ht.fvs.ni.m {FAwR}

Predicts height (m) from diameter (cm) by species, using functions from Wykoff et al. (1982).

Description

This vectorized function uses models and parameter estimates from Wykoff et al. (1982) to predict tree heights given over-bark diameter measurements (cm) taken at 1.37 m (4'6”). The function ht.fvs.ni.ft performs the computation in imperial units, and ht.fvs.ni.m is a wrapper for convenience.

Usage

ht.fvs.ni.ft(spp, dbh.in)
ht.fvs.ni.m(spp, dbh.cm)

Arguments

spp

Tree species. Must be one of: WP, WL, DF, GF, WH, WC, LP, ES, SF, PP, MH

dbh.cm

Tree diameter, cm, measured at 1.37 m. from the ground.

dbh.in

Tree diameter, in., measured at 1.37 m. from the ground.

Details

The species are: WP = white pine, WL = western larch, DF = Douglas-fir, GF = grand fir, WH = western hemlock, WC = western red cedar, LP = lodgepole pine, ES = Engelmann spruce, SF = subalpine fir, PP = ponderosa pine, and MH = mountain hemlock.

The function was fitted using least squares regression; the resposne variable was log of height and the predictor variable 1 / (DBH + 1).

Value

The function returns a vector of tree heights, in metres.

Note

The function doesn't perform any input checks. Caveat computator.

Author(s)

Andrew Robinson <[e-mail]>

References

Robinson, A.P., and J.D. Hamann. 2010. Forest Analytics with R: an Introduction. Springer.

Wykoff, W. R., Crookston, N. L., Stage, A. R., 1982. User's Guide to the Stand Prognosis Model. GTR-INT 133, USDA Forest Service, Ogden, UT.

Examples

ht.fvs.ni.m(c("DF, WH"), c(25, 27))