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


* Metric Name: SNV - Sawtimber  

* Tier: 2  

* Data Vintage: 2021  

* Unit Of Measure: Dry weight tons/acre  

* Metric Definition and Relevance: This metric expresses the amount of total existing, aboveground, live tree stem biomass measured in dry weight tons per acre for the Sierra Nevada region. This metric can be used to assess the sawtimber volume present at the 30m cell level.  

* Creation Method: The F3 model generated raster surfaces to provide an estimate of the total aboveground live tree stem biomass (ABGDLVSM).

2019 to 2021 Update: Values for 2021 were adjusted using the Ecosystem
Disturbance and Recovery Tracker (eDaRT), described in the Introduction. All
eDaRT events beginning August 1, 2019 through November 30, 2021 were
identified, and the corresponding Mortality Magnitude Index (MMI) values for
these events was summed, giving the estimated fractional canopy cover loss per
30m pixel over that time period. The MMI value for canopy cover loss was used
as a direct proxy to estimate biomass loss, using the formula:

 _2021 ABGDLVSM = 2019 ABGDLVSM – (2019 ABGDLVSM * MMI/100)_

Although the assumption of direct correlation between canopy cover and biomass
should be viewed with caution, it serves as a reasonable approximation for
representative mixed conifer forests in the Sierra Nevada affected by the
recent drought (Slaton et al. 2022).

  

* Credits: USDA Forest Service, Region 5, MARS Team