winkelmass: Calculate the Winkelmass (spatial regularity of individuals)

In johngodlee/compInd: Forest tree-tree competition indices

Calculate the Winkelmass (spatial regularity of individuals)

Description

Calculate the Winkelmass (spatial regularity of individuals)

Usage

winkelmass(x, k = 4)

Arguments

x	two column matrix of individual x and y coordinates
k	number of neighbours to consider

Details

literally in German, the 'angle measure', describes the degree of spatial regularity of individuals surrounding a given focal individual. The angle between each sequential neighbour with reference to the focal tree is calculated. As per the equation:

\frac{1}{k} \sum_{j=1}^{k} v_{j}

where v_{j} is 1 if the angle (\alpha) between neighbours is less than the critical angle, i.e. \alpha \le \frac{360}{k}, or 0 otherwise. As per von Gadow and Hui (2001) this function could be adapted to calculate regularity as a point attribute rather than an individual attribute.

As per von Gadow and Hui (2001) this function could be adapted to calculate spatial mingling as a point attribute rather than an individual attribute.

Normally expressed as the mean of values per structural unit to scale up.

Value

value of the competition index for each individual in the structural unit, i.e. plot.

References

von Gadow, K., Hui, G. Y. (2001). Characterising forest spatial structure and diversity. Sustainable Forestry in Temperate Regions. Proc. of an international workshop organized at the University of Lund, Sweden. Pages 20-30.

Examples

data(bicuar)
winkelmass(bicuar[,c("x", "y")], 4)

johngodlee/compInd documentation built on Aug. 5, 2024, 8:44 a.m.