All the ecosystem’s functions are controlled and delicately balanced. The effects of plants, animals, and microbes’ collective life activities (e.g., feeding, growing, moving, excreting waste) on the physical and chemical conditions of their environment are reflected in ecosystem functioning. Ecosystem functions (also called ecosystem processes or ecological processes) are biological, geochemical, and physical processes that occur or take place within an ecosystem. Herbivores eat the leaves and roots, and carnivores eat the leaves and roots.

Productivity, decomposition, energy flow, and nutrient cycling are the four major functional aspects of the ecosystem.  Decomposers break down complex organic materials into simple inorganic products that producers can use. The exchange of energy and nutrients in the food chain is at the heart of ecosystem functions. Plant and animal life, as well as the decomposition of organic matter and the production of biomass, are all supported by these exchanges.

Major Ecosystem Functions:

• Productivity: It is the rate at which biomass is produced per unit area in unit time by any trophic level. Weight (e.g., g/m2/yr) or energy (e.g., kcal/m2/yr) are both used to calculate it. The types are as follows:
• Basic output: It refers to the amount of biomass or organic matter produced per unit area by plants during photosynthesis over a given period of time. Gross primary productivity and net primary productivity are two subsets of this figure.
• Gross primary productivity is defined as the rate at which green plants produce total organic matter by photosynthesis per unit area per unit time. Plants use a significant amount of GPP for respiration. 
• Net primary productivity is the amount of energy left in the producers after respiration and stored as organic matter per unit time and area.
• Decomposition is the physical and chemical breakdown of complex organic matter (detritus) by decomposers. Fragmentation, catabolism, and leaching are the three processes involved.
• Humification produces a dark-colored amorphous substance called humus, which is high in cellulose and lignin and has a long shelf life. It’s incredibly resistant to microbial action and decomposes at a glacial pace. Some microbes degrade humus further, and mineralisation releases inorganic nutrients.
• The availability of oxygen affects decomposition. It also depends on the detritus’ chemical composition as well as the weather. When detritus contains more nitrogen and sugars than lignin and chitin, decomposition occurs more quickly. Decomposition is aided by a warm, humid environment. The flow of Energy In all ecosystems, the sun is the primary source of energy.
• Solar radiation that is photosynthetically active accounts for less than half of incident solar radiation. Plants and photosynthetic and chemosynthetic bacteria (autotrophs) fix the sun’s radiant energy and use it to produce food from inorganic materials. Plants only capture 2-10% of PAR, but this small amount of energy is enough to keep the entire world alive.

In an ecosystem with multiple trophic levels, energy flows from producers to various consumers.

Food Chains:

A food chain is an ecosystem’s nutrient interaction between living organisms (biotic components). Here, repeated eating occurs, in which each group of organisms eats the other and is then eaten by a different group of organisms. A food chain can only have four or five steps, and each step loses a significant amount of energy as heat. There is a one-way flow of energy in the food chain. There is a 10% energy transfer between trophic levels. Lindemann proposed the 10% law in 1942.

Ecological Pyramids:

An ecological pyramid is a graphical representation of ecological parameters such as biomass, energy, and the number of individuals present in different trophic levels of a food chain, with producers at the bottom and top carnivores at the tip. Charles Elton (1927) invented ecological pyramids, which are also called Eltonian pyramids.

All organisms at that trophic level must be included in energy content, biomass, or number calculations. If only a few individuals at any trophic level are considered, no generalisations can be made.

Nutrient cycling: 

Biogeochemical cycles, also known as nutrient cycles, are cyclic exchanges, transfers, and storage of biogenetic nutrients through various ecosystem components (biotic and abiotic), allowing the nutrients to be reused over and over. Two nutrient stores are the reservoir pool and the cycling pool. The reservoir pool holds biogenetic nutrients before being transferred to the cycling pool.

Ecological Succession:

The process of changes in the species structure of an ecological community over time is known as ecological succession. The pioneers, also known as the primary community or primary colonisers, are the first organisms to establish during an ecological succession. Climax community is the final, stable, self-sustaining biotic community that emerges at the end of biotic succession and is in perfect harmony with the physical environment. Climax has a wide range of niche specialisations and a lot of diversity. Serial or transitional communities are biotic communities that emerge during the process of biotic succession.

Conclusion:

Therefore, in this unit we learnt about the ecosystem and its main functions. The ecosystem is a self-regulatory and self-sustaining landscape (biosphere) structural and functional unit composed of a community of living beings and their physical environment, which interact and exchange materials.