Step 1 List what is known. 
Step 2 List what is needed.
Step 3 Gather information to complete an ESS analysis. ( Event to Sphere, Sphere to Sphere)
Step 4 Present your findings.

Step 1: List What Is Known
The two columns below illustrate the parallel jobs to be completed in Step 1. You do not need to conduct any research to do this step. Use your current knowledge and information from the scenario to fill in the lines provided.

In the space provided in the first column, list what you know about Yellowstone National Park fires.

Then look at the Earth System Diagram in the second column. Notice how the arrows go to and from the event and spheres. These arrows indicate that the cause and effect relationships go both from the event to the spheres and from the spheres to the event ( ). While thinking about these relationships, list your ideas about how the event--wildland fires--could possibly impact the four spheres that make up the Yellowstone National Park ecosystem.

List prior knowledge about Yellowstone National Park fires.

• In 1988, there were many wildland fires burning in Yellowstone National Park.
• The firefighters were unable to control the fires and the fires blazed all summer long.
• It was very hot and dry that summer. The region was suffering from a severe drought.
• A large portion of the Park was destroyed.
• Lightning caused some of the fires, human carelessness with lit matches and campfires caused some of the fires, and people may have set some of the fires.

List prior knowledge of Earth system science regarding wildland fires.

Wildland Fires Event  Biosphere

• Fires need fuel to burn. Dead branches and pine needles on the ground provide fuel for wildland fires.
• Fires need a source of heat to ignite. People provide heat to ignite wildland fires by being careless with lit matches or campfires. Some people even set wildland fires on purpose.
• Flames from wildland fires kill plants and animals.
• After wildland fires, populations of some animals decrease as a result of the loss of their food sources (plants or other animals).
• Animals that can escape fast-moving wildland fires may be forced to re-locate their homes.

Wildland Fires Event  Lithosphere

• The flames of wildland fires scorch rock surfaces.
• The intense heat from wildland fires causes some rocks to break apart into small fragments.

Wildland Fires Event  Atmosphere

• As mentioned above, fires need heat to ignite. Lightning contains a lot of heat energy. Lightning strikes ignite some wildland fires.
• Fire needs oxygen to burn. This is evident when you use a snuffer to put out a candle: a snuffer cuts off the oxygen supply to the flame and the flame goes out.
• Wildland fires produce smoke that contains ash and gaseous pollutants such as carbon dioxide (CO₂). Wind carries the ash and gases away from the fires.

Wildland Fires Event  Hydrosphere

• Yellowstone suffered from record low humidity and an extended drought during 1988. A lack of water caused the soil and vegetation to dry out. A lack of moisture in the soil and vegetation may have provided dry matter to ignite wildland fires.

Step 2:  List What Is Needed.   
Now that you have an idea of what you DO know about Yellowstone National Park and the impacts of the event on the spheres and the spheres on the event, you need to think about what you DO NOT know. Below, you will ask questions that will guide the research that may take place on the Internet, in the library, or with other sources. 

In the first column, list your questions about Yellowstone National Park fires. Ask questions in the second column to direct the research you will conduct in Step 3. These questions should help you to focus your research on finding information to complete the ESS analysis of the impacts that wildland fires could have on the four spheres that make up the Yellowstone National Park ecosystem.

List your questions regarding Yellowstone National Park fires.

• How much land was burned?
• Were all the animals killed?
• How long did the fires burn?
• Has any fire season in Yellowstone National Park before or since 1988 been as destructive?
• Have any inhabitants of the biosphere recovered from the fires?
• Were any inhabitants of the biosphere harmed to the point that they have not recovered from the fires?
• Were any homes or campers destroyed during the fires?
• Why was this fire so big?
• Do fires often occur in this region?

List your questions regarding the impacts that wildland fires could have on the four spheres that make up the Yellowstone National Park ecosystem.

• Are some inhabitants of the biosphere adapted to survive in fire-prone regions?
• Do some inhabitants of the biosphere benefit from wildland fires? If yes, then how?
• Are terrestrial (land) plants and animals the only inhabitants of the biosphere affected by wildland fires?
• What happens to the nutrient content of the lithosphere when it is burned?
• What happens to the pH of the lithosphere when it is burned?
• Will plants grow on soil that has been burned?
• Will there be more mudslides after a wildland fire since there is no longer vegetation holding the soil in place?
• What happens to the pH of streams and lakes after a wildland fire?
• How is the pH of precipitation affected by the smoke in the air from a wildland fire?

Step 3: Gather information to complete an ESS analysis.

Part I: Using the answers from your research, list any additional cause and effect relationships you found for the event and the spheres. These relationships should build on or be different from the ones you listed in Step 1. The answers you find should explain the possible causes and effects wildland fires could have on the spheres that comprise the Yellowstone National Park ecosystem. Keep track of where you locate information. You may need to look it up again when you do Step 4.

Wildland Fires Event  Biosphere

• Some plant species have adapted to living in fire-prone areas and surviving small fires. For example, the Douglas fir that lives in Yellowstone National Park survives wildland fires because it has a thick bark. The bark protects it from fires with low heat intensity. The Douglas fir is also self-pruning. That means it drops its dead branches to the forest floor. This decreases the chance of a fire climbing up the tree using dead branches as a "ladder".
• Some tree species must go through a fire before their seeds can germinate. One such tree is the lodgepole pine. This tree makes up roughly 80% of Yellowstone National Park's forest. It produces two types of cones. One is an open cone that spreads its seeds as soon as it is mature. The other is a closed cone that is sealed by a resin. Closed cones must be exposed to the intense heat of a fire before they can spread their seeds. The heat from the fire cracks open the cones and allows them to release their seeds. In this way the lodgepole pine re-seeds the burned forest floor.
• Many people camp in the Yellowstone area and live near the park. These people are in danger of losing all their possessions--even their lives--in wildland fires. For example, during the 1988 fires, residents had to be evacuated from Cooke City and Silver Gate because the flames were dangerously close to their homes. Only a few backcountry employee cabins were destroyed.
• Dry, dead plant material is fuel for wildland fires. The build up of fuel material is referred to as fuel loading. The greater the fuel load in a forest, the greater the chance of a wildland fire igniting and rapidly spreading throughout the ecosystem. This is what happened in Yellowstone in 1988. Controlled burning or salvage timbering removes the excess fuel. The removal of excess fuel is referred to as "fuel management." Fuel management decreases the chance of wildland fires becoming large, uncontrollable wildfires.
• Wildland fires burn in a patchwork pattern. The result is a more diverse landscape with some open areas among forested areas. The diverse landscape provides many types of habitats for many types of plants and animals. The result is increased biodiversity.
• Relatively very few large animals are killed during wildland fires. For example, the Yellowstone Park fires of 1988 only killed approximately five bison, 243 elk, one black bear, two moose and four deer.
• The initial destruction of vegetation by wildland fires decreases food supplies for herbivores. Populations of these animals may begin to decrease as a result of starvation or emigration. Herbivores are prey for carnivores. If herbivore populations decrease, then the food supply for carnivores decreases. Populations of carnivores may then decrease as a result of starvation or emigration.
• When substances are burned, such as trees in wildland fires, they leave behind ash. This is the fine, grayish material seen in the bottom of campfire pits or charcoal grills after their fires have gone out.

Wildland Fires Event  Lithosphere

• Wildland fires have always occurred in the northwestern Rockies. Between 1972 and 1987, 235 "prescribed" fires were allowed to burn in Yellowstone National Park. Those fires burned 33,000 acres of Yellowstone.
• The wildland fires of 1988 were the largest series of fires in the northern Rockies in the last 50 years. They burned 1.5 million acres--800,000 in Yellowstone Park and 700,000 outside the Park.
• Wildland fires burn humus, the nutrient-rich organic matter in the topsoil. The organic matter rapidly breaks down and releases its mineral nutrients.
• Intense heat plays a key role in cycling rock through the lithosphere. Heat from wildland fires can break apart rocks. The small rock fragments can be cemented together over time to form sedimentary rock.
• Ash particles (see Wildland Fires Event  Biosphere) are basic, meaning they have a high pH. Ashes produced by wildland fires increase the pH of soil.

Wildland Fires Event  Atmosphere

• Fire needs oxygen to burn. Wildland fires warm the air above them. The warm air rises and creates "updrafts." Updrafts "fan" wildland fires by adding oxygen to them. This causes the fires to become more intense and spread.
• Wildland fires start and spread most when the air is hot, dry, and windy (see above and Wildland Fires Event  Hydrosphere). At night, air temperatures are lower, humidity is higher, and winds are slower. For these reasons, wildland fires tend to "lay down" at night. This means they stop blazing and spreading and just slowly smolder.
• The air above wildland fires is full of burning embers that are carried by the wind. These burning embers fly through the air and land on unburned vegetation. This is how wildland fires spread rapidly. It is also why burn patterns are patchwork instead of solid.

Wildland Fires Event  Hydrosphere

• Heat from wildland fires may further remove moisture from the air and soil through the process of evaporation. During this process, heat transforms liquid water into a gas that rises into the atmosphere. By drying surrounding vegetation, the fire actually creates more burnable fuel in its path. This allows the fire to continue to spread.
• Precipitation can naturally extinguish wildland fires. On September 11, 1988, two inches of wet snow covered a large portion of Yellowstone National Park. The snow put out some of the flames and prevented the fire from spreading.
• During wildland fires, fire-fighting materials can pollute lakes and streams. For example, fire retardant material was accidentally dropped into Little Firehole River during the 1988 Yellowstone fires.

Part II: Using the answers from your research, list the cause and effect relationships that occur between and among the spheres. Note: Begin thinking about how these relationships may in turn affect the Yellowstone National Park ecosystem.

Atmosphere Biosphere

• Smoke contains ash particles, as well as many toxic gases. The thick, black toxic smoke makes seeing and breathing very difficult during wildland fires. This makes it hard to escape the deadly flames. People and animals can also die of suffocation or smoke inhalation during wildland fires.
• Lightning strikes may come in contact with vegetation. The heat from the lightning can ignite the fuel (vegetation) and cause a fire to start.
• Dry vegetation (see Atmosphere  Hydrosphere) is more flammable than wet vegetation. This means the drier the vegetation, the more likely it is to catch fire and burn.
• Old trees in dense forests block sunlight from reaching the ground below their canopy. Young seedlings cannot grow because they lack the sunlight they need to photosynthesize. During wildland fires, trees are removed from portions of a forest (see Wildland Fires Event  Biosphere). The canopy is opened up. Sunlight is able to shine through to seedlings in the open patches of forest floor. New vegetation is able to grow.

Atmosphere  Lithosphere

• Ash particles in the air can fall to the ground miles away from the wildland fire. Large deposits of ash may eventually cement together to form sedimentary rock.
• Mountains can block winds and keep them from fanning the fires (see Wildland Fires Event  Atmosphere).

Atmosphere  Hydrosphere

• Ash from burning plant and animal material can be washed from the atmosphere by precipitation. This ash may be carried to nearby streams.
• Ash particles in the air are condensation centers. This means water vapor can condense on the particles to form water droplets. Groups of water droplets form clouds. When the water droplets become too heavy for the air to hold, they fall from the sky as precipitation. Wildland fires increase the amount of condensation centers (ash) in the air. Therefore they may increase the amount of precipitation in surrounding areas.
• Hot, dry air increases the rate of evaporation of water from plants and soil. The heat causes the water to transform from a liquid state to a vapor. The vapor is released to the air.
• Smoke from fires contains carbon dioxide (CO₂). Carbon dioxide reacts with water in the atmosphere to form carbonic acid, H₂CO₃. The chemical equation for this reaction is H₂O + CO₂ H⁺ + HCO₃^- H₂CO₃. Carbonic acid has a low pH. It decreases the pH of precipitation. The result is more acidic precipitation.

Biosphere  Hydrosphere

• Ash particles in the water can clog the gills of fish and other aquatic organisms and choke them.
• A lack of rain can cause plants to dry out. Little water in plants makes it easier for them to catch fire.
• Pollution of waterways with fire-fighting materials (see Wildland Fires Event Hydrosphere) can lead to the death of aquatic organisms. For example, cutthroat trout were killed when fire retardant material was accidentally dropped into Little Firehole River during the 1988 Yellowstone fires.
• Decreased concentrations of dissolved oxygen in waterways (see Hydrosphere  Lithosphere) can result in the suffocation of aquatic organisms.
• Plant roots and leaves absorb water. Without vegetation to take up water from precipitation, more water will flow directly into streams. This can lead to increased flooding.
• Acidic precipitation (see Atmosphere  Hydrosphere) can decrease the ability of plants to take up nutrients. It can also "burn" the leaves of some sensitive plants. The result is an overall decrease in plant health and growth.

Biosphere  Lithosphere

• Plant roots hold soil in place. A decrease in vegetation can lead to increased erodibility of soil. An extreme example of such erosion is the mudslide activity in the northwestern United States. This region has suffered the loss of trees due to forest fires and heavy logging. Without vegetation to hold them in place, entire hillsides slide downhill when they become saturated with rain.
• The burning of the nutrient-rich topsoil increases the nutrient content of the soil (see Wildland Fires Event  Lithosphere). This fertilization aids in rapid re-vegetation of burned areas.
• An increase in soil pH (see Wildland Fires Event  Lithosphere) results in increased activity of nitrogen-fixing bacteria. I read this in an ecology textbook. Nitrogen-fixing soil bacteria convert nitrogen in the soil to a form that is usable by plants.

Hydrosphere  Lithosphere

• Increased precipitation (see Atmosphere  Hydrosphere)--as well as water used to put out the fire--may wash away loose soil (see Biosphere  Lithosphere).
• Increased erodibility of soil (see Biosphere  Lithosphere) may lead to more sediment washing into waterways (i.e. muddier water). High sediment loads in waterways causes the temperature of the water to increase. As water temperature increases, the amount of oxygen in the water decreases.
• Acidic precipitation (see Atmosphere  Hydrosphere) dissolves calcium carbonate (limestone) and weathers, or breaks down, this type of rock.
• Mountains block the movement of air (see Atmosphere  Lithosphere). Air currents are forced to move upward when they reach mountains. As they move upward, air currents cool. The water vapor in the air condenses until it becomes so heavy the air can no longer carry it. The air looses most of its water as precipitation by the time the air reaches the mountaintop. Therefore air that comes down the other side of the mountain is very dry. This is why there are often deserts on the leeward side (side away from the wind) of mountains.

Step 4: Present your findings
Prepare a report or presentation of your team's recommendations about the prescribed burning policy in Yellowstone National Park based on your ESS analysis.

Predictions based on ESS Analysis:
In 1988, wildland fires raged through the northern Rockies from May through September. The fires burned 1.5 million acres of the region. Eight hundred thousand acres of the burned land was in Yellowstone National Park. Because of huge economical losses created by these fires, the effectiveness of Yellowstone's fuel management policy is being debated. This policy allows naturally caused fires to burn to their natural end. The purpose of fuel management is to control the amount of fuel (dry, dead vegetation) building up in the Park. The goal of this policy is to reduce fire control costs and damages. Some government officials do not believe Yellowstone Park's fuel management policy meets these goals.

A group of government agencies has contacted our team of environmental biologists to resolve this policy debate. They have asked us to perform an Earth system science (ESS) analysis of the effects of fire on the Yellowstone ecosystem. The government agencies would like us to recommend whether or not naturally caused fires in national parks should be allowed to burn to their natural conclusion.

Wildland fires have always been common, natural occurrences in the northwestern Rockies of the United States. Flames spread across that area long before European settlers arrived there. When the Yellowstone National Park was established, park officials thought wildland fires destroyed the Park's ecosystem. People began to fight the fires. Fighting the fires is very expensive, though. Besides, the occasional natural fire removed dry, dead vegetation from the Park. Without these fires, fuel would build up. A large, uncontrollable fire could ignite. For these reasons, many national parks, including Yellowstone, established fuel management policy. Park services personnel began to allow naturally caused fires to burn to their natural end.

As mentioned above, the goals of Yellowstone National Park's fuel management policy are to reduce fire control costs and damages. Under this policy, some naturally caused wildland fires are allowed to burn without human interference. To be allowed to burn, these "prescribed" fires must meet certain criteria. The fires cannot endanger people, property, or resource values. They cannot cross the wilderness boundary. The weather conditions and forecast must be favorable (not too dry or too windy) so there is little danger of the fire growing or spreading out of control. There must also be enough resources available to put out the fires if the other criteria can no longer be met.

As requested, our team performed an ESS analysis of wildland fires in Yellowstone. The results of this analysis show that the Park's fuel management policy does accomplish its goals of reducing fire control costs and damages. The policy does this by limiting the occurrence of wildfires. Wildfires are wildland fires that become large and out of control. Wildfires create the most damage and cost the most to fight. Wildland fires become wildfires when there is a seemingly endless supply of the three ingredients needed for a fire to occur. These three ingredients are oxygen (A > E), heat (A > E and B > E), and fuel (B > E). Nature can provide all three of these ingredients. Oxygen and heat are controlled primarily by weather patterns. Park officials have no way of controlling the high winds that provide oxygen or the lightning that provides heat. The only thing park officials can control is the amount of fuel available in the area. By allowing small fires to burn dry, dead vegetation, park services keeps the fuel from building up.

As mentioned above, however, park officials cannot control the weather. The 1988 fire season was hot, dry, and windy. The hot, dry air (atmosphere) caused water (hydrosphere) to evaporate from living vegetation (biosphere) as well as dead vegetation. The plant material became so dry that the entire forest became fuel. Lightning struck the fuel and winds fanned the flames with oxygen. The fires burned and spread out of control (E). The causal chain of this set of reactions leading up to a wildland fire event can be represented as A > H > B > E. The fire control costs and damages of these fires were very high. However, the important thing to keep in mind is it was an abnormally hot, dry, windy fire season. The park officials could not control these factors. All they could do was try to reduce the amount of fuel in the region through prescribed burning.

Our ESS analysis of this situation also revealed many environmental benefits of wildland fires. First of all, wildland fires revive forests. After 50 to 100 years, forests (biosphere) become mature. They consist of only a few types of trees. The canopy of the large, mature trees closes in. No light from the atmosphere is able to reach the lithosphere below the canopy. New seedlings are unable to grow without sunlight. Also, the existing trees have taken up most of the nutrients from the lithosphere. New seedlings cannot grow without nutrients.

Wildland fires (E) allow seedlings to receive the sunlight and nutrients they require to grow. Wildland fires do this by thinning out forests. They remove some of the older trees (B) and open patches in the canopy. Sunlight (A) is able to shine through these patches and reach new seedlings (B). New vegetation is able to grow. The causal chain of this set of reactions is E > B > A > B. When fire (E) burns existing trees (B), their nutrients are released back to the soil (L). The nutrients become available to new seedlings (B). This, too, allows new vegetation to grow. The causal chain for this set of reactions is E > B > L > B.

When wildland fires (E) create open patches on the forest floor (L), they allow different types of new vegetation (B) to grow. Each type of vegetation provides a different type of habitat. The presence of different types of habitat allows many types of organisms to live in the area. The result is increased biodiversity. This is another way in which wildland fires benefit the biosphere. The causal chain of this set of reactions is E > B > L > B.

Based on our ESS analysis of the effects of wildland fires on the Yellowstone ecosystem, we recommend that the park services continue to follow their current fuel management policy. Controlling the amount of fuel available is the only way that park officials can control the spread of wildfires. Allowing small, natural fires to burn to their natural conclusion is a good way to remove fuel. In addition, fire is very beneficial to wildland ecosystems. Fire naturally revives forests and makes them healthier.