Description Usage Arguments Details Value Note Author(s) References See Also Examples
View source: R/checkStemDimensions.R
Stem class constructors allow one to specify both taper and total stem attributes such as volume and biomass. This function checks to make sure that any inconsistencies between the taper version of these attributes and those specified in the constructor are not too large. See below for details.
1 | checkStemDimensions(stem, tolerancePercent = 1, ...)
|
stem |
An object that is a subclass of
|
tolerancePercent |
The tolerance limit in percent (the default is 1 percent). Differences larger than this will result in a warning. |
... |
Just gobbled for now. |
If one specifies a volume (optional) for a “Stem” object in the constructor in addition to the taper data (required), the two may not necessarily be in agreement. The same is true for other attibutes like surface area, etc. This is okay for the usual Horvitz-Thompson type estimators where the sampling surface is flat (constant) within a given inclusion zone. The routines use the entered volume for estimation and the taper data for graphical display. However, the Monte Carlo sampling methods (such as distance limited sampling for down logs, or critical height sampling for standing trees) use the taper data to determine heights or diameters along the bole as part of the estimate. Thus, if the two values for volume (that in the volume slot and that given by integration of the taper data) are not closely commensurate, it can result in an unintended apparent bias in the simulations. Note also that methods like perpendicular distance sampling rely on the taper data for the inclusion zone, so there could be a bias produced here as well.
This function can be used to check how closely the slot and taper values correspond for a given “Stem” subclass object, and will print a warning if the discrepancy is too large. One should not ignore this warning in the cases mentioned above. More information on this is given in the reference below.
A list
is returned invisibly with...
stemID |
The stem ID value. |
tolerancePercent |
The value of the above argument specified by the user. |
volume |
A vector with elements: 1. volume from the slot, 2. volume from either the taper function or Smalian's, depending on solidType, 3. splined volume from the taper data, 4. the percent difference. |
surfaceArea |
A vector with elements: 1. surface area slot, 2. splined or taper SA depending on solidType, 3. percent difference. |
coverageArea |
As above in |
biomass |
A vector with elements: 1. biomass slot value, 2. conversion
from |
carbon |
As above for |
Note that as of sampSurf version 0.7-2 this function is run
automatically within the constructors for down logs or standing
trees. However, one can run it at any time as a check on the object,
just like one can invoke validObject
at any time.
Jeffrey H. Gove
Gove, J. H. 2014. Apparent bias in sampSurf. R sampSurf package vignette series paper.
"Stem"
, "downLog"
, "standingTree"
1 2 3 4 5 6 7 | ## Not run:
st = standingTree(dbh=20, height=20, solidType=3)
checkStemDimensions(st)
st2 = standingTree(dbh=20, height=20, solidType=3, treeVol=1.1*st@treeVol)
checkStemDimensions(st2)
## End(Not run)
|
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