Marsh edge for species B represents its:
A realized niche is the portion of environmental and resource space a species actually occupies under natural biotic interactions. If species B could persist throughout a marsh when alone but is confined to the marsh edge when a competitor is present, the edge represents its realized niche. The larger potentially occupiable area is its fundamental niche. “Preferred habitat” suggests active selection and does not establish whether exclusion or physiological tolerance determines distribution, while “optimal niche” is not the standard term for the observed restricted range. This interpretation re
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 13
