Week 2: Yellowstone Event to Sphere Interactions
The examples below address sphere > event and event > sphere interactions. When doing ESS analyses in the future, you can include your event > sphere and sphere > event interactions under one heading called “Event to Sphere Interactions”.

E > A
The forest fires could cause acid rain. As with industrial pollution, CO₂ from the fire would combine with the moisture in the atmosphere to form carbonic acid, or H₂CO₃.

E > A
Intense fires create their own upward air movement. Forest fires make "updrafts" of air like the warmth you can feel if you hold your hand about 12 inches above a candle flame.

E > A > E
The intense fires created their own upward air movement, increasing the wind velocity and drawing in oxygen at the base of the flames to continue to feed the fire.

A > E
I heard that lightning is a common cause of forest fires. This makes sense to me because the high temperature of a lightning bolt combined with the dry biomass often found in Yellowstone is a recipe for a forest fire.

Event and Hydrosphere

E > H
Burning pine needles, wood, and other plant material can produce an ash that may come down in nearby streams and change (either up or down) the pH of water.

H > E
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.

http://www.wildrockies.org/Fires-of-88/history.html

E > B
Removal of leaf litter and other debris, as well as plant competitors such as non-natives, makes it easier for native plants and pioneer plants (fireweed, lodgepole pine, etc.) to germinate.

E > B
Forest fires are sometimes needed in the life cycle of some living things. For example, some pinecones, like the lodgepole pinecones, need the heat of a fire to open them and release their seeds.

E > B
Animals that couldn't flee the flames were killed. Even those who could flee had trouble surviving after the fire because their habitat was severely altered.

B > E
Future fires will be less likely to occur after all the fuel (biomass) in an area has been combusted. For instance, when the plant litter on the ground is burned off, there is no more fuel for a new fire. And we know that a fire needs fuel. This makes sense to me because I read that leaf litter and other "burnables," which had collected on the Yellowstone forest floor since the previous fire 75 years ago, provided the fuel for the 1988 fire.

Event and Lithosphere

E > L
Intense heat from the fires may have caused some rocks to break apart as I have seen happen in campfires.

E > L
Heat from the fires can affect the topsoil. As an illustration, the fires baked out a lot of the living, nutrient-rich organic matter, called humus.

In the future, as you list event > sphere, sphere > event, and sphere > sphere interactions, as well as causal chains, it is important that you be able to explain why or how the interactions occur. For example, the E > A interaction above doesn’t merely state, “The forest fires could cause acid rain.” It gives the reason, "As with industrial pollution, CO₂ from the fire would combine with the moisture in the atmosphere to form carbonic acid, or H₂CO₃.” Such explanations display your understanding of the science behind the interactions. These explanations are valuable for you and others because they make your "Why?" or "How?" thinking visible, and they often lead you to think of additional ESS interactions.

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