Dynamic Wetlands

Grade Level: 9-12


Source: Nebraska Earth Systems Education Network, School of Natural Resources
By Roseanne Williby

Purpose

To increase student awareness of the value and importance of our wetlands

Background

What is a wetland?

Wetlands are called one of the world's most productive ecosystems. They produce more plant and animal life than woodlands or prairies. Characteristics, like water levels, naturally change seasonally and annually. Wetlands are in transition between aquatic and terrestrial systems where the water table is usually at or near the land surface or the land is covered by shallow water.

Wetlands go through a wet/dry cycle that is essential to its functioning. When it is dry, wetland plants start growing. These plants provide food for water birds and wildlife. When the water returns decomposition of dead plant matter is accelerated. This process provides nutrients for algae, insects and invertebrates.

Human intervention, like permanent drainage or filtering, can cause wetland deterioration and permanent damage. Since colonial times, America's wetlands have shrunk from 215 million acres to fewer than 95 million acres. So great is the concern that the Department of the Interior is working with other Federal agencies to develop a comprehensive set of recommendations to achieve the national objective of " no net loss of wetlands."

Along with strengthening programs and regulations that protect, maintain, and restore wetlands, an increase in public understands of the value of wetlands is also necessary.

Why are wetlands important?

Along with Nebraska, Alaska, Arkansas, Illinois, North Dakota, Ohio, Texas, and Wisconsin consider their wetlands a primary resource. 80 Percent of the nation's coastal fisheries are dependent on wetlands for spawning, nursery areas, and food sources. Over one third of the 564 plant and animal species threatened or endangered in the United States utilize wetland habitats during some time in their life cycle. They also serve as natural reservoirs, as ground-water recharge areas, and are important in protecting the quantity and quality of ground water used as a source of drinking water. Wetlands can reduce flood peaks by 80 percent, reduce erosion, and trap sediments. In addition, they supply timber, sports fishing, and water fowl hunting.

Wetlands are not all alike. Nebraska has four major categories of wetlands located across the state. For more information check, "Guide to Nebraska's Wetlands and Their Conservation Needs", a free guide from the Nebraska Game and Parks Commission.

Optional Activity

As a means of introduction, obtain and view a video of Nebraska Wetlands. A video can be obtained free from Joanna Halbgewachs, from the RWBJV(Rainwater Basin Joint Venture) Communication Committee, at the Natural Resources Conservation Service in St. Paul, NE. The address is 904 2nd Street, St. Paul, NE 68873, Ph, (308) 754-4462, FAX (308) 754-5504.

Introduction

Since wetlands do not always appear wet, they are not always recognized. Along with the presence of water at or near the surface and evidence of hydrophytic (water-loving) vegetation, wetlands have hydric soils present. Hydric soils have a spherical soil component surrounded by air spaces occupied by water.

Materials

Procedure

Construct two wetlands: one with constant drainage and one that maintains a well-saturated soil. Maintain the wetlands for two weeks (minimum) and observe daily the soil, plant life, water level, and animal life if desired.

  1. Take one of the containers and using the end of a scissors create 5 drainage holes. When this container is completed it will be placed on top of the two pencils in the pie pan to allow for drainage of the wetland.
  2. Place a layer of small gravel in both containers.
  3. Place a layer of sand and then soil in both containers. Create a slope by packing the materials higher on one side within each, leaving a lower spot on the one side.
  4. Add the mixture of sphagnum moss and humus as a thin layer on the top.
  5. Place the plants evenly throughout the containers.
  6. Add the water gradually down the side until it reaches the lowest soil level. Continue to replace water as necessary to maintain this water level in the non-draining container. Whenever water is added to the non-draining container, also add water to the drained container. In every respect treat these mini-ecosystems the same.
  7. If animals are added be sure to cover with a screen or netting. Otherwise it may be left uncovered.
  8. Place containers in a location with filtered sunlight.
  9. Make daily observations of the plants, animals, and soil.
  10. Take a small sample of the soil and mix with distilled water and determine the pH, then interpret as acid or alkaline.

Dynamic Wetlands Data Sheet

Day
Plants
Animals (Optional
Soil pH
Acid or Alkaline
1        
2        
3        
4        
5        
6        
7        
8        
9        
10        
11        
12        
13        
14        
15        


Conclusions

  1. a. What changes if any did you observe between the plants in the two containers?
    b. What may have been the cause?
  2. a. What changes if any did you observe between the soils in the two containers?
    b. What may have been the cause?
  3. (Optional) a. What changes if any did you observe between the animals in the two containers?
    b. What may have been the cause?
  4. What absorbs the pollutants in the terrarium?
  5. What are two benefits for constructing a wetland?
  6. What provided nutrients for the plants?
  7. How do the wetlands help to clean the water?

Teacher Hints

How To Prepare for This Activity

This activity should be placed early in the study of water resources for it establishes a basic understanding of what a wetland contains and how it may vary over time.

Since wetlands are defined as those areas inundated or saturated with water frequently enough to support a prevalence of vegetation that are typically adapted for life in saturated soil, it may be helpful to lead a discussion of how well each of the two created wetland models meet that description. Remember to keep in mind that temporary and seasonally flooded wetlands don't contain water all year round. They go through a wet/dry cycle that is essential to their productivity and functioning.

Material Acquisition

Since large containers are needed for each wetland it may be helpful to use gallon size plastic milk jugs, or larger plastic water containers that are purchased in grocery stores. Since budgets can be small and plants and special soils can be expensive, students may be asked to each contribute one of the items. Large groups of four or more per wetland model can also minimize the need for materials.

Once the wetland is assembled, observations can be made daily in fifteen minutes time.

Enhancing this Activity

When developing the importance of wetlands, additional research and attention can be directed in the following areas:

Benefits of the Activity

Regardless of age, even high school students enjoyed creating and monitoring the change of the two wetlands. When coupled with discussion and an enhancement activity, the investigation of wetlands provided a new awareness for students that stimulated an appreciation for these water resources.

Too often an understanding of water resources does not extend far beyond the teaching of the hydrologic cycle. With this better understanding of the wetlands as an ecosystem that needs preservation, a sense of stewardship is developed. A stewardship that helps students to appreciate the beauty of nature where they live.