tmpar <- par( mar = c(0,0,0,0), pty = "s" )
on.exit( {par( tmpar ); rm( tmp, tmpd, tmpr, tmpc, tmpar )} )

tmpd <- unique( trees.sp$date )
tmpc <- length( tmpd )
tmpr <- nrow( trees.sp ) / tmpc
tmp <- matrix( resid( trees.spaov ), tmpr, tmpc )
tmpid <- c("C","T")[ codes( trees.sp$type[1:tmpr] ) ]

pairs( tmp, as.character( tmpd ), panel = function( x, y )
   mpoints( x, y, tmpid ) )