rcs {dplR}  R Documentation 
Regional Curve Standardization
Description
Detrend multiple ringwidth series simultaneously using a regional curve.
Usage
rcs(rwl, po, nyrs = NULL, f = 0.5, biweight = TRUE, ratios = TRUE,
rc.out = FALSE, make.plot = TRUE, ..., rc.in = NULL, check = TRUE)
Arguments
rwl 
a 
po 
a 
nyrs 
a number giving the rigidity of the smoothing spline,
defaults to 0.1 of length of the maximum cambial age (i.e., the
length of the regional curve) if 
f 
a number between 0 and 1 giving the frequency response or wavelength cutoff. Defaults to 0.5. 
biweight 

ratios 

rc.out 

make.plot 

... 
other arguments passed to

rc.in 
for internal use. 
check 
a 
Details
This method detrends and standardizes treering series by calculating
an agerelated growth curve specific to the rwl
. The
detrending is the estimation and removal of the tree’s natural
biological growth trend. The standardization is done by either
dividing each series by the growth trend or subtracting the growth
trend from each series to produce units in the dimensionless
ringwidth index (RWI). The option to produce indices by
subtraction is intended to be used on series that have been subject to
variance stabilization (e.g., using powt
).
The spline approach uses an nyear spline where the frequency response
is 0.50 at a wavelength of 10 percent of the maximum cambial age
unless specified differently using nyrs
and
f
in the function caps
.
This attempts to remove the low frequency variability that is due to biological or stand effects. See the references below for further details on detrending in general, and Biondi and Qeadan (2008) for an explanation of RCS.
Value
A data.frame
containing the dimensionless and detrended
ringwidth indices with column names, row names and dimensions of
rwl
. If rc.out
is TRUE
then a
list
will be returned with a data.frame
containing the
detrended ring widths as above and a vector
containing the
regional curve.
Note
DendroLab website: https://dendrolaborg.wordpress.com/
Author(s)
Code provided by DendroLab based on programming by F. Qeadan and F. Biondi, University of Nevada Reno, USA and adapted for dplR by Andy Bunn. Patched and improved by Mikko Korpela.
References
Biondi, F. and Qeadan, F. (2008) A theorydriven approach to treering standardization: Defining the biological trend from expected basal area increment. TreeRing Research, 64(2), 81–96.
Cook, E. R. and Kairiukstis, L. A., editors (1990) Methods of Dendrochronology: Applications in the Environmental Sciences. Springer. ISBN13: 9780792305866.
Fritts, H. C. (2001) Tree Rings and Climate. Blackburn. ISBN13: 9781930665392.
See Also
Examples
library(utils)
data(gp.rwl)
data(gp.po)
gp.rwi < rcs(rwl = gp.rwl, po = gp.po, biweight = TRUE,
rc.out = TRUE, make.plot = FALSE)
str(gp.rwi)
gp.rwi < rcs(rwl = gp.rwl, po = gp.po, biweight = TRUE,
make.plot = TRUE, main = "Regional Curve")