sp.assoc: Total species association

Description

Calculate species association as a whole

Usage

sp.assoc(matr)

Arguments

matr

standard species matrix , with rows for plots and columns for species.

Value

Return Variance ratio, W, Chisq, etc, see details
piSpecies frequency
NNumber of plots
SNumber of species
TjTotal number of species for each plot
NumspmeanMean number of species
sigmaTsqVariance of species relative frequency
STsqVariance of species number
var.ratioVariance ratio
WW statiscit value: used in comparison with chi square.(n)

Details

Calculate species association using the following formula. Number of plots. N Number of species. S Number of plots occupied by certain species. n total number of species for each plot. Tj mean species number for all the plots. t Variance of species relative frequency: sigma^{2}{T}= sum{i}=1^{s}P{i}(1-P{i}). Variance of species number: S^{2}{T}=({1}{N})sum{j=1}^{N}(T{j}-t)^{2}. Species reative frequency P{i}={n{i}}{N}. Variance ratio: If VR > 1 Positively associated, If VR < 1 Negative associated VR = {S{T}^{2}}/{sigma{T}^{2}} W: used in comparison with chi square with n degrees of freedom. W = VR * N

References

Zhang Qiaoying, Peng Shaolin, Zhang Sumei, Zhang Yunchun, Hou Yuping. (2008) Association of dormintant species in Guia hill Municipal Park of Macao. Ecology and Environment. 17:1541-1547 GUO zhongling, MA yuandan, ZHENG Jiping, LIU Wande , JIN Zefeng.(2004) Biodiversity of tree species,their populations'spatial distribution pattern and interspecific association in mixed deciduous broadleaved forest in Changbai Mountains. Chinese Journal of Applied Ecology. 15:2013-2018 Shi Zuomin, Liu Shirong, Cheng Ruimei, Jiang Youxu.(2001) Interspecific association of plant populations in deciduous broad leaved forest in Baotianman. Scientia Silvae Sinicae. 37:30-35

Examples

Run this code

data(testdata)
spmatrix <- data2mat(testdata)
sp.assoc(spmatrix)

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