Patent Publication Number: US-6041173-A

Title: Method and system for simulating forest management

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This Application is a Continuation of application Ser No. 08/970,364, filed on Nov. 14, 1997, now U.S. Pat. No. 5,963,733, that issued on Oct. 5, 1999, that claims priority from Provisional Application No. 60/031,826, filed Nov. 26, 1996. 
    
    
     FIELD OF INVENTION 
     The present invention relates to computer simulation. More specifically, it relates to a method and system for simulating forest management. 
     BACKGROUND OF THE INVENTION 
     Computer simulations have been used for a number of years in forestry management. There are a number of different computer simulations known in the art that are used for forestry management. Forest inventory systems provide for a picture of timber resources at a specific moment in time. Forestry growth systems with mathematical growth models provide a way of simulating tree growth. Harvest schedule systems produce harvest and planting schedules find optimum harvest schedules for one or more stands of trees. 
     These forestry simulation tools have proven effective for specific applications, but they are difficult to use and customize. There are also a number of problems associated with using forestry simulations systems known in the art. Some of forestry simulation systems require a forestry manager input a large data file as batch job on a large mainframe computer and cannot be used on a time-shared computer. The batch forestry simulation may run for a significant amount of time, and the forestry simulation results are not instantaneous, but are delayed by some time period (e.g., a half-hour). 
     Other forestry simulation systems are used on personal computers but are application specific and are not designed to simulate more than one or two aspects of forest management at one time. Forestry simulation systems know in the art and used on personal computers are also written in programming languages like the C programming language that do not allow re-use of source code modules and are not easily adaptable. The forestry simulation systems known in the art typically do not have a graphical user interface that allow easy interaction with the underlying forestry simulation systems. 
     Today&#39;s forest manager should consider many complex factors simultaneously when managing forested land. Forestry management systems known in the art that consider one or two forestry management factors in isolation have proved to be ineffective in many situations to make accurate predictions for the management of forest lands. 
     Complex factors such as timber management, wildlife management, recreation, environmental quality and others are interrelated and need to be simulated together and not in isolation. Forestry simulations known in the art do not address today&#39;s complex forest management needs. The effective management of forest resources for multiple use has been hampered by a dearth of good simulation tools that can effectively consider multiple goals simultaneously. 
     SUMMARY OF THE INVENTION 
     In accordance with an illustrative embodiment of the present invention, the problems associated with simulating forestry management are overcome. A method and system are provided for simulating forestry management with an object-oriented forestry simulation that takes into account multiple complex factors. As is known in the art, object-oriented programming is used to design computer software that is easy to create, cost effective to modify and reusable. The object-oriented forestry simulation system includes a library of object-oriented modules for simulating various aspects of forestry management. The object-oriented forestry simulation system also includes a windowed graphical user interface that is used to view multiple forestry management factors as the forestry simulation progresses. 
     The object-oriented forestry simulation method includes maintaining a database containing a description of multiple forest resources and multiple management actions for managing the forest resources. The forest resources include trees, stands and wildlife. The management actions include cruise, grade, harvest, clear cut and plant. However, more or fewer forest resources and management methods could also be used. 
     An object-oriented forest resource model is constructed from the multiple forest resources in the database. An object-oriented management model is constructed from the multiple management actions in the database. The object-oriented management model is used for managing forest resources in the forest resource model. A simulation of forest resources over a pre-determined period of time is initiated using the object-oriented forest resource model. Periodically, the object-oriented management model is applied to the forest resources from the object-oriented forest resource model being used in the simulation to manage the forest resources. 
     An illustrative embodiment of the present invention uses object-oriented technologies to create a library of programmable components that is comprehensive, customizable and reflective of real world forest management. An illustrative embodiment of the present invention is capable of simulating many aspects of forest management simultaneously including: forestry operations, organization cash flow and environmental quality. An illustrative embodiment of the present invention allows forestry management to simultaneously consider multiple factors in designing a forest management plan and thereby provides solutions to forestry questions, such as multiple use management, that are difficult to answer. 
     The foregoing and other features and advantages of an illustrative embodiment of the present invention will be more readily apparent from the following detailed description, which proceeds with references to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a forestry simulation system; 
     FIG. 2 is a flowing diagram illustrating a method for forestry simulation; 
     FIG. 3 is a block diagram illustrating a Forest Control object; 
     FIG. 4 is a flow diagram illustrating a method for a Simulation Control object; 
     FIG. 5 is a block diagram illustrating Forest Resource objects; 
     FIG. 6 is a block diagram illustrating Forest Management objects; 
     FIG. 7 is a block diagram illustrating Rule objects; 
     FIGS. 8A and 8B are a block diagram illustrating Timer Assessment objects; 
     FIG. 9 is a block diagram illustrating additional Forest Simulation objects; 
     FIG. 10 is a block diagram illustrating Environment Quality objects; and 
     FIG. 11 is a block diagram illustrating a screen display of an exemplary forestry simulation for an illustrative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT 
     Forestry Simulation System 
     FIG. 1 illustrates a forestry simulation system 10 for an illustrative embodiment of the present invention. Forestry simulation system 10 includes a computer 12 with a computer display 14. Display 14 presents a windowed graphical user interface (&#34;GUI&#34;) 16 to a user. A database 18 contains a description of multiple forest resources and multiple management actions for the forest resources. Database 18 is stored in a memory system on computer 12 or in secondary storage such as a hard disk, floppy disk, optical disk, or other non-volatile mass storage devices. 
     An operating environment computer 12 of the present invention includes a processing system with at least one high speed Central Processing Unit (&#34;CPU&#34;). In accordance with the practices of persons skilled in the art of computer programming, the present invention is described below with reference to acts and symbolic representations of operations that are performed by the processing system, unless indicated otherwise. Such acts and operations are referred to as being computer-executed. 
     It will be appreciated that the acts and symbolically represented operations include the manipulation of electrical signals by the CPU. The electrical system represents data bits which cause a resulting transformation or reduction of the electrical signal representation, and the maintenance of data bits at memory locations in a memory system to thereby reconfigure or otherwise alter the CPU&#39;s operation, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to the data bits. 
     The data bits may also be maintained on a computer readable medium including magnetic disks, optical disks, computer memory (e.g., RAM or ROM) and any other volatile or non-volatile mass storage system readable by the computer. The data bits on a computer readable medium are computer readable data. The computer readable medium includes cooperating or interconnected computer readable media, which exist exclusively on the processing system or be distributed among multiple interconnected processing systems that may be local or remote to the processing system. 
     Method of Forestry Simulation 
     FIG. 2 is a flowing diagram illustrating a method 20 for forestry simulation. Method 20 includes maintaining a database (e.g., database 18) containing a description of multiple forest resources and multiple management actions for managing the multiple forest resources at step 22. The multiple forest resources include trees and stands. The management methods include accounting, cruise, grade, harvest, plant and scale. However, more or fewer forest resources and management methods could also be used. The forest resources and management actions are described below. 
     An object-oriented forest resource model is constructed from the multiple forest resources in the database at step 24. An object-oriented management model is constructed from the multiple management actions in the database at step 26. The object-oriented management model is used for managing forest resources in the forest resource model. A simulation of forest resources over a pre-determined period of time is initiated using the object-oriented forest resource model at step 28. At step 30, the object-oriented management model is periodically applied to the forest resources from the object-oriented forest resource model being used in the simulation to manage the forest resources. 
     Forest Resources and Management Actions 
     In an illustrative embodiment of the present invention, a description of multiple forest resources and multiple management actions included in database 18 are used with method 20 of FIG. 2 to create a forestry simulation. The description of multiple forest resources includes descriptions of trees, stands, tree growth parameters, stand growth parameters and wildlife (e.g., cavity nesting birds) and others as computer data stored in database 18. However, more or fewer forest resources could also be used. The computer data stored in database 18 includes tables and other data structures. 
     Trees are grouped into stands that represent larger geographic areas of similar forest types. Stands may be grouped into an ownership with specific ownership forest resource data. An ownership may be grouped into an organization with specific organization forest resource data. The tree and stand growth parameters include pre-defined defined growth curve data for Diameter at Breast Height (&#34;DBH&#34;) and total height. A DBH is known to those skilled in the forestry arts. 
     The description of multiple management actions includes descriptions of accounting practices and forestry management practices including cruising, grading, harvesting, planting, scaling and others (e.g., salaries of employees carrying out the management actions) as computer data stored in database 18. However, more or fewer management actions could also be used. Cruising, grading, harvesting, planting and scaling techniques are known to those skilled in the forestry arts and explained below. The multiple forest resources and multiple management actions stored as computer readable data are used to construct the object-oriented forest resource and object-oriented management action models at steps 26 and 28 of method 20 (FIG. 2). 
     Object-oriented Simulation Environment 
     In an illustrative embodiment of the present invention, object-oriented programming techniques are used. As is known in the art, an &#34;object type,&#34; also called an &#34;object class,&#34; comprises a data-type, services that operate on instances of the data type, and a set of object attributes in an object-oriented data-structure. An &#34;object attribute&#34; is a field of data in an object that partially defines that object&#39;s state. An &#34;object service&#34; implements and manipulates objects, usually by reading or changing the object attributes. &#34;Object-oriented design&#34; is a software development technique in which a system or component is expressed using objects. 
     An object typically is an object-oriented data-structure that has multiple components including a function table, containing a pointer to each &#34;object member&#34; or member function (i.e., sometimes known as an &#34;object method&#34;) defined in the object&#39;s class, an events table, for accepting events (e.g., OLE or ActiveX control events) and a data block, containing the current values for each object variable (i.e., data members, sometimes known as an &#34;object property&#34;). A computer software application has some reference to an object through an object pointer. A computer software application obtains this object reference by using some type of function call (direct or implied) in which that function allocates an object block in computer memory, initializes the function table, and returns a reference to allocated computer memory to an application. The computer memory may be local or distributed on a remote computer. 
     The Component Object Model (COM) and Distributed Component Object Model (DCOM) are models used for object-oriented programming and known to those skilled in the art. The COM and DCOM specify how objects within a single application or between applications (e.g., client/server applications) interact and communicate by defining a set of standard interfaces. Interfaces are groupings of schematically related functions through which a client application accesses the services of a server application. 
     Object Linking and Embedding (OLE) controls, such as OLE Version 2 OLE controls and ActiveX Controls by the Microsoft Corporation of Redmond, Wash., are based in part on the Component Object Model and allow the creation of objects of different formats which operate on data through defined interfaces, rather than operating on the applications responsible for the data. ActiveX is based in part on OLE technologies. An OLE or ActiveX control is an object that accepts and responds to events, such as a selection by a mouse or a key on a keyboard, or a selection by another object-oriented member function. Detailed information on the OLE object interface can be found in Inside OLE, 2nd edition, by Kraig Brockschmidt, Microsoft Press, Redmond Wash., 1995 which is incorporated herein by reference. 
     Forest Control Object 
     An illustrative embodiment of the present invention includes an object-oriented library of forest resource objects and management method objects stored in database 18. The object-oriented objects are grouped according to object functionality. 
     In an illustrative embodiment of the present invention, the object-oriented library is accessed through a single ActiveX control called a &#34;Forest Control object.&#34; FIG. 3 is a block diagram illustrating a Forest Control object 32. However, more controls could also be used Access to other objects in the library is made through Forest Control object 32. The Forest Control object is inserted into an ActiveX container and manipulated using an ActiveX compliant development environment. ActiveX containers are known to those skilled in the art. ActiveX compliant development environment includes languages such as Visual Basic and Visual C++ by Microsoft Corporation, and others. Once inserted, Forest Control object 32 object members give access to other objects in the object-oriented library. 
     Forest Control object 32 includes Organization, Simulation and Reset object members. However, more or fewer object members could also be used. The Organization object and Simulation objects are explained below. A number of ActiveX events are exposed by Forest Control object 32 so that a forestry simulation can be tracked and sampled as it is running. The ActiveX events include ForestMangerAction, HarvesterPreHarvest, HarvesterPostHarvest, PlanterPrePlant, PlanterPostPlant, AccountantOpenBooks, AccountantCloseBooks, SimulationTimer and SimulationFinished. However, more or fewer ActiveX events could also be used. For example a SimulationTimer event can be set to trigger once a year in a 100 year simulation allowing the simulated forest to be sampled for volume, timber cash flow, and habitat quality. As another example, a HarvesterPostHarvest event can be triggered after harvest events to sample a harvest volume. 
     Table 1 illustrates the components of the Forest Control object 32. However, more or fewer components could also be used. 
     
                       TABLE 1                                                     
______________________________________                                    
Forest Control object 32                                                  
Description                                                               
Forest Control object 32 is a top-level object through which other        
objects                                                                   
in the object library are accessed. Forest Control object 32 is an        
ActiveX/OLE control that is inserted on a form before access to other     
objects is possible. In addition to objects, Forest Control object 32     
provides a number of events that can be trapped to facilitate tracking    
of                                                                        
forestry simulation progress.                                             
Properties                                                                
Organization As Organization                                              
The Organization object contains the Ownership,                           
ForestManager and Accountant objects.                                     
Simulation As Simulation                                                  
The Simulation object controls the starting and stopping of a             
simulation.                                                               
Methods                                                                   
Reset                                                                     
Reset is called to clear the current simulation from memory. It is        
typically called before creating a new simulation.                        
Events                                                                    
The Forest Control object triggers a variety of events that can be caught 
in                                                                        
program code. The following is a list of available events. Although       
events                                                                    
are sent through the Forest Control object, they are initiated by other   
objects in the library and are described more fully in the text for       
those                                                                     
objects. The first word of each event designates the object that          
initiates                                                                 
the event (e.g., Accountant object for AccountantBeforeCloseBooks,        
etc.).                                                                    
AccountantBeforeCloseBooks                                                
AccountantAfterCloseBooks                                                 
AccountantBeforeOpenBooks                                                 
AccountantAfterOpenBooks                                                  
ForestManagerAction(Action As Long, Stand As Stand)                       
HarvesterPostHarvest(Stand As Stand)                                      
HarvesterPreHarvest(Stand As Stand)                                       
PlanterPostPlant(Stand As Stand)                                          
PlanterPrePlant(Stand As Stand)                                           
SimulationBegin                                                           
SimulationFinished                                                        
SimulationTimer                                                           
VolumeCalculatorPreCalc                                                   
VolumeCalculatorPostCalc                                                  
______________________________________                                    
 
    
     Simulation Control Object 
     In an illustrative embodiment of the present invention, a Simulation Control object creates a forestry simulation. The Simulation Control object creates a forestry simulation by looping through multiple forest resources objects such as trees and carrying out a list of management actions performed on the multiple forest resources objects over a pre-determined simulated time period (e.g., 100 years) 
     Statistics from the simulation such as the number, biomass, age of organisms (e.g., trees) and simulation time are obtained by sampling the simulation as it runs over the pre-determined simulated time period. However, sampling occurs while the simulation is temporarily stopped. There are two methods of sampling a simulation: using timer events and manually. 
     Timer events are triggered by the simulation when the simulation timer is set to a value&gt;0. When a timer event is triggered, the simulation is stopped internally. Sampling can then occur using a scripting program. When the timer event procedure ends, the simulation is restarted internally. There is no need to manually stop and start the simulation using timer events. 
     Manually triggering a sampling entails using a scripting program to temporarily stop the simulation, sample and restart the simulation. Manually triggering a sampling is useful when sampling is needed at times that can&#39;t be expressed as intervals. 
     To get a picture of how one or more factors (e.g., tree growth) is changing during a forestry simulation, sampling is done with a Cruiser object or a Biologist object. The Cruiser object and Biologist objects are explained below. 
     Table 2 illustrates properties, methods and events of the Simulation Control object. However, more or fewer properties, method and events could also be used. 
     
                       TABLE 2                                                     
______________________________________                                    
Simulation Control object                                                 
Description                                                               
The Simulation Control object implements starting, stopping and stepping  
through forestry simulations. A timer can be set that triggers an event   
each                                                                      
period. When Simulation Control object is finished, an event signaling    
the                                                                       
stop time has been reached is triggered.                                  
Properties                                                                
StopTime As Long                                                          
The time at which the simulation will stop.                               
Time As Long                                                              
Holds the current time of the simulation.                                 
Timer As Long                                                             
Sets the interval between SimulationTimer events. Set to zero if          
no timer events are desired.                                              
Methods                                                                   
Start( ) As Boolean                                                       
Call to start the simulation.                                             
Step( ) As Boolean                                                        
Call to simulate the next period of the simulation.                       
Stop( ) As Boolean                                                        
Call to stop the simulation.                                              
Events                                                                    
SimulationBegin                                                           
Triggered just before system begins simulating.                           
SimulationFinished                                                        
Triggered when the system has reached the stop time.                      
SimulationTimer                                                           
Triggered at each passing of the Timer interval. If Timer = zero          
then no SimulationTimer events are triggered.                             
Remarks                                                                   
•                                                                   
      Set the run time by setting the StopTime parameter.                 
•                                                                   
      Call Start( ) to begin a simulation, Step( ) to step through a      
      single period or Stop( ) to stop the simulation.                    
•                                                                   
      Access the current time using the Time member.                      
•                                                                   
      The Simulation Control object is accessed through the Forest        
      Control object.                                                     
______________________________________                                    
 
    
     FIG. 4 is a flow diagram illustrating a method 34 for the Simulation Control object to create an exemplary forestry simulation. At step 36, a test is conducted to determine whether a pre-determined time is less than a stop time. If so, at step 38 an open accounting books object member (e.g., from Accountant object) is called to track cash flow during a forestry simulation. When the accounting books are opened, income and expenses are set to zero. At step 40, a grow trees object member (i.e., from Stand object) is called to simulate the growing of trees in a stand. At step 42, one or more management actions are carried out (e.g., from ForestManager object including Biologist, Cruiser, Grader, Harvester, Planter, or Scaler objects). At step 44, an optional tree mortality object member (i.e., from Stand object) is called to simulate the mortality of trees in a stand (e.g., due to disease, insects, fires, etc.). At step 46, the accounting books are closed by calling a close accounting books object member (e.g., from Accountant object). At step 48, a simulation timer is triggered to complete the simulation with the Simulation Control object. At step 50, the Simulation Control object terminates. 
     However, more or fewer steps could also be used for the Simulation Control object. The steps in method 34 can also be executed in a different order than illustrated in FIG. 4 (e.g., simulation of tree mortality at step 44 can be completed on a stand of trees before management actions at step 42 are completed). 
     Forest Ecosystem Objects 
     In an illustrative embodiment of the present invention, a selected forest type is simulated corresponding to one or more ecological components in the selected forest type. The ecological components include one or more types of trees (e.g., spruce, fir, pine, etc.) Trees are described by TreeClass objects that give a number of trees by species and DBH classes. Tree growth is simulated using a pre-defined growth curve for DBH and total height. Trees are one of the multiple forest resource objects stored in database 18. 
     Forest Resource Objects 
     FIG. 5 is a block diagram illustrating Forest Resource objects 52. FIGS. 5-10 illustrate various objects of an illustrative embodiment of the present invention. However FIGS. 5-10 may not illustrate all object properties, methods, events or members that are illustrated in the corresponding table for the object. All object properties are not illustrated in FIGS. 5-10 for the sake of simplicity. 
     Forest Resources objects 52 use the description of multiple forest resources in database 18 described to create an object-oriented forest resource model at step 24 of method 20 (FIG. 2). In an illustrative embodiment of the present invention, Forest Resource objects 52 include one or more TreeClass objects 54 within a TreeClasses object 56 within a Stand object 58 within a Stands object 60 within an Ownership object 62 within an Organization object 64. 
     TreeClass objects are represented as more specialized objects (e.g., ConeTreeClass or TaperTreeClass described below). TreeClass objects define a base set of properties, methods and events that more specialized objects implement. Trees are measured at Diameter at Breast Height (&#34;DBH&#34;) and using Tree-Per-Acre (&#34;TPA&#34;). Table 3 illustrates properties, methods and events of TreeClass object 54. However, more or fewer properties, method and events could also be used. 
     
                       TABLE 3                                                     
______________________________________                                    
TreeClass object 54                                                       
Description                                                               
TreeClass object 54 is a generalized class of tree that defines a base    
set                                                                       
of properties, methods and events that other more specialized classes of  
trees implement when deriving from TreeClass object 54. For example, the  
ConeTreeClass and TaperTreeClass derive from TreeClass object 54 and      
therefore implement TreeClass object&#39;s 54 members. The ConeTreeClass      
object and the TaperTreeClass object are types of TreeClass object 54.    
Properties                                                                
Age As Long                                                               
Age of the trees.                                                         
BA As Long                                                                
Basal area per acre.                                                      
BarkThicknessRatio as Single                                              
Bark thickness ratio or diameter inside bark/diameter outside             
bark.                                                                     
CrownRatio As Long                                                        
Length of crown as a percent of total height (e.g., Ritchie,              
1987). Calculated as: BoleRatio = 1 - 1/(1 + exp(b0 + b1*H +              
b2CCFL + b3*In(BA) + b4*DBH/H + b5*SI))                                   
Where:                                                                    
H -- Total height.                                                        
CCFL -- CCF for trees with DBH larger than this tree&#39;s                    
DBH.                                                                      
BA -- BA of stand.                                                        
SI -- Stand site index.                                                   
MaximumCrownWidth As Long                                                 
Width of crown if tree is open grown. Calculated as:                      
MaximumCrownWidth = MCW0 + MCW1 * DBH -                                   
MCW2 * DBH.sup.2                                                          
DBH As Single                                                             
Diameter at breast height outside bark. The bottom of a tree is           
assumed to be at breast height.                                           
DIB(Single Height) As Single                                              
Returns the diameter inside bark at a given height.                       
DOB(Single Height) As Single                                              
Returns the diameter outside bark at a given height.                      
Defect As Single                                                          
Amount of volume that is not merchantable. Expressed as a                 
percent of gross volume.                                                  
HeightCrownBase As Single                                                 
Height of tree from base to base of crown.                                
HeightDBH As Single                                                       
Height of tree from base to DBH point.                                    
HeightTotal As Single                                                     
Height of tree from base to tip.                                          
IsMaxAgeTest as Long                                                      
Toggles mortality based on a maximum tree age. When                       
IsMaxAgeTest = True, ConeTreeClass object will die when its               
age reaches MaxAge.                                                       
MaxAge As Long                                                            
Maximum age ConeTreeClass is allowed to obtain. Only applies              
when IsMaxAgeTest is set to true.                                         
Species As Long                                                           
A numeric ID representing species.                                        
SetMCWParameters(Single MCW0, Single MCW1, Single MCW2)                   
Sets the values of the maximum crown width parameters.                    
TaperClass As Single                                                      
Taper class used to define shape of tree.                                 
TPA As Single                                                             
Trees per area. Valid if the ConeTreeClass is standing. If the            
ConeTreeClass has been harvested, the TreeCount member is                 
valid.                                                                    
TreeCount As Single                                                       
The number of individual trees this ConeTreeClass object                  
represents. Valid if the ConeTreeClass has been harvested. If the         
ConeTreeClass is standing, the TPA member is valid.                       
Methods                                                                   
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 4 illustrates properties, methods and events of TreeClasses object 56. However, more or fewer properties, method and events could also be used. 
     
                       TABLE 4                                                     
______________________________________                                    
TreeClasses object 56                                                     
Description                                                               
TreeClasses object 56 contains a list of TreeClass 54 objects. TreeClass  
objects 54 are accessed using an index.                                   
Properties                                                                
Count As Long                                                             
Returns the number of TreeClass objects 54 in the list. Read              
only.                                                                     
Methods                                                                   
Add( ) As Object                                                          
Creates a new TreeClass object 54 and adds it to the list. Returns        
the TreeClass object 54 created.                                          
Age as Long                                                               
Average age of tree class objects in the list.                            
BA(DBH As Single) As Single                                               
Sum of Basal Area (&#34;BA&#34;) for tree class objects with DBH                  
larger than that given in the list.                                       
CCF(DBH As Single) As Single                                              
Crown Competition Factor (&#34;CCF&#34;) for trees with DBH larger                
than that given (e.g., Krajicek et. al., 1961). Calculated as:            
        CCF = Σ(CW.sub.i.sup.2 * TPA.sub.i) * /4/43560              
Where i denotes the i.sup.th tree class object in the list with DBH       
larger than MinDBH and (&#34;pi&#34;) = 3.1415927 . . .                           
CrownRatio( ) As Single                                                   
Average crown ratio weighted by TPA (or TreeCount if                      
TreeClasses have been harvested).                                         
CrownClosure(DBH) As Single                                               
Crown Competition Factor for trees with HeightTotal &gt; Height.             
Calculated similarly as CCF.                                              
CrownWidth( ) As Single                                                   
Crown width of trees in the list.                                         
DBH As Single                                                             
Returns the arithmetic average DBH of tree class objects in the           
list.                                                                     
HeightTotal As Single                                                     
Average total height of tree class objects in the list.                   
Item(Index As Long) As Object                                             
Returns the TreeClass object 54 at the Index position in the list.        
QMD As Single                                                             
Quadratic mean diameter or the DBH of a tree with average BA.             
Calculated as: When TreeClasses object represents standing                
trees:                                                                    
        QMD = BA/TPA * 4 * 144/                                           
When TreeClasses object represents cut trees:                             
        QMD = BA/TreeCount * 4 * 144/                                     
RelativeDensity As Single                                                 
Relative density (e.g., Curtis, 1982). Calculated as:                     
        RelativeDensity = BA/QMD.sup.1/2.                                 
RemoveAll( )                                                              
Removes tree class objects from the list.                                 
Sort(Type as Long)                                                        
Sorts the tree class objects in the list. Type interpreted as a bit       
filed where bit 1 sorts by species and bit 2 sorts by DBH.                
Sorting order parallels bit order.                                        
TPA(MinDBH As Single, MaxDBH As Single) As Single                         
Returns the TPA for classes of trees with minimum DBH                     
MinDBH and maximum DBH less than MaxDBH.                                  
Events                                                                    
______________________________________                                    
 
    
     TreeClass objects 54 includes ConeTreeClass objects or TaperTreeClass object members. However, more or fewer TreeClass object 54 types could also be used. Cones and tapers are the two most common methods used to simulate the shape of trees in a stand. Table 5 illustrates properties, methods and events of ConeTreeClass object. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 5                                                     
______________________________________                                    
ConeTreeClass object                                                      
Description                                                               
The ConeTreeClass object represents a number of individual trees of the   
same species and DBH classes whose shape is described by a cone with      
base diameter equal to DBH and height equal to total height. The number   
of trees the ConeTreeClass represents is given either in the TPA member   
if the tree class is standing or the TreeCount member if the tree class   
has                                                                       
been harvested.                                                           
Properties                                                                
Age As Long                                                               
Age of the trees.                                                         
BA As Long                                                                
Basal area per acre.                                                      
BarkThicknessRatio as Single                                              
Bark thickness ratio or diameter inside bark/diameter outside             
bark.                                                                     
CrownRatio As Long                                                        
Length of crown as a percent of total height (e.g., Ritchie,              
1987). Calculated as: BoleRatio = 1 - 1/(1 + exp(b0 +                     
b1*H + b2*CCFL + b3*In(BA) + b4*DBH/H + b5*SI))                           
Where:                                                                    
H -- Total height.                                                        
CCFL -- CCF for trees with DBH larger than this tree&#39;s                    
DBH.                                                                      
BA -- BA of stand.                                                        
SI -- Stand site index.                                                   
MaximumCrownWidth As Long                                                 
Width of crown if tree is open grown. Calculated as:                      
        MaximumCrownWidth =                                               
        MCW0 + MCW1 * DBH - MCW2 * DBH.sup.2                              
DBH As Single                                                             
Diameter at breast height outside bark. The bottom of a tree is           
assumed to be at breast height.                                           
DIB(Single Height) As Single                                              
Returns the diameter inside bark at a given height.                       
DOB(Single Height) As Single                                              
Returns the diameter outside bark at a given height.                      
Defect As Single                                                          
Amount of volume that is not merchantable. Expressed as a                 
percent of gross volume.                                                  
HeightCrownBase As Single                                                 
Height of tree from base to base of crown.                                
HeightDBH As Single                                                       
Height of tree from base to DBH point.                                    
HeightTotal As Single                                                     
Height of tree from base to tip.                                          
IsMaxAgeTest as Long                                                      
Toggles mortality based on a maximum tree age. When                       
IsMaxAgeTest = True, ConeTreeClass object will die when its               
age reaches MaxAge.                                                       
MaxAge As Long                                                            
Maximum age ConeTreeClass is allowed to obtain. Only applies              
when IsMaxAgeTest is set to true.                                         
Species As Long                                                           
A numeric ID representing species.                                        
SetMCWParameters(Single MCW0, Single MCW1, Single MCW2)                   
Sets the values of the maximum crown width parameters.                    
TaperClass As Single                                                      
Taper class used to define shape of tree.                                 
TPA As Single                                                             
Trees per area. Valid if the ConeTreeClass is standing. If the            
ConeTreeClass has been harvested, the TreeCount member is                 
valid.                                                                    
TreeCount As Single                                                       
The number of individual trees this ConeTreeClass object                  
represents. Valid if the ConeTreeClass has been harvested. If the         
ConeTreeClass is standing, the TPA member is valid.                       
Methods                                                                   
Events                                                                    
Remarks                                                                   
•                                                                   
      Trees are represented as TreeClass objects. TreeClass objects,      
      whether they are ConeTreeClass objects or TaperTreeClass            
      objects, describe the number of trees of a single species and       
      DBH class. TreeClass objects that represent standing trees are      
      counted by the Trees-Per-Acre (&#34;TPA&#34;) member and have their         
      tree count (TreeCount) member equal to zero. TreeClass objects      
      that have been harvested, have their TPA values converted to        
      actual tree counts (TreeCount) using the stand acres.               
______________________________________                                    
 
    
     Table 6 illustrates properties, methods and events of TaperTreeClass object. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 6                                                     
______________________________________                                    
TaperTreeClass object                                                     
Description                                                               
The TaperTreeClass object represents a number of individual trees of the  
same species and DBH classes whose shape is described by a table of       
taper values.                                                             
Properties                                                                
Age As Long                                                               
Age of the trees.                                                         
BA As Long                                                                
Basal area per acre.                                                      
BarkThicknessRatio as Single                                              
Bark thickness ratio or diameter inside bark/diameter outside             
bark.                                                                     
CrownRatio As Long                                                        
Length of crown as a percent of total height (Ritchie, 1987).             
Calculated as: BoleRatio = 1 - 1/(1 + exp(b0 + b1*H +                     
b2*CCFL + b3*In(BA) + b4*DBH/H + b5*SI))                                  
Where:                                                                    
H -- Total height.                                                        
CCFL -- CCF for trees with DBH larger than this tree&#39;s                    
DBH.                                                                      
BA -- BA of stand.                                                        
SI -- Stand site index.                                                   
MaximumCrownWidth As Long                                                 
Width of crown if tree is open grown. Calculated as:                      
        MaximumCrownWidth =                                               
        MCW0 + MCW1 * DBH - MCW2 * DBH.sup.2                              
DBH As Single                                                             
Diameter at breast height. The bottom of a tree is assumed to be          
at breast height.                                                         
DIB(Single Height) As Single                                              
Returns the diameter inside bark at a given height.                       
DOB(Single Height) As Single                                              
Returns the diameter outside bark at a given height.                      
Defect As Single                                                          
Amount of volume that is not merchantable. Expressed as a                 
percent of gross volume.                                                  
HeightCrownBase As Single                                                 
Height of tree from base to base of crown.                                
HeightDBH As Single                                                       
Height of tree from base to DBH point.                                    
HeightTotal As Single                                                     
Height of tree from base to tip.                                          
IsMaxAgeTest as Long                                                      
Toggles mortality based on a maximum tree age. When                       
IsMaxAgeTest = True, ConeTreeClass object will die when its               
age reaches MaxAge.                                                       
MaxAge As Long                                                            
Maximum age TaperTreeClass is allowed to obtain. Only applies             
when IsMaxAgeTest is set to true.                                         
Species As Long                                                           
A numeric ID representing species.                                        
TaperClass As Single                                                      
Taper class used to define shape of tree.                                 
TPA As Single                                                             
Trees per area. Valid if the TaperTreeClass is standing. If the           
TaperTreeClass has been harvested, the TreeCount member is                
valid.                                                                    
TreeCount As Single                                                       
The number of individual trees this TaperTreeClass object                 
represents. Valid if the TaperTreeClass has been harvested. If            
the TaperTreeClass is standing, the TPA member is valid.                  
Methods                                                                   
Events                                                                    
Remarks                                                                   
•                                                                   
      The TreeCount member describes the amount of individual trees       
      represented by this tree class. It is only valid for TreeClass      
      members of the Harvester.                                           
•                                                                   
      The TPA member describes the amount of individual trees per         
      acre represented by this tree class. It is only valid for the       
      TreeClasses member of the Stand object.                             
______________________________________                                    
 
    
     TreeClass objects 54 describe the TPA of a unique species and a DBH class. There can be as many TreeClass objects 54 as needed in a Stand object 58 and additional objects for simulating tree growth other than TaperTreeClass and ConeTreeClass objects. 
     Stand objects are represented as more specialized objects that derive from the Stand object. Stand objects define a base set of properties, methods and events that more specialized objects implement. 
     Table 7 illustrates properties, methods and events of Stand object 58. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 7                                                     
______________________________________                                    
Stand object 58                                                           
Description                                                               
Stand object 58 contains a list of trees.                                 
Properties                                                                
Area As Single                                                            
The area of the stand.                                                    
Name As String                                                            
User supplied name.                                                       
TreeClasses As TreeClasses                                                
A TreeClasses object that contains the tree classes present in the        
stand.                                                                    
TreeType As Long                                                          
Sets the type of tree classes being held in this Stand object 58.         
IsMaximumAgeTest As Long                                                  
Determines whether the maximum age test will be carried out on            
tree classes.                                                             
IsMortality As Long                                                       
Determines whether mortality will be carried out.                         
IsRegeneration As Long                                                    
Determines whether regeneration will be carried out.                      
SiteIndex As Single                                                       
50 year site index                                                        
MaximumDensityCurve As Curve                                              
A maximum density curve used when mortality is being used.                
PlantingRule As Long                                                      
ID for default planting rule or rules that will be carried out if no      
planting rule is specified with a planting action.                        
ThinningRule As Long                                                      
ID for default thinning rule or rules that will be carried out if no      
thinning rule is specified with a thinning action.                        
SelectiveCuttingRule As Long                                              
ID for default selective cutting rule or rules that will be carried       
out if no selective cutting rule is specified with a selective            
cutting action.                                                           
ClearCutRule As Long                                                      
ID for default clear cut rule or rules that will be carried out if no     
clear cut rule is specified with a clear cut action.                      
Parameters As Object                                                      
The set of growth parameters.                                             
Methods                                                                   
SetTaper(Points as String)                                                
The set of taper points applied to tree classes within this stand.        
Events                                                                    
Remarks                                                                   
•                                                                   
      Trees are stored in the Stand object 58 as TreeClass objects 54     
      that specify the trees per acre for the different tree classes      
      present. Species and DBH describe unique tree classes.              
______________________________________                                    
 
    
     Table 8 illustrates properties, methods and events of Stands object 60. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 8                                                     
______________________________________                                    
Stands object 60                                                          
Description                                                               
Stands object 60 contains a list of stands. Stand objects 58 are          
accessed                                                                  
using an index.                                                           
Properties                                                                
Add( ) As Stand                                                           
Creates a new Stand object 58 and adds it to the list. Returns the        
Stand object 58 created.                                                  
Area As Single                                                            
The area of the stand.                                                    
Count As Long                                                             
Returns the number of Stand objects 58 in the list. Read only.            
Methods                                                                   
Item(Index As Long) As Stand                                              
Returns the Stand object 58 at the Index position in the list.            
Item(Name As String) As Stand                                             
Returns the Stand object 58 with a given name.                            
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 9 illustrates properties, methods and events of Ownership object 62. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 9                                                     
______________________________________                                    
Ownership object 62                                                       
Description                                                               
Ownership object 62 contains a list of stands from Stands object 60. An   
ownership is the highest level of forest resource containment.            
Properties                                                                
Age as Long                                                               
The average age of TreeClass objects 54 in stands. Read only.             
BA As Single                                                              
The total basal area of TreeClass objects 54 in stands. Read              
only.                                                                     
DBH As Single                                                             
The average DBH of TreeClass objects 54 in stands. Read only.             
Name As String                                                            
User supplied name.                                                       
Stands As Stands                                                          
A list of stands in the ownership.                                        
TotalHeight As Single                                                     
The average total height of TreeClass objects 54 in stands. Read          
only.                                                                     
CFF As Single                                                             
The average crown competition factor of TreeClass objects 54 in           
stands. Read only.                                                        
Methods                                                                   
TPA(MinDBH As Single, MaXDBH As Single) As Single                         
The average TPA for TreeClass objects 54 in stands with                   
minimum DBH MinDBH and maximum DBH less than                              
MaxDBH.                                                                   
Events                                                                    
Remarks                                                                   
•                                                                   
      Access the Stand objects 58 through the Stands member.              
______________________________________                                    
 
    
     Table 10 illustrates properties, methods and events of Organization object 64. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 10                                                    
______________________________________                                    
Organization object 64                                                    
Description                                                               
Organization object 64 corresponds to an organization that manages        
forested lands. The organization holds other objects related to           
ownership                                                                 
and management.                                                           
Properties                                                                
Accountant As Accountant                                                  
Tracks income and expenses as a simulation runs.                          
ForestManager As ForestManager                                            
Coordinates the harvesting and planting of trees in stands. The           
Harvester, Planter, Cruiser, Scaler and Grader objects are                
assessed through the ForestManager.                                       
Name As String                                                            
User supplied name.                                                       
Ownership As Ownership                                                    
Represents the extent of land ownership or land management by             
the organization. Ownership contains a list of stands that                
together make up the land that is owned or managed by the                 
organization.                                                             
Methods                                                                   
Events                                                                    
Remarks                                                                   
•                                                                   
      Access Ownership object 62, ForestManager object and                
      Accountant object through Organization object 64.                   
•                                                                   
      The Organization object 64 contains an Ownership object 62,         
      which in turn contains a list of Stand objects 60. Organization     
      object 64 also includes a ForestManger and an Accountant object     
      member. The ForestManager coordinates harvesting and planting       
      activities on the ownership. The Accountant tracks the flow of      
      income and expenses.                                                
______________________________________                                    
 
    
     Forest Management Objects 
     Coordinating the management of forestry operations is done using the Forest Management objects. FIG. 6 is a block diagram illustrating Forest Management objects 66. Forest Management objects 66 uses the description of multiple management actions in database 18 to create an object-oriented management model at step 26 of method 20 (FIG. 2). Forest Management objects coordinate management activities among a set of management objects. Forest Management objects 66 apply management actions to forest resources. 
     A ForestManager object is an employee of Organization object 64 that coordinates forest management among a number of other management objects including a Biologist, Cruiser, Grader, Harvester, Planter and Scalar object-oriented objects. The ForestManager object uses a list of actions that describe management tasks to be carried out on stands via the other management objects. The actions specify a year, stand, and action to be carried out (e.g., plant, clear cut, selective cut, etc.). As a management object performs an action, it &#34;bills&#34; the organization via the Accountant for its services. An Accountant object subtracts expenses from a budget. The timber in a stand is &#34;sold&#34; according to its graded value with the sale going into the budget as income. Cash flow for Organization object 64 can be tracked during a simulation by sampling the Accountant object. 
     As is illustrated in FIG. 6, ForestManager object 68 uses an Actions object 70 and an Action object 72 with a list of management actions along with a list of management rules to carry out the management actions. Table 11 illustrates properties, methods and events of ForestManager object 68. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 11                                                    
______________________________________                                    
ForestManager 68                                                          
Description                                                               
ForestManager object 68 coordinates forest management activities among    
the management objects. Each management period ForestManager 68           
loops through a list of management actions and instructs the other        
Forest Management objects 66 to carry out management actions if any       
are scheduled.                                                            
Properties                                                                
Actions As Actions                                                        
Holds a list of actions to be carried out during a simulation.            
Biologist As Biologist                                                    
The Biologist object calculates habitat quality indices.                  
Cruiser As Cruiser                                                        
The Cruiser object calculates the timber volume present in                
stands.                                                                   
Grader As Grader                                                          
The Grader object grades and values volumes.                              
Harvester As Harvester                                                    
The Harvester object harvests stands when the average age of              
trees in a stand exceeds the rotation age by deleting trees in the        
stand.                                                                    
IsAutoThin As Long                                                        
Determines whether the auto thin method is turned on.                     
Name As String                                                            
User supplied name of object.                                             
Planter As Planter                                                        
The Planter object plants trees in stands.                                
Scaler As Scaler                                                          
The Scaler calculates volumes in trees.                                   
Salary As Single                                                          
The cost of ForestManager&#39;s services for one period. At the end           
of the period, the ForestManager&#39;s salary is billed to the                
organization.                                                             
Time As Long                                                              
Returns the current period for this ForestManager object.                 
Methods                                                                   
Events                                                                    
ForestManagerAction(Action As Long, Stand As Stand)                       
Triggered after the ForestManager object performs an action on            
a stand.                                                                  
Remarks                                                                   
•                                                                   
      Set up actions for the simulation using the ForestManager&#39;s         
      object 68 Actions object.                                           
•                                                                   
      Other member&#39;s of Forest Management objects 66 may carry out        
      tasks independent of the scheduled actions at any time during a     
      simulation. For example, Cruiser object 84 can be told calculate    
      standing volume once a period from the scripting language           
      independently of ForestManager object 68.                           
______________________________________                                    
 
    
     Table 12 illustrates properties methods and events of Actions object 70. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 12                                                    
______________________________________                                    
Actions object 70                                                         
Description                                                               
Actions object 70 contains a list of Action objects 72. Action            
objects 72 are accessed using an index.                                   
Properties                                                                
Count As Long                                                             
Returns the number of Action objects 72 in the list. Read only.           
Methods                                                                   
Item(long Index) As Action                                                
Returns the Action object 72 at the Index position in the list.           
Add( ) As Action                                                          
Creates a new Action object 72 and adds it to the list. Returns           
the Action object 70 created.                                             
RemoveAll(long index)                                                     
Removes all Action object 72 from the list.                               
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 13 illustrates properties methods and events of Action object 72. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 13                                                    
______________________________________                                    
Action object 72                                                          
Description                                                               
Action object 72 specifies a forest management action to be performed, a  
stand to perform it on, a period at which it is performed and a rule      
that                                                                      
defines how it will be carried out. Action objects 72 are stored within   
the                                                                       
Actions object 70.                                                        
Properties                                                                
Stand As Object                                                           
Stand object 58 that the action is to be performed on.                    
Time As Long                                                              
The time at which the action is to be performed.                          
Type As Long                                                              
A number specifying the type of action to be performed.                   
0 - Plant.                                                                
1 - Thin.                                                                 
2 - Selective cut.                                                        
3 - Clear cut.                                                            
RuleID as Long                                                            
A numeric Id identifying the rule to be used to carry out the             
action. This number equates to a rule object in the consultant            
who will carry out the action.                                            
RuleName as String                                                        
A text description of the rule name                                       
Methods                                                                   
Events                                                                    
Remarks                                                                   
•                                                                   
    The rule used to carry out an action is defined in the appropriate    
    consultant. For example, if a clear cut action contained a rule ID of 
    3,                                                                    
    the ClearCutRule object with ID of 3 stored in the ClearcutRules      
    object of the Harvester object is used.                               
______________________________________                                    
 
    
     Management plans are simulated by having ForestManager object 68 instruct a Harvester object 74 and a Planter object 76 to carry out management actions. Management actions specify the period, stand and action to be carried out and its associated rule. 
     Harvester object 74 carries out clear cuts, selective cuts or thinnings. If clear cut is used, all trees are removed from the stand. If selective cut is used, a graph of trees per acre to leave versus DBH class is used to determine the trees to cut. Thinnings can be based on DBH or crown ratio using from below, from above or even selection methods. After a harvest has occurred, the HarvestList member of the Harvester object 74 contains a list of harvested trees by stand. 
     Table 14 illustrates properties, methods and events of Harvester object 74. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 14                                                    
______________________________________                                    
Harvester object 74                                                       
Description                                                               
Harvester object 74 harvests timber in stands using either thinning, a    
clear                                                                     
cut or a selective cut method. If a selective cut is used, trees are      
removed                                                                   
until densities match a predefined size class distribution. The           
harvested                                                                 
trees can be accessed and scaled for volume by the Scaler object.         
Clear Cut                                                                 
If clear cut is selected, Harvester object 74 removes all trees           
in the stand being harvested.                                             
Selective Cut                                                             
When selective cutting, Harvester object 74 removes trees                 
until the stand TPA &lt;= the TPA specified.                                 
Properties                                                                
ClearCuttingRules As ClearCuttingRules                                    
A ClearCuttingRules object that holds a set of                            
ClearCuttingRule objects that defines how clear cutting is                
carried out.                                                              
Name As String                                                            
User supplied name of object.                                             
PayRate As Single                                                         
Rate of pay for each stand harvested. Billed to organization              
after each harvest.                                                       
SelectiveCuttingRules As SelectiveCuttingRules                            
A SelectiveCuttingRules object that holds a set of                        
SelectiveCuttingRule objects that define how selective                    
cutting is carried out.                                                   
TallyPeriod As Long                                                       
Length of time Harvester will accumulate harvested trees                  
into TreeClasses member before resetting TreeClasses to 0.                
ThinningRules As ThinningRules                                            
A ThinningRules object that holds a set of ThinningRule                   
objects that defines how thinning is carried out. See                     
ThinningRules.                                                            
HarvestList As HarvestList                                                
A HarvestList object that holds the list of stands that were              
harvested in the current period.                                          
Methods                                                                   
SetTPA(Points As String)                                                  
A set of points with the format &#34;DBH1, TPA1; DBH2,                        
TPA2; . . &#34; that specifies the trees per acre for DBH                     
classes. The harvester compares the trees per acre in the                 
stand and removes those tree classes that have more than                  
that specified here. For DBH classes not specified, the                   
Harvester linearity interpolates.                                         
Events                                                                    
HarvesterPreHarvest(Stand As Stand)                                       
Triggered before a stand is harvested. The stand to be                    
harvested is passed as a parameter.                                       
HarvesterPostHarvest(Stand As Stand)                                      
Triggered after a stand has been harvested. The stand                     
harvested is passed as a parameter.                                       
Remarks                                                                   
• Harvester object 74 is internally instructed by the               
        ForestManager 68 to harvest according to the actions              
        specified in the Actions member of the ForestManager 68.          
• The HarvesterPostHarvest event can be used to trigger             
        Scaler object 80 to calculate the volume of the harvested         
        trees.                                                            
• If selective harvesting is to occur, the SetTPA( ) member         
        is called.                                                        
• After harvesting, the TreeClass objects 54 that were              
        harvested are listed in the TreeClasses object 56. Each           
        TreeClass object 54 in TreeClasses object 56 have their           
        Count member set to the number of individuals of that tree        
        class that were harvested and the TPA member set to               
______________________________________                                    
        0.                                                                
 
    
     Planter object 76 plants trees according to a list of saplings. Saplings are TreeClass objects 54 that are inserted into Stand objects 58 at a time of simulated planting. 
     Table 15 illustrates properties, methods and events of Planter object 76. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 15                                                    
______________________________________                                    
Planter object 76                                                         
Description                                                               
Planter object 76 plants trees according to its list of saplings.         
Properties                                                                
Name As String                                                            
User supplied name.                                                       
PlantingRules As PlantingRules                                            
A PlantingRules object that holds a list of PlantingRule objects          
which define how planting is carried out                                  
Methods                                                                   
Events                                                                    
PlanterPrePlant(Stand As Stand)                                           
Triggered before a stand is planted. The stand to be planted is           
passed as a parameter.                                                    
PlanterPostPlant(Stand As Stand)                                          
Triggered after a stand is planted. The stand planted is passed           
as a parameter.                                                           
Remarks                                                                   
•                                                                   
      Planter object 76 is internally instructed by ForestManager         
      object 68 to plant stands according to the actions set up for the   
      simulation.                                                         
•                                                                   
      Set up the tree to the planted using the Saplings member.           
      tree classes re planting when this rule is carried                  
______________________________________                                    
      out.                                                                
 
    
     Cash flow is tracked through the use of an Accountant object 78. Both the ForestManager object 68 and Accountant object 78 are &#34;employees&#34; of Organization object 64 (FIG. 5). Their costs are accounted for as a fixed salary each period. 
     Table 16 illustrates properties, methods and events of Accountant object 78. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 15                                                    
______________________________________                                    
Accountant object 78                                                      
Description                                                               
Accountant object 78 tracks cash flow during a simulation. Organization   
wide income and expenses are accessed through object members.             
Opening the Books                                                         
When the books are opened, income and Expense are set to 0.               
Closing the Books                                                         
When the books are closed, fixed costs and the Accountant object&#39;s 78     
salary are added to Expense. NetPresentValue and the                      
InternalRateOfReturn are also calculated.                                 
Properties                                                                
Balance As Single                                                         
Tracks the balance during an entire simulation.                           
Expense As Single                                                         
Tracks the expenses for they year. Transferred to the                     
balance when the books are closed. Zero at the beginning                  
of the year.                                                              
FixedCostsPerArea As Single                                               
Operation expense incurred on a per area basis. Transferred               
to the balance when the books are closed.                                 
FixedCostsPerPeriod As Single                                             
Operation expense incurred on a per simulation period                     
basis. Transferred to the balance when the books are closed.              
FixedCostsPerStand As Single                                              
Operation expense incurred on a per Stand basis.                          
Transferred to the balance when the books are closed.                     
Income As Single                                                          
Tracks the income for they year. Transferred to the balance               
when the books are closed. Zero at the beginning of the                   
year.                                                                     
InitialExpense As Single                                                  
Operation expense that is incurred once at the beginning of               
a simulation.                                                             
InternalRateOfReturn As Single                                            
The internal rate of return that is calculated as a result of             
the management of forest resources.                                       
MinimumAcceptableRate As Single                                           
The minimum acceptable rate of return used to calculate the               
internal rate of return.                                                  
Name As Single                                                            
Name of the accountant object.                                            
NetPresentValue As Single                                                 
the net present value calculated as a result of the                       
management of forest resources.                                           
Salary As Single                                                          
The cost of Accountant&#39;s services for one year. At the                    
end of the year, the Accountant&#39;s salary is billed to the                 
organization.                                                             
Time As Single                                                            
Simulation time.                                                          
Methods                                                                   
Events                                                                    
AccountantBeforeOpenBooks                                                 
Triggered just before the books are opened.                               
AccountantAfterOpenBooks                                                  
Triggered just after the books are opened.                                
AccountantBeforeCloseBooks                                                
Triggered just before the books are closed.                               
AccountantAfterCloseBooks                                                 
Triggered just after the books are closed.                                
Remarks                                                                   
•                                                                   
    Add any external expenses to the Expense member before the books      
    are closed so that they will be included in NPV and IRR cash flow     
    calculations.                                                         
______________________________________                                    
 
    
     Harvested trees can be scaled using a Scaler object 80 then graded using a Grader object 82. The resulting value can be added to the organization&#39;s income using Accountant object 78. 
     Table 17 illustrates properties, methods and events of Scaler object 80. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 17                                                    
______________________________________                                    
Scaler object 80                                                          
Description                                                               
Scaler object 80 calculates the volumes in trees.                         
Properties                                                                
IsTallyLogVolumes As Long                                                 
The VolumeCalculator can tally volume into log classes.                   
1 - Tally volumes into log classes. Log volumes are accessed              
through the LogVolumes object.                                            
0 - Don&#39;t tally volumes into log classes. The Log volumes                 
object will be empty.                                                     
IsTallyTreeVolumes As Long                                                
The VolumeCalculator can tally volume into tree classes.                  
1 - Tally volumes into tree classes. Tree volumes are accessed            
through the TreeVolumes object.                                           
0 - Don&#39;t tally volumes into tree classes. The TreeVolumes                
object will be empty.                                                     
LogVolumes As LogVolumes                                                  
Holds timber volume tallied by log classes. Species, diameter             
and length determine unique log classes. This object will be              
empty unless IsTallyLogVolumes is set to true.                            
MinDBH As Single                                                          
A minimum DBH used to determine which tree classes                        
contribute volume to volume tallies.                                      
Name As String                                                            
User supplied name.                                                       
PayRate As Single                                                         
Rate of pay for each TreeClasses object scaled. Billed to                 
organization.                                                             
TreeVolumes As TreeVolumes                                                
Holds timber volume tallied by tree classes. Species and DBH              
determine unique tree classes. This object will be empty unless           
IsTallyTreeVolumes is set to true.                                        
VolumeCalculator As VolumeCalculator                                      
Calculates volume and tallies it into log and tree classes.               
TallyMode as Long                                                         
Determines whether volume tallies are averaged each call the              
Scale( ). If TallyMode = 0, volume tallies are averaged each call         
the Scale( ). If TallyMode = 1, averaging does not occur. The             
Average( ) method should be called manually to average the                
tallies.                                                                  
Methods                                                                   
Scale(TreeClasses As TreeClasses)                                         
Instructs the Scaler to scale the TreeClasses given. The resulting        
volumes calculated from the scale is accessed through the                 
VolumeCalculator object.                                                  
Average( )                                                                
Instructs the Scaler to average the volume tallies                        
Clear( )                                                                  
Instructs the Scaler to clear the volume tallies.                         
Events                                                                    
Remarks                                                                   
•                                                                   
      Scale trees by calling the Scale( ) member, passing a               
      TreeClasses object 54. Then access the resulting volume through     
      the LogVolumes object or TreeVolumes objects in the Scaler&#39;s        
      object 80 VolumeCalculator object.                                  
•                                                                   
      The LogVolumes object can be given to Grader object 82 for          
      grading and calculating the value of the volume.                    
•                                                                   
      The Scaler object 80 calculates the volume of individual trees.     
      Therefore, the Count member of the TreeClass object 54 is used      
      in calculations rather than the TPA member.                         
•                                                                   
      Access Scaler object 80 through ForestManager object                
______________________________________                                    
      68                                                                  
 
    
     Table 18 illustrates properties, methods and events of Grader object 82. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 18                                                    
______________________________________                                    
Grader object 82                                                          
Description                                                               
Grader object 82 grades and values timber volume. Grader object 82 takes  
the log volumes in a LogVolumes object and sorts the volume into grade    
classes that are described in the Grader&#39;s Grades object. The grading     
process fills in the value and volume fields of Grades object.            
Properties                                                                
Grades As Grades                                                          
A Grades object that is used to both set up grades and to obtain          
the volume and value of timber after grading has occurred.                
Grades are entered into the Grades object in order of decreasing          
value.                                                                    
Name As String                                                            
User supplied name of Grader.                                             
PayRate As Single                                                         
Rate of pay for each LogVolumes object graded. Billed to                  
organization after each grading.                                          
Methods                                                                   
Grade(LogVolumes As LogVolumes)                                           
Grades the volume passed as a parameter and returns the                   
resulting grades. The volume and value of each Grade object in            
the Grades object can be sampled after the function returns.              
Events                                                                    
Remarks                                                                   
•                                                                   
      First create a set of grades using the Grades member of the         
      Grader object. Call Grade( ) passing the LogVolumes object to       
      be graded. The LogVolumes object can be created using either        
      the Cruiser or Scaler objects. Each LogVolume object in the         
      LogVolumes object is compared to each Grade object in the           
      Grades object. Grades are compared from the first Grade object      
      in the list to the last Grade object in the Grades object. The      
      first Grade object that matches the LogVolume object is used as     
      the grade for that volume. The total value for the grade is         
      incremented using the Grade&#39;s rate value and the LogVolume&#39;s        
      board foot value. If a LogVolume object does not match any          
      Grade objects, it does not contribute to grade volume or value.     
      The Grade object&#39;s NumberUngraded tracks the number of              
      LogVolume objects with no matching grades. When the Grade( )        
      function returns, the Grades object can be sampled for the result.  
•                                                                   
      The resulting graded volume is accessed through the Grades          
      object.                                                             
•                                                                   
      Grader&#39;s object 82 list of grades should be set up prior to         
      grading. They should be entered into Grades object in order of      
      decreasing value.                                                   
______________________________________                                    
 
    
     Cruiser object 84 calculates stand volume by &#34;cruising&#34; one or more stands. The tallies can be by stand, tree class or log. Cruiser object 84 is used to do volume calculations and can be configured for a number of board feet and cubic feet measures. 
     Table 19 illustrates properties, methods and events of Cruiser object 84. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 19                                                    
______________________________________                                    
Cruiser object 84                                                         
Description                                                               
Cruiser object 84 calculates the volume of standing trees. Volumes for    
any                                                                       
number of stands can be calculated. Volume can be summarized by stand,    
tree class and log class. The stands past to the Cruise( ) method and     
minimum DBH setting determines the trees whose volume is calculated.      
Volume is calculated using the VolumeCalculator object that contains      
settings for determining how volume is summarized. Once volume is         
calculated, it is returned through the StandVolumes, TreeVolumes and      
LogVolumes classes.                                                       
Properties                                                                
IsTallyLogVolumes As Long                                                 
The VolumeCalculator can tally volume into log classes.                   
1 - Tally volumes into log classes. Log volumes are accessed              
through the LogVolumes object.                                            
0 - Don&#39;t tally volumes into log classes. The LogVolumes object           
will be empty.                                                            
IsTallyTreeVolumes As Long                                                
The VolumeCalculator can tally volume into tree classes.                  
1 - Tally volumes into tree classes. Tree volumes are accessed            
through the TreeVolumes object.                                           
0 - Don&#39;t tally volumes into tree classes. The TreeVolumes                
object will be empty.                                                     
IsTallyStandVolumes As Long                                               
The VolumeCalculator can tally volume by stand.                           
1 - Tally volumes by stand. Stand volumes are accessed through            
the StandVolumes object.                                                  
0 - Don&#39;t tally volumes by stand. The StandVolumes object will            
be empty.                                                                 
Name As String                                                            
User supplied name of object.                                             
MinDBH As Single                                                          
A minimum DBH used to determine which tree classes                        
contribute volume to volume tallies.                                      
PayRate As Single                                                         
Rate of pay for each stand cruised. Billed to organization.               
VolumeCalculator As VolumeCalculator                                      
Calculates volume and tallies it into log and tree classes.               
LogVolumes As LogVolumes                                                  
Holds timber volume tallied by log classes. Species, diameter             
and length determine unique log classes. Set IsTallyLogVolumes            
to true end call the Cruise( ) method to fill the LogVolumes              
object.                                                                   
TreeVolumes As TreeVolumes                                                
Holds timber volume tallied by tree classes. Species and DBH              
determine unique tree classes. Set IsTallyTreeVolumes to true             
and call the Cruise( ) method to fill the TreeVolumes object.             
StandVolumes As StandVolumes                                              
Holds timber volume tallied by stand. Set IsTallyStandVolumes             
to true and call the Cruise( ) method to fill the StandVolumes            
object.                                                                   
Methods                                                                   
Cruise(StandList As String)                                               
Instructs the cruiser to cruise the list of stands given. Format          
for StandList is &#34;Stand1; Stand2; . . . &#34; where &#34;Stand1&#34;, etc. is         
the name of individual stands to be cruised. The resulting                
volumes calculated from the scale is accessed through the                 
VolumeCalculator object.                                                  
Events                                                                    
Remarks                                                                   
•                                                                   
      Cruise stands by calling the Cruise( ) member, passing a list of    
      stands. Then access the resulting volume through the                
      StandVolumes, TreeVolumes or LogVolumes objects.                    
      Remember to set which volume summaries will be valid using          
      the IsTallyStandVolumes, IsTallyTreeVolumes and                     
      IsTallyLogVolumes properties.                                       
•                                                                   
      The LogVolumes object can be given to Grader object 82 for          
      grading.                                                            
______________________________________                                    
 
    
     Rule Objects 
     FIG. 7 is a block diagram illustrating Rule objects 86. Rule objects 86 define how the multiple management actions are carried out. Each management action has a rule associated with it that defines how the management action will be carried out. ClearcuttingRules object 88, ClearcuttingRule object 90, SelectiveCuttingRules object 92, SelectiveCuttingRule object 94 and ThinningRules object 96 and ThinningRule object 98 are stored in Harvester object 74. 
     Table 20 illustrates properties, methods and events of ClearcuttingRules object 88. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 20                                                    
______________________________________                                    
ClearCuttingRules object 88                                               
Description                                                               
ClearCuttingRules object 88 implements a list of ClearCuttingRule         
objects                                                                   
90. ClearCuttingRules object 88 is accessed through Harvester object 74.  
Properties                                                                
Count As Long                                                             
Returns the number of ClearCuttingRule objects 90 in the list.            
Methods                                                                   
Add( ) As ClearCuttingRule                                                
Creates a new ClearCuttingRule object 90 and adds it to the list.         
Returns the ClearCuttingRule object 90 created.                           
Item(Index As Long) As ClearCuttingRule                                   
Returns the ClearCuttingRule object 90 at the Index position in           
the list.                                                                 
RemoveAll( )                                                              
Removes all ClearCuttingRule objects 90 from the list.                    
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 21 illustrates properties, methods and events of ClearcuttingRule object 90. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 21                                                    
______________________________________                                    
ClearCuttingRule object 90                                                
Description                                                               
ClearCuttingRule object 90 is a rule that defines how a clear cut action  
will be carried out. Clear cutting rules differ only by their cost, which 
is                                                                        
accounted for each time the rule is carried out. ClearCuttingRule         
objects                                                                   
90 are stored in the ClearCuttingRules object 88 which is accessed        
through                                                                   
Harvester object 74.                                                      
Properties                                                                
Cost As Single                                                            
Cost per acre for a clear cut action. Cost of clear cut is                
accounted for at the time of each clear cut action.                       
Name As String                                                            
Name of this clear cut rule.                                              
ID As Long                                                                
Numeric ID uniquely identifying this clear cutting rule from              
other clear cutting rules.                                                
Methods                                                                   
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 22 illustrates properties methods and events of SelectivecuttingRules object 92. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 22                                                    
______________________________________                                    
SelectiveCuttingRules 92                                                  
Description                                                               
SelectiveCuttingRules object 92 holds a list of SelectiveCuttingRule      
objects 94.                                                               
Properties                                                                
Count As Long                                                             
Returns the number of SelectiveCuttingRule objects 94 in the              
list.                                                                     
Methods                                                                   
Add( ) As SelectiveCuttingRule                                            
Creates a new SelectiveCuttingRule object 94 and adds it to the           
list. Returns the SelectiveCuttingRule object 94 created.                 
Item(Index As Long) As SelectiveCuttingRule                               
Returns the SelectiveCuttingRule object 94 at the index position          
in the list.                                                              
RemoveAll( )                                                              
Removes all SelectiveCuttingRule objects 94 from the list.                
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 23 illustrates properties, methods and events of SelectivecuttingRule object 94. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 23                                                    
______________________________________                                    
SelectiveCuttingRule 94                                                   
Description                                                               
SelectiveCuttingRule object 94 is a rule that defines how a selective     
cutting action will be carried out. When selective cutting occurs, a      
size                                                                      
density curve is used to define the TPA of trees to leave standing. The   
size density curve is set by calling the SetTPA( ) method.                
Properties                                                                
Cost As Single                                                            
Cost per selective cutting action carried out.                            
Name As String                                                            
Name of this selective cutting rule.                                      
ID As Long                                                                
Numeric ID uniquely identifying this selective cutting rule from          
other selective cutting rules.                                            
Methods                                                                   
SetTPA(Points as String)                                                  
Sets the minimum TPA curve                                                
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 24 illustrates properties methods and events of ThinningRules object 96. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 24                                                    
______________________________________                                    
ThinningRules object 96                                                   
Description                                                               
ThinningRules object 96 holds a list of ThinningRule objects 98.          
Properties                                                                
Count As Long                                                             
Returns the number of ThinningRule objects 98 in the list.                
Methods                                                                   
Add( ) As ThinningRule                                                    
Creates a new ThinningRule object 98 and adds it to the list.             
Returns the ThinningRule object 98 created.                               
Item(Index As Long) As ThinningRule                                       
Returns the ThinningRule object 98 at the Index position in the           
list.                                                                     
RemoveAll( )                                                              
Removes all ThinningRule objects 98 from the list.                        
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 25 illustrates properties, methods and events of ThinningRule object 98. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 25                                                    
______________________________________                                    
ThinningRule object 98                                                    
______________________________________                                    
Description                                                               
ThinningRule object 98 is a rule that defines how a                       
thinning action will be carried out.                                      
Properties                                                                
Cost As Single                                                            
 Cost per thinning action carried out.                                    
Name As String                                                            
 Name of this thinning rule.                                              
Method As Long                                                            
 Thinning method.                                                         
TriggerType As Long                                                       
 Type of thinning trigger.                                                
Triggervalue As Single                                                    
 Value of thinning trigger.                                               
TargetType As Long                                                        
 Name of this thinning rule.                                              
TargetValue As Single                                                     
 Value of thinning target.                                                
MinimumMarker As Single                                                   
 Minimum value for thinning marker.                                       
MaximumMarker As Single                                                   
 Maximum value for thinning marker.                                       
MarkerType As Long                                                        
 Type of thinning marker.                                                 
Name As String                                                            
 Name of this thinning rule.                                              
ID As Long                                                                
 Numeric ID uniquely identifying this thinning                            
 rule from other thinning rules.                                          
Methods                                                                   
SetTPA(Points as String)                                                  
 Sets the minimum TPA curve                                               
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     PlantingRules object 100 and PlantingRules object 102 are stored in Planter object 76. When Harvester object 74 or Planter object 76 is told to carry out an action, it looks up the rule associated with that action in its list. Any number of rules can be made for each action. 
     Table 26 illustrates properties, methods and events of PlantingRules object 100. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 26                                                    
______________________________________                                    
PlantingRules object 100                                                  
______________________________________                                    
Description                                                               
PlantingRules object 100 holds a list of PlantingRule objects 102.        
Properties                                                                
Count As Long                                                             
 Returns the number of PlantingRule objects 102 in the list.              
Methods                                                                   
Add( ) As PlantingRule                                                    
 Creates a new PlantingRule object 102 and adds                           
 it to the list. Returns the                                              
 PlantingRule object 102 created.                                         
Item(Index As Long) As PlantingRule                                       
 Returns the PlantingRule object 1 02 at the Index position in the list.  
RemoveAll()                                                               
 Removes all PlantingRule objects 102 from the list.                      
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 27 illustrates properties, methods and events of PlantingRule object 102. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 27                                                    
______________________________________                                    
PlantingRule object 102                                                   
______________________________________                                    
Desription                                                                
PlantingRules object 102 is a rule that defines how a planting action     
will be carried out.                                                      
Properties                                                                
Cost As Single                                                            
 Cost per planting action carried out.                                    
Name As String                                                            
 Name of this planting rule.                                              
ID As Long                                                                
 Numeric ID uniquely identifying this planting                            
 rule from all other planting rules                                       
Saplings As TreeClasses object 56                                         
 TreeClasses object 56 that defines what tree classes                     
 are planted when this rule is carried out.                               
Methods                                                                   
Events                                                                    
______________________________________                                    
 
    
     Rules can also be specified by stand. Each Stand object 58 can have a default rule for each action associated with it. When no rule is specified for an action, the default rule for the stand applies. In addition to scheduled thinnings, the ForestManager object 68 assesses the density of stands each period to determine if a thinning is needed. If so, the Harvester object 74 is instructed to thin the stand using a default thinning rule for the stand. 
     Timber Assessment Objects 
     FIGS. 8A and 8 B are a block diagram illustrating Timber Assessment objects 104. Timber Assessment objects 104 provide functionality for measuring the volume and value of timber. Cruiser object 84 calculates stand volume by &#34;cruising&#34; one or more stands using a VolumeCalculator object 106 in FIG. 8A. Cruising and volume calculation is known to those skilled in the forestry arts. Volume is tallied by stand, tree class or log class. Cruiser object&#39;s 64 VolumeCalculator object 106 is used to do the volume calculations and can be configured for a number of board feet and cubic feet measures. 
     Table 28 illustrates properties, methods and events of VolumeCalculator object 106. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 28                                                    
______________________________________                                    
VolumeCalculator object 106.                                              
______________________________________                                    
Description                                                               
VolumeCalculator object 106 calculates the timber volume of trees.        
Volume is calculated in cubic and board foot values.                      
Board foot values are calculated using Scribner Decimal C log rules       
(e.g.,                                                                    
Bell, 1988). Cubic foot volume is calculated as a truncated cope          
(e.g., Bell, 1988). A minimum DBH for merchantable trees,                 
a minimum log diameter for merchantable logs and the log length           
can be set to customize volume calculations. Log scaling can be           
done using either Eastside (rounding) or Westside (truncation)            
scaling rules. The VolumeCalculator calculates the volume of              
trees one at a time. These volumes are tallied in LogVolumes              
and TreeVolumes objects. The volume calculation for each tree             
can be traced by catching the VolumeCalculatorPostCalc                    
event. This event passes the last TreeClass whose volume was              
calculated and the number individuals trees it represents.                
Properties                                                                
IsCalcEvent As Long                                                       
 Determines whether the VolumeCalculatorCalc event                        
 is raised for the next tree class                                        
 calculated.                                                              
LogLength As Single                                                       
 Length of log to be used in segmenting a tree.                           
Logvolumes As LogVolumes                                                  
 A LogVolumes object that holds the Logvolume objects                     
 for the last calculated tree                                             
 class.                                                                   
MaxDefect As Single                                                       
 Maximum defect aflowed for log to contribute volume                      
 to net volume tally.                                                     
MaxNetVolume As Single                                                    
 Minimum net volume of log for log to contribute                          
 volume to net volume tally.                                              
MinDiameter As Single                                                     
 Minimum log diameter for log to contribute                               
 volume to gross volume tally.                                            
MinLength As Single                                                       
 Minimum log length for log to contribute                                 
 volume to gross volume tally.                                            
VolumeType As Long                                                        
 Type of volume to calculate.                                             
ScalingRule As Long                                                       
 Scaling rule to be used in volume calculations.                          
 1- Westside scaling rules. Log diameters are truncated to                
 the nearest inch.                                                        
 2- Eastside scaling rules. Log diameters are rounded to the nearest      
inch.                                                                     
Events                                                                    
VolumeCalculatorpreCalc(TreeClass As TreeClass, TreeCount As Double)      
 Triggered before the VolumeCalculator calculates                         
 the volume of a tree.                                                    
VolumeCalculatorPostCalc(TreeClass As Treeclass,                          
TreeCount As Double)                                                      
 Triggered after the VolumeCalculator calculates the                      
 volume of a tree. Sample the                                             
 CurrentLogVolumes member to determine the volume                         
 of each log in the TreeClass given.                                      
Remarks                                                                   
• VolumeCalculator object 106 is an object member                   
  of both Cruiser object 84 and                                           
  Scaler object 80 Prior to instructing Cruiser object                    
  84 or Scaler object 80 to calculate                                     
  volume, the LogLength, MinDBH, MinLogDiameter                           
  and ScalingRule properties of                                           
  their respective VolumeCalculators are set.                             
• Cruiser object 84 and Scaler object 80 are told what types of     
categories                                                                
  VolumeCalculator object 106 is to tally volume into: tree classes,      
  log classes or both.                                                    
______________________________________                                    
 
    
     After Harvester object 74 harvest trees, Scaler object 80 calculates the volume of timber in the harvested trees using a traditional volume calculations known to those skilled in the forestry arts. Scaler object 80 determines harvested volume using VolumeCalculator object 106 with a HarvestedTreeClasses object member from a HarvestList object member generated by Harvester object 74 after a harvest. Scaler object&#39;s 80 VolumeCalculator object 106 can be configured the same way as the Cruiser object&#39;s 84 VolumeCalculator object 106. 
     Grader object 82 calculates the value of timber volumes using a traditional log grading system known to those skilled in the forestry arts. Grader object 82 grades harvested timber using LogVolumes object 112 of the Scaler object 80 with Grades object 108 and Grade object 110. The resulting list of grades returns the volume and value of the harvested timber by grade. The value can be added to the organization&#39;s income using Accountant object 78. 
     Table 29 illustrates properties, methods and events of Grades object 108. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 29                                                    
______________________________________                                    
Grades object 108                                                         
______________________________________                                    
Description                                                               
Grades object 108 implements a list of Grade objects 110.                 
Grader object 82 uses Grades object                                       
108 to grade log volumes. Grades should be entered                        
in order of decreasing value.                                             
Properties                                                                
Count As Long                                                             
 Returns the number of Grade objects 110 in the list.                     
NumberUngraded As Long                                                    
 Returns the number of LogVolume objects that did                         
 not match any Grade objects 110                                          
 during grading. LogVolume objects that remain                            
 ungraded do not contributed to grade                                     
 volume or value.                                                         
Volume As Single                                                          
 Returns the volume of Grade objects 110 in the list.                     
 This will only be valid after a                                          
 grading has occurred.                                                    
Value As Single                                                           
 Returns the value of Grade objects 110 in the list.                      
 This will only be valid after a                                          
 grading has occurred.                                                    
Methods                                                                   
Add( ) As Grade                                                           
 Creates a new Grade object 110 and adds it to the list.                  
 Returns the Grade object 110 created.                                    
Item(Index As Long) As Grade                                              
 Returns the Grade object 110 at the                                      
 Index position in the list.                                              
RemoveAll()                                                               
Removes Grade objects 110 from the list.                                  
Events                                                                    
Remarks                                                                   
• Grader object 82 attempts to match Grade object 110               
  from the first in the list to the                                       
  last. The first Grade object whose specifications                       
  match the LogVolume object in                                           
  question is used to assign a grade to the LogVolume object.             
  Therefore, that Grade                                                   
  objects 110 are entered in decreasing value with the first              
  entered having the highest                                              
  value and the last entered having the lowest value.                     
______________________________________                                    
 
    
     Table 30 illustrates properties, methods and events of Grade object 110. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 30                                                    
______________________________________                                    
Grade object 110                                                          
______________________________________                                    
Description                                                               
Grade object 110 holds grade specifications that are                      
used to implement log grading. Using grades, timber                       
value can be assessed.                                                    
Properties                                                                
MaxDefect As Single                                                       
 The maximum defect that a log may have to                                
contribute volume to this grade.                                          
MinDiameter As Long                                                       
 The minimum diameter that a log should have to                           
 contribute volume to this grade.                                         
MinLength As Long                                                         
 The minimum length that a log should have to contribute                  
 volume to this grade.                                                    
MinNetVolume As Single                                                    
 The minimum net volume a log should have to contribute                   
 volume to this grade.                                                    
Name As String                                                            
 The name of the grade.                                                   
Rate As Single                                                            
 Value per unit volume for this grade. After Grader object                
 82 calculates grades, the value of a grade becomes                       
 the volume of the grade multiplied by the rate.                          
Species As String                                                         
 Species object for this grade.                                           
Value As Single                                                           
 Value for the volume in this grade.                                      
Volume As Single                                                          
 The volume of timber in this grade.                                      
Methods                                                                   
Events                                                                    
Remarks                                                                   
• A grade is uniquely defined by its name, species,                 
  minimum diameter and minimum                                            
  length specifications.                                                  
______________________________________                                    
 
    
     The volume of wood present in logs is determined by Scaler object 80 and Cruiser object 84 using a VolumeCalculator object 106 with a LogVolumes object 116 including a LogVolume object 118. 
     Table 31 illustrates, properties methods and events of LogVolumes object 112. 
     
                       TABLE 31                                                    
______________________________________                                    
LogVolumes object 112                                                     
______________________________________                                    
Description                                                               
LogVolumes 112 object holds a list of LogVolume objects 114.              
An index is used to access                                                
objects in the list.                                                      
Properties                                                                
NetAsSingle                                                               
 Net volume.                                                              
Count As Long                                                             
 The number of Logvolume objects 114 in the list.                         
Gross As Single                                                           
 Gross volume.                                                            
Total As Single                                                           
 Total volume.                                                            
Methods                                                                   
 Item(Index As Long) As LogVolume                                         
 Returns the LogVolume object 114 with the index given                    
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 32 illustrates properties, methods and events of LogVolume object 114. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 32                                                    
______________________________________                                    
LogVolume object 114                                                      
______________________________________                                    
Description                                                               
LogVolume object 114 holds the volume of timber tallied into              
log classes. Species, diameter and length uniquely define                 
log classes. Volume is available in cubic and board foot values.          
Board foot values is calculated using Scribner Decimal                    
C log rules. (e.g., Bell, 1988) Cubic foot volume                         
is calculated as a truncated cone.                                        
Properties                                                                
Diameter As Long                                                          
 Diameter of this log volume class.                                       
Gross As Single                                                           
 Gross volume.                                                            
Length As Long                                                            
 Length of this log volume class.                                         
NetAsSingle                                                               
 Net volume.                                                              
Species As String                                                         
 Species of this log volume class.                                        
Total As Single                                                           
 Total volume.                                                            
Methods                                                                   
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     The volume of wood present in trees is determined by Scaler object 80 and Cruiser object 84 using a VolumeCalculator object 106 with a TreeVolumes object 116 including a TreeVolume object 118. Table 33 illustrates properties, methods and events of TreeVolumes object 116. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 33                                                    
______________________________________                                    
TreeVolumes object 116                                                    
______________________________________                                    
Description                                                               
TreeVolumes object 116 holds a list of TreeVolume objects 118.            
An index is used to access                                                
objects in the list.                                                      
Properties                                                                
Age As Single                                                             
 Average age of tree classes. Read only.                                  
BA As Single                                                              
 If TreeVolume objects 118 are derived from Cruiser calculations,         
 the BA is BA per 110 acre. If TreeVolume objects 118                     
 are a result of Scaler calculations, then BA is total                    
 BA for trees harvested. Read only.                                       
Count As Long                                                             
 The number of TreeVolume objects 118 in the list. Read only.             
DBH As Single                                                             
 Returns the arithmetic average DBH of TreeVolume objects                 
 118 in the list. Read                                                    
 only.                                                                    
Gross As Single                                                           
 Gross volume. Read only.                                                 
Net As Single                                                             
 Net volume. Read only.                                                   
Total As Single                                                           
 Total volume. Read only.                                                 
HeightTotal As Single                                                     
 Average total height. Read only.                                         
Sort(Type as Long)                                                        
 Sorts the list of TreeVolumes objects 116. Type interpreted              
 as a bit filed where bit 1                                               
 sorts by species and bit 2 sorts by DBH.                                 
 Sorting order parallels bit order.                                       
TPA As Single                                                             
 Trees per acre. Invalid if TreeVolumes object 116                        
 when derived from Scaler object                                          
 80. Read only.                                                           
TreeCount As Single                                                       
 Trees per acre. Valid if TreeVolumes object 116 when                     
 derived from Scaler object 80.                                           
 Read only.                                                               
QMD As Single                                                             
 Returns the quadratic mean diameter or the DBH of                        
 a tree with average BA. Read only.                                       
Methods                                                                   
Item(Index As Long) As StandVolume                                        
 Returns StandVolume object with the index given.                         
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     Table 34 illustrates properties, methods and events of TreeVolume object 118. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 34                                                    
______________________________________                                    
TreeVolume object 118                                                     
______________________________________                                    
Description                                                               
TreeVolume object 118 holds the volume of timber tallied by stand.        
Species and DBH uniquely                                                  
define TreeVolume objects 118 within Treevolumes object 116.              
Properties                                                                
Age As Single                                                             
 Average age of tree classes.                                             
BA As Single                                                              
 Average BA per acre.                                                     
DBH As Single                                                             
 DBH.                                                                     
Gross As Single                                                           
 Gross volume.                                                            
Net As Single                                                             
 Net volume.                                                              
Species As String                                                         
 Species.                                                                 
Total As Single                                                           
 Total volume.                                                            
HeightTotal As Single                                                     
 Average total height.                                                    
TPA As Single                                                             
 Trees per acre. Invalid if TreeVolume object 118                         
 when derived from Scaler object 80.                                      
TreeCount As Single                                                       
 Trees per acre. Valid if TreeVolume object 118 when                      
 derived from Scaler object 80.                                           
Methods                                                                   
Events                                                                    
Remarks                                                                   
______________________________________                                    
 
    
     The volume of timber present in a stand is determined by Cruiser object 84 using a VolumeCalculator object 106 with a StandVolumes object 120 including a StandVolume object 122 (FIG. 8B). 
     Table 35 illustrates properties, methods and events of StandVolumes object 120. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 35                                                    
______________________________________                                    
StandVolumes 120                                                          
______________________________________                                    
Description                                                               
StandVolumes object 120 holds a list of StandVolume objects 122.          
An index is used to access objects in the list.                           
Properties                                                                
Age As Single                                                             
 Average age of tree classes. Read only.                                  
BA As Single                                                              
 Average BA per acre. Read only.                                          
Count As Long                                                             
 The number of StandVolume objects 122 in the list. Read only.            
Gross As Single                                                           
 Gross volume. Read only.                                                 
Net As Single                                                             
 Net volume. Read only.                                                   
Total As Single                                                           
 Total volume. Read only.                                                 
TotalHeight As Single                                                     
 Average total height. Read only.                                         
TPA As Single                                                             
 Trees per acre. Read only.                                               
Methods                                                                   
Item(Index As Long) As StandVolume                                        
 Returns StandVolume object 122 with the index given.                     
Events                                                                    
Remarks                                                                   
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     Table 36 illustrates properties, methods and events of StandVolume object 122. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 36                                                    
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StandVolume object 122                                                    
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Description                                                               
StandVolume object 122 holds the volume of timber tallied by stand.       
Stand name uniquely define                                                
StandVolume objects 122 within the StandVolumes object 120.               
Properties                                                                
Age As Single                                                             
 Average age of tree classes. Read only.                                  
BA As Single                                                              
 BA per acre. Read only.                                                  
Gross As Single                                                           
 Gross volume. Read only.                                                 
Net As Single                                                             
 Net volume. Read only.                                                   
Stand As String                                                           
 Name of stand this StandVolume object                                    
122 represents. Read only.                                                
Total As Single                                                           
 Total volume. Read only.                                                 
TotalHeight As Single                                                     
 Average total height. Read only.                                         
TPA As Single                                                             
 Trees per acre. Read only.                                               
QMD As Single                                                             
 Quadratic mean diameter or the DBH of                                    
 a tree with average BA. Read only.                                       
Methods                                                                   
Events                                                                    
Remarks                                                                   
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     FIG. 9 is a block diagram 124 illustrating additional Forest Simulation objects including a HarvestList object 126, HarvestedTreeClass object 128, and a BDQ object 130. Harvester 74 uses HarvestList object 126 and HarvestedTreeClasses object 128 to summarize harvested by stand after a harvest. HarvestList object 126 includes a list of HarvestedTreeClasses objects 128 in a list. HarvestedTreeClasses object 128 includes a list of harvested TreeClass objects 54. BDQ object 130 provides a TPA versus DBH for a set of TreeClass objects 54. 
     Table 37 illustrates properties, methods and events of HarvestList object 126. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 37                                                    
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HarvestList object 126                                                    
______________________________________                                    
Description                                                               
List of HaverstedTreeClasses objects 128 in the harvest list.             
Properties                                                                
CountAsLong                                                               
 Returns the number of HarvestedTreeClasses                               
 objects 128 in the harvest list.                                         
Methods                                                                   
Item(Index as Long) As HarvestedTreeClasses                               
 Returns the HarvestedTreeClasses object 128 with the index given.        
Find(Stand as String) As HarvestedTreeClasses                             
 Returns the HarvestedTreeClasses object 128                              
 that corresponds to the stand given.                                     
Events                                                                    
Remarks                                                                   
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     Table 38 illustrates properties, methods and events of HarvestedTreeClasses object 128. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 38                                                    
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HarvestedTreeClasses object 128                                           
______________________________________                                    
Description                                                               
List of harvested TreeClasses objects 56.                                 
Properties                                                                
Count As Long                                                             
 Returns the number of TreeClasses objects 56 in the list.                
Stand As String                                                           
 Returns the name of the stand to which this                              
 HarvestedTreeClasses object 128                                          
 corresponds                                                              
Methods                                                                   
Age as Long                                                               
 Average age of tree class objects in the list.                           
BA As Single                                                              
 Sum of basal area for tree class objects in the list.                    
CCF(DBH) As Single                                                        
 Crown competition factor for trees with DBH larger than                  
 that given (e.g., Krajicek et. al., 1961). Calculated as:                
  CCF = Σ(CW.sub.i.sup.2 * TPA) * /4/43560                          
 Where i denotes the i.sup.th tree class object in the                    
 list with DBH larger than MinDBH                                         
CrownRatio() As Single                                                    
 Average crown ratio weighted by TreeCount.                               
CrownClosure(DBH) As Single                                               
 Crown competition factor for trees with HeightTotal &gt; Height.            
 Calculated similarly as CCF.                                             
Defect As Single                                                          
 Returns the % defect for tree class object in the list.                  
DBH As Single                                                             
 Returns the arithmetic average DBH of tree class objects in the list.    
HeightTotal As Single                                                     
 Average total height of tree class objects in the list.                  
Item(Index As Long) As Object                                             
 Returns the tree class object at the Index position in the list.         
QMD As Single                                                             
 Quadratic mean diameter or the DBH of a tree                             
 with average BA. Calculated as:                                          
 When TreeClasses object represents standing trees:                       
  QMD = BA/TPA*4*144/                                                     
 When TreeClasses object represents cut trees:                            
QMD = BA/TreeCount*4*144/                                                 
RelativeDensity As Single                                                 
 Relative density (e.g., Curtis 1982). Calculated as:                     
  RelativeDensity = BA/QMD.sup.1/2.                                       
Sort(Type as Long)                                                        
 Sorts the tree class objects in the list. Type interpreted as            
 a bit filed where bit 1 sorts                                            
 by species and bit 2 sorts by DBH. Sorting order parallels bit order.    
TPA(MinDBH As Single, MaxDBH As Single) As Single                         
Events                                                                    
Remarks                                                                   
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     Table 39 illustrates properties, methods and events of BDQ object 130. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 39                                                    
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BDQ object 130                                                            
______________________________________                                    
Description                                                               
BDQ object 130 provides a TPA versus DBH for a set                        
of TreeClass objects 54.                                                  
Members                                                                   
TPA(long MInDBH, long MaXDBH) as Single                                   
 Returns a TPA for classes of trees between MInDBH and MaxDBH.            
Remarks                                                                   
• BDQ averages DBH to the nearest whole #. For example,             
  a TreeClass 54 with DBH                                                 
  = 12.7 will be reported by BDQ as a 13 inch TreeClass.                  
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     Environmental Quality Objects 
     In an illustrative embodiment of the present invention, quality of a simulated forested environment can also be assessed using one or more Environmental Quality objects 134. FIG. 10 is a block diagram illustrating Environmental Quality objects 134. Environmental Quality objects include a Biologist object 136, a HabitatIndices object 138 and a CavityNestingBirdHabitatlndex object 140. 
     Biologist object 136 calculates the quality of habitat for specific species using HabitatIndices object 138. Biologists object 136 HabitatIndices object member holds the results of habitat quality calculations. CavityNestingBirdHabitatlndex object 140 is a habitat index for birds that prefer a specific habitat in stands in older growth forests. However, other objects for other biological species besides birds could also be used by Biologist object 136. 
     Table 40 illustrates properties, methods and events of Biologist object 136. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 40                                                    
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Biologist object 136                                                      
______________________________________                                    
Description                                                               
Biologist object 136 samples stands for habitat quality                   
by calculating indices that reflect the                                   
quality of habitat for a certain species. Habitat Indices                 
can be calculated for any number of                                       
stands.                                                                   
Members                                                                   
Name as String                                                            
 User supplied name of object.                                            
HabitatIndices as HabitatIndicies                                         
 List of HabitatIndencies objects to calculate. Read only.                
PayRate as Float                                                          
 Rate of pay for each stand sampled.                                      
 Billed to organization after completing sample.                          
HabitatIndex as Sample(string StandList)                                  
 Instructs the Biologist to calculate the habitat                         
 indices defined in the HabitatIndices                                    
 object for the stands given. Format for StandList                        
 is &#34;Stand1;Stand2; . . .&#34; where                                          
 &#34;Stand1&#34;, etc. is the name of individual stands                          
 to be sampled. The habitat indices                                       
 calculated from the sample is returned through                           
 a HabitatIndices object 138.                                             
Remarks                                                                   
• Set up habitat index objects using the HabitatIndices             
  object member, then call                                                
  Sample( ) to calculate them.                                            
• Loop through the habitat index objects in the HabitatIndices      
  object 138 to access the                                                
  value of the indices.                                                   
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     Table 41 illustrates properties, methods and events of HabitatIndices object 138. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 41                                                    
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HabitatIndices object 138                                                 
______________________________________                                    
Description                                                               
HabitatIndices object 138 holds a list of habitat index objects.          
Members                                                                   
Add(long Type)                                                            
 Creates a new habitat index object of the type                           
 specified and adds it to the list.                                       
 Returns the habitat index object created.                                
Count as Long                                                             
 Returns the number of habitat index objects in the list.                 
HabitatIndex as Item(long Index)                                          
 Returns the habitat index object at the Index position in the list.      
Remarks                                                                   
______________________________________                                    
 
    
     Table 42 illustrates properties, methods and events of CavityNestingBirdHabitatlndex object 140. However, more or fewer properties, methods and events could also be used. 
     
                       TABLE 42                                                    
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CavityNestingBirdHabitatIndex 140                                         
______________________________________                                    
Description                                                               
CavityNestingBirdHabitatIndex object 140 is a                             
habitat index for birds that prefer habitat in stands                     
with older growth. The index is calculated as:                            
Index = stand average height/TargetHeight * stand                         
average age/TargetAge * stand area.                                       
Members                                                                   
TargetAge as Float                                                        
 Ideal tree age for cavity nesting bird habitat.                          
TargetHeight as Float                                                     
 Ideal tree height for cavity nesting bird habitat.                       
HabitatIndex as Float                                                     
 Value of habitat index.                                                  
Remarks                                                                   
• Access HabitatIndices object 138 through                          
  the HabitatIndices member of Biologist                                  
  object 136.                                                             
• Set the target age and height. After calling                      
  the Sample object member Biologist                                      
  object 136 the HabitatIndex member will be set with                     
  the value for this index.                                               
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     Implementation 
     An illustrative embodiment of the present invention includes components written in Visual C++, Visual Basic, ActiveX and OLE all by Microsoft Corporation of Redmond, Wash. The components are used on a Windows 95 or Windows NT operating systems by Microsoft. However, the present invention is not limited to these programming languages, development environments or operating systems, and others can also be used. An object-oriented library of objects including the object-oriented objects illustrated in Tables 1-2 is included with an illustrative embodiment of the present invention. 
     A forestry simulation is typically conducted on large number of stands over a long pre-determined time period such as 100 years. The forestry simulation typically includes simulating the growth of hundreds of thousands of trees with TreeClass objects 54. 
     FIG. 11 is a block diagram illustrating an exemplary screen display 142 for an exemplary forestry simulation for an illustrative embodiment of the present invention. Screen display 142 includes first window 144 illustrating a screen display for the Simulation Control object, a second window 146 illustrating a screen display for forest resources including standing volume by stand, tree class and log viewer and a third window 148 illustrating a screen display for management actions applied to the forest resources. Second window 146 includes Douglas Fir and Grand Fir simulated trees in a simulated stand using one or more of TaperTreeClass object, or Stand object 58. Third window 148 includes management actions of clear cut, plant and thin applied to the forest resources of trees and stands in second window 146 using one or more of ClearCuttingRule object 90, ThinningRule object 98 or PlantingRule object 102. 
     It should be understood that the programs, processes, methods, systems and apparatus described herein are not related or limited to any particular type of computer apparatus (hardware or software), unless indicated otherwise. Various types of general purpose or specialized computer apparatus may be used with or perform operations in accordance with the teachings described herein. 
     In view of the wide variety of embodiments to which the principles of the invention can be applied, it should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the present invention. For example, the steps of the flow diagrams may be taken in sequences other than those described, and more or fewer elements or component may be used in the block diagrams. 
     The claims should not be read as limited to the described order or elements unless stated to that effect. In addition, use of the term &#34;means&#34; in any claim is intended to invoke 35 U.S.C. §112, paragraph 6, and any claim without the word &#34;means&#34; is not so intended. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.