Description Usage Arguments Details Functions References
Compute the Individual Species Area Relationship ( ISAR ) or Local Species Richness, for a given multitype point pattern.
1 2 3 4 |
X |
Multitype point pattern of class |
r |
Vector of sizes for neighbourhoods, e.g. |
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 |
ntype |
Sets the n'hood type to |
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.
isar.index
: Shortcut for 4-nearest neighbour value.
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.
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