Look for complete geospatial metadata in this layer's associated xml document available from the download link

* Metric Name: Seral Stage  

* Tier: 2  

* Data Vintage: 04/2023  

* Unit Of Measure: Categorical 1 - 3 (seral stage), continuous variable 0-1 representing percentage of a HUC (early and late seral stage)  

* Metric Definition and Relevance: The seral stages are categories that represent the developmental progression of forest ecosystems from initial establishment or following a stand replacing event (e.g., high severity fire) to a forest dominated by trees in the upper age classes for a given forest type. Late seral forests are also often characterized by multiple ages of forest trees and dead and dying trees in some form of equilibrium. Seral conditions across landscapes were highly variable prior to major European settlement in the western US. These patterns were highly attuned to dominant disturbance regimes and the multi-scaled variability in environmental conditions across topographic and climatic gradients. These patterns helped to reinforce fire regimes dominated by low- to moderate-severity fire across much of the region and provided for multiple habitat requirements for a wide variety of species.

This metric contains three related data layers. The first is an assignment to
each 30 meter pixel of the seral stage it is currently in, either early, mid,
or late seral stage. The other two layers represent the proportion of a HUC 12
watershed that is in 1) early seral stage or 2) late seral stage.

  

* Creation Method: The FVEG data, used in characterizing vegetation and habitat conditions for a number of metrics in this kit, contain data on tree size (see FVEG discussion below). Seral stages for forested lands are binned into one of three categories of tree size (Early, Mid, Late) and those are defined by tree diameter, per the CWHR system. 

Late Seral conditions have been lumped into a single classification (24” and
up).

The first layer provided here assigns a early, mid, or late seral value to
each cell based on dominant tree size in the canopy. Null or NoData values in
this raster represent areas of non-forest. The second and third data layer
provided identify the proportion of the HUC12-scale (typically 10,000-30,000
acres in size) that is either early seral forest or late seral forest,
respectively. These patterns can be highly variable at finer-scales so we used
a HUC 12 watershed as the unit for expressing relative abundance. For each
HUC12, the proportion of the watershed covered by the evaluated seral stage
has been calculated.

  

* Credits: FVEG 2023 \--CALFIRE, CDFW, LANDFIRE, California Forest Observatory (SALO), USDA Forest Service