Earth, the most beautiful planet, is loaded with a plethora of flora and fauna. Various types of terrains from the chilly Arctic circle to the dry Atacama, from the Amazon rainforest to the hot Sahara desert. For us, this type of diversity in terrains provide us with majestic land formations and various oceans and water bodies which provide animals and humans with all the necessities. With animals comes a chain in which animals and plants are fed on which provides energy and releases energy at the same time this phenomenon is called the food chain. This starts from producers, the ones who take energy directly from the sun to make food. Primary consumers rely on producers for food. Secondary consumers then eat primary consumers and the chain goes on until it reaches the tertiary or quaternary consumer. Let’s take an example of a Savanna food web :
The picture shows a perfectly constructed food chain, we have grass as producers, insects and animals like wildebeests, gazelles and impala as primary consumers and secondary consumers in the form of aardvarks, mongoose and pangolin. But the most important part of the food chain would probably be the tertiary and quaternary consumers such as servals, cheetahs and wild dogs. Quaternary consumers are the top predators who do not have predators other than humans hunting them or dying off due to climate change. These predators include hyenas, lions and leopards. These consumers eat all the lower levels of the food chain but will never get eaten themselves. Humans also belong to quaternary consumers. But have you ever imagined what will happen if we remove all the top predators eg Lions and hyenas and so on from the savannah? There will be a huge increase in the herbivore population which will drive all the grasslands out as the spike in herbivore population will increase the amount of grass and shrubs eaten or I'll make it even easier for you:
The difference is visible by the above picture when there are no predators in an ecosystem, herbivores grow in population and graze on grasslands and shrubbery until there's none remaining, this is called overgrazing. So as I mentioned above if we remove the predators from the savannah ecosystem animals like cape buffalo, gazelle's and wildebeests will graze on the savannah grass and seeds not allowing them to grow properly again this also cause drought-like conditions and also soil erosion. That's the main reason why carnivores are necessary to keep the herbivore population in check.
What is a Trophic Cascade?
A trophic cascade is a natural phenomenon of exclusion of a top predator from a food web which causes a huge imbalance in the ecosystem structure and its nutrient cycling. The perfect example of a trophic cascade is the introduction of wolves in the Yellowstone National Park, wolf population was wiped out in 1926 and after that elk population grew quite large as there were no natural predators to keep a check on them. This rise in population caused overgrazing and soil erosion which damaged the soil profile so much so it even caused the rivers to change their course.
But during the 90s the wolves were reintroduced as the park finally decided to deal with the huge populations of herbivores and to control their population, this change hugely contributed to the environment as elks who loved to graze without fear in valleys and gorges have started to avoid going there as wolves will be able to trap them easily. Elks also started to stay away from river banks which finally allowed the trees and plants alongside the river banks to thrive again, beavers ecosystem engineers provided ecological niches for other small insects and fishes. The dams beavers build provide ecosystems for otters and various other fish species. Wolves are known as keystone species as they have a huge impact on their food web.
Humans and animals have been coexisting for millions of years and we've wiped out a huge population of predators due to them hunting on livestock which ended up causing huge problems in the world.
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