Lesson 7 Natural Disasters and Environmental Change Chapter 2 - Ecology Lesson 7 Natural Disasters and Environmental Change

TCAP Coach 5th grade Science Source TCAP Coach 5th grade Science

Objectives The student will predict the effects of human actions and/or natural disasters on the environment.

Natural Disasters and Environmental Change Ecosystems are constantly changing. The plants and animals living in an ecosystem change the ecosystem just by going about their daily lives. Over time, even bigger changes can happen.

Natural Disasters and Environmental Change A lake ecosystem may eventually dry up and become a forest. An area may go through a long drought and eventually change from a lush ecosystem to a dry one.

Natural Disasters and Environmental Change

Natural Disasters and Environmental Change A deserted parking lot may become overgrown with small plants and, in time, trees. All ecosystems experience gradual change over time.

Ecological Succession The gradual process of change in an ecosystem is called ecological succession. There are two types of ecological succession.

Natural Disasters and Environmental Change Primary succession is succession that happens where an ecosystem was not present before. An abandoned parking lot that slowly turns into a meadow is an example of primary succession. Another example is an ecosystem that develops in a very rocky area or on a sand dune.

Primary Succession

Natural Disasters and Environmental Change Secondary succession is another type of ecological succession. Secondary succession occurs where an ecosystem has previously existed. For example, secondary succession occurs when a lake ecosystem gradually fills in and grows into a forest.

Natural Disasters and Environmental Change

Natural Disasters and Environmental Change Secondary succession also happens in ecosystems that have been disrupted by humans or by natural disasters. Land development can cause secondary succession. So can natural disasters such as earthquakes, volcanoes, and fires.

Natural Disasters and Ecosystems Natural disasters such as earthquakes, volcanoes, storms, floods, droughts, and fires can all cause big changes in an ecosystem.

Natural Disasters and Ecosystems Think of an area that usually receives very little rainfall. A large storm may lead to flooding in the area, which may destroy plants and trees. Animals may be left without homes.

Natural Disasters and Ecosystems The organisms in the ecosystem must adapt to their changed environment. Some organisms may die out. This may leave room for new organisms to live in the ecosystem. Eventually, the entire ecosystem may change.

Natural Disasters and Ecosystems

Natural Disasters and Ecosystems One example of a natural disaster and how it changed the surrounding environment is the eruption of Mt. St. Helen's in Washington.

Natural Disasters and Ecosystems In 1980, Mt. St. Helen's erupted, destroying hundreds of aces of forest lands. The heat from the ash burned and flattened the forest ecosystem.

Natural Disasters and Ecosystems Eventually, though, small plants began to grow in the destroyed areas. The area is now experiencing secondary succession, and may become a very stable ecosystem over time.

Natural Disasters and Ecosystems

Fires and Ecological Succession Did you know that natural fires can be good for an ecosystem? There are some types of ecosystems that stay healthy because of fires. In some parts of the country, wild fires are allowed to burn because they allow room for certain types of plants and trees to grow.

Fires and Ecological Succession In fact, there are some types of trees that will not release their seeds unless they are exposed to very high temperatures.

Fires and Ecological Succession Many plants in these types of ecosystems are adapted to fires. As a community, the organisms that live in fire-adapted ecosystems depend on fires to maintain the balance of the ecosystem.

Fires and Ecological Succession

Fires and Ecological Succession A fire allows some trees to be cleared in order for others to grow. This in turn provides food for organisms that need it.

Fires and Ecological Succession

Fires and Ecological Succession The secondary succession that happens after a fire helps ecosystems stay healthy and maintain their diversity.

1. Which of these is most likely to happen first in secondary succession after a volcanic eruption? a. Animals move out of the ecosystem. b. Flood waters destroy a natural habitat. c. Small plants begin to grow. d. Trees cast shade over small plants.

a. Animals move out of the ecosystem. 1. Which of these is most likely to happen first in secondary succession after a volcanic eruption? a. Animals move out of the ecosystem.

2. Small plants and shrubs have begun to grow on a stone cliff 2. Small plants and shrubs have begun to grow on a stone cliff. This is an example of a. environmental succession b. ecological change c. secondary succession d. primary succession

2. Small plants and shrubs have begun to grow on a stone cliff 2. Small plants and shrubs have begun to grow on a stone cliff. This is an example of d. primary succession

a. earthquake b. volcano c. fire d. flood 3. Which of these natural disasters can actually help maintain the health of an ecosystem? a. earthquake b. volcano c. fire d. flood

3. Which of these natural disasters can actually help maintain the health of an ecosystem? c. fire