Associate editor Chris Johns has been appointed editor in chief of National Geographic magazine, succeeding William L. Allen, who retired at the end of the year. Johns, whose photographs began appearing in the magazine in 1985, is the ninth full-time editor in the society's 116-year history.

Johns began making changes almost immediately, combining the photography and illustration departments. Dennis Dimick, illustration editor, will head the new department and has been named associate editor for illustrations. The director of photography position was eliminated; Kent Kobersteen, who had held that title since 1998, left the magazine...