Ecology Lab Essay

Custom Student Mr. Teacher ENG 1001-04 30 December 2016

Ecology Lab

The ecosystem is composed of the producers, consumers, decomposers and the nonliving or abiotic components (Ecology, 1997). The producers are the plants that produce food through photosynthesis. The consumers have two types: herbivores or primary consumers and carnivores or secondary consumers. The herbivores are the animals that only eat plants while the carnivores are the animals that only eat meat. The animals that eat mixtures of plants and meat are called omnivores. Human beings are considered as omnivores. Fungi and bacteria are some of the decomposers in the ecosystem.

The nonliving or abiotic components of the ecosystem are consisting of the dead organic matter and nutrients found in soil and water. What if all humans became vegetarians? Would it be beneficial to the earth or ecosystem? First of all, let me discuss the principle behind the food chain, food web and energy flow. “In a food chain, the sun’s energy is used by plants to make food. The plants are eaten by herbivores, which, in turn, are eaten by carnivores. Both plant and animal substances decompose when they die and return mineral substances to the soil where bacteria use them to provide carbon dioxide gas.

Carbon dioxide and the sun’s energy then enter the chain again. ” (Food Chains, 1992) But the situation in the ecosystem is not as simple as stated in the food chain so it is more advantageous to use the principle of food web. For example, a rat ate a grain from a plant, and then the rat was eaten by a snake. But the snake was also eaten by a honey bunger. The honey bunger serves as an intermediate link which is a higher level of predator than the snake. This makes food web more complicated. Also, energy is transferred in a food web. This transfer of energy in a food web is called energy flow (Energy Flow, 2008).

Energy flow involves several trophic or feeding levels. When energy is passed on from one trophic level to another trophic, about 90% of the energy is lost due to respiration and some are being lost as heat in the environment. The top consumer of the food chain is the one who receives the less amount of energy. Energy in the food web is measured in terms of heat. The law of thermodynamics is also used to measure the energy lost and gain by the trophic levels. Another concept that can be useful in answering the question is the ecological pyramid.

“An Ecological Pyramid (or trophic pyramid) is a graphical representation designed to show the biomass or productivity at each trophic level in a given ecosystem. Biomass pyramids show the abundance or biomass of organisms at each trophic level, while productivity pyramids show the production or turn-over in biomass. Ecological Pyramids begin with producers on the bottom and proceed through the various trophic levels, the highest of which is on top. ” (Ecological pyramid, 2008) The trophic level with the highest number of population is the producer while the top most trophic level has the lowest number of population.

Would it be beneficial if all humans became vegetarians? The above principles and information can be used to answer this question. It would not be beneficial if all humans will be vegetarians since this act might cause imbalances in the food web and in the ecosystem. Humans also contribute in the maintenance of the numbers of species in a given ecosystem. If humans will only eat plants, the population of the animals we are eating like cows, pigs and chickens will grow. Since these animals are herbivores or primary consumers, this will result to greater competition for foods derived from plants.

The population of secondary consumers will be outnumbered by the primary consumers. This will in turn cause another growth in the population of primary consumers since the number of secondary consumers will not be enough to feed on the primary consumers. Again, this will cause disruption of the ecological pyramid. In terms of energy flow and thermodynamics, it is still not beneficial if all human beings will be vegetarians. Given with two scenarios: (a) humans feed directly on plants and (b) humans feed on animals like cows or chickens that also feed on food from plant sources, in what scenario can humans receive greater amount of energy?

In the first scenario, humans are included in the trophic level next to producers which are the primary consumers while in the second scenario, humans are considered as secondary consumers. Also in the first scenario, the humans’ only source of energy is the producer which is the food from plant while in the second scenario; the humans’ sources of energy are the animals and the plants that were eaten by those animals. Even though 90% of the energy acquired by the animals that feed on plants is lost due to respiration, there is still a remainder of 10% that the human can receive when he/she will feed on those animals.

Summing up and comparing all the energies received by humans in each scenario then we can say that humans can get a 10% higher amount of energy in the second scenario than in the first scenario. Like what was stated prior to this paragraph, the top most consumer of the food web who feed on plants will receive the least amount of energy. Also in the first scenario where humans feed directly on plant foods, lesser amounts of heat and carbon dioxide are released in the environment. In terms of ecosystem productivity, the humans can get higher net productivity when they act as secondary consumers than when they act as primary consumers.

What is net productivity? “Net productivity is the amount of energy trapped in organic matter during a specified interval at a given trophic level less that lost by the respiration of the organisms at that level. ” (Ecosystem productivity, 2004) Humans can indirectly acquire higher net productivity when they eat animals that feed on plant materials. Using all the arguments mentioned, one can conclude that it is not beneficial, for both humans and ecosystem, if all humans will be vegetarians.

We must always bear in mind that all things in excess will not be advantageous or beneficial.


“Ecological pyramid”. 2008. http://en. wikipedia. org/wiki/Ecological_pyramid “Ecology”. 1997. Funk and Wagnalls New Encyclopedia Vol. 9. 12 “Ecosystem productivity”. 2004. http://users. rcn. com/jkimball. ma. ultranet/BiologyPages/N/NetProductivity. html “Energy Flow”. 2008. http://en. wikipedia. org/wiki/Energy_flow “Food chains”. 1992. The World of Animals. Australia: Regency Publishing Group. 9

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