of pole-sized trees to have an option for a shelterwood seed cut.  A MAGIS solution selects from among these options for the resulting schedule.
      The network coverage used in MAGIS consists of both the existing road network and any proposed roads that are to be considered in the solution.  Road 'options' are added by the user; existing roads may be reconstructed or decommissioned.  Fixed road costs (the cost of building, reconstructing or decommissioning the link) are entered by link, or can be calculated from a lookup-table in MAGIS.  Proposed roads may be built for one planning period (as 'temporary' roads) or as permanent additions to the network.  Timber harvest is loaded onto the network at specified nodes, by specified logging systems (all user defined).  Traffic is routed from the loading points to the 'exit' nodes where it is assumed it either leaves the currently defined network or arrives at a distant mill site.
      MAGIS solutions are based on an objective function  to be maximized (or minimized) and any number of constraints.  The user defines all functions to be calculated in solution, and chooses the objective function and constraints.  For example, a simple solution might be to maximize present net value, constrain road building to a certain level (in miles or by cost, or by location), and constrain harvest volume to a certain level, area, or time frame (or some combination thereof).  Other constraints could be put on types of activities, adjacent treatments, or acres of vegetative states (for example, one could set a minimum number of acres of 'old growth' types).
      The solution is expressed in terms of 'when', 'where', 'what', and 'how': MAGIS selects 'resource projects' which are the specific treatment on a given polygon, the period in which it is implemented, and how (and where) the timber is loaded onto the network.  Additionally, the values for all 'effects functions' are recorded in a table. These effects functions are the calculations of present net value, costs, revenues, acres of activities, management regimes, size classes, volume classes and so on.   Map Displays of the solution are available in various permutations, as well as the summary tables.  Further GIS analysis and display of the solution could be accomplished using ArcGIS directly with the MAGIS output as attributes to the GIS coverages. More.

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