Succession is the process of change from one plant community into another as a result of environmental circumstances. For example, a pineland in southern Florida changes into a tropical hardwood hammock without fire, a normal successional sequence. However, with regular fire, the process is set back—succession is stopped—and pineland is maintained.

Successional relationships exist in all South Florida plan communities. At the bottom are permanently flooded communities. Freshwater areas will lead to sawgrass and related shallow wetlands, and marine or estuarine areas will lead to mangrove swamps. At the top are hypothetical uplands without vegetation. Both examples of soil types and conditions lead to pinelands. Slash pine forests would dominate moist locations, while sand pines would dominate dry, well-drained soils of ancient sand dunes peripheral to the Everglades.

Green plants form the base of food chains. In that role, they are called primary producers by ecologists. Green plants use sunlight in photosynthesis, initially to split water into hydrogen and oxygen, a reaction that requires energy. “Reduced” hydrogen is incorporated into energy-containing substances that drive the biochemistry of plant growth and produce energy-storing substances such as sugars, which can also be linked together to form cellulose, a major plant structural material. Oxygen is a waste product of the photosynthetic process. Each of the food chain steps is called a trophic level. Green plants (trophic level one) become the food of herbivores (trophic level two), also known as primary consumers. Herbivores consume plants for their growth and reproduction, and themselves become the prey of carnivores (trophic level three), or secondary consumers. Lower carnivores become the prey of higher carnivores (trophic level four and higher) in the food chain, which may have more levels ending in “top” carnivores. Dead material, including whole organisms, fecal material, and sloughed-off fragments such as hair and skin, become detritus, which is energy-containing material available to decomposers—bacteria and fungi. The preponderance of detritus is plant remains, either whole plants or plant parts such as twigs, leaves, flowers, dead seeds, and roots. Bacteria and fungi are the principal organisms that use detritus as a food source.

As a generalization, only about 10% of the energy of each trophic level is transferred to the next level. About 90% is lost in the effort expended in finding food, digestion, growth, reproduction, and other work.

Inadequately shown in the figure is the reality that animal species are seldom confined to a specific trophic level. Herbivores, for example, are opportunistic carnivores.

Using the term food web instead of food chain emphasizes the multiple trophic pathways of real life. Larval amphibians, for example, (tadpoles or pollywogs) are mostly herbivores but are also known for cannibalism. Upon transferring to adult frogs, they become strictly carnivores so a food web diagram would need to show larval and adult frogs separately.

Lodge, Thomas E.. The Everglades Handbook. CRC Press. Kindle Edition.