Software for Land Management Planning
Analysis and Geographic
MAGIS EXPRESS is structured
primarily as a timber harvest-road access tool. Two GIS coverages
(or shapefiles) are used: Treatment units and Roads. 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. 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 EXPRESS (and
in MAGIS Professional) 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. Proposed roads may be built for one planning period
(as 'temporary' roads) or as permanent additions to the network.
Fixed road costs (the cost of building, reconstructing or decommissioning
the link) are entered by link
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 amounts of non-timber outputs, 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.
For more detailed information or technical
Rocky Mountain Research Station
Forestry Sciences Laboratory
800 E. Beckwith
Missoula, MT 59801