Why is there more stability in a large food web then in a small food chain?

Answer 1

In a large food web, there are more producers and consumers, so if one branch experiences a shift in numbers, it doesn't affect the rest of the web as much. In a small food chain, the consumers have so few choices; if one of those choices is eliminated, the survival of the consumers is jeopardized. Diversity. Let's say a food chain is made up of one kind of plant, one kind of herbivore, and one kind of carnivore. If there's a drought and the plant dies off, the herbivores have nothing to eat and they starve, and then the carnivores have nothing to eat. Or, if disease kills off a few herbivores, the carnivores will drop in population due to having less to eat.This means that in the next season there will be many more herbivores than carnivores (due to prey species' high rate of reproduction) and this surplus will deplete the plant supply, meaning that in due time the herbivores will have nothing to eat, and they will die, which means that the carnivores will have nothing to eat... in essence, small fluctuations spell collapse for the entire ecosystem. In a larger food chain, there will be some species of plants that are more drought-resistant than others and those will feed the herbivores. Certain species of herbivores that are resistant to disease will remain to feed carnivores after other herbivores have died from disease. Et cetera.