Bio.2.1.4
Explain why ecosystems can be relatively stable over
hundreds or thousands of years, even though populations
may fluctuate (emphasizing availability of food, availability
of shelter, number of predators and disease).
hundreds or thousands of years, even though populations
may fluctuate (emphasizing availability of food, availability
of shelter, number of predators and disease).
Availability of Necessities
Some organisms are capable of producing exponentially. Their population could be in the millions, billions, or even trillions! But there's something that keeps that from happening. Without food or shelter, an organism will die. If there is too many on one organism, all of the food supply and shelter will be gone. This is why ecosystems have carrying capacities. This refers to how many organisms that environment can support. That's why populations usually stay in check if the balance of other aspects of nature are working properly. Every now and then, there is a drought, flood, fire, or other natural disaster that sweeps over an ecosystem. While it might damage and lower population numbers, the ecosystem can remain stable. They can remain stable because even though there is less resources for the organisms, there are also less organisms. As the food supple increases, so will the population. They work and in hand.
Predators
Just like with the amount of food produced and the population or organisms, predation is similar. In the chart to the left, you can see that as the number of deer (prey) rose, the number of wolves (predator) also rose shortly after. The number of predators usually directly follows the number of prey. This helps to keep the ecosystem stable because it prevents over population.
Disease
Disease can interrupt ecosystem balance. Disease can dramatically and quickly lower population. Sometimes it's needed, and other times it can almost eradicate a species. Disease in the wild can be uncontrollable and just has to take it course. Sometimes a population can slowly build back up. Sometimes the population will remain low for a very long time and may never rise again. An ecosystem can remain stable by compensating for what was lost. If that organism did something special, another organism might try to make up for it or the ones remaining might work very hard.
Ecosystems are extremely complex and have many systems that keep everything in motion. While in some instances some of the processes might slow down, they will find a way to continue and provide.
Carrying Capacity
The document below is an activity that will help teach carrying capacity. It deals with the population of minnows in a lake. Scroll through or print it out and have fun!