As the name suggests, “Eco” stands for habitat or environment while “system” stands for arrangement. You can understand an ecosystem as a complex arrangement established by the constant interaction between the biotic and abiotic factors in a specific area.
In ecology, an ecosystem is a fundamental unit where all the living components like plants, animals and microbes interact with the non-living components like water, air, and land. There is a series of interactions existing between them in order to maintain the balanced energy flow on the planet.
Functions of Ecosystem
Identification and enumeration of flora and fauna of an ecosystem provide a complete idea about its species composition. Different species occupy different places, i.e., different trophic levels according to their sizes, habitat, foraging habits etc. This vertical distribution of floral and faunal species into ordered levels is called as stratification.
For instance, the trees are at the uppermost vertical strata of the forest; following that are shrubs in second place, herbs on the third strata, while the grass capture the bottom strata.
We can understand the proper functioning of the ecosystem concerning the four following aspects:
- Energy flow
- Nutrient Cycling
Content: Functions of Ecosystem
You can simply define productivity as the “Rate of generation of biomass”.
Any ecosystem requires a constant supply of solar energy to function and sustain itself. The producers of that particular ecosystem absorb this energy and convert it into consumable biomass to pass to the next trophic level. We refer to this rate of production of biomass as productivity.
Primary production: The amount of biomass generated by plants during photosynthesis per unit area over a period of time is primary production.
We can categorize primary productivity into two parts:
- Gross Primary Productivity (GPP): It refers to as total organic biomass generation by the plants during photosynthesis.
- Net Primary Productivity (NPP): It refers to the biomass remaining for the consumption of above trophic levels after subtracting the respiration loss by the plants.
NPP = GPP – R
Secondary Productivity: It refers to the rate of organic biomass produced by consumers.
We measure the biomass in its dry weight form. The unit to measure this dry weight is g/m-2/yr‑2 or Kcal/m-2/yr-2.
Factors affecting Primary Productivity
The primary productivity relies on the type of producers, which are mainly plants inhabiting a particular ecosystem. It also depends on various other factors, including:
- Availability of mineral nutrients
- Photosynthetic capacity of the plants
- Availability of solar radiation
- Temperature (Mainly it affects the enzyme action)
The rate of productivity differs from ecosystem to ecosystem. The total net primary productivity of the entire biosphere is around 170 billion tons (dry weight). Despite the fact that the land ecosystem is lesser than the water, its NPP is 115 billion tons. Whereas the aquatic ecosystem only generates 55 billion tons of biomass. The reason behind this is the low availability of light and deficiency of nutrients for producers.
Decomposition is a process where complex organic substances get broken down into their smaller, simpler, inorganic form. Decomposers are the agents responsible for Decomposition.
In an ecosystem, the process of Decomposition aids the disintegration of the organic debris so that its remnants get mixed with soil again. This may include the Decomposition of dead animals, plant parts like leaves, bark, fruits, flowers, or even faecal matter. This waster, known as detritus, serves the role of raw material for the process of Decomposition.
Similarly, decomposers turn complex organic matter into its inorganic constituents like carbon dioxide, water and nutrients. We refer to this process as Decomposition.
The Decomposition occurs in many steps. Most of them take place simultaneously.
- Fragmentation: In this process, the decomposer breaks the bigger materials into smaller pieces.
- Leaching: This process causes the percolation of water-soluble water nutrients into the alluviation zone of earth strata. This leads to the loss of important nutrients in the soil.
- Catabolism: This refers to the enzymatic and chemical breakdown of the organic debris into simpler inorganic molecules.
- Humification: Humus refers to the dark, amorphous, colloidal, acidic, microbial-resistant substance that acts as a reservoir of nutrients for the growing plant. This is formed of nothing but the decomposed remnants of the organic matter. The process of formation of humus is humification.
- Mineralisation: The remnants of the humus are broken down by several microbes releasing the inorganic nutrients in the soil. This process is known as mineralisation.
Factors affecting Decomposition
- Chemical nature of Detritus: If the detritus contains easy-to-digest materials like proteins and sugars, then the Decomposition will be faster. However, if it is composed of hard-to-digest materials like lignin, cellulose, suberin etc., then the process of Decomposition is quite slow.
- Proper aeration: The presence of oxygen favours the growth of good bacteria. Thus, proper aeration fastens the process of Decomposition.
- Moisture content: Moist content is easy to digest, and thus, they are decomposed easily. But if the moisture content exceeds a certain limit, then it hampers the process and decreases the rate of Decomposition.
- Temperature: Temperature plays a role where the enzymes come into play, as every enzyme has its optimum temperature to work. Most of the enzymes involved in the decomposition process work optimally at room temperature, i.e., between 25-30o C. Very high or very low, both the temperature ranges are unfavourable for the decomposition process.
In any kind of ecosystem, all the organisms placed at different trophic level depends upon producers to meet their need for food. Either in a direct or indirect manner, the producers run the unidirectional flow of energy by absorbing it from the sun, converting it into organic biomass to passing it to the upper trophic levels. This is just like the first law of thermodynamics, where the energy travels from one entity to another, but only its form changes.
Moreover, as per the universal tendency of disorderliness, the most amount of energy is scattered randomly in the environment, and only a very small amount moves to the next level. This might sound like the second law of thermodynamics which suggests that complete energy transfer is never possible as some energy scatters during the process of transfer.
Planet earth is an open system for energy where the sun acts as the ultimate source of energy except for thermal ecosystems in deep seas. Out of 100 % of the total solar radiation, only 50 % comes to the plants as Photosynthetically active radiation (PAR).
From this 50 %, the plants are only capable of absorbing only 1-5% of the total parts of PAR, and the rest gets scattered in the sky. Plant use this energy to synthesise biomass, known as GPP. After the plant’s own respiratory loss, 0.8-4 % of the energy, i.e., NPP, sustains in the ecosystem for the upper trophic organisms.
In this way, the energy keeps on flowing in the ecosystem.
The cycling of nutrients between living and non-living aspects of the ecosystem is referred to as the biogeochemical (“Bio”- Living; ‘Geo’- Rock; ‘Chemical’- Element) cycle. The nutrients constantly flow between living organisms and the physical environment. More than 40 elements are there in the ecosystem needed for the life processes and thus are continuously recycled.
The primary function of the biogeochemical cycle is to make up for the deficit that occurs due to an imbalance in flow and outflow.
Standing state: The quantity of nutrients present in the soil at any given time period is termed a standing state.
This may include the number of nutrients like carbon, nitrogen, phosphorus, sulphur, calcium etc. The standing state of the soil may vary for different kinds of ecosystems. It also relies on seasons. With the help of biogeochemical cycling, the nutrients are never lost from the ecosystem but are recycled over and over again.
The nutrient cycles occur in 2 types of places depending on their reservoirs.
- Gaseous: It involves gaseous nutrient cycles that occur in the atmosphere.
Example: Oxygen, nitrogen, hydrogen, carbon.
- Sedimentary: These reservoirs occur in the earth’s crust.
Example: Sulphur and phosphorous.
Factors affecting the Nutrients cycle
Physical factors regulate the release rate of nutrients into the ecosystem. This may include:
The ecosystem influences our life in every possible way. Thus in order to have thorough knowledge about the ecosystem, one must study its functions properly.
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