Mangroves are woody plants that form the dominant vegetation of mangrove forests. Mangrove forests form along the banks of estuarine rivers. They form dense thickets of prop roots and aerial stems, which in turn trap sediments and move the shallow mud flats and delta areas seaward. The mud, stems, and roots make excursions into mangroves difficult, a real biological adventure.
Mangroves are highly productive areas contributing to the food chains of coastal oceanic areas.
The biomass and diversity of invertebrates per unit area of mangroves and adjacent mud flats is very high. Seabirds using mangroves as rookeries and by depositing their guano, they return valuable nitrogen from the oceans to the mangrove forest. Many oceanic organisms rely on mangroves for part of their life cycle, so mangroves are nurseries for ocean fisheries. The thick mangrove forests also protect low coastal areas in storms. However, humans have tended to look upon mangrove swamps as useless vegetation blocking their access to the coast, so mangroves have been destroyed in many areas by human development.