FOCUS: From standing snags to lying logs, dead wood is essential in a forest, though its importance is often overlooked. As wood decays, a succession of plants, animals, fungi, and bacteria come and go, each decomposing it further. At every stage, snags and rotting logs are hubs of activity, providing food, shelter, perches, travel corridors, and many other functions in the forest ecosystem.
Objective: To begin to explore and ask questions about snags and rotting logs.
Give small groups of children a rotting log to investigate with their senses. Ask children to touch the log with their eyes closed, to tap on the log, to smell it, and then to look at it. What do they notice?
Materials: rotting logs (one per small group); plastic tarp or newspaper for each log.
ROTTING LOG INVESTIGATION and JOURNAL ACTIVITY
Objective: To examine a rotting log, looking for evidence of living things – plants, animals and fungi – that live on or in it, and to record observations about them.
Work in small groups of three or four children with an adult. Provide each group with a rotting log to examine. The logs can be placed on tarps on the ground or examined in place in the woods. Ask the children to examine the outside of their log. How many different things do they notice growing on it?
Have them use magnifying lenses to look closely at the different growths. Give each one a name (e.g. yellow spots, green moss, black sprouts, orange crusty blotches). Or consult the Common Fungi on Rotting Logs guide to identify fungi they discover on their logs. Have the students make detailed drawings of their logs, labeling details they notice. Share their drawings in small groups.
Have the children gently pull off bark and loose pieces of wood, using flashlights to peer inside, looking for animals or signs of chewing. It is helpful to put wood fragments into a white dish basin in case any critters are hiding in them. Look for tunnels and chambers filled with frass, sawdust-like material from animal droppings or chewing. Is it lighter or darker than the surrounding wood? (Darker frass has gone through an insect’s digestive tract.)
Have children put any animals they find into small, clear jars for closer study. Children can examine them with magnifying lenses and try to find them on the Soil, Litter, and Log Critter guide. Have each child pick one animal to draw in their journals. Afterward, pass around critters in jars for all to see and admire. Then carefully collect animals and return them, with the logs, to the forest floor.
Materials: for each small group: rotting log,* newspaper, tarps or white plastic sheet, white dish basin, magnifying lenses, small clear jars with lids, plastic spoons, flashlight, science journals or clipboards and paper, pencils, crayons or colored pencils; Soil, Litter and Log Critter guide; optional: plastic sled for transporting the logs, Common Fungi on Rotting Logs guide, Soil, Litter, and Log Critter – Information Sheet.
*If necessary in cold temperatures, collect logs ahead of time and store in an above-freezing sheltered place in plastic bags.
UPPER GRADES CHALLENGE: Invertebrate Investigation (Grades 5-6)
Objective: To notice characteristics of some major groups of invertebrate animals.
Each student should select one animal from their log to investigate further. Encourage them to examine it with a magnifying lens, counting legs and body sections, looking for eyes, antennae, wings, mouthparts, and any other features that might help with identification. Using the Log-dweller Drawing sheet, have each student make a sketch of their animal and compare it to the pictures on the Soil, Litter, and Log Critter guide and descriptions in the Animal Information sheet. Have students try to identify what group their animal belongs to. Some of the groups most commonly found in rotting logs include::
- Worms (segmented bodies, but no legs, eyes, antennae, or wings)
- Snails and slugs (no legs, a slimy foot, eyes on stalks, tentacles)
- Insects (six legs, three body sections, wings, antennae, eyes)
- Sowbugs/woodlice (seven pairs of legs, antennae, oval bodies with many segments)
- Spiders (eight legs, two body sections, usually eight eyes, no wings or antennae)
- Daddy long-legs (eight long and thin legs, one body section, two eyes, no antennae or wings)
- Mites (tiny oval bodies, eight tiny legs, often bright red)
- Centipedes (long and flattened bodies, many segments, one pair of legs per segment)
- Millipedes (long and cylindrical bodies, many segments, four or more legs per segment)
What features did they notice about the animal they drew? To which group of invertebrates does it seem to belong? Why do they think so? Afterward, return animals to the logs and to the forest floor where they were collected.
Materials: magnifying lenses, critters in clear jars with lids from Rotting Log Investigation, Soil, Litter, and Log Critter guide and Soil, Litter, and Log Critter – Information sheet; Log-dweller Drawing sheet or journals, pencils; optional: clipboards.
Objective: To look for evidence of animal activity in or on dead and decaying wood outside.
Take the children to look for dead branches, standing dead trees, and rotting logs. Look for loose or peeling bark, woodpecker or insect holes or tunnels, fungi. What evidence can the children find of animals using the dead wood? Have each group make a list and then compare notes. How many different kinds did the group find? Based on this evidence, is dead wood important to animals and other organisms in the forest?
Materials: Snag and Log Search card, journals or clipboards and paper, pencils.
Objective: To examine bark beetle engravings on wood and look for clues about the life cycle of these insects.
Provide each small group of children with a piece of a log or branch with bark beetle engravings. Ask the children to be nature detectives and try to figure out how the designs on the logs could have been made. Have the children use magnifying lenses to examine the patterns and describe them while an adult draws the design for all to see. The adult can ask questions to guide the investigation: Which is the thickest tunnel? Does it go up and down on the trunk or sideways? What about the side tunnels – are they as thick as the main tunnel? Do any of the side tunnels twist or turn? Review the life cycle of a typical insect – egg-larva-pupa-adult. Ask the children to make some guesses about how bark beetles might have created this pattern in the wood. Then read the bark beetle story while students look at the engravings.
To begin, help each child to find a main tunnel with side tunnels radiating from it. On each main tunnel, look for a small thumb-like projection, either in the middle or at one end. Have the children follow the instructions as you read the story below:
The Ash Bark Beetle Story
On a warm day in early summer, a tiny beetle crawls out through a hole in the bark of an ash tree where he spent the winter. Last year he was just a larva, but now he is a flying beetle, about the size of a peppercorn. He flies off to look for just the right ash tree, for each kind of bark beetle needs a particular kind of tree. When he finds it, he chews a hole through the bark and then makes a chamber in the wood. (Look for a thumb-like projection on the main tunnel, usually in the middle.) A female soon arrives in the chamber, and after they mate she begins to make a tunnel in the wood. It will be one of the main tunnels. Along the sides of the tunnel she chews out tiny notches. (With magnifying lenses, look for the tiny notches, little dents in the walls of the main tunnel.) She lays one egg in each notch. Now, her work done, she leaves the tree and flies away. Soon her eggs begin to hatch. The tiny, hungry larvae chew the wood around them. As they chew they make tunnels away from the main tunnel. (Notice the tiny tunnel that begins at each notch.) Though it is dark inside the wood, the larvae can feel the vibrations of the other larvae chewing away in their neighboring tunnels. As they chew and grow their tunnels get larger too. (Notice how each tunnel starts small and then gets bigger.) Then in midsummer each larva makes a chamber in which to rest. (Notice the oval chamber at the end of each side tunnel.) Inside the chambers, the larvae turn into pupae, and inside the pupa cases the larvae change into adults with wings and legs and a hard body. When the time is right the beetles break out of their pupa cases. They chew their way out through the bark and fly away, leaving behind their beautiful designs carved into the wood.
Afterward, ask the children why the tunnels usually don’t cross each other. (Larvae can hear or feel the chewing of neighboring larvae.) Where would you expect to find holes in the bark of the tree? (By each pupating chamber and by the mating chamber.) If the bark is available, look for exit holes at the ends of the side tunnels.
Optional: Have children make a rubbing of the engravings with crayons or soft pencilsd.
Materials: Bark Beetle Set: samples of bark beetle engravings on wood and bark; The Ash Bark Beetle Story; Some Bark Beetles and Their Galleries diagrams and descriptions; National Geographic Bark Beetle Photo; for each child: magnifying lens, paper, pencils or peeled crayon pieces for rubbings.
Objective: To notice the changes that take place as a log decays and turns into soil.
Ahead of time, collect three similar-sized small logs in different stages of decay (solid, freshly-cut log; log with moss and/or fungi growing on it; very decayed log) and fill a tray with dark soil, wood fragments, and small seedlings. Place them inside or behind the time machine so they are hidden from view. The door to the time machine should be hinged on the bottom so the operator can open and close it without the audience being able to see inside.
Dress up as a scientist or professor and tell the students you’ve invented a time machine that can show what will happen to a log in the future. Explain that they will need to help out in the experiment. Assign some children to be chewing insects, some to be wind, some to be rain, and some to chant the changing of the seasons. Show the children the solid, freshly-cut log and have a few children feel its weight. Now place this log inside the time machine and have the children chant their parts while you turn the dial to advance the time. Allow four years to go by. Open the time machine and now pull out the moss-covered log so that the original log will appear to have aged. After showing this log to the students, repeat the “experiment” advancing the time by four more years. Now pull out the very decayed log to show them. Finally, replace this log in the time machine and advance the time four more years (twelve years in all). Pull out the tray of soil, wood fragments, and seedlings. Ask the children what eventually happens to trees when they die. (They turn into soil.) Point out how the decayed log becomes a rich nursery bed for new trees to take root.
Materials: Box decorated to look like “time machine” with door flap hinged on the bottom and large circular dial marked with the four seasons; three logs of similar dimensions in different stages of decay (fresh to rotted); tray of dark soil with rotted wood fragments and small seedlings; costume for professor/scientist or other imaginary character (e.g. lab coat, funny nose and glasses, wig).
PUPPET SHOW “Cleaning House”
Objective: To meet some inhabitants of standing snags and rotting logs and learn how they contribute to the process of change and decay.
Perform the puppet show or have a group of children perform it for the class. Afterward, ask questions to review the key details and vocabulary in the story. What different animals lived in the tree when it was a standing snag? (Sapsucker, squirrel, owl, carpenter ants.) What different animals lived in it when it became a rotting log on the ground? (Salamanders, insects, spiders, worms.) How did the animals change the tree over time? (Weakened it by digging, chewing, tunneling.) What are some other ways that dead trees are important in a forest? (Perches, drumming, place to find food, safe place to rear young.) Is it a good idea for Benjy Bear to “clean up” the forest by removing dead wood? (No! Decaying wood has many functions in the forest.)
Materials: puppets, script, props, stage.
Objective: To share observations about rotting logs and their inhabitants.
Have children complete this sentence: “My favorite discovery in a rotting log or snag was __________________because_______________________ .”