Software for Land Management Planning
Analysis and Geographic
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.