RBSE Class 12 Biology Notes Chapter 14 Ecosystem

These comprehensive RBSE Class 12 Biology Notes Chapter 14 Ecosystem will give a brief overview of all the concepts.

RBSE Class 12 Biology Chapter 14 Notes Ecosystem

→ In nature ecosystem is the structural and functional unit, it is made up of abiotic and biotic components. Abiotic components are inorganic nutrients, water, precipitation, air and soil. The biotic components are producers, consumers and decomposers. Each ecosystem has characteristic physical structure resulting from interaction amongst abiotic and biotic components.

→ The two structural features of any ecosystem are species composition and stratification. Depending upon the source of food every organism occupies a place in an ecosystem.

→ Productivity, decomposition, energy flow and nutrient cycling are the four components of an ecosystem. Primary productivity is the rate of capturing of sun’s energy or biomass production of the producers. It is divided into two types: Gross primary productivity (GPP) and net primary productivity (NPP). This rate of capturing solar energy is called GPP. NPP is the remaining biomass or energy left after utilisation of producers. Secondary productivity is the rate of assimilation of food energy by the consumers. In decomposition, complex organic compounds of detritus are converted to carbon dioxide, water and inorganic nutrients by the decomposers. 

→ Decomposition process involves three main process fragmentation, leaching and catabolism. Energy flow is unidirectional. First plants capture solar energy and then food is transferred from producers to decomposers finally. Organisms of different trophic levels are connected to each other for food or energy relationship forming a food chain. The storage and movement of nutrients elements through the different components of the ecosystem is called Nutrient cycling, it is of two types gaseous and sedimentary. Products of ecosystem processes are named as ecosystem services e.g., purification of air and water by forests. The biotic community is dynamic and undergo changes with the passage of time in order to be in equilibrium with the surrounding environment. This is called ecological succession. It involves the establishment of pioneering community to the most adaptable climax community which remain most adaptable to the existing environmental conditions at a given period of time.

→ Ecosystem: Structural and functional unit of nature.

→ Biotic components: Autotrophs, herbivores and carnivores;

→ Abiotic components: Soil, air and water.

→ Productivity: Rate of biomass production. Expressed in g²yr^-1 or k cal m-2y^-1.

→ Gross Primary Productivity (GPP): Rate of production of organic matter during photosynthesis.

→ Net Primary Productivity (NPP): Gross primary productivity minus respiratory losses (R)
NPP = GPP-R

→ Decomposition: Process of breakdown complex organic matter into simplar inorganic substances by decomposers.

→ Food chain: Transfer of food from one organism to another organism, this transfer of food makes a chain called food chain. Two types, grazing food chain and detritus food chain.

→ Trophic Level: It is the specific place occupied by an organism in the food chain in an ecosystem.

→ Standing Crop: Each trophic level has a certain mass of living material at a particular time called the standing crop.

→ Ecological Pyramid: It is the geographical representation of relation between producers and consumers in terms of number, biomass and energy in the form of pyramid.

→ Ecological Succession: Gradual, sequential and predictable change in the species composition in an area over a period of time.

→ Nutrient Cycling: The movement of nutrient elements through the various components of an ecosystem.