Unit Goals While our surrounding landscape may appear unchanged when casually observed from day to day and year to year, the biological communities and the geographical features upon which they depend are indeed constantly changing. In reality, there is not a 'balance' in nature that holds it steady, but instead a vibrant ecosystem that reacts to a variety of forces and allows populations and communities to rise and fall as conditions permit. In this unit the students will recognize these interactions by studying River Bend's woodland ecosystem, make an assessment of current conditions, and then gather further information to help future students to gauge various impacts and changes in River Bend's ecosystem over the years to come. This unit is specifically designed to address appropriate AAAS Project 2061 benchmarks as well as fifth grade Minnesota Academic proposed Science Standards. Please email us for more information. Summary Before your visit, please review with your students: Basic principles of scientific investigation The concept of an ecosystem The basic concepts of biological succession Forces that cause change on the landscape, primarily erosion and weathering. The general types of tests and observations that we will be making during the visit Importance of dressing for the day's weather conditions At River Bend: During the introduction we will review the above material Students will be divided into teams, about 3-4 students per team Part of the field experience will be spend studying the biological communities in River Bend's Big Woods and part examining the physical factors in the ecosystem, particularly geographic changes in the Straight River valley. Preparation: recent climate pattern current climate data Forest study - at each group's study plot (Forest worksheet) (Forest Instruction Sheet): canopy cover tree diameter basal area understory density River study - at series of points along "Great Bend" of river (River worksheet) (River Instruction Sheet): Tributary stream data stream height stream width Straight River data river width turbidity soil pH water pH In the closing we will: Inquire about students' results and provide local perspective Inform the students about next year's experiences Talk of upcoming events at River Bend Invite the students to return on their own with family and friends Back in the classroom: Monitor results from other classes and from previous years Research terrestrial habitat stewardship issues

What is an ecosystem?

An ecosystem is a self-sustaining, self-regulating community of plants and animals interacting with one another and the physical environment upon which they are dependent. Non-living parts of the ecosystem include sunlight, air, water, and the land.

How are ecosystems dependent on the physical environment?

Every living organism has needs and preferences when it comes to their surroundings. Some animals are very specific, others can live almost anywhere (or have sub-species that can). As the physical surroundings change, so do the plants and animals that live there. It can work the other way, too, as plants and animals can have impacts on their surroundings that effect the ability of other plants and animals to live there.

What are some examples of how biological (living) parts of an ecosystem change from year to year?

From bare land arise plants that prefer open space and plenty of sunlight. As those plants mature, other plant species move in as well, eventually shading out the early plants before themselves losing out to other species. Meanwhile, every stage of plant growth also has certain species of animals associated with it. For example, white-tail deer thrive in areas of early succession with plenty of short shrubs, bushes, and grasses, but don't fare as well in the deep, tall forests with little undergrowth that come later. On the other hand, raccoons do better in old, mature woods but not so well in a young forest with few old, dead trees in which to live.

Here is a good web page that tells more about forest succession in Minnesota.

What are some examples of how the landscape in an ecosystem changes from year to year?

The forces of wind, rain, moving water, gravity, sunlight, temperature, plant growth, and animal activity are always changing the physical landscape around us. Two primary categories of these changes are erosion and weathering.

Erosion Erosion is simply the removal of ground materials (soil, sand, rocks) by water or wind. While most people are already familiar with this term, it's often easy to forget about deposition. Everything that is washed away has to be deposited somewhere else. These are the most obvious natural forces and they are still changing our landscape today.

Weathering Weathering refers to different forces that are changing rocks in a very short time, even day to day. If you throw a rock down on the sidewalk and the rock breaks, that's a type of weathering called physical weathering. Physical weathering happens whenever some force breaks a rock into smaller pieces by forcing them apart. Another type of weathering, called chemical weathering occurs when something "eats away" at a rock rather than breaking it apart, such as water dissolving a rock or sunlight changing the color of a rock.

What are some basic principles of a scientific investigation?

Science is often a process of performing scientific tests to investigate and learn things. For example, we can test a sample of water to see how much oxygen is present in a pond. In order for such tests to have any meaning, there are some rules (or "principles") that we must remember:

• Follow all directions and safety instructions for a test carefully.
• Do each test the same way each time you do it.
• When measuring something, be as exact as possible.
• Doing the same test several times and taking an average can give you a better answer to question than doing just one test.

What do we need to remember when we visit River Bend?

1. The quieter we are, the better.
2. Listen to your leader.
3. Be careful and safe with all tools and equipment
4. Raise your hand if you have something to say.
5. Do not pick anything unless given permission.
6. Stay where you leader asks you to be.
7. Be respectful of nature - and of each other!

2011 Data Reports

Send us your ideas by email!

• Create model of a river valley ecosystem out of some media, and another predicting how it will look 20 years from now.
• Monitor the results from other classes posted on this site to include in graphing. (In the future, most value will be gained by comparing results from different years).
• Research other types of terrestrial ecosystems, in North America and around the globe.
• Monitor and research current news stories on land changes, such as mud slides, sink holes, bank erosion, etc.