drawTreePop {ssExtra}R Documentation

Generate a Synthetic Northern Hardoods Population

Description

This routine will generate a simulated northern hardwoods population to the user's specifications where diameters are drawn from a three-parameter Weibull distribution. The heights and spatial process are as described below.

Usage

drawTreePop(tract,
            solidTypes = c(1.5, 3),
            topDiams = c(0, 0),
            B = 80,
            hgt.sd = 6,
            a = 4,
            b = 8,
            c = 2,
            inhibitDist = 3,
            showPlot = TRUE,
            startSeed = 144,
            runQuiet = FALSE,
            ...)

Arguments

tract

A "Tract" or "bufferedTract" object in either ‘English’ or ‘metric’. The units for this object specify the units for all other arguments, so be careful.

solidTypes

See the argument of the same name in standingTree.

topDiams

See the argument of the same name in standingTree.

B

The basal area per acre, always in ‘English’.

hgt.sd

Standard deviation for height for rnorm(0, hgt.sd) perturbations always in ‘English’.

a

Weibull location parameter always in ‘English’.

b

Weibull scale parameter always in ‘English’.

c

Weibull shape parameter always in ‘English’.

inhibitDist

This is the inhibition distance and it is in the same units as tract. Please see SSI for more details.

showPlot

TRUE: plot the sampled dbh distribution against the Weibull; FALSE: no plot.

startSeed

A scalar specifying a random number seed for the Weibull draws, spatial locations, &c. See initRandomSeed for details.

runQuiet

TRUE: no feedback; FALSE: feedback if available.

...

Further arguments passed on to sampleTrees.

Details

This routine will set up a reasonable simulated population of trees for northern hardwoods based on the Weibull diameter distribution parameters and height equation from Fast and Ducey (2011).

The spatial coordinates are drawn within the tract using an inhibition process; the spatial package code is used here because it is faster than the corresponding routine in the spatstats package.

The input units are always ‘English’ for everything but the tract, which can be either; the output units are the same as that of the tract. Therefore, if the tract is metric, then the returned tree list is also.

Value

A data frame with the synthetic trees that can be cast to standingTrees.

Note

Note especially the the basal area, height perturbations, and Weibull parameters are always entered in ‘English’ units, regardless of whether the “Tract” object (and thus, the output tree data frame) is in metric. This is for people (like the author) that still have English as their primary units-of-measure.

Author(s)

Jeffrey H. Gove

References

Fast, A. J. and M. J. Ducey. 2011. Height-diameter equations for select New Hampshire tree species. Northern Journal of Applied Forestry, 28(3):157–160.

See Also

sampleTrees

Examples

#
# a simple example...
#
## Not run: 
tr = Tract(c(x=100, y=100), cellSize=1)
btr = bufferedTract(10, tr)
s.trees = drawTreePop(btr, B=120) #BA = 27.5/ha
head(s.trees)

## End(Not run) 

[Package ssExtra version 0.1-2 Index]