PDF Figure 1 (Understory and Canopy after 5 years)

Name :______________________________________ Date: ______________

Ecological Succession

In this lab you will apply what you learned about succession to the ecological changes that occur after a fire. Determine the type of trees present after 5, 20, 50 and 100 years after the activity. Is this primary succession or secondary succession? Explain your answer.

Helena National Forests As you travel around Montana, you likely notice the beauty trees provide and also the variation among different areas. Identifying trees provides the ability to make conclusions about the type of environment. A variety of trees grow in the Helena National Forest, each with a specific niche or ecological role. Trees are site-specific and grow in a particular area based on climate, soil type, disturbances, shade tolerance or intolerance, and succession.

As learned, succession refers to the replacement of one plant community by another after a disturbance such as fire, a wind storm, or a logging or construction operation. One rule that can be applied to the distribution of trees is the tolerance for shade. Shade-intolerant trees often occupy the site after a significant disturbance, but as they grow and shade the site, shade-tolerant trees become established underneath them. Without another disturbance the shade tolerant trees will eventually shade out the intolerant trees. Trees that can reproduce under their own canopies are considered to be climax species on the site. Trees that initially occupy the site after a disturbance are considered seral species.

For each figure 1-6, count how many of each species of tree are found in the field, using the key as a guide. Add up all of the trees to find the total number of trees present in the field. Calculate the percentage of each tree species at each observed time period. Use the following formula: Number of specific tree ? TOTAL number of trees = ______ X 100 = ______%

Tree species

Number of Trees

% of Total

Figure 1 (Understory and Canopy after 5 years)

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

Figure 2 (Understory after 20 Years)

Tree species

Number of Trees

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

% of Total

July 1, Noon ? air temperature: 75?F, soil surface temperature: 84?F Figure 3 (Understory after 50 Years)

Tree species

Number % of of Trees Total

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

July 1, Noon ? air temperature: 70?F, soil surface temperature: 68?F

Figure 4 (Canopy after 20 Years)

Tree species

Number of

Trees

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

% of Total

Figure 5 (Canopy after 50 Years)

Tree species

Number % of of Trees Total

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

Figure 6 (Canopy after 100 Years)

Tree species

Number of

Trees

% of Total

Ponderosa Pine

Aspen

Chokecherry

Serviceberry

Englemann Spruce

Douglas Fir

TOTAL

Procedure B:

Using the data in the tables you just completed, construct two graphs. The first graph will show the changes in the percentage of each tree species in the understory from 5 to 50 years after the hay field was abandoned. The second graph will show the changes in the percentage of each tree species in the canopy from 5 to 100 years after the hay field was abandoned.

Use the percentages of each tree species from figures 1, 2, and 3 to construct your graph of the understory changes.

Use the percentages of each tree species from figures 1, 4, 5 and 6 to construct your graph of the canopy changes.

After completing both graphs, answer the following analysis questions.

1. Describe, in terms of decreasing or increasing percentage, what happened to each of the following tree populations from 5 to 100 years after the field was abandoned:

a. Ponderosa pine - ____________________________________________ b. Aspen - _________________________________________________ c. Chokecherry - ______________________________________________

d. Serviceberry - _____________________________________________ e. Englemann Spruce - ____________________________________________

f. Douglas fir - _________________________________________________

2. Using the understory figures 2 and 3, which tree species disappeared between 20 and 50 years after the field was abandoned? (Note: do not include trees that had already disappeared after 20 years.)

_______________________________________________________________________

3. Use the canopy figures 4, 5 and 6 to answer the following questions:

a. Which tree species disappeared between 20 and 50 years after the field

was

abandoned?

________________________________________________________

b. What tree species appeared between 20 and 50 years after the field was abandoned?

_________________________________________________________

4. What happened to the air temperature and soil surface temperature in the understory between 20 and 50 years after the field was abandoned? ______________________________________________________________

5. Think about the types of trees growing after 20 years in the understory. Are they tall or short species? ________ Now think about the types of trees growing after 50 years. Are they tall or short species? ________

6. Based on your answers to questions 4 and 5, what caused the change in the air and soil temperature between 20 and 50 years after the field was abandoned? _______________________________________________________________________ _____________________________________________________

7. Which trees/shrubs are shade tolerant and which trees/shrubs are not?

7. In this activity you have observed the changes that occurred in the types of plants that grew 100 years after the fire. What other types of organisms would be affected by the changes that occurred? _______________________________________________________________________

______________________________________________________________

8. Will the community of organisms in the forest change significantly over the next few years? _______ Why or why not? _____________________________

_______________________________________________________________________

9. After such disturbances, would you expect to a forest to become the climax community again? ___________ Why or why not? ________________________

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download