What is Ecology, Concept and Definition of Ecology, What is Environment, What is Ecosystem, Functions of Ecosystem
Concept of Ecology and Environment
Ecology can be defined as a scientific study of the interactions of organism with their physical environment and with each other. The term ecology is derived from the Greek word ‘oikos’ meaning ‘house’, combined with the word ‘logy’ meaning the science of or the study of’. Literally, ecology is the study of the earth as a “household, of plants, human beings, animals and micro-organisms. They all live together as interdependent components. The term ecology was first used by German zoologist Ernst Haeckel in 1869.
An ecosystem is defined as a community of life forms in concurrence with non-living components, interacting with each other. The term ecosystem was coined by Arthur Tansley in 1935. Environment is the sum total of all conditions and influences that affect the development and life of all organisms on earth. Thus it can be said as one’s surrounding.
- Autecology: The study of relationship of individual species with the environment. Synecology: The study of plant communities in relation to their habitats of a given ecosystem.
- Gaia hypothesis: This refers to a scientific hypothesis which states that the earth is a complex living entity, with the sustenance of life dependent on the self-regulating interactions among organisms and their inorganic surroundings.
- For instance, climatic conditions depend on the interactions among living organisms like human beings and their non-living atmosphere, all of which regulate each other constantly.
- The Gaia hypothesis is named after the mythical Greek goddess Gaia who personifies the earth.
- It was first proposed by British scientist James Lovelock in his 1972 paper “Gaia as seen through the atmosphere.”
Levels of Organisation of Ecology
The seven major ecological levels of organisations are:
Organisms- They makes the basic unit of study in ecology. At each level, the biological unit has a specific structure and function. At this level, the form, physiology, behaviour, distribution and adaptations in relation to the environmental conditions are studied.
Population-In ecology, a population is a group of individuals of the same species, inhabiting the same area, and functioning as a unit of biotic community.
Biological Community- Biological/ Biotic community organisation results from interdependence and interactions amongst population of different species in a habitat. This is an assemblage of populations of plants, animals, bacteria and fungi that live in an area and interact with each other.
What is Ecosystem
Ecosystem- The ecosystems are parts of nature where living organisms interact amongst themselves and with their physical environment. An ecosystem in composed of a biotic community, integrated with its physical environment through the exchange of energy and recycling of the nutrients.
Ecosystems can be recognised as self-regulating and self-sustaining units of landscape, e.g., a pond or a forest.
Landscape- A landscape is a unit of land with a natural boundary having a mosaic of patches, which generally represent different ecosystems.
Biome- This is a large regional unit characterized by a major vegetation type and associated fauna found in a specific climate zone. The biome includes all associated developing and modified communities occurring within the same climatic region, e.g., forest biomes, grassland and savanna biomes, desert biome,etc. On a global scale, all the earth’s terrestrial biomes and aquatic systems constitute the biosphere.
Biosphere- Biosphere is a part of earth where life can exist. It represents a highly integrated and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land).
Important Terms related to Ecosystem
Ecotone: An ecotone is a zone of junction or a transition area between two biomes (diverse ecosystems).
• Ecotone is the zone where two communities meet and integrate. For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem.
• Other examples are grassland (between forest and desert), estuary (between fresh water and salt water) and riverbank or marshland (between dry and wet).
Ecocline: Ecocline is a zone of gradual but continuous change from one ecosystem to another when there is no sharp boundary between the two in terms of species composition. Ecocline occurs across the environmental gradient (gradual change in abiotic factors such as altitude, temperature (thermocline), salinity (halocline), depth, etc.).
Edge Effect: Edge effect refers to the changes in population or community structures that occur at the boundary of two habitats (ecotone). Sometimes the number of species and the population density of some of the species in the ecotone is much greater than either community. This is call as edge effect. The organisms which occur primarily or most abundantly in this zone are known as edge species.
• In the terrestrial ecosystems edge effect is especially applicable to birds.
• For example, the density of birds is greater in the ecotone between the forest and the desert.
• Niche refers to the unique functional role and position of a species in its habitat or ecosystem. The functional characteristic of a species in its habitat is refer as “niche” in that common habitat. In nature, many species occupy the same habitat, but they perform different functions:
Habitat niche – where it lives, food niche – what is eats or decomposes & what species it competes with, Reproductive niche how and when it reproduces, Physical & chemical niche – temperature, land shape, land slope, humidity & another requirement. Niche plays an important role in the conservation of organisms. If we have to conserve species in its native habitat, we should have knowledge about the niche requirements of the species.
Functions of an Ecosysytem
Ecosystems are complex dynamic system, they perform following functions:
1. Energy flow through food chain
2. Nutrient cycling (biogeochemical cycles)
3. Ecological succession or ecosystem development
4. Homeostasis (or cybernetic) or feedback control mechanisms
Ponds, lakes, meadows, marshlands, grasslands, deserts and forests are examples of natural ecosystem. Many of you have seen an aquarium; a garden or a lawn etc. in your neighborhood. These are man-made ecosystem
Energy Flow in an Ecosystem
The cycle of energy is based on the flow of energy through different trophic levels in an ecosystem. Ecosystem is maintain by the cycling energy and nutrients obtained from different external sources. Sun is the primary source of energy for all ecosystems on Earth. Of the incident solar radiation less than 50 percent of it is photosynthetically active radiation (PAR). PAR, designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis.
Plants capture only 2-10 per cent of the PAR and this small amount of energy sustains the entire living world. The energy of sunlight fix in food production by green plants pass through the ecosystem by food chains and webs from one trophic level to the next. In this way, energy flows through the ecosystem.
The trophic level of an organism is the position it occupies in a food chain. The trophic level is the number of steps an organism is from start of the chain. A given organism may occupy more than one trophic level simultaneously. One must remember that the trophic level represents a functional level, not a species as such. A given species may occupy more than one trophic level in the same ecosystem at the same time; for example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms.
•At the first trophic level, primary producers use solar energy to produce organic material through photosynthesis.
•The herbivores at the second trophic level use the plants as food which gives them energy. A large part of this energy is use for the metabolic functions of these animals such as breathing, digesting food, supporting growth of tissues, maintaining blood circulation and body temperature.
•The carnivores at the next trophic level feed on the herbivores and derive energy for their sustenance and growth. If large predators are present, they represent still higher trophic level and they feed on carnivores to get energy.