Mangal along a tropical bay characteristically shows zonation. On the outfacing edge, fully exposed to high tides twice each day, is the seaward zone, which is inhabited by a small subset of tree species, Sonneratia alba, Avicennia spp., and Rhizophora spp. In the middle zone typically occur members of the Rhizophoraceae (mangrove family), the so-called Rhizophora zone or mesozone. The back, inland portion of mangal, also called the landward zone, which less frequently is covered by sea water and can receive freshwater from ground water or land runoff, is where the mangal associates can survive. There may be a gradual transition from mangal to terrestrial forest, but, in general, it does not appear that back mangal is merely a sere (stage) in succession from mangrove plants to a terrestrial forest.
Species that colonize the outer edge of mangal, such as Sonneratia alba and Avicennia alba, are able to remain firmly rooted as seedlings when they are regularly inundated by high tides. The species that first establish mangal most often possess a major system of aerial roots. Such roots not only help to anchor the plant and keep it raised out of water, but also create a tangle of crossed and looping roots. Within that tangle of roots collect sediments, including organic matter from decaying plant organs.