spaa (version 0.2.2)

sp.assoc: Total species association

Description

Calculate species association

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

pi

Species frequency

N

Number of plots

S

Number of species

Tj

Total number of species for each plot

Numspmean

Mean number of species

sigmaTsq

Variance of species relative frequency

STsq

Variance of species number

var.ratio

Variance ratio

W

W 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 relative 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

See Also

See also sp.pair for association between each pair of species.

Examples

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