Detrend multiple ring-width series simultaneously using a regional curve.
rcs(rwl, po, nyrs = NULL, f = 0.5, biweight = TRUE, ratios = TRUE,
rc.out = FALSE, make.plot = TRUE, ..., rc.in = NULL, check = TRUE)
A data.frame
containing the dimensionless and detrended
ring-width 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.
a data.frame
with series as columns and years as
rows such as that produced by read.rwl
a data.frame
containing two variables. Variable one
(series
in the example below) gives the series
ID as either character
s or factor
s. These
must exactly match colnames(rwl)
. Variable two
(pith.offset
in the example below) must be integral
values and give the years from the beginning of the core to the pith
(or center) of the tree. The minimum value is 1.
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 nyrs
is NULL
.
a number between 0 and 1 giving the frequency response or wavelength cutoff. Defaults to 0.5.
logical
flag. If TRUE
then a robust
mean is calculated using tbrm
.
logical
flag. If TRUE
(the default) then
indices are calculated by division, if FALSE
indices are
calculated by subtraction.
logical
flag. Returns the regional curve along
with the ring-width indices if TRUE
.
logical
flag. Makes plots of the raw data and
regional curve if TRUE
.
other arguments passed to
plot
.
for internal use.
a logical
flag. Bypass input checks by setting
this to FALSE
.
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.
This method detrends and standardizes tree-ring series by calculating
an age-related 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
ring-width 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 n-year 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.
Biondi, F. and Qeadan, F. (2008) A theory-driven approach to tree-ring standardization: Defining the biological trend from expected basal area increment. Tree-Ring Research, 64(2), 81–96.
Cook, E. R. and Kairiukstis, L. A., editors (1990) Methods of Dendrochronology: Applications in the Environmental Sciences. Springer. ISBN-13: 978-0-7923-0586-6.
Fritts, H. C. (2001) Tree Rings and Climate. Blackburn. ISBN-13: 978-1-930665-39-2.
detrend
, chron
, cms
,
caps
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")
Run the code above in your browser using DataLab