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General ecology: basic terms and definition
Although the definition of Ecology has been modified over time it is still a science of functioning the nature and relationships between different elements of ecosystems. Unfortunately, the term "ecology" is currently overused. Commonly understanding of the term in society is reduced to meaning that "eco" is good (ecological fuel, ecological food, ecological vacation etc.) and "non-eco" is bad or worse. This meaning can be understood as a care about environment protection, however there is a science - sozology - that deals with protection of environment and the word "sozo" should be used in description of different elements (like a fuel, food, vacation, washing powder etc.) as a less burden on the environment or without any impact on environmet.
Ecology is the study of interaction among living organisms (plants, animals, microbes) as well as interaction with its abiotic environment (temperature, water, air, soil, light, etc.).
The definition of ecology has evolved throughout the centuries. The term Ecology was originally defined in the mid-19th century. The original definition was made by Ernst Haeckel, who defined ecology as the study of the relationship between organisms and their environment (from the Greek oikos meaning house and logos meaning science). This classical Haeckelian definition takes into consideration both the living and the non-living components. However, this definition neglected microorganisms, the chemical products of organism metabolism and ecological systems on larger scales or on higher hierarchical levels than organisms.
As a result of new findings, other definitions of ecology have been proposed: in 1954 Andrewartha and Birch stated that ecology is the study of the distribution and abundance of organisms, and in 1971 Odum proposed that ecology should be defined as the study of ecosystems, so the study of the processes - the structure and function of nature.
Ecology can be divided into two complementary fields of study:
Autecology - ecology of individual individual organisms or the population of one species; this includes physiological ecology, animal behaviour and the dynamics of a population.
Synecology - ecology of whole plant and animal communities, which study the relationships between populations and biocoenosis: fito- and zoocoenosis. This includes terrestrial and aquatic ecosystem ecology.
Ecology is primarily a science that mobilizes a number of various scientific disciplines including botany, zoology, geology, climatology and hydrogeology. It is relative to other ecological disciplines such as systematics, genetics, physiology, behavioral ecology and evolution.
Hierarchy in ecology
Species is a group of organisms capable of interbreeding and producing fertile offspring and reproductively isolated from other such groups.
Population is a group of interbreeding individuals, reproductively isolated, of the same species living in the same place at the same time, potentially interacting.
Community is created by two (possible more) populations of different species living in the same place.
Ecosystem – of living organisms, their physical environment, and all their interrelationships in a particular unit of space. Types of ecosystems – terrestrial, aquatic, artificial, natural.
Each ecosystem is the sum of two components:
• biocoenosis – all organisms in a given area (plants, animals, microorganisms and relationships relationships between each other, and with the environment,
• biotop – non biological parts of the ecosystem, external environment.
In an ecosystem, every organism must obtain energy in order to survive. According to the way it is obtained, we can divide them into:
• producers – energy from inorganic sources phototrophs & chemotrophs.
• consumers – energy from living organisms (organic sources).
• herbivore – animal which consumes plants.
• carnivore – animal which consumes other animals.
• omnivore –animal which consumes both animals and plants.
• decomposers – energy from dead organic matter (organic sources).
Biome is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate.
Biosphere (from Ancient Greek βίος (bíos) 'life' and σφαῖρα (sphaîra) 'sphere'), also called the ecosphere (from Ancient Greek οἶκος (oîkos) 'settlement, house' and σφαῖρα (sphaîra) 'sphere'), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to matter [Biosphere in The Columbia Encyclopedia, 6th ed. (2004) Columbia University Press].
In an ecosystem, each organism occupies its own space, which, together with the factors is necessary for survival, allows it to survive.
• habitat – place where an organism lives e.g. trees, rocks, buildings;
• environment – the surroundings of an organism made up of biotic and abiotic factors.
There are two important laws in the field of classical ecology:
Liebieg law (of the minimum) – growth of an organism is limitated not by total resources available at environment, but by the scarcest resource (limiting factor). An extension of this law is Shelford's principle of ecological tolerance.
Shelford’s law (of the toleranc) – principle which states that an organism’s survival success is based on a complex set of conditions, so each organism has a certain minimum, maximum, and optimum level of each environmental factor.
• tolerance = the ability of an organism to live within a range of environmental conditions.
Different kind of species in ecosystem:
• Common species – a species typically both abundant and widespread in ecosystem;
• Uncommon species – rare or scarce organisms, not so abundant in ecosystem;
• Dominant species – a species that exerts much influence on other species (most common/abundant, make up more of the biomass;
• Indicator species (bioindicator) – a species that reflects biotic or abiotic state of the nvironment, e.g. a pollution, species competition or climate change;
• Extant species – a taxon some of whose members are living at the present time;
• Extinct species – a taxon no member of which has no living representatives;
• Invasive species – are animal or plant species from another region of the world that don't belong in their new environment mostly delivered by humans sometimes other animal species.
Gause’s law –The competitive exclusion principle (CEP) , “...two species with identical niches (and compete for a single resource) cannot coexist together indefinitely...” Georgii F. Gause [1934].