Prairie Ecosystem - Gizmos

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Learning Objectives

Students will:

· Identify the producer in an ecosystem.

· Classify consumers as herbivores or carnivores.

· Investigate the interdependence of the organisms in an ecosystem.

· Determine what each organism eats based on the results of experiments.

· Explore the long-term effects of changes to the ecosystem.

Vocabulary: Prairie Ecosystem

Carnivore – an organism that eats only animals.

· Examples of carnivores in North America are wolves, coyotes, mountain lions, hawks, eagles, and snakes.

Consumer – a creature that feeds on organic matter because it cannot produce it.

· All animals, all fungi, and even a few plants are consumers.

· A cow chewing grass, a person eating steak, and an earthworm digesting manure represents consumers in action because, in each case, the animal is eating organic matter.

Ecosystem – a community of living things along with their natural environment.

Equilibrium – a state of balance and stability.

Extinct – no longer in existence. (An organism is extinct if it has died out.)

Food chain – a sequence of organisms in which each organism feeds on the one below.

· Example: Grass à Cricket à Frog à Snake à Hawk.

· In this food chain, crickets eat grass, frogs eat crickets, snakes eat frogs, and hawks eat snakes.

Herbivore – an animal that eats plants.

· Examples of herbivores in North America are deer, elk, bison, beavers, and crickets.

Organism – a living thing.

Population – all the organisms of a certain kind in a particular place.

Prairie is a flat or gently hilly land dominated by grasses and has few or no trees.

· The word "prairie" generally refers to an area of North America east of the Rocky Mountains.

Producer – an organism that can convert simple inorganic matter (such as water and carbon dioxide) into organic matter (like sugar and protein).

· Plants are producers because they use the energy of the Sun to create organic materials from carbon dioxide and water.

Scientific Background

An ecosystem combines the living and non-living elements of a particular environment. An ecosystem consists of two parts:

· Community – all the living things, or organisms, in the ecosystem.

· Habitat – the physical environment, including the landscape, soils, water, and climate.

Within an ecosystem, each organism interacts with other organisms. One of the simplest types of interactions occurs when one organism eats another. Food chains can represent feeding relationships. In a food chain, each organism eats one other organism. Food chains generally begin with producers, organisms that don't depend on other organisms for energy. The most familiar producers are plants, which generate energy from the Sun. Organisms that rely on other organisms for energy are called consumers. Herbivores are consumers that eat plants, carnivores eat animals, and omnivores eat plants and animals.

The food chain in the Prairie Ecosystem Gizmo is Grass à Prairie dog à Ferret à Fox. Changes to the population of any organism in the food chain will affect the others. For example, removing prairie dogs will increase the grass population and decrease the ferret and fox populations. Removing ferrets will hurt foxes, help prairie dogs, and hurt the grass.

Of course, real ecosystems are much more complex. Food webs are diagrams that show all the food sources for each type of organism.

Environmental Connection

The American prairie was once a great grassland stretching from the Rocky Mountains to Indiana, from Texas to central Canada. Native grasses adapted to frequent droughts by growing deep root systems to extract moisture from the soil. When European-American settlers first started exploring the region, there were as many as 50 million bison (commonly called buffalo) and over a billion prairie dogs living on the prairie.

But rich prairie soils are also prime agricultural land, and since the late 1800s, much of the prairie has been fenced off and converted to farms and ranches. During the 1870s, the great bison herds were systematically slaughtered until only 25 bison remained alive in 1894. Species such as pronghorns, prairie dogs, and burrowing owls declined due to hunting, poisoning, and habitat loss. The black-footed ferret population was reduced to only 18 animals by 1986. Today less than 2% of North America's original 3.6 million square kilometers (1.4 million square miles) of prairie are undisturbed.

Today many prairie species are making a comeback. Bison now number over 500,000, and about 700 black-footed ferrets are in the wild. Agricultural scientists are finding ways to convert annual crops, such as wheat, sunflowers, and sorghum, into perennials with deep root systems that reduce soil loss. The prairie will never be the same as it once was, but with attention and care, what is left can be preserved.

Gizmo Overview

In the Prairie Ecosystem Gizmo, you will investigate life in a prairie dog town. In this simplified ecosystem, prairie dogs eat grass, ferrets eat prairie dogs, and foxes eat ferrets. You can alter any population and then play the simulation to see how populations respond to the change.

The Student Exploration sheet contains three activities:

Ø Activity A – You will investigate how grass availability affects the other populations.

Ø Activity B – You will determine what each animal eats and display that information in a food chain.

Ø Activity C – You will investigate the long-term effects of sudden changes to the ecosystem.

Click the image below to begin your exploration.