Logging, or commerical logging, involves cutting trees for sale as timber or pulp. The timber is used to build homes, furniture, etc and the pulp is used to make paper and paper products. Logging is generally categorized into two categories: selective and clear-cutting.
Selective logging is selective because loggers choose only wood that is highly valued, such as mahogany.
Clear-cutting is not selective. Loggers are interested in all types of wood and therefore cut all of the trees down, thus clearing the forest, hence the name- clear-cutting.
You may be wondering if selective logging is better for the forest than clear-cutting?
This is a very interesting question! You think it would be, but actually selective logging can be very damaging to the surrounding trees which are not selected for loggging. What happens is that the heavy equipment used to cut the selected trees often damages the surrounding trees. It is estimated that 40% (40 out of 100 trees) die from just one tree that is selectively logged (Kricher, 1997). That's a lot of damage!
Which logging practice is worse, selective logging or clear cutting?
It depends on who you ask. According to NASA, clear cutting is much more damaging to a tropical rain forest because when all of the trees are removed, the soil loses its nutrients and becomes barren (NASA, 1998).
However, according to Ashton, in some cases, it is better to clear-cut a forest than to selectively log it. With selective logging, the largest trees are taken which means a loss in the seed source. The trees remaining often shade seedlings (small plants) that need sunlight to grow and eventually become trees. Clear-cutting is better when the soil already contains seeds. With clear-cutting, all of the seedlings are exposed to an equal and uniform amount of light. This equal amount of sunlight helps the young plants to grow and eventually become trees (Ashton lecture, 2005).
Is there a type of logging practice that is not so damaging to the environment you may ask?
Yes, there is. It's called strip logging. This type of logging is designed to mimic or copy the natural succession (re-growth) of a rainforest.
How does it work?
Strip logging involves the clear-cutting of a relatively thin strip of forest that parallels a river (goes along the river) along a slope. A gallery forest (bordering the river) is left intact, but a strip is cut immediately upslope and the desirable timber is removed by a road that is also designed to parallel the river. Following this, another strip is cut several years later immediately upslope to the first strip and the road. Nutrients eroded (broken down) from the newly cut strip wash down slope and aid in spreading the recovery of the first strip (Kricher, 1997, p. 346). The process allows the strip to regenerate (regrow) while selecting another strip upslope. It also prevents erosion (the wearing down of nutrients from the soil) because the strip is buffered by a row of trees remaining and a supply of nutrients from the newly cut strip. Smart, huh?
Why does logging happen?
Logging occurs for many economical reasons, such as: agriculture (planting crops), cattle-ranching, mining, oil and gas extraction, development, and subsistence-farming. The logs, or wood, are also used to make homes, furniture, paper, pencils, wood-chips for packaging products, fuel for cooking and providing heat for homes, etc.
Can we use other materials for building homes and furniture?
Sure! Why not use plastic, metal, stone, brick, or even sponge glass! Sponge glass is found in the ocean and is one of the strongest and most durable materials in nature.
What can we do as consumers (buyers) to decrease the logging of rainforests? Be creative. Here's a start:
- Always use both sides of paper when writing, drawing, photo-copying, typing, faxing, etc.
- Recycle all paper products.
- Buy recycled paper and paper products: notebook paper, paper towels, toilet paper, books, etc.
- Read the newspaper on-line.
- Use pencils until they become stubs. Think of pencils as pieces of gold; you'll never lose them if you do.
- If you do buy wood or furniture made of wood, make sure it is Certified wood. This means the trees were legally cut-down.
- If you buy a product that is packaged with wood-chips, write the company and suggest they use another packaging material, hmmm, like recycled paper, straw, or hay. Hey! That sounds good.
- Write letters of protest to companies which log illegally or in ways which are harmful to the environment.
- Okay, now you try...
What are some of the effects of logging irresponsibly?
- Loss of bio-diversity. Many species live in, on, or near primary trees. When these trees are cut down, species lose their habitat, source of food, and shelter. Also, primary trees provide seeds for new trees to grow. When these trees are cut, the seed source is lost.
- Extinctions. Many species can not live without trees. When trees are cut, animals lose their homes, source of food, and shelter.
- Erosion. Trees and leaves (leaf litter) provide nutrients for the soil in rainforests. Without trees, a rainforest becomes barren and without life. Trees also prevent erosion by absorbing water, thus preventing the washing away of nutrients in the top-soil.
- Flooding. Trees keep the soil stable by absorbing rain water. Rainforests receive 1,500-3,000 mm of water annually (hmmm, how many inches is that?) That's a lot of water! Without trees, flooding and mud-slides can occur causing serious environmental and ecomonic damage. Seedlings (young plants) and existing trees can be wiped out as well as nearby homes and buildings. Many people have lost their lives due to massive floods and land slides.
- Obstruction of rivers and streams. With erosion and flooding, the soil and silt often runs into rivers and streams. This sedimentation (soil and silt) clouds the water and sometimes prevents fish and other species from making their nests and laying their eggs. For example, salmon need clear rivers and streams with small pebbles to make their nests and lay their eggs.
- Forest fragmentation affects the living space of species. It cuts their habitat into fragments or pieces. This can have a serious affect on their habitat, food availability, and migration patterns. Many species have decreased or even become extinct due to forest fragmentation.
- Climate change. Trees sequester (store) carbon. When trees are cut or burned down, the carbon is released into the atmosphere in the form of carbon dioxide. Carbon dioxide is a green house gas which means it absorbs heat. This absorption of heat is called global warming and has serious environmental and economical consequences. It increases the earth's temperature, thus causing glaciers to melt and sea-levels to rise; it disrupts earth's weather patterns. For example, droughts, massive floods, and extremely powerful hurricanes are just some of the effects of global warming.
What's happening with logging in Costa Rica?
Costa Rica has lost over 60% of its forest cover to logging, agriculture, and cattle ranching. Although 40% of Costa Rica's land contains forests, only a small percentage of primary forests remain. The peninsula of Osa, an area barely 25 kilometers wide and 57 kilometers long, contains the last primary forests of the entire Pacific coast of Central America. Unfortunately, this peninsula is being illegally logged.
Why are primary forests important? Primary forests are rich in bio-diversity. In the entire peninsula, there are more than 1,513 species of plants unique to the area. There are also about 500 species of trees. In Corcovado alone, one of the two national parks in the Osa peninsula (Corcovado and Piedras Blancas), scientists have documented 124 species of mammals and 375 species of birds. According to the environmental organization, Fundacion Neotropica,the trees in the Osa peninsula are comparable -in structural complexity and biological diversity -with those of Amazonia, Central Africa, and Asia. When these trees are logges, bio-diversity is lost.
Why is it being logged? Loggers are interested in the most desirable species of trees. Some of these species are: cristobal, mahogany, nazareno, espavel, and cedar.
Why isn't it being protected? Although the logging is low-intensity and continues to be prohibited, the government is granting permits for controlled cutting called "plans of operation." The problem is there isn't enough forestry workers to enforce and monitor controls. With a limited amount of forestry workers and a lack of economic resources, illegal logging is occuring.
A social issue as well? The 6,000 inhabitants of Osa have suffered unemployment for years. Sawmill owners entice these jobless inhabitants with money in exchange for permits or "plans of operation" to log on their properties.
Is there a solution? What do you think?
Can reforestation of these primary forests restore bio-diversity? Although reforestation takes place in commercial or secondary forests, it can not replace lost bio-diversity.
What's being done? The Minister of the Environment is coordinating volunteers, the national police, and other state institutions to patrol the peninsula and monitor "plans of operation."
Time to show yourself what you have learned:
- What is the difference between selective logging and clear-cutting?
- In your opinion, which category of logging is more harmful to the environment and why?
- What is strip logging and what are its benefits?
- Why does logging occur? For what reasons?
- Can you match these words with their meaning:
parallel a.) regrowth
leaf litter b.) habitat is cut into pieces
regeneration c.) provides nutrients to soil
fragmentation d.) goes along or next to
6. Choose the correct word: When primary forests are cut down, bio-diversity _____________ (increases or decreases).
7. A synonym (a similar word) for sequester is _________.
8. Fill in the blanks: Trees _______ carbon. When trees are cut or burned down, the carbon is ________ into the atmosphere in the form of ____________.
Carbon dioxide is a green house gas which means it absorbs heat. This absorption of heat is called ___________ and has serious environmental and economical consequences.
9. What are two effects of global warming?
10. Name two materials we can use to build homes instead of using wood.
Math question: If rainforest receive 1,500-3,000 mm of water annually, how many inches is that?
Answers are located after the references (please don't look until you have completed all 10 questions).
Pen Pal conversation: Discuss with your pen pal possible solutions to the illegal logging in the Osa peninsula. Be creative. Remember to write to your Pen Pal in the Comments Section after this lesson.
Kricher, J. (1997). A Neotropical Companion: An introduction to the animals, plants, & ecosystems of the New World Tropics. New Jersey: Princeton University Press.
If you would like to read the complete article on logging in the Osa peninsula, click on this link:
Answers to the questions:
1. Selective logging only cuts down certain trees (valuable trees), whereas clear-cutting cuts down all of the trees.
2. This is your opinion...there is no "right answer"
3. Strip logging involves the clear-cutting of a relatively thin strip of forest that parallels a river (goes along the river) along a slope. A gallery forest (bordering the river) is left intact, but a strip is cut immediately upslope and the desirable timber is removed by a road that is also designed to parallel the river. Another strip is cut several years later upslope from the first strip. Nutrients are replaced from the remaining trees upslope.
4. Logging occurs for many economical reasons, such as: agriculture (planting crops), cattle-ranching, mining, oil and gas extraction, development, and subsistence-farming. The logs, or wood, are also used to make homes, furniture, paper, pencils, wood-chips for packaging products, fuel for cooking and providing heat for homes, etc.
5. parallel d.) goes along or next to
leaf litter c.) provide nutrients to soil
regeneration a.) regrowth
fragmentation b.) habitat is cut into pieces
6. When primary forests are cut down, bio-diversity decreases.
8. Trees sequester carbon. When trees are cut or burned down, the carbon is released into the atmosphere in the form of carbon dioxide. Carbon dioxide is a green house gas which means it absorbs heat. This absorption of heat is called global warming and has serious environmental and economical consequences.
9. Warmer temperatures and a rise in sea levels.
10. Stone and sponge glass!
Math answer: If rainforests receive 1,500-3,000 mm of water annually, how many inches is this? To solve this we need to go from mm to cm to inches. We can use this logic to help us do the conversion. If there are 10 mm in 1 cm (a 10:1 ratio) then in 1,500 mm there are 150 cm. To convert cm to inches, we use the conversion: 1 inch= 2.54 cm. So, 150 cm = ______ inches/cm. If we divide 150 by 2.54, we will solve the question. The answer is about 60 inches of rain, and that's on the low end of the range!
How did you do? I bet you did super!
Note: This integrated lesson is designed for 3rd grade students. The following California standards are addressed in this lesson:
Reading: Vocabulary and Concept Development (1.6): Use sentence and word context to find the meaning of unknown words.
Reading Comprehension: Comprehension and Analysis of Grade-Level-Appropriate Text (2.6): Extract appropriate and significant information from the text, including problems and solutions.
Writing applications: Write narratives (2.1): Write narratives: (a) Provide a context within which an action takes place.
Life Science: Students know living things cause changes in the environment in which they live: some of these changes are detrimental to the organism or other organisms, and some are beneficial.
Social Studies: Students understand the role of rules and laws in our daily lives and the basic structure of the U.S. government (3.42): Discuss the importance of public virtue and the role of citizens, including how to participate in a classroom, in the community, and in civic life.
Algebra and Functions: Express simple unit conversions in symbolic form (1.4) (e.g.,____ inches=____ feet x 12).
The Mongabay Kids site (kids.mongabay.com) aims to help children learn about rainforests and the environment. This site is still under development and I am working to add additional content as time permits. If you have comments or are interested in submitting educational content for the site, please feel free to contact me.
The site is available in many different languages, including Portuguese, Chinese, French, Spanish, Japanese, and German.