Biomass in Ecology and Ecosystems

Biomass, in terms of ecology, can be defined as the various kinds of living organisms found in an ecosystem or environment. It consists of a producer, a list of consumers, and finally, the decomposers. It can also be defined in terms of masses of one or more than one species (species biomass) or the mass of all the species living in a community (community biomass). Biomass includes all microorganisms, plants, and animals.

Biomass Definition

In ecological terms, biomass is defined as the total mass of all the living biological organisms living present in a given ecosystem at a given time. The reason to measure biomass determines the parameters of how to calculate the biomass of a region. In most cases, biomass is calculated as the total natural mass of the organisms. For example, in the case of salmon fishery, the total wet weight of all the salmons determines the total biomass. However, in other applications, only the tissue masses of the organisms are considered, and the bones, teeth, horns, and shells are excluded. In some other calculations, the mass of organically bound carbon atom (C) is calculated.

To date, the total live biomass on earth is calculated as 550-560 billion tonnes C, and the total primary production of biomass annually is more than 100 billion tonnes C. The total biomass of bacteria can be almost equal to that of the plants and animals in total. The total DNA base pairs on earth have a total weight of 50 billion tonnes, as approximated by taking global diversity into consideration.

Various Parts of a Biome

A biome is the total number of living organisms living in an ecosystem. Every ecosystem consists of the following parts of the biome. 

• Producer

The living organisms that can produce their own food are called the producers. In most ecosystems, plants comprise of the producers. They make their own food in the form of starch by performing photosynthesis in the presence of sunlight. However, there are many other organisms like algae and some bacteria that can make their own food. All these organisms are considered as the producer of food in the ecosystem.

• Primary Consumer

The primary consumers are those living organisms that cannot produce their own food but live on the producers. The producers are the primary food source for primary consumers. The primary consumers mainly consist of the herbivores, and the omnivores in any ecosystem. For example, cows, buffaloes, giraffes, elephants are all primary consumers.

• Secondary Consumer

Secondary consumers also cannot make their own food. They rely on primary consumers for their primary food source. The secondary consumers are mainly carnivores or omnivores, and they feed on the herbivores. For example, tiger, lion, jackals, bears, and snakes are all secondary consumers.

• Tertiary Consumer

Tertiary consumers also cannot make their own food. They feed on secondary consumers as their primary food source. The tertiary consumers are also carnivores or omnivores, who feed on other carnivores. For example, kites and eagles are tertiary consumers.

• Decomposer

The decomposers feed on the dead and decaying organic matter generated by the producers, primary consumers, secondary consumers, and tertiary consumers. They generally do not kill the organism but feed on the decaying materials generated from the dead bodies of these organisms. Examples of decomposers will be bacteria, fungi, vultures, to name a few. 

In addition to these parts of the biome, there are other types of organisms that make up the ecosystem. An example of these organisms is parasites. Parasites extract their nutrient from the body of other organisms and can harm the host organisms in the process. There are two types of parasites- ectoparasites and endoparasites. Ectoparasites live outside the body of the host. For example, leech, that sucks blood from the host organism. Endoparasites live inside the body of the host. For example- any pathogenic microorganism like bacteria, fungi, protozoan, virus, etc. which are the causal agent of several pathogenic diseases.

Pyramid of Biomass

According to the pyramid of biomass definition, it is the relationship between the biomass and its respective trophic level by calculating the total biomass at each trophic level in an ecological community for a defined period. It can be measured in terms of the total biomass in each trophic level per unit area. The units in which they are measured are gram per meter square or calories per meter square.

In a pyramid, the bottom rung comprises of the producers (or the autotrophs). It is succeeded by the primary consumers, secondary consumers, and so on till it reaches the apex predators at the top of the pyramid (also known as the heterotrophs).

The pyramid of biomass can be upright or inverted, depending on the type of ecosystem. For example, a forest ecosystem shows an upright pyramid, with the mass of the producers being the highest amongst all the living organisms in that ecosystem. However, a pond ecosystem will make an inverted pyramid of biomass since the producers in that ecosystem, the phytoplankton contributes the least to the total biomass of the system. The consumers make the maximum biomass. That is why the phytoplankton in a pond reproduces very quickly, although they have a shorter life span. 

Example of Biomass - Terrestrial Biomass

The terrestrial biomass comprises of the ecosystem that is found on land. The base of the ecological pyramid consists of the largest contributor to the total biomass, the plants as the producers. Some of the examples of these producers are grass, shrubs, and trees. These plants have higher biomass than the consumers that eat them- cows, zebras, giraffes, buffaloes, deer, small insects, and many more. The secondary consumers like the tigers, lions, bears, snakes have lower biomass than the primary consumers. In a grassland ecosystem, grasses are the primary producers. The pyramid of biomass is broadest at the bottom and tapers at the top.

Example of Biomass - Ocean Biomass

In ocean biomass, the phytoplanktons are the producers. They reproduce rapidly but have a short life span. The primary consumers, the zooplankton, have larger biomass than the phytoplanktons, making the pyramid of ocean biomass an inverted type. In fact, the zooplanktons are the largest contributor to the total biomass of the ocean ecosystem. The tertiary consumers, for example, the herrings and krills, are lesser in biomass than the zooplankton.  The fourth trophic level comprises predatory fishes like the seals, gannets, and swordfish. The pyramid tips off with the apex predators like the baleen whales or the shortfin mako sharks.

Conclusion

Biomass comprises the organic matters of all the living organisms in an ecosystem. the interrelationship amongst the different rungs of the biomass pyramid determines the ecosystem of that place.