The Importance of Primary Producers

Hopefully, everyone is aware by now that not only are plants far more abundant than us, but we would not be alive without them.  The Earth is covered in plants and has been for many eons. They produce oxygen, and are a main source of food for not only us, but countless groups of animals.  In my biology class, we’ve learned a lot about the importance of plants and the rarity of large animals. Apart from being very interesting on its own, there were surprising health implications that I would love to share!

Trophic levels represent an organism’s level in their ecosystem and specifically in the food chain.  The first level is primary producers, which in a nutshell is everything that becomes food for some other kind of organism, but feeds on no organisms itself.  The biggest group of primary producers is obviously plants. The next tropic levels are consumers, including primary, secondary, and tertiary consumers where primary are herbivores, secondary are omnivores, and tertiary are carnivores.  The highest level is the decomposers, which feed on dead organic material after the producers and consumers die. There are countless types of relationships between and within the levels that make the system that is the Earth run as it does today.

Most people know that there are far more plants than herbivores, more herbivores than omnivores, and more omnivores than carnivores.  These distinctions also include size. Essentially, the bigger an animal, the more rare it is. Why is this? You may come up with a simple, obvious answer—as the levels of prey get bigger, the predators themselves need to be bigger in order to be able to physically consume their prey.  But then what about a herbivore, which feeds on plants much larger than itself, or big animals that feed on tiny things. For instance, take the baleen whale, which feeds on phytoplankton so small that they can’t be seen; surely the whale is not as large as it is as a result of its diet!

The answer to the question of why higher trophic levels have smaller numbers lies in the concept of energy flow.  The first law of thermodynamics says that energy is conserved. However, when plants receive energy from the sun, they only take in 1-2% of the overall energy to conduct photosynthesis.  When the next trophic level consumes the plants, they only absorb less than 10% of the energy contained by the plant. As each trophic level consumes the one below it, less than 10% of the remaining energy is consumed.  With this process, we can see that energy transfer is highly inefficient. Therefore, by the time it gets up to the level of tertiary consumers, there is not nearly enough energy to support as many organisms as are contained in the levels below.  Additionally, because larger animals require more energy to move and live, the effect of energy inefficiency is compounded. Not that this is a problem; everything is organized perfectly in nature, and if this was not so, then predators could theoretically increase and deplete more of Earth’s resources.

How does this relate to health, you ask?   Well, it has important implications for diet.  We can see through energy transfer that the most energy is actually contained in plants, rather than meats higher up the food chain.  Therefore, this knowledge is almost like a hit back at people who say that vegetarians are missing essential nutrients by not eating meat, or that a vegetarian diet is not sustainable.  I’m not a vegetarian, but this lesson showed the wonders of plants and the powers and variation they possess. There are social implications as well—could harnessing the energy from plants and making farming more efficient stop the mistreatment of animals?  Or contribute to an end to world hunger? Obviously the problem has many more scientific complexities that I did not delve into here, but it is something to consider nonetheless.

In another health tangent, my interest was piqued by the discovery of the brand Gaia Herbs, which preaches “a living laboratory” and a celebration of the symbiotic relationship between people and plants, represented by the production of organic herbs, health supplements, and homeopathic products.  What if all producers of food and medication viewed plants as a “living laboratory?” How would our health and society be different today?

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