A quick workaround to have a filled.contour plot with natural log10-log10 scale (instead of the default natural log scale) plotmat <- function(mat,main='',factor='M',MeasuredResponse='Coexistence') { X <- as.numeric(rownames(mat)) Y <- as.numeric(colnames(mat)) if(factor=='C') { Y <- Y/0.16 } rownames(mat) <- as.numeric(X) colnames(mat) <- as.numeric(Y) colorFun <- colorRampPalette(c("black","darkblue","blue","green", "orange",'yellow',"red","darkred",'white')) lX <- log(X, 10) lY <- log(Y, 10) pretty.X.at <-