Marshes and swamps occupy mid to low elevations while fens, aquatic plant communities and willow swamps occur on mid to upper slopes.
(Marshes and swamps; occupy; mid; to low elevations; T:while fens, aquatic plant communities and willow swamps occur on mid to upper slopes) (fens, aquatic plant communities and willow swamps; occur; L:on mid to upper slopes)
Marshes and swamps fens, aquatic plant communities and willow swamps
occupy occur
mid to low elevations T:while fens, aquatic plant communities and willow swamps occur on mid to upper slopes
L:on mid to upper slopes