1. How it Started
1.1. Natural Causes--Weather Patterns
1.1.1. When sea surface temperatures change, this causes changes in the jet streams
1.1.1.1. Weather that normally moves from west to east instead moves towards the poles.
1.1.1.2. There is not enough water in the Midwest area to provide sufficient precipitation for itself, so this area depends on precipitation from the West.
1.2. Human Causes--Poor Farming Techniques
1.2.1. Overgrazing of pastures meant that these grasses would die more quickly after not receiving any water.
1.2.2. When deep-rooted plants were replaced with short-rooted crops, the new plants were not able to hold as much water and were not able to reach the water deeper in the soil.
1.2.2.1. The soil did not have much moisture in it and after so long of not receiving water it was so dry that winds were able to sweep it up and create dust storms.
1.2.2.1.1. These dust storms further severed the drought by reducing solar radiation, and in turn reducing evaporation and precipitation.
2. Recovery
2.1. Some Parts of the Ecosystem Were Able to Heal With Time
2.1.1. Animals like the grassland birds were severely affected by droughts like these, however in time many of them were able to restore the area and survive.
2.1.1.1. In the drought of 1988, most of the species were able to recover after a year. However, it was estimated that if these affects lasted for long times that it could have detrimental effects on the species.
2.2. Some Parts of the Ecosystem Were Changed Forever
2.2.1. As previously mentioned, some plants had taken over in areas and the plants that were previously growing were unable to compete and were replaced with plants that could better survive drought conditions.
3. What It Was
3.1. The Dust Bowl was a very severe drought in the Great Plains/Midwest regions from approximately 1930-1940
3.1.1. It was coined the Dust Bowl because topsoil would be blown away by high winds, creating dust storms (like the one seen in the opening picture).
3.1.2. As seen in later parts of this concept map, there were extreme consequences of this event on the environment, drastically affecting the Great Plains habitats.
4. How Wildlife Was Affected
4.1. Plants
4.1.1. Many plants dried out and died, causing empty patches in prairies.
4.1.1.1. Sometimes these empty patches were replaced with invading plants that could survive more easily without rain.
4.1.1.1.1. These invading plants were able to stick around after the drought ended, permanently changing the ecosystem since the previous plants could not compete.
4.1.1.2. Other times these areas were just topsoil that would be lifted away by the wind
4.1.2. Affected plant development and growth.
4.1.2.1. As with any drought, the plants were not able to grow as well without water. If they were able to grow, they could only do so in areas that had decent levels of shade from another plant or structure.
4.2. Animals
4.2.1. Livestock and wild animals were exposed to the dust storms, killing them in one way or another.
4.2.1.1. It would cause them to go blind if it got in their eyes.
4.2.1.2. It would enter their lungs and give them pneumonia.
4.2.1.3. It would fill their stomachs and they couldn't digest it.
4.2.2. Bird populations suffer during droughts.
4.2.2.1. 75% of grassland birds were affected.
4.2.2.2. Species richness and diversity are affected during droughts.
4.2.2.3. There is a decline of nesting success during droughts
4.2.3. Large losses of fish populations in lakes and rivers
4.3. Habitats
4.3.1. Future generations of plants and animals were affected
4.3.1.1. When there is a poor growing/mating season in one year, it puts a harsher limit on the population's growth for the following year.
4.3.1.2. Since ecosystems depend on the plants in the habitat, there is less energy that can support higher trophic levels.
4.3.2. Layers of soil were eroded.
4.3.2.1. This made it even more difficult for plants in the following season to grow, once again making it more difficult to sustain higher trophic levels.
4.3.2.2. The less precipitation, the dryer the soil, creating more dust and wasting the energy and minerals in the topsoil put there through decomposers like worms.
5. Prevention in the Future
5.1. Farming practices were changed and improved so that humans have less of an effect on natural disasters such as these.
5.1.1. A great example showing education on this subject is shown in Alfred and Nixon's "Grass for Conservation in the Southwest Plains" suggesting many ways to decrease the effects of drought.
5.1.1.1. Switching crops each growing season and growing them properly
5.1.1.2. Creating waterways
5.1.1.3. Preventing overgrazing