Foundation species

A foundation species can occupy any trophic level in a food web (i.e., they can be primary producers, herbivores or predators).

[3] A study conducted at the McKenzie Flats of the Sevilleta National Wildlife Refuge in New Mexico, a semiarid biome transition zone, observed the result of loss of a variety of different dominant and codominant foundation species of plants on the growth of other species.

[4] Another study observed the effects of loss of foundation eastern hemlocks (Tsuga canadensis) in a forest ecosystem.

This study observed the effects that a loss in eastern hemlocks would have on the populations of arthropods, such as ants, beetles, and spiders, since these species are known indicators of environmental change.

It was found that species at the base of the food web are less strongly, and carnivores are more strongly facilitated in foundation species' food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length.

[11][12][13][14][15][16] This form of non-trophic facilitation by foundation species has been found to occur across a wide range of ecosystems and environmental conditions.

[17][18] In harsh coastal zones, corals, kelps, mussels, oysters, seagrasses, mangroves, and salt marsh plants facilitate organisms by attenuating currents and waves, providing aboveground structure for shelter and attachment, concentrating nutrients, and/or reducing desiccation stress during low tide exposure.