ECOLOGICAL CONCEPTS: DEFINITIONS
By Aymeric Dufresnoy - Updated on 2022/05/25
Biosphere: the part of our planet where life has developed. It comprises 3 distinct zones: the hydrosphere (aquatic environments), the atmosphere (aerial environments) and the lithosphere (terrestrial environments).
Ecozone : an ecological unit of continental size. Each biogeographical territory is thus characterised by a certain similarity in the distribution of fauna and flora. There are 8 ecozones on the Earth's surface: the Afrotropical, Indomalayan, Antarctic, Australasian, Nearctic, Neotropic, Oceanic and Palearctic ecozones .
To distinguish an ecozone from a biome, one can remember that ecozones are "one big block" while biomes are geographically distributed in different parts of the world.
Biome (or ecoregion): a group of ecosystems characteristic of a biogeographical area. Biomes are delimited based on their vegetation and the animals that are adapted to them. The biome is fundamentally characterised by its climate, in particular temperature and precipitation. The same biome may be present in several distinct ecozones. There are 14 terrestrial biomes.
Landscape: Based on no scientific characteristics, strictly speaking, landscape is the set of elements that can be observed from a specific location. It is not the same as the geographical environment, which includes invisible elements, but it is the visible aspect of the geographical space.
Ecosystem: the set of living beings (the biocenosis) that live within an environment (the biotope) and interact with each other within and with that environment. It is the basic unit of scientific ecology. The concept of ecosystems can be applied at all scales.
Biotope: a particular physical environment with specific physical characteristics (temperature, humidity, climate)
Biocenosis: a group of living beings (animals, plants, micro-organisms) interacting and therefore interdependent.
Population: a population is a group of individuals of a particular species living in a particular ecosystem at a particular time. The number of individuals in the population defines the population size. Therefore, the size of the population varies over time due to births, deaths, immigration and emigration. The population increases or decreases according to environmental conditions and available resources .
Individual: synonymous with organism, it is the basic building block of ecology, the starting point of the ecological levels (seen above). If we want to go into the details of the individual, we change the field of study and move from ecology to physiology (interaction and understanding of organs).
Extinct species: a species that no longer has a living representative, either in the wild or in captivity
Umbrella species: a species which, by protecting it, allows the preservation of a large number of other related species, thanks to a similar ecological niche. A slightly similar concept also exists with so-called "flagship species". An iconic species is a species that is characteristic of a habitat. It can be used as a symbol for a place, a country, a culture, an organisation or a cause (e.g. the Beaver is the emblem of Canada and the Fern is the emblem of the New Zealand 15-a-side rugby team (the All Blacks)).
Engineer species: species that by their mere presence and activity significantly modify their environment (e.g. earthworms allow the aeration of soils by digging thousands of galleries and turning over the earth from the inside, thus favouring microbial activity favourable to plants).
Keystone species: a species that has a disproportionate effect on its ecosystem in relation to its population, thus affecting many other organisms. Keystone species cause cascade effects if they were to disappear (e.g. if bees were to disappear, they would bring with them a multitude of other species that are linked to the flowers they pollinate) .
Cascading effect: inevitable and sometimes unforeseen chain of events due to an act affecting a system.
Ecosystem service: an ecological concept that allows natural phenomena to be monetised, as a "value" of ecosystems, or even of Nature in general. According to this concept, "ecosystems provide humanity with goods and services necessary for their well-being and development" (Millennium Ecosystem Assessment, 2004)
Ecological niche: this is one of the major theoretical concepts of ecology: it is the set of needs necessary for a species or population to be considered viable in time and space. This concept is based on two groups of parameters :
- Abiotic (or physico-chemical) conditions, i.e. the characteristics of the living environment that influence living beings (and sometimes significantly modified by these organisms) such as temperature, sunshine, humidity, wind, precipitation, soil pH, presence of minerals in the soil, soil aeration, relief, water salinity, water pH, etc.
- Biotic (or biological) conditions are the influences that living beings have on other living beings in the same environment. Example: predation, diseases and parasitism, intra- or interspecific competition, the presence of partners for reproduction, the proximity of humans, the modification of the environment by another individual, ...
Home range: natural area where a living creature lives on a daily basis. This area allows the animal to meet its primary needs (food, shelter, breeding partners). This concept can be considered at the species level (the home range of the snow leopard is found in Mongolia, western China, Nepal, Bhutan, northern India, Pakistan, Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan and southern Russia) but also at the level of a subspecies, a population or even a specific individual. It is therefore a concept that describes the actual distribution of an animal.
Territory: a geographical area or place occupied by a group (a clan, a family) or an isolated individual at a given time, the territory does not involve the entire species. Territoriality is a mechanism for managing the limited available resources of animals in the same niche and is particularly common in carnivores. The individual (e.g. tigers) or the group (e.g. chimpanzees) actively defends its boundaries against intruders
A territory is therefore a part of a larger home range. In migratory species (birds, fish, wildebeest, ...) the home range is huge and the territory varies according to the time of year.
Fragmentation of the habitat: artificial phenomenon of space fragmentation, it is a primordial notion in landscape ecology. This fragmentation can prevent a species from moving as it should in the absence of human activity.
According to the UN and the IPCC, habitat fragmentation is considered one of the main threats to biodiversity.
Ecological corridor: connections between biodiversity reservoirs, allowing the movement of populations. Some animal or plant populations need to disperse to complete their life cycle, so corridors allow the survival of certain species. Some examples of ecological corridors are permanent vegetation cover along watercourses, watercourses, water points and wetlands, and forest arms connecting two forest reservoirs. Ecological corridors can take many forms and do not necessarily imply physical continuity. Areas without wind turbines or electricity poles, for example, provide corridors for bats due to the absence of electromagnetic waves.