In this lesson, students will begin their study of Michigan ecosystems by first considering the uniqueness of Earth as the only known planet to support life. The presence of the biosphere, the portion of the Earth and the atmosphere that supports life, distinguishes our planet from all others. The biosphere extends from the highest mountain top to the deepest ocean floor. If the Earth were the size of a classroom globe, the average thickness of the biosphere would be less than the thickness of a coat of paint covering that globe.

Variations in the Earth’s climate, topography, and soil create areas that support different types of plants. These areas are called biomes. Examples include grasslands, tundra, tropical forest, temperate forests, boreal forests, and deserts. The state of Michigan is located within the Temperate Deciduous Forest Biome found throughout eastern North America, northeastern Asia, and western and central Europe.

An ecosystem is a community of organisms interacting with one another and the non-living environment. These interactions involve plants, animals, and microorganisms, as well as non-living components including sunlight, air, water, soil, and nutrients. Ecosystems can be as small as a fallen tree in a forest or as large as the Great Lakes region. The relationships within the ecosystems and not the size define them.

Many scientists think of ecosystems in terms of a hierarchical arrangement, where one ecosystem fits naturally within another. For example, the rotting log ecosystem may be part of a lowland evergreen ecosystem, which is embedded in a northern hardwood forest ecosystem, contained within the larger Great Lakes basin ecosystem. By extending this thinking, we can conclude that the Earth itself is one large ecosystem, containing all of these smaller ecosystems that interact with each other. Ecology is the study of organisms and their relationships with one another and their non-living environment.

By examining types of vegetative landcover in Michigan and wildlife habitat offered by each, we can view ecosystems on the scale of landscapes. Examples of naturally occurring landscape-scale ecosystems include forests, wetlands, lakes, rivers, prairies, and coastal dunes. Other landscape-scale ecosystems are more heavily influenced by humans, including agricultural lands, as well as urban areas (cities and suburbs).

Ecosystems change over time. This change in ecosystems can take place naturally over time through succession, or the natural progression of change may be altered by human disturbance. Ecosystems that have been altered by natural or human-caused disturbances may sometimes be restored by human intervention, restore themselves, or change into a different type of ecosystem altogether. Part of the process of ecosystem change is the succession of plant communities. For example, a once-bare crop field left fallow for years will first support annual weeds and flowers. Later, perennial plants invade, followed by shrubs and trees, which some day may make a forest. Natural disturbances may also cause succession to move backwards, such as a fire returning a forest to bare ground.

In Michigan, we also observe changes in freshwater ecosystems (these are rivers, inland lakes, wetlands, and the Great Lakes). Over hundreds or thousands of years, lakes may slowly fill with sediments, growing warm and shallow. The changing conditions allow for invasion of cattails and other wetland plants. Over time, the lake could become a marsh (grass dominated), or swamp (tree dominated), and someday eventually support a forest. Nothing on Earth stays the same —ecosystems are always changing.

Human interaction within ecosystems is an important aspect of understanding ecosystems. Humans have the power to change the environment, more than any other living organism. Humans manage ecosystems such as farms, forests, gardens, and lawns – in order to meet society’s real and perceived needs. In recent years, science and technology have made it possible for the world to support far more humans than was previously possible and for some to enjoy a more comfortable lifestyle. These comforts have come at a price. Lack of careful consideration to the long-range effects of particular actions has sometimes led to undesirable environmental changes. For example, in the process of managing ecosystems, people destroy many of the “native” plants and animals so that the plants and animals they value most (corn, red pine, Kentucky bluegrass, etc.) can grow unimpeded. The result is that ecosystems altered by people (i.e., cleared land, planted forests, urban parks, lawns, and farm fields) are generally less diverse than unaltered ones (potentially resulting in the loss of species).

Students should understand how their use of natural resources directly or indirectly impacts the environment and how ecosystems might be managed wisely so that the needs of society’s growing population and desires can be met without jeopardizing the well-being of future generations. Throughout this unit, students should be encouraged to evaluate everyday examples of resource consumption (what to eat for lunch, buying a new toy, using paper products at school, etc.) in terms of their potential impact on the natural environment. Finally, students should be challenged to think of consumer purchase decisions that might not impact the environment in any way. Students should be able to differentiate between examples of consumer choices that do or do not jeopardize the needs and well-being of future generations.