Congratulations! You have now advanced to the third and final level of ecology, where we will explore the interactions between communities and their physical and chemical environments. In this section on ecosystem ecology, you will learn more about how energy from the sun flows through every living thing, and about how life is connected to all of the infamous chemical cycles you learned in the 5th grade. Even better—as if you aren’t excited enough—we will provide the answer to one of nature’s biggest mysteries: "Why are there so many plants on earth?" That’s right, folks. Fasten your seat belts.
HabitatsBefore we get too far into this business, let’s make sure you understand exactly what an ecosystem is. No, we are not trying to insult your intelligence.
If you have been on this ecology roller coaster with us since the beginning, you learned that populations are groups of interacting organisms of the same species. Then, you learned that communities are groups of interacting populations of different species. This means that a community consists of all the living things, sometimes called biotic factors, in an environment. An ecosystem, the next ecological level above communities, includes all of the living and nonliving things, sometimes called abiotic factors, in an environment.
The abiotic portion of an ecosystem is called a habitat. It consists of all of the chemical resources, like soil, water, air, carbon, nitrogen, phosphorous, and Twinkies, and physical conditions, like temperature, salinity, moisture, humidity, and sunlight, of an environment. Ecosystem ecologists study how communities interact with their habitats, specifically how things like energy and chemicals get into and out of ecosystems. We will start with energy. Onward and upward, young Shmooper. Next.
Both abiotic and biotic factors in a habitat can affect the evolution of an organism. A great example is sexual selection, where members of one sex drive the creation or maintenance of certain traits in the other. Examples include the following: deer antlers, bird coloration, and giraffe necks.