Analysis by Fraver & White 2005 called "absolute increase"

Description

Absolute-increase method is the alternative to percent-increase method.

Usage

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absoluteIncrease(data, abs = NULL, abs.threshold = NULL, 
  m1 = 10, m2 = 10, buffer = 2, gfun = mean, length = 2)

Arguments

data

A data.frame with series as columns and years as rows such as that produced by read.* function of dplR .

abs

Optional parameter usable for precomputed absolute increases (data frame).

abs.threshold

Threshold of absolute-increase, see destription.

m1

Determines the number of years to be averaged (including target year) for period prior the potential releas.

m2

Determines the number of years to be averaged (excluding target year) for period subsequent the potential release.

buffer

Number of years determining how close to one another two releases can be.

gfun

Determines if M1 and M2 values are mean or median for selected period.

length

Determines how many years have to be given critera exceeded to be considered as release.

Details

In cases where species autecology (mean growth rate, species sensitivity, and range of growth responses) is well known, it is possible to determine the absolute threshold for release detection, instead of thresholds based on relative growth. Empirically determined absolute-increase threshold for each species roughly corresponded to 1.25 times the standard deviation (Fraver & White 2005). The absolute-increase method has only one threshold, and no distinction is made between moderate and major releases.

Value

Return list object with

releases

By length and buffer filtred absolute increases.

years

Release years per tree.

years_list_total

Number of releases per year.

pgc

Reduced absolute increase values.

all_releases

All absolute increases above threshold.

Note

Check reference.

Author(s)

Pavel Fibich <pavel.fibich@prf.jcu.cz>, Jan Altman <altman.jan@gmail.com>, Tuomas Aakala <tuomas.aakala@helsinki.fi>, Jiri Dolezal <jiriddolezal@gmail.com>

References

Fraver, S. & White, A.S. 2005. Identifying growth releases in dendrochronological studies of forest disturbance. Canadian Journal of Forest Research-Revue Canadienne De Recherche Forestiere, 35, 1648-1656.

See Also

absoluteIncreaseALL, plotRelease, reduceByLB

Examples

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data(relData)

abs<-absIncrease(relData1)
mabs.threshold<- absTreshold(abs)
fw <- absoluteIncrease(relData1,abs,mabs.threshold)
plotRelease(relData1,abs,fw, 1, method="FraverWhite")