Ecology: Biology of Interactions. III-02. Ecosystem Components
If one focuses on ecosystem functioning, the following components can be distinguished: recyclable inorganic matter, detritus, environment, producers, consumers, and decomposers.
III-2. Ecosystem components
Into what components can an ecosystem be divided? One option follows the biogeocenosis framework: biocenosis (phytocenosis + zoocenosis + microbiocenosis) + geocenosis (edaphotope + climatotope). This classification emphasizes the origin of components.
If we focus on ecosystem functioning, we can distinguish:
1) recyclable inorganic matter: inorganic substances involved in biological cycling (e.g., H2O, CO2, NH4+, etc.);
2) detritus: organic matter outside organisms;
3) environment: air, water, substrate;
4) producers: organisms synthesizing organic matter from inorganic matter;
5) consumers: organisms whose main role is transforming organic matter from one form to another;
6) decomposers: organisms whose main role is breaking down organic matter to inorganic matter.
Thus, living organisms are divided into three functional groups—producers, consumers, and decomposers. These groups correspond to three process types affecting organic matter: creation, transformation, and destruction.
Autotrophs synthesize organic matter from inorganic sources using external energy; heterotrophs consume other organisms or their remains; mixotrophs combine both strategies. Two main autotrophic pathways are photosynthesis and chemosynthesis.
By resource acquisition mode, organisms can be osmotrophs (absorbing dissolved substances) or phagotrophs (ingesting particulate food).
Ecological roles are not always sharply separable in physiology; classification often depends on dominant functional role in ecosystem processes.
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Type of nutrition
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Autotrophs
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Heterotrophs
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Osmotrophs
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Sun
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Fungi
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Phagotrophs
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Animals
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Having understood the ways of nutrition, let's move on to the ecological roles of organisms. There are three of them. Producers (Latin producentis - one who produces) produce organic matter from inorganic matter. Naturally, this role is performed by autotrophs - plants and cyanobacteria capable of photosynthesis, as well as chemosynthetic bacteria. Although this group of organisms is distinguished based on the ability of its representatives to synthesize organic substances, it should not be forgotten that any organism in this group simultaneously transforms organic matter (for example, when building its own body) and destroys it (extracting energy from it). The main role of consumers (Latin consume - I consume) is the transformation of organic matter. In contrast, decomposers (Latin reducere - to return) perform the function of destroying organic substances into inorganic ones. However, it is not easy to draw a line between consumers and decomposers. Each of the heterotrophs (both the tiger and the honey fungus on a rotting stump) both creates its own organic matter and "burns" part of the organic matter obtained from food. School biology confidently knows from somewhere that an earthworm is a decomposer, and a human is a consumer, although both obtain organic matter, and partially destroy it into inorganic substances, and partially spend its components for the synthesis of their own substance. The main difference between these animals is not in their physiology, but in which of their functions the author of the school textbook pays more attention to. Perhaps there is no fundamental difference between consumers and decomposers? From the perspective of what they spend the obtained organic matter on, generally, there is none. But from the perspective of its acquisition, there is. Some organisms consume others, while others utilize organic matter reserves. Therefore, it is more correct to consider phagotrophs (animals) as consumers, and osmotrophs (fungi and heterotrophic bacteria) as decomposers.