FUNCTIONS OF AN ECOSYSTEM FUNCTIONS OF AN ECOSYSTEM

FUNCTIONS OF AN ECOSYSTEM

FUNCTIONS OF AN ECOSYSTEM • Ecosystem functions mainly comprise the interactions of various components in an ecosystem • They are interconnected by energy, nutrients and minerals • The survival of an ecosystem depends on – Flow of energy-- Non cyclic food chain – Biogeochemical cycle –Cyclic food chain - circulation of nutrients and minerals

Important functions of an ecosystem are • • • Energy Primary production Secondary production Food chain Food web Trophic levels Energy flow Ecological pyramid Biogeochemical cycles

ENERGY FLOW • Energy is the ability to do work • Main source - the radiant energy or light energy derived from the sun Energy Trapped Producers Utilized Consumers Consumed Secondary consumer

SOURCE OF ENERGY • Ecosystems - composed of a variety of abiotic components such as soil, water, atmosphere, radiation from the sun • Soils provide nutrients, water act as home and a medium for organisms • The atmosphere provides carbon dioxide for photosynthesis and oxygen for respiration Solar radiation 2 cal / sq. cm. /min Earth surface (Solar flux or solar constant) 95 -99% Lost by reflection • Sunlight is necessary for photosynthesis • Photosynthesis provides the energy for plant growth and metabolism and the organic food for animal life 0. 02% Energy reach earth (Plant utilize)

• Ecosystems - composed of producers, consumers and decomposers • Producers or autotrophs - manufacture their food by photosynthesis • Consumers - get their energy and nutrients by feeding directly or indirectly on producers • Herbivores - consumers that eat plants for their energy and nutrients

• Consumer organisms that feed on this organic matter or detritus are known as detrivores or decomposers • The organic matter that is consumed by the detritivores is eventually converted back into inorganic nutrients in the soil • Energy flow and energy transformation in an ecosystem obeys the law of thermodynamics

FATE OF ENERGY

THERMODYNAMICS The first law of thermodynamics • It states that “energy can neither be created nor destroyed, but it can simply change in form” • The light energy of the sun is converted into electrical energy in the chlorophyll • The electrical energy is converted into chemical energy during photosynthesis • The chemical energy is transformed in to heat energy during metabolism • The heat energy is transformed into mechanical energy for doing work • Energy can neither created nor destroyed i. e. the energy of ecosystem is constant and thus it obeys the first law of thermo dynamics

The second law of thermodynamics • It states that “during energy transfer, large part of energy is degraded into heat and dissipates” • When energy is transferred from producers to herbivores about 90% of energy is lost as heat • The change of energy from one form to another the free energy diminishes and thus it obeys the second law of thermo dynamics

Flow of energy between phyto and zooplankton • Ecological efficiency Et = Pt Pt-1 • Et will be equal to the amount of herbivore (Pt) divided primary productivity(Pt-1 ) in marine ecosystem ie. 20% plants to herbivores and 15 -10% at higher tropic levels

ENERGY AND MATTER TRANSFER IN ECOSYSTEM • The transfer of energy from one trophic level to another is called energy flow • This flow of energy is always unidirectional and never returns back • So, energy can be utilized once in the ecosystem and otherwise it will go as waste heat

• Energy flows from one trophic level to another • Green plants or other photosynthesizing organisms use light energy from the sun to manufacture carbohydrates for their own needs • Chemical energy is processed in metabolism and dissipated as heat in respiration • Plants convert the remaining energy to biomass • The stored energy, is transferred to the second trophic level, which comprises grazing herbivores, decomposers and detrital feeders

• Energy at the second trophic level - lost as heat in respiration; fraction becomes new biomass • More steps between producer and final consumer, the less energy remains available • In a food web there are more than four links, or five levels • Energy flowing through the trophic levels is dissipated as heat • The process whereby energy loses its capacity to do work is called entropy

• The energy transfer between producers and herbivores is only 10% • Remaining 90% is lost through faces, respiration and unused energy or heat • Hence, the amount of energy available decreases from trophic level to another trophic level • Short food chain - final consumers will get a large amount of energy • Long food chain - final consumer will get a lesser amount of energy

TROPHIC STRUCTURE • The trophic structure is an arrangement of autotrophs and succeeding such of heterotrophs is called as trophic structure in which each successive consumer level is called a tropic level • Also called as feeding levels Trophic levels • Autotrophs - producers synthesis their own food by themself • Herbivores – consumers of only plants • Carnivores- consumers of only animals • Omnivores – consumers of both plants and animals • Decomposers- Decomposers of dead and decaying matters

• Each step of the food chain is called trophic level. • • • • Each food chain contains many trophic levels Autotrophs - Trophic level Herbivores – Trophic level Carnivores- Trophic level Omnivores – Trophic level Decomposers Trophic level 1 2 3 4 5

• The different feeding levels in the food chain are called trophic levels • Food chains comprised of many feeding or nourishing levels and each level is called trophic level • The first trophic level in the food chain is called primary producers, the second trophic level is primary consumers (herbivores) and the third level is primary carnivores • Lower the number of trophic levels, higher the transfer of energy to the top level organisms in the food chain • The energy transfer will be very less to the top predator, if the food chain is having more than three levels of trophic tiers

ENERGY TRANSFER- TROPHIC LEVELS • Trophic level is simply a feeding level which often represented in a food chain or food web • Primary producers - bottom of the trophic level; then primary consumers (herbivores), then secondary consumers (carnivores feeding on herbivores) and so on when we consider of moving up the food chain • It moves from plants to herbivores to carnivores • Food chain does not take into account decomposers and detritivores which make up their own trophic pathways

Energy transfer in fish production