- Metric Name:  Density - Large Trees

- Data Vintage:  2022

- Unit Of Measure: Percent live trees per pixel

Large trees are important to forest managers as they have a greater likelihood of survival from fire, provide sources of seed stock, wildlife habitat, and contribute to other critical processes like carbon storage and nutrient cycling. Large trees are often the focus of management in order to protect existing ones and to foster future ones. In consultation with National Forests, “large trees” have been designated as greater than 30” dbh.

Creation Method: To determine the cutoff for the definition of large trees in the southern California area (> 30” dbh - need reference ), a statistical relationship between tree dbh and tree height was developed. We used Forest Inventory & Analysis (FIA) 2022 plot data from the region, testing three fits of DBH ~ HGT: Saturating (Michelis Menton), Power, or Linear. Saturating was the best according to Akaike information criterion (AIC). (need references for all this). We then extracted heights that predicted DBH cut-offs:

Predicted DBH (in) , Height (ft), RMSE (in)

1 2.5 1.5

6 14.5 2.4

11 27 5.3

24 64.5 6.8

30 83.5 7.3

Block statistics were run on California Forest Observatory (CFO) canopy height pixels greater than or equal to 83.5’ (25m) with 3x3 window to calculate the sum for input cells within a 30m rectangular neighborhood. This assigned number of pixels per 30m (900m2) cell. Resultant values of 1 through 9 were converted to percent. All background values were calculated to equal 0, meaning 0% large tree existence.

- Credits:  California Forest Observatory (Salo Sciences), 2020

California Forest Observatory - Salo Sciences: 
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