Different Species & Ecosystem Engineering

  • A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance.
  • Such species are described as playing a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem and helping to determine the types and numbers of various other species in the community.
  • The role that a keystone species plays in its ecosystem is analogous to the role of a keystone in an arch. While the keystone is under the least pressure of any of the stones in an arch, the arch still collapses without it.
  • Similarly, an ecosystem may experience a dramatic shift if a keystone species is removed, even though that species was a small part of the ecosystem by measures of biomass or productivity. It became a popular concept in conservation biology. 
  • Although the concept is valued as a descriptor for particularly strong inter-species interactions, and it has allowed easier communication between ecologists and conservation policy-makers, it has been criticized for oversimplifying complex ecological systems.

Foundation species;

  • In ecology, the term foundation species is used to refer to a species that has a strong role in structuring a community.
  • 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 in 1972, who applied it to certain members of marine invertebrate and algae 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 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 processes.

  • Umbrella species are species selected for making conservation-related decisions, typically because protecting these species indirectly protects the many other species that make up the ecological community of its habitat.
  • Species conservation can be subjective because it is hard to determine the status of many species.
  • With millions of species of concern, the identification of selected keystone species, flagship species or umbrella species makes conservation decisions easier.
  • Umbrella species can be used to help select the locations of potential reserves, find the minimum size of these conservation areas or reserves, and to determine the composition, structure and processes of ecosystems.

Indicator species:

  • An indicator species is any biological species that defines a trait or characteristic of the environment.
  • For an example, a species may delineate an ecoregion or indicate an environmental condition such as a disease outbreak, pollution, species competition or climate change. Indicator species can be among the most sensitive species in a region, and sometimes act as an early warning to monitoring biologists.
  • Animal species have been used for indicators for decades to collect information about the many regions. Vertebrate are used as population trends and habitat for other species.
  • Species identification is very important for the conservation of biodiversity. Approximately 1.9 million species have been identified, but there are 3 to 100 million species. Some of them haven’t been studied.
  • There are new species every year that are unknown and are still being discovered each year. 
  • Indicator species serve as measured environmental conditions.
  • Indicator species are also known as sentinel organisms, i.e. organisms which are ideal for biomonitoring. Organisms such as oysters, clams, and cockles have been extensively used as biomonitors in marine and estuarine environments.
  • For example, the Mussel Watch Programme is a world-wide project using mussels to assess environmental impacts on coastal waters. Their well-documented feeding habits, stationary condition and their role as integral parts of the food chain are some of the main reasons why oysters and mussels are widely used biomonitors.

  • An endangered species is a species which has been categorized as likely to become extinct.
  • Endangered (EN), as categorized by the International Union for Conservation of Nature (IUCN) Red List, is the second most severe conservation status for wild populations in the IUCN’s schema after Critically Endangered (CR).

What is a flagship species?

  • A flagship species is a species selected to act as an ambassador, icon or symbol for a defined habitat, issue, campaign or environmental cause.
  • By focusing on, and achieving conservation of that species, the status of many other species which share its habitat – or are vulnerable to the same threats – may also be improved.
  • Flagship species are usually relatively large, and considered to be ‘charismatic’ in western cultures.
  • Flagship species may or may not be keystone species and may or may not be good indicators of biological process.

What is a priority species?

  • The terms “flagship” and “keystone” have generally consistent definitions across the conservation community, however “priority species” is a WWF term, and is solely for the purposes of planning and simple communication.
  • For WWF, a “priority species” may be either a flagship or a keystone species and is chosen to represent an ecoregion or region.
  • A “priority species” is reflective of a key threat across that ecoregion – such that conservation of the species will contribute significantly to a broader threat mitigation outcome. It is often crucial to the economic and/or spiritual wellbeing of peoples within that ecoregion.

  • An ecosystem engineer is any organism that creates, significantly modifies, maintains or destroys a habitat. These organisms can have a large impact on the species richness and landscape-level heterogeneity of an area. 
  • As a result, ecosystem engineers are important for maintaining the health and stability of the environment they are living in.
  • Since all organisms impact the environment they live in in one way or another, it has been proposed that the term “ecosystem engineers” be used only for keystone species whose behavior very strongly affects other organisms.

Type

Two different types of ecosystem engineers:

Allogenic engineers

  • Allogenic engineers modify the environment (biophysical) by mechanically changing living or nonliving materials from one form to another.
  • Beavers are the original model for ecosystem engineers; in the process of clearcutting and damming, beavers alter their ecosystem extensively.
  • The addition of a dam will change both the distribution and the abundance of many organisms in the area.
  • Caterpillars are another example in that by creating shelters from leaves, they are also creating shelters for other organisms which may occupy them either simultaneously or subsequently.
  • An additional example may be that of woodpeckers or other birds who create holes in trees for them to nest in.
  • Once these birds are through with them, the holes are used by other species of birds or mammals for housing.

Autogenic engineers

  • Autogenic engineers modify the environment by modifying themselves.
  • Trees are a good example, because as they grow, their trunks and branches create habitats for other living things; these may include squirrels, birds or insects among others.
  • In the tropics, lianas connect trees, which allow many animals to travel exclusively through the forest canopy.

Source: WikiPedia & WWF

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