dmd.volume: Density Management Volume Estimation

In mwritchie/standview: R Package for Density Management Diagrams

Density Management Volume Estimation

Description

This function provides estimates for volume and dominant height for stand density management diagrams, where available.

Typically, in a DMD, the volume is roughly interpolated between plotted iso-volume lines. With dmd.volume, the user can specify qmd and tpa values as input to generate estimated volumes from published volume equations.

Usage

dmd.volume(ineq  = 2,
           max.sdi=NULL,
           tpa=NULL,
           qmd=NULL,
           ba=NULL,
           use.metric=FALSE)

Arguments

ineq	Selects supplimental equations. This must be an integer value 2, 3, 6, 7, or 9. Value is 2 for Long and Shaw (2005) Ponderosa pine equations, Value of 3 for Jang et al. (2021) Ponderosa pine equations. Value of 6 for Long and Shaw (2012) California mixed-conifer Value of 7 for Drew and Flewelling (1979); Long et al. (1988). Value of 9 for McCarter and Long (1986). Default=3.
max.sdi	Input of limiting stand density index (units are trees per acre for use.metric=FALSE or trees per hectare for use.metric=TRUE); default=NULL. This value must be supplied for ineq=7.
tpa	Input of stand trees per unit area as a vector of values. Function requires two of three stand descriptors (tpa, qmd, ba). Units are trees per acre for use.metric=FALSE and trees per hectare for use.metric=TRUE.
qmd	Input of stand average diameter (inches for use.metric=FALSE or cm for use.metric=TRUE). Function requires two of three stand descriptors (tpa, qmd, ba)
ba	Input of stand basal area (square feet per acre for use.metric=FALSE or square meters per hectare for use.metric=TRUE). Function requires two of three stand descriptors (tpa, qmd, ba).
use.metric	Use metric units (logical), default= FALSE.

Value

Returns a data frame with trees per unit area, quadratic mean diameter, basal area per unit area. Additionally the data may contain volume, volume standar error, height, height standar error, biomass, biomass standard error crown closure percent and crown closure percent standard error, if functions are available for these metrics. These supplimental metrics are not available for all values of ineq. If unavailable the output is NA (missing). Units are metric if use.metric=TRUE. The metric units are: stems per hectare, centimeters, square meters per hectare, cubic meters per hectare, and meters respectively). Units are English if use.metric=FALSE (stems per acre, inches, square feet per acre, cubic feet per acre, and feet respectively). Note that standard error estimates are only available for ineq=3; other published equation sets do not include sufficient information for this. The standard error of estimates from ineq=3 is calculated by means of the delta method (manuscript in preparation).

Note

This function returns a dataframe that represents multiple observations; these could be a single chronosequence. The observations could also be for sampled independent stands. The species for the observations should match the species identified by the value ineq. So if ineq=2 is chosen, then the volumes returned will be from Long and Shaw (2005) for ponderosa pine. Currently biomass and crown cover percent are produced only for ineq=3. Note that it is assumed that the units of tpa and qmd match the specification of use.metric. If use.metric=TRUE then it is assumed qmd is cm and tpa=trees per ha. If use.metric=FALSE, then qmd is inches and tpa=trees per acre. There is no provision for using English units to derive metric output or vice-versa. Vectors passed in must match in length. See Examples below.

Author(s)

Martin W. Ritchie, Research Forester, US Forest Service, Pacific Southwest Research Station. Email: [e-mail]

References

Drew, T.J. and J.W. Flewelling (1979). Stand density management: an alternative approach and its application to Douglas-fir plantations. For. Sci. 25(3):518-532

Jang, W.S., M.W. Ritchie and J. Zhang (2021) Improved equations for the density management diagram isolines of ponderosa pine stands. For. Sci. 67(1):93-102

Long, J.N., J.B. McCarter, and S.B. Jack. (1988) A modified density management diagram for coastal Douglas-fir. West. J. Appl. For. 3(3):88-89.

Long, J.N. and J.D. Shaw. (2005) A density management diagram for even-aged ponderosa pine stands. West. J. Appl. For. 20(4):205-215.

Long, J.N. and J.D. Shaw. (2012) A density management diagram for even-aged Sierra Nevada mixed-conifer Stands. West. J. Appl. For. 27(4):187-195.

McCarter, J.D. and J.N. Long (1986) A logdepole pine density management diagram. West. J. Appl. For 1(1):6-11.

Reineke, L.H. (1933) Perfecting a stand density index for even-aged forests. J. Ag. Res. 46:627-638.

Examples

# 1. This example generates a prescription and plots over Long and Shaw (2005)

library(standview)
DF<-dmd.volume(ineq=2,
               qmd=c(2, 2.5, 14, 15.5, 19),
               tpa=c(300, 150, 140, 80, 80),
               use.metric=FALSE)
DF
#pdf("myplotv1.pdf", width=6, height=8) # recommended to set a 6x8 canvas
opar <- par(mar = c(3.0,2.0,2.5,2.5))

dmd.view(ineq=2, use.metric=FALSE ) # call dmd.view.

points(x=DF$tpa.ac, y=DF$qmd.in, cex=0.75, pch=21, col="black")
segments(300, 1, DF[1,]$tpa.ac, DF[1,]$qmd.in, lwd=2)
for(i in 1:4){
  segments(DF$tpa.ac[i], DF$qmd.in[i], DF$tpa.ac[i+1], DF$qmd.in[i+1], lwd=2)
}
arrows(280, 19, 120, 14.8, length=0.10 )
text(300, 22, "Commercial thin")
text(300, 20, paste(round(DF$volume.ft3ac[3]-DF$volume.ft3ac[4]), "cu.ft./ac removed"))

par(opar)
#dev.off()


# 2. Obtaining volume estimates for a file using gama05 data example
mygama<-gama05  # make a copy of the data file provided with standview package
DF<-dmd.volume(ineq=3,
               qmd=mygama$qmd,
               tpa=mygama$tpa,
               use.metric=FALSE) # generate volume and dom. ht.
# add values to the dataframe.
mygama$volume <- DF$volume
mygama$height <- DF$height

mwritchie/standview documentation built on March 29, 2024, 2:32 a.m.