U.S. Forest Service Post-Fire Vegetation Conditions on the National Forests
Basal Area Loss - In the context of RAVG analysis, basal area loss measures the percent change in basal area or tree cover (relative number of live trees on the site) from the pre-fire condition. In the 2008 RAVG tables, basal area loss is reported as four classes of percent change in tree cover and is expressed in square feet. Basal area loss does not describe a permanent loss of basal area within a forest, but simply describes the amount of change in the live tree cover immediately (30 days after wildfire containment) after a wildfire that undergoes RAVG analysis.
Canopy Cover – See Crown Cover.
Crown Cover – This is 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. (Society of American Foresters. The Dictionary of Forestry, John A. Helms, Editor, 1998).
Deforested Vegetation Condition - This term describes 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 type of management activities that are needed to recover the area.
It is different than the professional definition of the term deforestation, which connotes a permanent change in land use.
Forested Vegetation Condition - This term describes areas where fire severity was classified as low resulting in forest conditions where initial assessment shows enough live trees remain 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 growth and vigor of the forest.
LANDFIRE - Also known as the Landscape Fire and Resource Management Planning Tools Project, is a five-year, multi-partner project producing consistent and comprehensive maps and data describing vegetation, wildland fuel, and fire regimes across the United States. It is a shared project between the wildland fire management programs of the U.S. Department of Agriculture Forest Service and U.S. Department of the Interior. The project has four components: the LANDFIRE Prototype, LANDFIRE Rapid Assessment, LANDFIRE National, and Training/Technology Transfer.
LANDFIRE data products include layers of vegetation composition and structure, surface and canopy fuel characteristics, and historical fire regimes. LANDFIRE National methodologies are science-based and include extensive field-referenced data. LANDFIRE data products are designed to facilitate national- and regional-level strategic planning and reporting of wildland fire management activities. Data products are created at a 30-meter grid spatial resolution raster data set.
LANDFIRE National data products are produced at scales that may be useful for prioritizing and planning hazardous fuel reduction and ecosystem restoration projects; however, the applicability of data products varies by location and specific use, and products may need to be adjusted by local users. LANDFIRE meets agency and partner needs for data to support large landscape fire management planning and prioritization.
National Forest System – A nationally significant system of Federally owned units of forest, range, and related land consisting of national forests, purchase units, national grasslands, land utilization project areas, experimental forest areas, experimental range areas, designated experimental areas, other land areas, water areas, and interests in lands that are administered by the U.S. Forest Service or designated for administration through the Forest Service. Also see Section 11 of Forest and Rangeland Renewable Resources Planning Act of 1974 (P.L. 93-378, 88 Stat. 476, 16 U.S.C. 1609).
Non-USFS – Non-USFS includes forest, range, and related lands not under the administration of the U.S. Forest Service. Included in this category are privately owned, other Federal, State, or County lands.
Rapid Assessment of Vegetation Condition after Wildfire (RAVG) - see What is RAVG?
Silvicultural Examination - Silvicultural examination is the process of gathering field data of a forest stand to determine its current condition. Silvicultural and other management decisions are based on the data collected from these examinations.
Silvicultural Prescription – A silvicultural prescription is a written document that describes management activities needed to implement treatments or treatment sequences. The prescription documents the results of an analysis of present and anticipated site conditions and management direction. It also describes the desired future vegetation conditions in measurable terms. The desired condition is a basis for treatment, monitoring, and evaluation.
Treatment – This term describes any of a set of management activities that can assist the prompt recovery of forestlands. Management actions include any combination of live, dead, and dying wood removal, or disposal (with or without commercial value) by any feasible method, including but not limited to logging, piling, masticating, and burning, for site preparation. In addition, planting, seeding, and monitoring for natural regeneration without site preparation are appropriate management activities designed to foster the prompt recovery following wildfire. 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.
Unmappable - As labeled on a RAVG table and map, "unmappable" refers to the areas depicted on the map and the acres listed in the table that cannot be mapped. This may be due to clouds that obscure portions of the fire in the pre- or post-fire imagery, or due to Landsat 7 data gaps that exist when an L7 post-fire image is used for a fire.
USFS - United States Forest Service lands, see National Forest System above.
Vegetation Group – The Vegetation groups are based on LANDFIRE Existing Vegetation Types (EVT) data. This provides a consistent national vegetation classification system to produce uniform statistics in vegetation resources from vegetation cover data at the national level. RAVG crosswalks were developed from LANDFIRE Existing Vegetation Type Descriptions, Society of American Foresters forest cover types, Society for Range Management rangeland cover types, and the National Vegetation Classification Standard (NVCS).
U.S. Forest Service
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Last modified: Monday, 28-Feb-2011 13:23:49 EST