Activity: Disturbance and Succession
Objective: To create a model of succession in which a pond dries up and becomes a forest.
Grade level: 6 th
Format: Lab activity
Materials: Per student or student group – Aluminum baking pan (5 cm deep), gravel, potting soil to fill the pan, petri dish or shallow plastic saucer (less than 4 cm deep), masking tape, pen or marker, ruler, spray bottle, grass seeds, mixed birdseed and/or flower seeds.
Supplies can be found in a grocery store or hardware store. Total cost of supplies was about $5.00.
Description: In this activity, students model the gradual transition of a pond to a meadow to a forest.
Lab procedure: First, students fill an aluminum baking dish with soil to represent a meadow (for detailed procedure see attached student handout). A shallow, water-filled saucer sunk into the meadow represents a pond. Students sprinkle grass seeds on both the meadow and pond every few days. Water is not added directly to the pond, instead the pond water is allowed to evaporate. After several days, the pond dries out and seeds begin to grow. Students add birdseed and flowers to the meadow and dried pond to represent the transition from a grassy meadow to a forest. Setting up the lab and planting seeds takes 20-30 min; observing the lab takes about 5 min per day.
Words of wisdom: Before planting the seeds, I discussed natural and man-made disturbances and succession with students. I set up a schedule where students watered their labs with a plant sprayer and added more seeds every 3 days. Most of the “ponds” dried up within 3-4 days. We kept the experiment going for about 2 weeks.
Modifications: After doing this activity, students may enjoy a visit to an area that has experienced disturbance and regrowth.
Resources: This activity was modified from “Turn a pond into a forest” in Habitats: Making
Homes for Animals and Plants by Pamela M. Hickman, Addison-Wesley: Menlo Park,
CA (1993), pp. 60-63. Information about succession in Oregon is in the Multnomah
County outdoor school curriculum workbook.
Your name and Fellow year: Heather Petcovic, 2000-2001
School or outreach event where activity was used: Gregory Heights Middle School, Portland

Name: ___________________________________ Date: __________ Period: ______
D ISTURBANCE AND SUCCESSION
What do you think would happen if the grass in your yard or a local park were never cut again? At first you’d be wading through a lot of tall grass. Gradually, the seeds of nearby plants would be carried by the wind and settle in the grass. Soon, you’d have lots of plants growing along with the grass, and after many years, it would become a small forest. This slow replacement of one kind of habitat (your yard or park) by another habitat (a forest) is called succession.
Succession is going on all the time; it’s part of nature. Succession turns abandoned farmland into forest, changes small ponds into dry land, and helps areas burnt by fires to become green again.
Any process, whether natural or man-made, that destroys habitats is called a disturbance . It may take a few years or even a few hundred years after a disturbance for succession to return things to the way they were. For example, in
Oregon it takes at least 250 years for an old growth forest to recover from a disturbance! Sometimes a habitat or community never recovers from a disturbance; for example, a wetland that is drained and filled can never again become a wetland. In
Portland, over 80% of the wetlands have been filled or drained.
In real life, succession after a disturbance may take years to hundreds of years to re-build a habitat. Instead of waiting that long, we will make a model of succession in which a pond gradually becomes a forest.
A. Lab Procedure
1. Place 1 cm of gravel in the bottom of the baking tray for drainage. Cover this with about 4 cm of soil. This will become the meadow. Write your table group’s names on the tape and attach it to the outside of the baking tray.
2. Place the petri dish in the soil in the center of the baking tray so that the top edge of the dish is level with the soil surface. Sprinkle soil into the bottom of the petri dish.
This will become the pond.
3. Slowly pour water into the baking tray so that the petri dish is full. Lightly spray the meadow with the plant sprayer until the soil is damp.
4. Sprinkle a handful of grass seeds over the entire dishpan, including in the pond.
5. Observe the meadow and pond every day. Record observations in the data table.
6. Continue sprinkling grass seeds over the meadow and pond every 3 to 4 days. This represents additional seeds that are blown into the meadow.

7. Lightly water the meadow and pond with the plant sprayer once a week. Do not refill the pond! This represents rain that has fallen on the meadow and pond.
8. After 1 week, sprinkle some flower seeds and birdseed on the soil along with the grass seeds. The larger plants that will grow represent the gradual invasion of shrubs and trees into the meadow habitat. Over time, the meadow will transform into a forest.
B. Data Collection:
Date Observations of the pond Observations of the meadow

C. Lab Questions (Please use complete sentences)
1. In your own words, write the purpose of this activity (this can be a question).
2. How long did it take for the seeds on land to begin to grow?
3. What happened to the seeds that fell in the pond while the pond had water in it?
4. What happened to the seeds that fell in the pond after the pond had dried up?
5. How long did it take for the pond to dry up?
6. What event or events might cause a real pond to become a forest?
7. What sort of animals might live in the meadow habitat you created? Would you expect these same animals to live there once the forest plants (the taller flowers) started to grow?