Landfire Sucession Classes, DRECP

The Succession Classes (SCLASS) layer characterizes current vegetation conditions with respect to the vegetation species composition, cover, and height ranges of successional states that occur within each biophysical setting. SCLASS can also represent uncharacteristic vegetation components, such as exotic species, that are not found within the compositional or structural variability of successional states defined for a biophysical setting. Succession classes do not directly quantify fuel characteristics of the current vegetation, but rather represent vegetative states with unique succession or disturbance-related dynamics, such as structural development or fire frequency.


To produce SCLASS, the historical reference conditions of these successional states were derived from the vegetation and disturbance dynamics model VDDT (Vegetation Dynamics Development Tool) (LF_1.0.0 CONUS only used the vegetation and disturbance dynamics model LANDSUM). The area contained in succession classes is compared to the simulated historical reference conditions to calculate measurements of vegetation departure, such as fire regime condition class.
SCLASS is used in landscape assessments.


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 historical fire regimes and vegetation conditions using the disturbance dynamics model VDDT. 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Project also produces maps of current vegetation and measurements of current vegetation departure from simulated historical reference conditions.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:Succession Classes categorize current vegetation composition and structure into up to five successional states defined for each LANDFIRE Biophysical Settings (BpS) Model. An additional category defines uncharacteristic vegetation components that are not found within the compositional or structural variability of successional states defined for each BpS model, such as exotic species. These succession classes are similar in concept to those defined in the Interagency Fire Regime Condition Class Guidebook (www.frcc.gov). This layer is created by linking the BpS Group attribute in the BpS layer with the Refresh Model Tracker (RMT) data and assigning the Succession Classes attribute. This geospatial product should display a reasonable approximation of Succession Classes, documented in the Refresh Model Tracker. The current successional classes and their historical reference conditions are compared to assess departure of vegetation characteristics; this departure can be quantified using methods such as Fire Regime Condition Class (FRCC).Five successional classes, "A" (1) - "E" (5) define successional states represented within a given BpS model. 'UN' (6) represents uncharacteristic native vegetation for the BpS model on which these vegetation conditions are found. These are taken to represent vegetation cover, height, or composition that would not have been expected to occur on the BpS during the reference condition period. 'UE' (7) represents uncharacteristic exotic vegetation for the BpS model on which these vegetation conditions are found. Additional data layer values were included to represent Water (111), Snow / Ice (112), Barren (131), and Sparsely Vegetated (132). Urban (120) and Agriculture (180) are provided to mask out such areas from analysis of vegetation departure.To use this layer for assessing vegetation departure from historical reference conditions, it is necessary to combine this layer with LANDFIRE BpS and LANDFIRE map zone data layers. The subsequent combination of map zone, Bps, and Succession Class can then be found within LANDFIRE Historical Reference Condition tables. Caution is warranted in assessing vegetation departure across map zone boundaries, as the classification schemes used to produce BpS and Succession Classes may vary slightly between adjacent map zones. Furthermore, reference conditions are simulated independently for each map zone, resulting in potentially unique measurements of reference conditions for a given BpS between adjacent map zones.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.