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Calculate stand height metrics from tree list data

Source: R/calc_ht_metrics.R
calc_ht_metrics.Rd

calc_ht_metrics() computes several stand height metrics for a given tree list.

Usage

calc_ht_metrics(tree_list, digits = 1)

Arguments

tree_list

A data frame with tree records for one FIA plot. Must have columns DIA (tree diameter), HT (tree height), ACTUALHT (tree actual height, ACTUALHT < HT indicating a broken top), CCLCD (FIA crown class code), TPA_UNADJ (trees per acre).

digits

Optional integer indicating the number of digits to keep in the return values (defaults to 1).

Value

A named list of computed height metrics for the input tree list, as described in Details.

Details

Stand height metrics are based on live trees (STATUSCD == 1), and are are assigned 0 by definition if no live trees are present. Height metrics are returned in a named list with the following elements:

  • $numTrees: number of live trees >= 5.0 in. (12.7 cm) diameter

  • $meanTreeHt: mean height of trees >= 5.0 in. (12.7 cm) diameter

  • $meanTreeHtBAW: basal-area weighted mean height of trees >= 5.0 in. (12.7 cm) diameter

  • $meanTreeHtDom: mean height of canopy dominant/co-dominant trees >= 5.0 in. (12.7 cm) diameter

  • $meanTreeHtDomBAW: basal-area weighted mean height of canopy dominant/co-dominant trees >= 5.0 in. (12.7 cm) diameter

  • $maxTreeHt: height of the tallest tree >= 5.0 in. (12.7 cm) diameter

  • $predomTreeHt: predominant tree height, as the mean height of the tallest trees >= 5.0 in. (12.7 cm) diameter comprising up to 16 trees per acre (39.5 trees per hectare)

  • $numSaplings: number of live saplings (trees >= 1.0 in. but < 5.0 in. diameter, i.e., >= 2.54 cm but < 12.7 cm)

  • $meanSapHt: mean height of saplings

  • $maxSapHt: height of the tallest sapling

For the purpose of height calculations, metrics based on "canopy dominant/co-dominant" include open grown trees, i.e., include trees with FIA crown class codes CCLCD of 1 (open grown), 2 (dominant) or 3 (co-dominant), but exclude trees with CCLCD of 4 (intermediate) or 5 (over-topped).

Examples

calc_ht_metrics(plantation)
#> $numTrees
#> [1] 89
#> 
#> $meanTreeHt
#> [1] 44.8
#> 
#> $meanTreeHtBAW
#> [1] 45.3
#> 
#> $meanTreeHtDom
#> [1] 44.8
#> 
#> $meanTreeHtDomBAW
#> [1] 45.3
#> 
#> $maxTreeHt
#> [1] 51
#> 
#> $predomTreeHt
#> [1] 50.7
#> 
#> $numSaplings
#> [1] 2
#> 
#> $meanSapHt
#> [1] 34.5
#> 
#> $maxSapHt
#> [1] 43
#>