Environmental Science: Ecology

A Closer Look at Ecosystems

An example of an ecological niche may be as simple as a sunflower growing in your backyard. The role the sunflower plays is that is absorbs water and nutrients for photosynthesis. But look more closely, and you will also see that a sunflower provides a habitat as well as food for bees and insects. Below you will find three fundamental concepts that are essential to the field of ecology. An ecosystem may be large or small. It may be a mud puddle in your backyard or hundreds of acres of forest land. Ecosystems change. They change naturally and in response to human activities and interferences. We will discuss both natural ecosystem changes and changes that are caused by humans. Each living thing in an ecosystem plays a role in the function of that ecosystem. An organism's ecological niche is the role of a species in an ecosystem. It includes all the physical, chemical, and biological conditions that a species needs to live and function in its ecosystem.

ECOSYSTEM CONNECTIONS This diagram shows you how the abiotic and biotic factors of an ecosystem are connected. Abiotic factors are represented by circles; biotic factors are represented by rectangles.

Ecosystem Survival All ecosystems survive by two main processes: energy flow and recycling of matter. Energy Flow Energy flows through an ecosystem in a one-way direction. Energy enters an ecosystem in the form of photons (highly energized light particles) from the sun. It is absorbed and converted by plants through the process of photosynthesis, and then it is stored as energy in plant materials. Consumers then eat the plants and convert the energy to other forms, using it for growth, movement, and reproduction. Along the way, some energy is used by each successive organism. A significant amount of the energy, though, is simply lost as heat to the atmosphere. Once energy is lost as heat, it cannot be recycled. Thus, all ecosystems depend on continual inputs of energy from the sun. The diagram shows you how energy flows in an ecosystem, beginning with the sun. Phosphorous Cycle Unlike energy, matter does recycle in an ecosystem. You are likely already familiar with this fact. Plants and animals use nutrients from their environment to grow. Then, when they die, they return those nutrients to the environment through the process of decay. The diagram will help you visualize this idea. You can follow the arrows to see how the nutrient phosphorus cycles in an ecosystem. We will discuss matter and nutrient cycles more in later lessons.

The Value of Ecosystems

Ecosystems provide us with a number of services and goods. For example, bees that pollinate vegetable crops, soils that filter our groundwater, and tropical seas that provide us with recreational opportunities are all provided by ecosystems. Unlike most things that we purchase with money, however, ecosystem goods and services are priceless because ecosystems are made of multiple natural processes that can easily be disrupted. Unfortunately, this does not stop humans from putting a price on the environment, which can cause extensive problems. For example, scientists estimate that pollinators such as bees provide us with about $20 to $40 billion worth of services every year—the cost of the crops that would not survive without them. In another example, we pay about $20 to take a carload of people into the Grand Canyon. Does this amount adequately reflect the value of the trip? More important, does it adequately pay for the cost of human impact on the natural Grand Canyon ecosystem?

Visualizing Connections

In nature, one ecological factor is the connections of animals in their environment. For example, the owl depends on the mouse for survival; the mouse only survives if it can escape being eaten. To extend this example even further, consider the following points: If all the mice suddenly died off, the owls would have to find a new food source, move somewhere else, or face dying off, too. If all the owls died off, the mouse population might get out of control. Then plants that are in turn eaten by the mice could start disappearing too fast. So, owls dying off could affect many species. If all the trees were lost, then the owls would lose sites for nesting and for hunting. Again, the mouse population might boom as a result, and that too would mess up the balance in the environment you saw. Both animals depend on their environment for a number of other things: air, water, climate, soil, other animals, and plants. They also depend on things being in balance—too many owls or too many mice or not enough trees could shake up the whole environment and keep it from functioning as it should.

LET'S REVIEW!

In this lesson, you have covered the following points: Ecology is the study of how living things interact with the living and non-living components of their environment. Living things are categorized, from simplest to most complex, into the following levels of organization: organism, species, population, community, ecosystem, biome, and biosphere. All ecosystems depend on the abiotic factor solar energy. Other essential abiotic factors of ecosystems include air, water, and nutrients in soil. All the living things in an ecosystem are the biotic factors of that ecosystem. Abiotic and biotic components of ecosystems interact and are connected with each other. Energy flows through an ecosystem, but matter cycles in an ecosystem.

ECOSYSTEMS

The Everglades The Everglades, located in south Florida, is one of the most unique ecosystems in the world. It is home to thousands of plant and animal species, including both alligators, and surprisingly, crocodiles. The Florida Everglades is the ideal environment because it has the perfect balance of fresh and salt water. It is this delicate balance that enables both crocodiles and alligators to coexist in the same location. There is no other habitat on Earth where this can happen. Unfortunately, as the population increases in south Florida, the Everglades ecosystem has been affected. Increased development and withdrawal of freshwater, pollution, and the use of pesticides has negatively impacted the plants and animals that are present here. Scientists continue to study the relationship between the organisms and their ecosystem and hope to be able to conserve this ecosystem for future generations.

Non-living and Living Components of Ecosystems

Two types of components make up Earth's ecosystems: abiotic and biotic factors. Abiotic factors are the non-living things found in an ecosystem such as water, air, nutrients, soil, and solar energy. Solar energy is an essential abiotic component of all ecosystems because it directly or indirectly provides the energy that all organisms need to survive. It is the energy that drives photosynthesis and makes all life possible. Biotic factors are the living parts of ecosystems, such as bacteria, ants, humans, etc. The categories of the biotic components of an ecosystem include: Producers: plants and phytoplankton that produce their own food through photosynthesis or chemosynthesis; Consumers: animals that get their food by eating plants or other animals; Decomposers: mostly bacteria and fungi that break down dead organisms; earthworms are also considered decomposers.

Introduction to Ecology In this lesson, we will begin our study of how living things interact with their environment and with each other. The study of living things in their environment is called ecology. Ecology looks at how living things interact with everything around them, both living and non-living. It includes the study of how living things get what they need from their environment, how the environment is in turn affected by living things, and how humans affect the balances between other living things and their environment. In short, ecology is the study of the connections in nature.

What You Should Know This lesson is an introduction to our next major area of study: ecology. We are leaving the geological sciences to begin our study of the biological sciences. OBJECTIVES Define ecology Describe the interconnectedness between organisms and their environment. Explain the concepts of habitat, niche, and biodiversity. Describe major components of ecosystems. Differentiate between the two major components of ecosystems. Identify and order the levels of organization from smallest to largest: organism, species, population, community, ecosystem, biome, biosphere. Summarize the importance of energy flow and cycling of matter in an ecosystem.

Connections in Nature

You have probably heard it said before that everything in nature is connected. This diagram shows a food web, which is a collection of many food chains within one ecosystem. Both a food chain and a food web show the feeding relationships within an ecosystem. The arrows go from each organism toward the organism that eats it. For example, the nematode eats the fungi, which eats the plant. This food web is a perfect example of how every living thing is somehow connected to other living things in its environment. Not only do the living organisms depend on each other, but they depend on non-living factors such as air, water, soil, and nutrients. And once the bacteria population increases, then the arthropods and nematodes will begin to reproduce more, which will disrupt the ecosystem ... you get the idea. Something that disrupts one organism can disrupt them all.

ecosystem

a community where populations of different species interact with one another and with their non-living environment

biome

a geographical area with similar climate and soils, which contains similar organisms

population

a group of interacting individuals of the same species occupying a specific area

species

a group of organisms that live together and can interbreed

biodiversity

a measure of the variety of species in an environment

organism

a single living thing

biosphere

all of Earth's ecosystems

community

consists of all the populations of different species that live and interact in a given area

habitat

the place where an organism lives and reproduces

ecological niche

the role of a species in its ecosystem

ecology

the study of connections in nature