Vegetation Departure (Landfire VDEP), Oregon

Fire Regime Data products formerly referred to as FRCC and FRCC Departure Index are now called Vegetation Condition Class (VCC) and Vegetation Departure (VDEP)

Vegetation Departure (VDEP) data product ranges from 0 - 100 to depict the amount current vegetation has departed from simulated historical vegetation reference conditions. This departure results from changes to species composition, structural stage, and canopy closure.

Abstract

Broad-scale alterations of historical fire regimes and vegetation dynamics have occurred in many landscapes in the U.S. through the combined influence of land management practices, fire exclusion, ungulate herbivory, insect and disease outbreaks, climate change, and invasion of non-native plant species. The LANDFIRE Project produces maps of simulated historical fire regimes and vegetation conditions using the LANDSUM landscape succession and disturbance dynamics model. The LANDFIRE Project also produces maps of current vegetation and measurements of current vegetation departure from simulated historical reference conditions. These maps support fire and landscape management planning outlined in the goals of the National Fire Plan, Federal Wildland Fire Management Policy, and the Healthy Forests Restoration Act. Data Summary: The Vegetation Departure (VDEP) data layer categorizes departure between current vegetation conditions and reference vegetation conditions according to the methods outlined in the Interagency Fire Regime Condition Class Guidebook (Hann and others 2004). For the full product description, please refer to Rollins and others 2007, "Developing the LANDFIRE Fire Regime Data Products" available at www.landfire.gov, however, LANDSUM was not incorporated into the LF_1.1.0 methods. Technical Methods: Hydrologic unit codes (HUCs) were used within LANDFIRE mapping zones to stratify the calculation of vegetation departure. Within each biophysical setting (BpS) in each subsection, we compare the reference percentage of each succession class (SClass) to the current percentage, and the smaller of the two is summed to determine the similarity index for the BpS. This value is then subtracted from 100 to determine the departure index. This departure index is represented using a 0 to 100 percent scale, with 100 representing maximum departure. It is important to note that the LANDFIRE VCC approach differs from that outlined in the Interagency Fire Regime Condition Class Guidebook (Hann and others 2004) as follows: LANDFIRE VCC is based on departure of current vegetation conditions from reference vegetation conditions only, whereas the Guidebook approach also includes departure of current fire regimes from those of the reference period. The reference conditions are derived from vegetation and disturbance dynamics model VDDT. The current conditions are derived from the corresponding version of the LANDFIRE Succession Class data layer; please refer to the product description page at www.landfire.gov for more information. The proportion of the landscape occupied by each SClass in each BpS unit in each subsection is used to represent the current condition of that SClass in the VCC calculation. The areas currently mapped to agriculture, urban, water, barren, or sparsely vegetated BpS units are not included in the VCC calculation; thus, VCC is based entirely on the remaining area of each BpS unit that is occupied by valid SClasses. Additional data layer values were included to represent Water (111), Snow / Ice (112), Urban (120), Barren (131), Sparsely Vegetated BpS (132), and Agriculture (180). Summarization at the national and state levels does not change the relevance of LANDFIRE data that are available to support management decisions at the unit level. The advantages of a nationally consistent data set and repeatable methodology preclude any short comings of the LANDFIRE data products when used at the local level. Field plot data contributed either directly or indirectly to this LANDFIRE National data product. Go to for more information regarding contributors of field plot data. REFRESH 2008 (lf_1.1.0): Refresh 2008 (lf_1.1.0) used 2001 data as a launching point to incorporate disturbance and its severity, both managed and natural, which occurred on the landscape after 2001. Specific examples of disturbance are: fire, vegetation management, weather, and insect and disease. The final disturbance data used in Refresh 2008 (lf_1.1.0) is the result of several efforts that include data derived in part from remotely sensed land change methods, Monitoring Trends in Burn Severity (MTBS), and the LANDFIRE Refresh events data call. Vegetation growth was modeled where both disturbance and non-disturbance occurs. References: Hann, W.; Shlisky, A.; Havlina, D.; Schon, K.; Barrett, S.; DeMeo, T.; Pohl, K.; Menakis, J.; Hamilton, D.; Jones, J.; Levesque, M. 2004. Interagency Fire Regime Condition Class Guidebook. Interagency and The Nature Conservancy Fire Regime Condition Class website. USDA Forest Service, U.S. Department of the Interior, The Nature Conservancy, and Systems for Environmental Management. Available online: www.frcc.gov.