SSDM: Stacked Species Distribution Modelling

#' A stack of three environmental variables
#'
#' A stack of three 30 arcsec-resolution rasters covering the north part of the
#' main island of New Caledonia 'Grande Terre'. CRAINFALL and
#' TEMPERATURE rasters are climatic variables from the WorldClim database, and SUBSTRATE raster is from
#' the IRD Atlas of New Caledonia (2012) (see reference below).
#'
#' @format A stack of three rasters: \describe{ \item{RAINFALL}{Annual mean
#'   rainfall (mm)} \item{TEMPERATURE}{Annual mean temperature (x10 degree
#'   Celsius)} \item{SUBSTRATE}{Substrate type (categorical variable)} }
#'
#' @references R.J. Hijmans, C.H. &  Graham (2006) "The  ability  of climate
#'   envelope  models  to  predict  the  effect  of  climate  change  on species
#'   distributions." \emph{Global Change Biology} 12:2272-2281
#'   \url{http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2006.01256.x/full}
#'
#'   E. Fritsch (2012) "Les sols. Atlas de la Nouvelle-Caledonie (ed. by J.
#'   Bonvallot, J.-C. Gay and E. Habert)" \emph{IRD-Congres de la
#'   Nouvelle-Caledonie, Marseille.} 73-76
#'
"Env"