Difference between revisions of "FVS"

Revision as of 22:54, 26 September 2010

General System description

System name: Forest Vegetation Simulator

Acronym: FVS

Brief overview

The Forest Vegetation Simulator (FVS) is a family of forest growth simulation models. The basic FVS model structure has been calibrated to unique geographic areas to produce individual FVS variants. Since its initial development in 1973, it has become a system of highly integrated analytical tools. These tools are based upon a body of scientific knowledge developed from decades of natural resources research.

Scope of the system

The Forest Vegetation Simulator (FVS) is a model used for predicting forest stand dynamics, and is used extensively throughout the United States. FVS is the standard forest dynamics model used by various government agencies including the USDA Forest Service, USDI Bureau of Land Management, and USDI Bureau of Indian Affairs. It is also used by state agencies, industry, educational institutions, and private landowners.

Forest managers have used FVS extensively to summarize current stand conditions, predict future stand conditions under various management alternatives, and update inventory statistics. Output from the model is used as input to forest planning models and many other analysis tools. In addition, FVS has been linked to other Forest Service corporate software such as databases and geographic information systems.

Uses of FVS are not restricted to timber management applications. Other uses of FVS include considering how management practices affect stand structure and composition, determining suitability of stands for wildlife habitat, estimating hazard ratings for insect outbreaks or wildfires, and predicting losses from fire and insect outbreaks.

System origin

FVS, and the suite of tools that support it, are the products of hundreds of contributors over a period of more than 30 years. FVS is descended from the Prognosis Model, which was conceived by Al Stage in 1973 and was developed for forest conditions in the northern Rocky Mountains. In the 1990's, other models such as TWIGS and GENGYM were incorporated into the Prognosis framework, and the system was renamed the Forest Vegetation Simulator. Over the years a number of extensions have been added, such as the insect, disease, and fire and fuels extensions. A number of post processing programs have been added as well.

The entire FVS suite is in the public domain, and is available for free download from http://www.fs.fed.us/fmsc/fvs/index.shtml

Support for specific issues

FVS can assist forest planners and managers, who are under ever increasing pressure to design and implement stand management alternatives that are biologically and economically sound and meet a wide variety of objectives. Costs associated with timber harvesting are continually increasing and any stand entry must generate enough revenue to justify the treatment. Meanwhile, forest managers must maintain or improve the health, condition, and scenic value of the landscape, reduce the risk of catastrophic fires, and maintain canopy structure and diversity to satisfy various forest practices legislation. Traditional forest management practices such as clear cutting are often not acceptable. Forest Managers are faced with implementing innovative management alternatives, of which the long-term effects on the resource are unknown. They must consider the risks and potential effects of insects, diseases, wildfires, and other disturbances. FVS is a tool that can assist in these areas.

Support for specific thematic areas of a problem type

FVS was originally designed as a silvicultural tool to aid in the planning of timber management. It has evolved into a much more robust system, useful in inventory processing, conservation and restoration efforts, sustainability determinations, and many other applications

Data and data models

Typical spatial extent of application

The typical projection unit in FVS is a stand, but the size of the projection unit is not limited. Many stands may be included in a simulation, alllowing analysis at the level of the smallest project, such as a thinning on several acres, all the way up to the watershed and landscape level, such as a national forest plan.

Forest data input

FVS uses input at the tree level (such as species and DBH) and at the stand level (such as site index). The data requirements are minimal, and many values are dubbed in by the model if not provided in the input data. For example, if the height of a tree is not included the model will calculate one. Similarly, stand-level attributes not found in the data either have default values (such as a default maximum basal area) or are calculated by the model (such as forest type).

Input files may be either text files or Microsoft Access database files, and there is a specific format requirement for each. There is a tool for translating Forest Inventory and Analysis (FIA) data into FVS-ready files. There is a utility in the Forest Service's Field Sampled Vegetation (FSVeg) system to use the inventory data housed there and create FVS-ready files. There are also utilities in the FVS suite for formatting other types of existing data files for use with FVS. Alternatively, data can be input from a keyboard directly into the FVS system by a user.

Type of information input from user (via GUI)

FVS is currently exclusively a PC application. The graphical user interface (GUI) for FVS is called 'Suppose'. Suppose is a typical Windows application with windows, menus, text boxes, lists, etc. The user selects the types of activities to simulate, and fills in the necessary attributes. For example, in order to simulate a harvest, the user selects the type of harvest, year of harvest, and residual target, and then optionally selects things like the target species, size range, and harvest efficiency.

Models

Forest models

The entire FVS system is a collection of models. There are separate models for things like tree growth, mortality, regeneration, understory vegetation, fire, fuels, wood volumes, carbon, biomass, insects, diseases, and economics. A model to simulate the effects of climate change is also in development. Things like habitat suitability and risk to a particular pest can be easily calculated or inferred from the FVS outputs.

Social models

FVS does not have a social model, as such. However, it is often used to infer effects on aesthetics, recreational opportunities, water quality, wildlife, and other socially important elements. For example, aesthetic quality may be a goal in a particular area, so alternative management scenarios can be simulated to determine the relative potential aesthetic impacts of each.

Decision Support

Typical temporal scale of application

FVS operates in time intervals known as 'cycles', which are typically 10 years in length. The user can specify the number of years in each cycle, and can include up to 40 total cycles in a simulation.

Definition of management interventions

Management can include harvests, thinnings, prunings, site preparation, planting, prescribed fire, fuel treatments, etc. Any number of activities can be scheduled at any time during a simulation. Activities may be scheduled to occur in a particular year, or they may be scheduled to occur when a specific condition is met. For example, a harvest could be scheduled for 2035 and a planting scheduled for 2037, or the harvest could be scheduled to occur when the stand basal area exceeds 100 and the planting could be scheduled to occur two years later. Management can be as simple or complex as the user desires. Simulations are easily edited and re-run to gain knowledge of a range of possible scenarios.

Output

Types of outputs

The outputs from FVS are in the form of text files or Microsoft Access database files. The user can select from a list of standard outputs. The outputs are produced for every time period in the simulation, and can include things like calibration statistics, stand composition, age, average tree size, stand density, wood volumes (standing and removed), regeneration, fuels (live, dead, down), fire effects, carbon, biomass, individual tree attributes, insect and disease info, and economics. The user also has the option to have the model do custom calculations and report those in output files. For example, a user could have FVS calculate the basal area per acre of a particular species in a particular size range.

Post processing tools in the FVS suite can create files needed as input to other software products. For example, specialized treelist files can be created for use with the Stand Visualization System (SVS), which can create 3-dimensional views of the stand. Other software, such as FlamMap, allow a user to enter the values output by FVS.

Spatial analysis capabilities

If latitude and longitude are included in the input data, it is a simple process to link the output tables from FVS with spatial analysis tools like GIS. These types of operations are performed frequently.

System

System requirements

FVS is a fully functioning, stand-alone application that currently runs exclusively on the Windows operating system. It does not rely on any other software for operation.

Architecture and major DSS components

?Describe the basic architecture of the system in software and hardware. Desktop client-server, web based, as well as the integration with available systems. Basic data flow, focusing on retrieval of required input and propagation and implementations of decisions. Mention its modular and scalability capabilities.

Usage

FVS is the standard forest dynamics model used by various government agencies including the USDA Forest Service, USDI Bureau of Land Management, and USDI Bureau of Indian Affairs. It is also used by state agencies, industry, educational institutions, and private landowners. It is used in research, planning, and management.

Computational limitations

Any number of projection units (stands) can be processed in a simulation. There is a limit of 500 plots or points in any projection unit. There is a limit of 40 time period 'cycles' for any simulation, but the length of the cycles can be controlled by the user.

User interface

FVS is a robust, complex system, and it requires a bit of training to fully understand it. However, the Suppose interface puts much of the functionality into common terminology, and greatly simplifies the process of creating simulations. Completion of a self-tutorial is sufficient to give most users the abiltiy to create simple simulations. Additional self-training or instructor-lead training are usually required for more sophisticated simulations.

Documentation and support

There is extensive documentation for the FVS system available at http://www.fs.fed.us/fmsc/fvs/documents/index.shtml The FVS staff also maintains a helpdesk that can be accessed either by phone (970-295-5770)or e-mail (wo_ftcol_fvs@fs.fed.us). User training and support are top priorities for the FVS staff.

Installation

FVS is distributed primarily through installation programs that are available for free download (http://www.fs.fed.us/fmsc/fvs/software/setup.php). No special permissions are necessary for the installation.