Glossary

In the context of RAVG analysis, the percent change in basal area relative to the pre-fire condition. Basal area loss does not describe a permanent loss of basal area within a forest, but simply describes the amount of change in live basal area at the time of assessment. Also called basal area mortality or percent change in basal area.

The ground area covered by the crowns of trees or woody vegetation as delineated by the vertical projection of crown perimeters. It is commonly expressed as a percent of total ground area. Also called crown cover. (Society of American Foresters. The Dictionary of Forestry, John A. Helms, Editor, 1998).

In the context of RAVG analysis, the percent change in live canopy cover relative to the pre-fire condition. Depending on the vegetation type and fire characteristics, the canopy cover loss estimate for an extended assessment may differ significantly from that of an initial assessment. Also called canopy cover mortality or percent change in canopy cover.

Vegetation dominated by trees with interlocking crowns, typically at least 60% crown cover.

See Canopy Cover

A temporary condition of the forest vegetation after a wildfire has burned at such high severity that not enough trees were left alive for the forest to naturally regenerate and function normally. It is a signal that reforestation treatments are required to re-establish forest cover promptly. As a rule, this describes a resulting forest with less than 20% canopy cover. A follow-up diagnosis followed by a silvicultural prescription is required to complete the final assessment and determine the type of management activities that are needed to recover the area. Also a severity class used in RAVG assessments in 2007, in which percent basal area loss is at least 50% .

A post-fire condition in which fire severity was classified as low, with the initial assessment showing enough live trees remaining for the forest to function normally. Most of the area has more than 20% canopy cover. A follow-up diagnosis and silvicultural prescription may be required to complete the final assessment and determine what type of management activities are needed to maintain the growth and vigor of the forest. Also a severity class used in RAVG assessments in 2007, in which percent basal area loss is less than 50% .

Vegetation dominated by trees with crowns not usually touching, typically with 25-60% crown cover.

The process of gathering field data for a forest stand to determine its current condition. Silvicultural and other management decisions are based on the data collected from these examinations. RAVG data can be a useful tool for prioritizing field exams.

A written document that describes management activities needed to implement treatments. It documents the results of an analysis of present and anticipated site conditions and management direction. It also describes desired future vegetation conditions in measurable terms. The desired conditions are a basis for treatment, monitoring, and evaluation.

Any of a set of management activities that can assist in the prompt recovery of forestlands. Treatments can include any combination of live, dead, or dying wood removal or disposal (with or without commercial value) by logging, piling, masticating, burning, or other methods. In addition, planting or seeding, with or without site preparation, are appropriate management activities designed to foster prompt recovery following wildfire. In some cases, the preferred "treatment" is natural regeneration and monitoring. Treatments also include follow-up activities to control vegetation that competes with desired trees during the early establishment period, usually 1 to 5 years after establishment, using any viable method that meets Land and Resource Management Plan direction.

As used in RAVG products, any pixels/acreage that are masked because of any condition in the pre- or post-fire imagery that would prevent a valid vegetation condition assessment. They include clouds, cloud shadows, active fire, smoke, snow, and open water. Data gaps in Landsat 7 imagery caused by the failure of the scan-line corrector are also routinely masked.

In the context of RAVG analysis, broad vegetation classes used for spatial analysis of burned area. The RAVG vegetation groups are based on the LANDFIRE Existing Vegetation Types (EVT) dataset, which provides a consistent national classification system to produce uniform statistics from vegetation cover data at the national level. Crosswalks to RAVG vegetation groups were developed from LANDFIRE Existing Vegetation Type Descriptions, Forest Types of the United States, Society of American Foresters forest cover types, Society for Range Management rangeland cover types, and the National Vegetation Classification Standard (NVCS). LANDFIRE Existing Vegetation Cover (EVC) data were used to inform the canopy closure aspect (closed canopy, open canopy or non-tree). The eight RAVG vegetation groups are defined as follows:

• Deciduous Open Tree Canopy - Open canopy dominated by deciduous tree species, with deciduous species contributing more than 75% of the total tree cover.
• Deciduous Closed Tree Canopy - Closed tree canopy dominated by deciduous tree species, with deciduous species contributing more than 75% of the total tree cover.
• Evergreen Open Tree Canopy - Open canopy dominated by evergreen tree species, with evergreen species contributing more than 75% of the total tree cover.
• Evergreen Closed Tree Canopy - Closed tree canopy dominated by evergreen tree species, with evergreen species contributing more than 75% of the total tree cover.
• Mixed Evergreen-Deciduous Open Tree Canopy - Open canopy dominated by a combination of evergreen and deciduous tree species, with each contributing 25 to 75% of the total tree cover.
• Mixed Evergreen-Deciduous Closed Tree Canopy - Closed tree canopy dominated by a combination of evergreen and deciduous tree species, with each contributing 25 to 75% of the total tree cover.
• Pinyon-Juniper Woodland - Area dominated by open stands of Pinus edulis (pinyon) and Juniperous menosperma (juniper). The total canopy cover is generally 25 to 60% but may be less than 25%. This vegetation group is found in the southwestern portion of the United States.
• Grassland / Shrubland / Non-Vegetation - All conditions not dominated by trees. Grasslands are dominated by herbaceous plants (generally forming at least 25% cover) with trees, shrubs, and dwarf shrubs accounting for less than 25% of total vegetation. Shrubland includes areas where the shrub component is generally greater than 0.5 meters tall with individuals or clumps overlapping but not touching. Non-vegetation describes areas completely bare of vegetation, like rock outcrops, lava fields, and water bodies.

Forest covers associated with the six deciduous and evergreen groups are described in Forest Cover Types of the United States (Society of American Foresters, F.H. Eyre, Editor, 1980). Many of the vegetation types associated with the non-tree group are described in Rangeland Cover Types of the United States (Thomas N. Shieflet, Editor, Society for Range Management, 1994).

Areas designated by Congress as a part of the National Wilderness Preservation System.