ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...

, the foundation species are species that have a strong role in structuring a

community A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, tow ...

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

Paul K. Dayton Paul Kuykendall Dayton (born April 8, 1941 in Tucson, Arizona) is a biological oceanographer and marine ecologist at the Scripps Institution of Oceanography. Dayton works in Benthic zone, benthic ecology, marine conservation, evolution, natural h ...

in 1972,Dayton, P. K. 1972
Toward an understanding of community resilience and the potential effects of enrichments to the benthos at McMurdo Sound, Antarctica
pp. 81–96 in Proceedings of the Colloquium on Conservation Problems Allen Press, Lawrence, Kansas. who applied it to certain members of marine

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

and

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

communities. It was clear from studies in several locations that there were a small handful of species whose activities had a disproportionate effect on the rest of the marine community and they were therefore key to the resilience of the community. Dayton’s view was that focusing on foundation species would allow for a simplified approach to more rapidly understand how a community as a whole would react to disturbances, such as pollution, instead of attempting the extremely difficult task of tracking the responses of all community members simultaneously. The term has since been applied to a range of organisms in ecosystems around the world, in both aquatic and terrestrial environments. Aaron Ellison ''et al.'' introduced the term to terrestrial ecology by applying the term foundation species to tree species that define and structure certain forest ecosystems through their influences on associated organisms and modulation of

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

processes.

Examples and outcomes of foundation species loss

A study conducted at the McKenzie Flats of the

Sevilleta National Wildlife Refuge The Sevilleta National Wildlife Refuge is a protected area of New Mexico managed by the United States Fish and Wildlife Service as part of the National Wildlife Refuge System. It is located in the Chihuahuan Desert, 20 miles north of Socorro, New ...

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. This transition zone consists of two

Chihuahuan Desert The Chihuahuan Desert ( es, Desierto de Chihuahua, ) is a desert ecoregion designation covering parts of northern Mexico and the southwestern United States. It occupies much of far West Texas, the middle to lower Rio Grande Valley and the lower P ...

species, black grama (''

Bouteloua eriopoda ''Bouteloua eriopoda'', commonly known as black grama, is a perennial prairie grass that is native to the Southwestern United States. Its main means of reproduction is by stolons, as its ratio of viable seeds to sterile ones is naturally low. The ...

)'' and creosote bush (''

Larrea tridentata ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish language, Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of n ...

)'', and a shortgrass

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, ...

species, blue grama ('' Bouteloua gracillis)''. Each species dominates an area with a specific soil environment. Black grama dominates sandy soils, while blue grama dominates in soils with high clay content, and creosote bush dominates fine-textured soil with surface gravel. This study noted that responses to the loss of foundation species is dependent on a variety of different factors from the ability of a species to recover to the climate conditions of the ecosystem to the patterns in dominance and explored the possible reasons for the outcomes of the study. The results indicated that in areas with just one dominant foundation species, its loss caused a shift in dominance to a mixed dominant community. For example, the creosote bush dominated shrubland saw a shift in dominance to 32% by other shrubs, 26% by perennial grasses, and 22% by perennial forbs following the removal of creosote bush. Another finding was that regardless of the community type and the species removed, the loss of foundation species resulted in an overall increase in black grama supporting the notion that the outcome is greatly affected by recovery ability of species removed or loss. Another study observed the effects of loss of foundation eastern hemlocks (''

Tsuga canadensis ''Tsuga canadensis'', also known as eastern hemlock, eastern hemlock-spruce, or Canadian hemlock, and in the French-speaking regions of Canada as ''pruche du Canada'', is a coniferous tree native to eastern North America. It is the state tree o ...

'') in a forest ecosystem. Eastern hemlocks are a foundation species in eastern North American forests, but have been threatened by the accidental introduction of woolly adelgid. This study observed the effects that a loss in eastern hemlocks would have on the populations of

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s, such as ants, beetles, and spiders, since these species are known indicators of environmental change. The results found that in areas of hemlock removal, there was an overall increase and influx of arthropod species. Researchers suggested that this was due to an increase in open habitats from the loss of the hemlocks. The results of this hemlock study corroborated with those from the previous McKenzie Flats study discussed in that the loss of foundation species led to a proliferation of species diversity in the affected area. These results seem to contradict a long-standing belief that foundation species play a vital role in communities and ecosystems by creating habitats for organisms, suggesting that in some circumstances they bottleneck species diversity. Foundation species play a vital role in structuring a community; however, this can be in a variety of different ways. The presence of a foundation species has the ability to either reduce or increase species diversity depending on its particular role in a specific ecosystem. The studies discussed highlighted examples in which foundation species limited species diversity in similar and differing taxa (the McKenzie Flats and eastern hemlock studies, respectively); however, there are many other examples in which removal of foundation species could decrease species diversity within the same or differing taxa.

References

{{modelling ecosystems Ecology

Examples and outcomes of foundation species loss

See also

References