Geographic Information Systems
at the Virginia Department of Forestry

GIS Layer diagram.What Is GIS?

A Geographic Information System (GIS)
is a specialized, database-driven computer information system. The database contains observations of spatially distributed features, activities or events, which can be defined in space as points, lines or areas.

The GIS allows users to capture, store, display, manipulate and analyze geographically referenced data.

Foresters and other decision-makers can use GIS to discover and demonstrate spatial relationships, making GIS a valuable tool to explore management and policy alternatives.

GIS at the Virginia Department of Forestry (VDOF)

GIS plays an important role at VDOF as an information repository and as a decision support tool. VDOF also leverages other geographic technologies to complement its GIS. In the field, VDOF personnel use Geographic Positioning System (GPS) units to map, measure and navigate to features. Remote Sensing (RS) uses data such as aerial photography, satellite imagery and LIDAR, and is used to inventory and investigate the forest resources in Virginia. GIS, GPS, and RS are used alone or in combination in various VDOF applications including:

Wildfire Risk Assessment

Click here for a larger version of the Wildfire Risk Assessment graphic.VDOF has recently updated its Wildfire Risk Assessment to more objectively reflect the potential for wildfire across Virginia. By building a GIS model that assigns relative weights and ranks to input layers, VDOF has produced a map of Wildfire Risk that will help the agency perform community Firewise outreach, better allocate resources, and increase response preparedness.

Input layers include Slope, Aspect, Landcover, Distance to Railroads, Distance to Roads, Population Density, and Historical Fire Occurrence. For more detailed information about modeling methodology, go to the GIS Data Downloads page and read the Info file (metadata) for the Wildfire Risk Assessment.

Urban-Wildland Interface Analysis

The areas at greatest risk for forest fire are those at the urban-wildland interface, or where people and forests meet. A wildfire mitigation project is currently underway that will update and refine the wildfire risk analysis described above.

Another goal of this project is to improve decision-making capabilities for fire suppression and prevention activities by adding to the GIS database. Data are being collected on locations and attributes of wildfire suppression resources, woodland home communities, and historical fire incidents.

Understanding the spatial relationship of these and other features will help VDOF concentrate their prevention education, resource allocation, and emergency response efforts where fire poses the greatest risk.

Forest Resource Assessment

There are many factors that influence the quantity, quality and sustainability of the forest resources in Virginia. Click to enlarge: Forest Resource AssessmentIn 1995 VDOF augmented its 1992 forest inventory with GIS analysis to perform the Forest Resource Assessment. This assessment examined the impact of growing rural and suburban populations on the forest resource as a whole, and more specifically on the forestlands available to support commercial timber production.

The assessment showed that forestland is becoming increasingly fragmented by residential and commercial development, and that it is difficult to determine which portion of the timber resource is truly available for production. At the time of the study only 55% of the 15.4 million acres of forestland was considered to available for timber production.

Forest Land Use Mapping and Forest Inventory and Analysis

To act as stewards for the development and sustainability of Virginia's forest resources, it is critical for VDOF to evaluate not just the quantity of forestlands, but also their spatial arrangement. To this end, VDOF is using their Forest Inventory and Analysis (FIA) plot data in conjunction with 2000 Landsat TM satellite imagery to classify the landscape into forest, non-forest, and water. The resulting raster layer will be used in numerous GIS analyses, including future forest resource assessments, forest fire risk modeling, water quality management, fragmentation analyses, forest economics, and conservation efforts.

Mapping of Gypsy Moth Defoliation and Tree Mortality

Click to enlarge: Mapping of Gypsy Moth Defoliation and Tree Mortality

As part of its forest health monitoring efforts, VDOF has used GIS to help quantify and track the spatial patterns of forest disturbance from insect infestations and extreme weather events.

The primary focus has been on gypsy moth defoliation and tree mortality; however, damage from cicada, leaf-scratch, cankerworm, as well as ice and hail storms have been mapped when appropriate. Impacted forestlands have been mapped since 1984 using aerial surveys of known problem areas.

State Forest Property Inventory and Stand Mapping

Click to enlarge: State Forest Property Inventory and Stand Mapping

VDOF owns and manages more than 20 State Forests. All State Forest property boundaries are mapped using GIS.

Timber stands have been mapped for attributes such as forest type, stand age, and management activities for the Cumberland, Appomattox-Buckingham and Prince Edward-Gallion State Forests.

Using GIS helps VDOF efficiently monitor and manage the forests.


Riparian Buffer Tax Credit Program Management

The 2000 Virginia General Assembly enacted the Riparian Buffer Tax Credit to provide a tax credit to those who, during a harvest, retain forest buffers along waterways. The forested riparian buffer must remain intact for 15 years once established, and VDOF has been mandated to perform annual compliance checks of the buffers. To efficiently manage the compliance monitoring, VDOF is using GIS and satellite imagery change detection analysis to minimize unnecessary field visits. By using multiple dates of satellite imagery, VDOF can evaluate whether there has been disturbance of the buffer area and notify the VDOF Forester in that work area to perform a visual field inspection.

Forest Sustainability Project: Louisa County

To sustain the quality and quantity of forests to meet the environmental, economic, and recreational needs of Virginians, VDOF must understand and mitigate the threats to the forest resource. Forest sustainability was examined in Louisa County, a jurisdiction greatly influenced by forests and forestry. Louisa County is also influenced by its location between Richmond and Charlottesville and the Interstate 64 corridor running through it. VDOF used GIS and 1-m resolution digital aerial photography to map forest areas as a basis for the analysis. An overlay of tax parcel boundaries showing the property ownership divisions in the county demonstrated that although Louisa County may have large contiguous blocks of forested area, these blocks are usually owned my numerous people and that the potential for fragmentation is high.

Large (700 acre) forest patch Same large (700 acre) forest patch
with Ownership overlay
Large (700 acre) forest patch Same 700 acre forest patch with Ownership overlay.

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