isarF: Individual Species Area Relationship

In antiphon/spatialsegregation: Segregation Measures for Multitype Spatial Point Patterns

Description

Compute the Individual Species Area Relationship ( ISAR ) or Local Species Richness, for a given multitype point pattern.

Usage

isarF(X, r = NULL, target = NULL, v2 = FALSE, v3 = FALSE, v4 = FALSE, ...)

isar.index(X, r = 4, ntype = "knn", ...)

Arguments

X	Multitype point pattern of class ppp (see package 'spatstat')
r	Vector of sizes for neighbourhoods, e.g. geometric graph with different ranges.
target	Default NULL. Calculate only for target type. If NULL computes for each type + mean over all types.
v2	Logical. Estimate species-to-neighbours-ratio instead of just total number of species.
v3	Logical. Instead of summing number 1 for each species present, sum the average X$mass of each species present.
v4	Logical. Estimate ISAR using empty space probabilities instead of direct counts (equals the normal version in all my tests)
...	Further parameters for the function segregationFun.
ntype	Sets the n'hood type to knn by default in isar.index.

Details

Extension of ISAR-function introduced in WGGH07. In effect calculates the expected amount of different types present in the neighbourhood of a point in the pattern.

The function isarF is the calculation function for different neighbourhoods. Uses function segregationFun.

The function isar.index is a shortcut to get a single value for the pattern. Uses 4-nn graph by default.

Functions

• isar.index: Shortcut for 4-nearest neighbour value.

References

Rajala, Illian: A family of spatial biodiversity measures based on graphs, Env. Ecol. Stat. 2012

Wiegand, Gunatilleke, Gunatilleke, Huth: How individual species structure diversity in tropical forests. PNAS, nov 16, 2007.

antiphon/spatialsegregation documentation built on Nov. 21, 2020, 10:39 p.m.