E_VOL_AB_HmDm_HT.f: Estimate volume for stem and sections

In TapeR: Flexible Tree Taper Curves Based on Semiparametric Mixed Models

Estimate volume for stem and sections

Description

Estimate volume for a complete stem from bottom to tip or for a section defined by lower and upper diameter or height. Variances for estimated volumes are calculated.

Usage

E_VOL_AB_HmDm_HT.f(
  Hm,
  Dm,
  mHt,
  sHt = 0,
  A = NULL,
  B = NULL,
  iDH = "D",
  par.lme,
  Rfn = list(fn = "sig2"),
  IA = F,
  nGL = 51,
  ...
)

Arguments

Hm	Numeric vector of stem heights (m) along which diameter measurements were taken for calibration. Can be of length 1. Must be of same length as Dm.
Dm	Numeric vector of diameter measurements (cm) taken for calibration. Can be of length 1. Must be of same length as Hm.
mHt	Scalar. Tree height (m).
sHt	Scalar. Standard deviation of stem height. Can be 0 if height was measured without error.
A	Numeric scalar defining the lower threshold of a stem section for volume estimation. Depends on iDH. If iDH = "D", a diameter (cm), if iDH = "H", a height (m). If NULL, section starts at lowest point.
B	Numeric scalar defining the upper threshold of a stem section for volume estimation. Depends on iDH. If iDH = "D", a diameter (cm), if iDH = "H", a height (m). If NULL, section ends at tip.
iDH	Character scalar. Either "D" or "H". Type of threshold for section volume estimation. See A or B.
par.lme	List of taper model parameters obtained by TapeR_FIT_LME.f.
Rfn	list with function name to provide estimated or assumed residual variances for the given measurements, optionally parameters for such functions
IA	Logic scalar. If TRUE, variance calculation of height estimate based on 2-point distribution. If FALSE, variance calculation of height estimate based on Normal approximation.
nGL	Numeric scalar. Number of support points for numerical integration.
...	not currently used

Details

calculates the volume for a complete stem or sections defined by A and B, which might be defined as diameter or height. The parameter Rfn can be used to force the taper curve through the measured points (e.g. by Rfn=list(fn="zero"), cf. resVar).

Value

a list holding nine elements:

• E_VOL: Estimated volume (m^3).

• VAR_VOL: Variance of the volume estimate.

• Hm: Height of diameter measurement (m).

• Dm: Diameter measurement (cm).

• Ht: Tree height (m).

• Da: Diameter at lower section threshold (cm).

• Db: Diameter at upper section threshold (cm).

• Ha: Height at lower section threshold (m).

• Hb: Height at upper section threshold (m).

• Rfn: Function applied for estimated or assumed residual variance.

Author(s)

Edgar Kublin

References

Kublin, E., Breidenbach, J., Kaendler, G. (2013) A flexible stem taper and volume prediction method based on mixed-effects B-spline regression, Eur J For Res, 132:983-997.

See Also

TapeR_FIT_LME.f

Examples

# example data
data(DxHx.df)
# taper curve parameters based on all measured trees
data(SK.par.lme)

#select data of first tree
Idi <- (DxHx.df[,"Id"] == unique(DxHx.df$Id)[1])
(tree1 <- DxHx.df[Idi,])

## Calculate the timber volume for the whole stem
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1],
                          sHt = 0, # no height variance assumed
                          par.lme = SK.par.lme)
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for the whole stem, using Rfn="zero"
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1],
                          sHt = 0, # no height variance assumed
                          par.lme = SK.par.lme,
                          Rfn = list(fn="zero"))
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for the whole stem
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1],
                          sHt = 1, # no height variance assumed
                          par.lme = SK.par.lme)
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for the whole stem, using Rfn="zero"
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1],
                          sHt = 1, #  height variance assumed
                          par.lme = SK.par.lme,
                          Rfn = list(fn="zero"))
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for a selected section given a height (0.3 - 5 m)
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1], 
                          sHt = 1, 
                          par.lme = SK.par.lme, 
                          A=0.3, 
                          B=5, 
                          iDH = "H")
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for a selected section given a height (0.3 - 5 m)
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], 
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1], 
                          sHt = 1, 
                          par.lme = SK.par.lme, 
                          A=0.3, 
                          B=5, 
                          iDH = "H", 
                          Rfn=list(fn="zero"))
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance
VOL$Rfn

## Calculate the timber volume for a selected section given a diameter
## threshold (30cm - 15cm) (negative value if A<B)
VOL <- E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3],
                          Dm=tree1$Dx[3], 
                          mHt = tree1$Ht[1], 
                          sHt = 1, 
                          par.lme = SK.par.lme, 
                          A=30, 
                          B=15, 
                          iDH = "D")
VOL$E_VOL #' expected value
VOL$VAR_VOL #' corresponding variance

## Not run: 

## The variance estimate resulting from the tree height uncertainty using
## a Normal approximation takes much longer...
ptm <- proc.time()
E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], Dm=tree1$Dx[3], mHt = tree1$Ht[1], 
                   sHt = 1, par.lme = SK.par.lme, IA=FALSE)
proc.time() - ptm


##... than the calculation using a 2-point distribution...
ptm <- proc.time()
E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], Dm=tree1$Dx[3], mHt = tree1$Ht[1],
                   sHt = 1, par.lme = SK.par.lme, IA=TRUE)
proc.time() - ptm

##...fastest if no height variance is assumed
ptm <- proc.time()
E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], Dm=tree1$Dx[3], mHt = tree1$Ht[1],
                   sHt = 0, par.lme = SK.par.lme, IA=FALSE)
proc.time() - ptm

## Also the number of supportive points for the numerical integration
## influences the calculation time
ptm <- proc.time()
E_VOL_AB_HmDm_HT.f(Hm=tree1$Hx[3], Dm=tree1$Dx[3], mHt = tree1$Ht[1],
                   sHt = 0, par.lme = SK.par.lme, IA=FALSE, nGL=10)
proc.time() - ptm
##' End(Not run)

TapeR documentation built on Aug. 16, 2023, 9:07 a.m.