Unit - PopulationsLife ScienceLesson 3

Population Growth of Pine Beetles

Teacher Notes

Purpose:

This activity will allow students to discuss and explore the factors that affect the population of pine beetle in the forest. Pine beetles are a native to the Colorado forest however; there are factors that affect the rate of population growth as well as its decline.

In a forest that is in equilibrium the mountain pine beetle will experience one generation of growth each year with a normal death rate of elderly and new beetles. For this activity we will keep it simple and not factor in the normal death rate and only look at normal growth, accelerated growth, and unnatural decline.

Time: 1 – Class period

Materials:

Pinto Beans

Medicine Cups

Worksheet

Laminated “Event Strips”

Lesson Overview:

Have students discuss what factors they think will cause the pine beetles to either grow or decline in population. Have them think back to the story of Buford the Mountain Pine Beetle and their notes to help jog their memory. Once the students have shared their brainstorming organize the information in a table similar to below. Fill in and discuss the other pieces that the students fail to think of. Keep this information on the board until the game activity is complete.

BEETLE POPULATION
Normal Growth / Accelerated Growth / Unnatural Decline
Factors that affect forest orbeetles / Food / Healthy Forest / Stressed Forest / Few mature trees
Predators / Normal / Decrease in / Increase of
Temperature / Normal / Long growing season / Long cold winter
Drought / No drought / Prolong drought
Fire / Ground fire / No Fire / Intense Fire

Begin the game. Student groups will each be given a starting population (make sure each groups gets between 50-150 pinto beans). Have them calculate their beginning population on their worksheet.

After each groups has calculated their beginning population. Begin the game by handing each group a “event” strip. It is their job to decide, as a group, whether or not the event would cause a growth or decline. The event strip has a number (1 cup, 2 cups, 3 cups) that decide how many beans should be added or subtracted. Take around a bowl so that each group can either dump in or take out the number of cups required.

Name: ______

Population growth

With your group brainstorm some ideas of some of the factors that might cause the pine beetles to produce more generations than normal and things that might cause the pine beetle population to decrease.

Write your (and your groups) ideas below. Be prepared to share as a class.

______

______

______

______

______

______

After the class discussion the teacher will write the groups ideas up on the board. Copy down the main factors that cause the population to grow more than normal or less than normal.

More Beetles than NormalLess Beetles than Normal

______

______

______

______

______

______

Name: ______

Population Growth Graphing Activity.

You and a partner will investigate how the population of Beetles may grow or decline over time.Your teacher will pass out beans to each group. These beans represent your starting population.

1 Bean = 25 beetles.

Count how many beans you have then calculate how many beetles you have.

Number of beans = ______Number of Beetles (# of beans X 25) ______

As you go through this activity keep in mind that 1 beetle can produce 75 offspring in one generation! That’s a lot of babies!

Your teacher will hand out some information strips that tell you something that happened to your forest. It is up to your group to discuss how this event affects your beetles. Once you have decided how this will affect your beetle population you then need to either have it grow or decline for that generation. Use the table below to document your population change over time.

Year / Starting Population
(Number of beans) / Event / Growth or Decline / Population added or subtracted (Number of beans added or subtracted) / Ending Population (Number of Beans)
2012
2013
2014
2015
2016
2017

Name: ______

On the graph below, make a bar graph for each year of beetle population. Start your graph with your starting beetle population then plot the ending population at the end of each year.

______

Your forest experienced an intense fire that wiped out much of the lodgepole pine trees.

(2 cups)

Your forest has experienced two years of drought. The lodgepole pines in the forest are becoming more stressed.(2 cups)

Your forest is mostly healthy this year with a few stressed parts of the forest. (1 cup)

Your forest has experienced a mild winter and a long growing season.(3 cups)

Your forest is healthy this year and there are a lot of woodpeckers, Red-breasted Nuthatch, and wasps in the forest this year. (1 cup)

Your forest had a very, very, cold long winter.(2 cups)

Your forest had some ground fires that were not very intense this year, but water hasn’t been able to sink into the ground because of it. The forest is more stressed because of it. (2 cups)

Your forest experienced a fire about 5 years ago, many new young lodgepole pine stands are growing and healthy. The other trees in the forest are dead and falling down. (1 cup)

Your forest hasn’t had a drought in a few years, many trees are mature, and few are dead.

(1 cup)

Forest managers have been suppressing fires in your forest to keep humans safe. Very little new forest is growing and the current forest is maturing. (3 cups)

TEACHER KEY - EVENT STRIPS

NORMAL POPULATION – These events cause normal growth

  • Your forest is mostly healthy this year with a few stressed parts of the forest. (1 cup)
  • Your forest hasn’t had a drought in a few years, many trees are mature, and few are dead. (1 cup)

ACCELERATED POPULATION – These events cause accelerated growth

  • Your forest has experienced two years of drought. The lodgepole pines in the forest are becoming more stressed. (2 cups)
  • Your forest has experienced a mild winter and a long growing season. (3 cups)
  • Your forest had some ground fires that were not very intense this year, but water hasn’t been able to sink into the ground because of it. The forest is more stressed because of it. (2 cups)
  • Forest managers have been suppressing fires in your forest to keep humans safe. Very little new forest is growing and the current forest is maturing. (3 cups)

DECLINE IN POPULATON – These events cause declines in population

  • Your forest experienced an intense fire that wiped out much of the lodgepole pine trees. (2 cups)
  • Your forest is healthy this year and there are a lot of woodpeckers, Red-breasted Nuthatch, and wasps in the forest this year. (1 cup)
  • Your forest had a very, very, cold long winter. (2 cups)
  • Your forest experienced a fire about 5 years ago, many new young lodgepole pine stands are growing and healthy. The other trees in the forest are dead and falling down. (1 cup)

Activity 5Page 1