| niche.test {adehabitatHS} | R Documentation |
Monte-Carlo Test on Parameters of the Ecological Niche
Description
niche.test tests for the significance of two parameters of the
ecological niche of a species (marginality and tolerance), using
Monte-Carlo methods. This is a bivariate test.
Usage
niche.test(x, pts, nrep = 999, o.include = TRUE, ...)
Arguments
x |
a raster map of class |
pts |
an object inheriting the class |
nrep |
the number of permutations |
o.include |
logical, passed to |
... |
further arguments passed to |
Details
niche.test tests the significance of two parameters describing
the ecological niche: the marginality
(squared length of the vector linking the average available habitat
conditions to the average used habitat conditions in the ecological
space defined by the habitat variables), and the tolerance (inertia of
the niche in the ecological space, i.e. the sum over all variables of
the variance of used pixels).
At each step of the randomisation procedure, the test randomly allocates the n points in the pixels of the map. The marginality and the tolerance are then recomputed on this randomised data set.
Actual values are compared to random values with the help of the
function biv.test.
Value
Returns a list containing the following components:
dfxy |
a data frame with the randomized values of marginality (first column) and tolerance (second column). |
obs |
the actual value of marginality and tolerance. |
Warning
biv.test uses the function kde2d of the package MASS.
Author(s)
Mathieu Basille basille@ase-research.org
Clement Calenge clement.calenge@ofb.gouv.fr
See Also
biv.test for more details on bivariate tests.
histniche for the histograms of the variables of the niche.
Examples
## Not run:
data(chamois)
niche <- niche.test(chamois$map,
chamois$locs,
side = "bottom")
names(niche)
## End(Not run)