Table 3 Candidate ALS metrics used in the models. The predefined metrics for Lorey’s height are marked with †, and for the other attributes with *

H_mean

*

Mean echo height

H_mean²

*

Square of the mean echo height

H_var

Variance of the echo heights

H_{Prop_above_mean}

Proportion of echoes above H_mean

H_{Prop_above_2m}

*

†

Proportion of echoes above 2 m

H₂₅

25th percentile of the echo height distribution

H₅₀

50th percentile of the echo height distribution

H₇₅

75th percentile of the echo height distribution

H₉₀

90th percentile of the echo height distribution

H₉₅

†

95th percentile of the echo height distribution

Terrain_Slope

*

†

Slope, calculated from the digital terrain model.

Time_diff

*

†

Time between the ALS acquisition date and the field reference date, expressed as a decimal number of growth seasons.