(Title)alconway.wikispaces.com/file/view/Soils+#+6+Wetland+Soils... · Web viewExplain the difference between mineral topsoil and organic topsoil. 14. Name two minerals and their

Field Biology Packet Soils # 6

BACKGROUND INFORMATION

You can pick out wetland characteristics by observing a picture like the one below. What can you see in a generic wetland photograph? List at least three characteristics of wetlands that are evident in this picture.

1. _________________2. __________________3. __________________

There are three characteristics that must be evident for an land area to be considered a wetland:a. The area must be inundated (flooded) or at least saturated up to 7.5% of the time during the

growing season. A growing season begins when the first buds on plants appear and ends with first frost.

b. The soil is hydric or wet enough during the growing season to be classified as anoxic (no oxygen). Frequently the top layer accumulates organic material faster than it can decompose (detritus).

c. Hydrophytes (water-loving plants) are the predominant vegetation. Examples of these plants are cordgrass, cattails, and bald cypress trees.

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WETLANDS AND THEIR SOILS


Wetlands are lands where saturation with water is the dominant factor that determines the nature of soil development and determines the types of plant and animal communities living in the soil and on its surface. Wetland soils are saturated with water creating anaerobic conditions in the soil itself.

Plants and animals that live in wetland soils must be adapted for life in these conditions. An example is the bald cypress tree that resides in wetlands. The bald cypress has “knees” that emerge from the wetland. These knees are an extension of the root system that enables the tree to obtain oxygen for use by its growing roots. What a great adaptation!

The prolonged presence of water creates conditions that promote the development of characteristic wetland soils. How are wetland soils (hydric soils) different from the other soils that have been studied? What are the functions and values of wetlands and why do we need to protect the wetlands locally and globally?

OBJECTIVES

Students will define wetlands in order to explain why wetland soils look very different from sandy, silt

and clay soils. explain functions and values of wetlands in order to determine their worth in the global

environment.

MATERIALS

Article on wetlands and wetland soils from Environmental Concern, Inc.Jigsaw questions

PROCEDURE

1. Form “teaching groups” of five students. Each student selects a Roman numeral from I, II, III, IV, V.

2. Join with other students in your group (I, II, III, IV, V)3. Read the Background section carefully and individually answer the first four questions in

the Analysis section.4. Using the article on wetlands, work as a group to answer only the questions assigned to

your group. In this way you will become “experts” on the information assigned to your group.

5. Then, return to your original group and teach them the information you learned from the questions you answered Be the end of sharing time, all group members will have the entire set of questions and the corresponding answers.

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ANALYSIS

Answer the questions using complete sentences; the answers are implied or are part of the article, “Wetland Functions and Soil”. STUDENTS ANSWER QUESTIONS 1 TO 4. INDIVIDUALLY.

1. What is the dominant factor that determines the nature of wetland soil?

2. Define anaerobic.

3. What is the scientific term for wetland soils?

4. List the three characteristics that determine whether an area is a wetland.

GROUP I QUESTIONS

5. Explain how a wetland acts as a sponge.

6. Wetlands also absorb nitrogen and phosphorus that flow into the wetland. Wetlands are full of diverse vegetation. How and why do these two sentences relate?

7. Explain the term groundwater recharge.

8. Explain the steps in eutrophication.

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GROUP II QUESTIONS

9. Explain two causes of erosion.

10. Create a list of 10 different plants and animals that are found in wetlands. Name at least one bird.

11. How do migrating birds effectively use wetlands?

12. Explain the term anoxic. How does this condition forming soils?

GROUP III QUESTIONS

13. Explain the difference between mineral topsoil and organic topsoil.

14. Name two minerals and their corresponding colors when they are found oxidized. What does oxidized mean?

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15. Gleyed is a new term relating the hydric soil. Explain the meaning of gleyed.

16. Plants need to obtain air – carbon dioxide and oxygen. Plants use carbon dioxide and water to make oxygen and sugar in the process photosynthesis. Why and how do plants use oxygen? How do plants obtain these gases when they are inundated with water?

GROUP IV QUESTIONS

17. What is a tree “knee”?

18. Explain the wetland plant adaptation called “rhizomes”. Where are rhizomes found and why do they develop?

19. How have saltwater plants adapted to the excess salt content in the water?

20. What does “buttressed” mean, and why do buttressed trees develop in wetlands?

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GROUP V QUESTIONS 21. Name three ways that destruction of wetlands is harmful to biotic organisms or abiotic substances.

22. What are four steps that will help to ensure a healthy future for wetlands?

23. What is “Swampbusters”, and what program has replaced “Swampbusters”?

24. What is the problem with the concept of “no net loss?”

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“Wetland Functions and Soil”I.

1. What do you think of when you hear the word “wetlands”? You might think of smelly, dirty water or of mucky, useless land. But did you know that wetlands help us in our everyday lives? Simple acts like drinking water, catching fish, eating a favorite vegetable, or listening to bird songs all depend on our having healthy wetlands. Wetlands matter!

2. For instance, wetlands act as filters of pollutants. The have earned a reputation as “nature’s sponge.” Wetlands catch runoff which is rain water that drains from land, soaking it up before it reaches open water, such as rivers or lakes. In this way, many pollutants that are in runoff, such as pesticides, herbicides, factory wastes, or heavy metals (copper, iron, etc.) are absorbed into the wetland plants and do not enter the waterway.

3. Wetlands also act as filters of nutrients, such as phosphorus and nitrogen. If these nutrients remain in water, they will cause large amounts of algae to bloom on the surface of the water. When the algae die, they fall to the bottom and begin to decompose. Large amounts of oxygen are used up in the process of decomposition, and there is not enough oxygen left for the fish and other animals in the water. A forested streamside wetland can keep this from happening by removing as much as 80% of the phosphorus and 90% of

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the nitrogen from the water. Farm ponds and other wetlands can help rivers and lakes by filtering excess fertilizer that runs off fields and lawns.

4. In fact, wetlands absorb so much water that they can actually help control flooding. Wetlands soak up water from runoff during storms and slowly release the water into rivers and streams during the next few weeks. This is the process called recharging the groundwater. This slow release of water, rather than a flood of water right after a storm, can prevent flooding. If there had been 3% more wetlands preserved in the upper Mississippi River Valley, the massive flooding that occurred in 1993 could have been prevented.

II.

5. The land itself is conserved whenever wetlands stop erosion. Erosion occurs in numerous ways. One cause of erosion is wave action along a shore. Waves can wash away soil and sand from the shoreline. Wetland plants can help slow down the waves down and prevent soil and sand from being washed away. Another cause of erosion is from stormwater runoff. Runoff picks up sediment on its way to a stream. If the runoff goes through a wetland, the plants will slow down the water, and the sediments will begin to fall out of the water. First, the heavier, larger particles fall out, and then the smaller, lighter ones. Wetlands are nature’s way of slowing erosion.

6. Wetlands also provide us with many of the foods we eat. Cranberries and rice are grown in flooded plains and bogs. Blueberries and persimmons grow in wetlands. Crabs and shrimp are wetland food products also Rockfish, bluefish, catfish, perch, pickerel, salmon, and other fish need wetlands during the earlier part of their life. Hence, a wetland functions as a nursery.

7. Finally, wetlands provide a home for thousands of species of birds, mammals, and other animals and plants. Wetlands play a role in keeping our water clean. It is up to us to make sure that wetlands are not harmed. About 43% of endangered species need wetlands for survival. That is almost half of our endangered species. Wetlands obviously encourage biodiversity.

8. The soil in a wetland is “special” because of the amount of water present during the growing season of the wetland plants. The spaces between the soil particles are frequently filled with water. This water pushes out the air (oxygen and carbon dioxide) because no two substances can occupy the same space at the same time. Anoxic conditions are created by the water, and wetland soils are called “hydric” soils.

III.

9. Wetland soil layers may be organic or mineral. Organic soils are characterized by a deep layer of decaying plant matter at the soil surface. This layer of organic matter keeps getting thicker because dead plant matter accumulates faster than it can decompose under anoxic conditions (remember matter needs oxygen to decompose).

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10. Mineral soils are made of sand, silt, and clay and other elements such as iron and manganese. Soil forms in layers called horizons. Typical soil horizons might include a surface of dark organic matter that blends into a layer of oxidized soil of various shades of brown. This oxidized later is usually a mixture of organic and mineral soils. Beneath this might be a layer of mottled mineral soil that is sometimes wet and sometimes dry because the water table changes with the seasons. This change causes elements like iron to turn rust red and manganese to turn black. The mottled layer is often gray in color with specks of red and black. Below this is a layer of gleyed mineral soil that is (or was) always wet. This layer has no bright colors and is usually gray, greenish gray, or bluish gray.

11. In “hydric’ soil, the surface organic layer may be thick or thin depending on whether it is being washed away or not. The oxidized soil layer is thin or missing. The mottled layer may be thick or thin depending on how often water is present and how much the water table changes. The gleyed layer is often very close to the surface, especially if water is present all the time.

12. Plants must adapt to such watery conditions. The soil is very different, therefore, the plants must be very different. Wetland plants are hydrophytes, which simply means water (hydro) plants (phytes). These plants are able to grow on anoxic soil; hence, they must get their oxygen in another way. Wetlands plant often have hollow tubes that carry oxygen from the air down to their roots. Don’t plants produce the oxygen we need? Yes, through the process of photosynthesis, plants take the sun’s energy along with carbon dioxide and water and combine them in a different way to manufacture sugar, oxygen, and water. But plants also consume oxygen, just as animals do. Every plant cell, just like every animal cell, performs the process of cellular respiration. Plants take in oxygen and use the sugar to make carbon dioxide and water. This process releases the energy that the cells need so plants can live and grow.

IV.

13. Another adaptation that some trees use to survive in wetlands is to develop “knees”. Knees are thought to be part of the root system that rises above the water to bring oxygen from the air to the roots.

http://courses.soil.ncsu.edu

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Cypress knee


14. Rhizomes are another adaptation that plants use to reproduce and grow in wetlands. Rhizomes are underground shoots from the stem of a plant that are connected to the root system. The new plants will be genetically identical to their parents. Reproduction by rhizomes is typically done when the parent plant is under stress. Wetland environments put stress on plants because there is little to no oxygen for good root development.

15. Wetlands can contain either freshwater or tidal to marine water. Salt is another stressor for the plants that are growing there. A grass called Spartina alterniflora is able to withstand high salt concentrations. The Spartina copes with the salt by taking it up into its tissues and then excreting it through leaf pores. Salt crystals can actually be seen on the Spartina leaves.

16. Many trees have another adaptation seen as buttressed tree trunks. This means that the base of the tree is widened for support because the soil is very wet, and the roots cannot take as firm a hold as they do in dry upland soils. Instead the base is widened for support!

V.

17. Wetland destruction, often termed “wetland alteration”, adversely affects native species, disrupts flood patterns, degrades water quality, and threatens numerous freshwater habitats. Destruction usually happens because of housing developments or commercial sites. However, the 21st century began with a growing desire to preserve, conserve, and restore wetland ecosystems. The federal government, activists, and biologists are struggling to understand and protect our dynamic and multifaceted environments. Although experts may not agree on a single system for classifying types of wetlands or the means to save them, an appreciation for ecologic, scientific, and economic value of wetlands is shared by all.

18. Wetlands depend upon protective legislation and cooperation from residents and tourists

alike. Water conservation, proper disposal of wastes, management of invasive species, and responsible recreation are positive steps that can ensure a healthy future for our wetlands. Section 404 of the Clean Water Act is the foundation for Federal regulation of

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Buttressed tree trunk


some activities that occur in or near the nation’s wetlands. This regulatory plan intends to control discharge from dredge or fill materials into wetlands and other water bodies throughout the USA.

19. The Food Security Act of 1985 implemented “Swampbusters,” a program that seeks to remove federal incentives for the agricultural conversion of wetlands by rendering farmers who have drained or converted wetlands after 1985 ineligible for most farm subsidies. Government programs affected by “Swampbusters” are listed in Section 1221 of the Food Security Act. The Food Agriculture, Conservation and Trade Act of 1990 amended “Swampbusters” and created the Wetland Reserve Program which provides financial incentives to farmers to restore and protect wetlands through the use of long-term easements.

20. To compensate for the intentional destruction of wetlands by land developers, wetland mitigation seeks to maintain the “no net loss” strategy by requiring developers to implement projects for the restoration or creation of an alternate wetland area. Wetland mitigation was set forth in Section 404 of the Clean Water Act which legally allows for the destruction of wetlands provided that their loss is compensated for by the restoration or creation of new wetland areas. However, opponents of the controversial strategy claim that mitigation fails to compensate for the large-scale destruction of natural wetlands because complex ecological systems such as soil chemistry, food chains, and vegetation that are specific to wetlands will take hundreds of years to become established. Today, most wetland mitigation projects are less than a decade old, and their success remains to be discovered. The 1984 Henderson Wetlands Protection Act required the DEP (Department of Environmental Protection) to consider mitigation projects prior to issuing a permit to dredge and fill a wetland region. Progress is being made.

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(Title)alconway.wikispaces.com/file/view/Soils+#+6+Wetland+Soils... · Web viewExplain the difference between mineral topsoil and organic topsoil. 14. Name two minerals and their