1
What is a forest? What are the three main types of forests, and what influences which forest type is found in a given area?
INFOGRAPHIC 28.1
True or False: Forests are home to more than 50% of Earth’s terrestrial life and are the main site of terrestrial photosynthesis.
TRUE
High-latitude and high-altitude forests characterized by a short growing season, a lot of snowfall, and thin, acidic soils are:
temperate forests with trees that drop their leaves in winter, such as oak and maple.
boreal forests with evergreen trees that bear needlelike leaves, such as spruce and fir.
savanna forests with trees that have long taproots and thick, fire-resistant barks, such as acacia and eucalyptus.
tropical forests with trees that are highly valued as timber for their rot-resistant wood, such as mahogany and teak.
B
Tropical rain forests have thin, acidic soils, yet they contain dense vegetation and high biodiversity. How can these tropical forests have poor soil but support such diverse arrays of plant and animal life?
Tropical forests experience warm temperatures year round that support numerous species of decomposers who rapidly turn dead plant and animal matter into nutrients. Plants take up these nutrients the moment they are released and store them (generally in their root mats). Thus the short, rapid nutrient cycles, along with the nutrients being locked up in living tissue counter the effects of heavy rains washing away the minerals in the soil and support the dense vegetation found in the tropical rainforests.
2
What is the three-dimensional structure of a forest, and how are the plant species found there adapted to their level of the forest?
INFOGRAPHIC 28.2
The understory of a forest is made up of:
trees that push through and grow above the level of the forest canopy.
the seedlings, ferns, herbs, and wildflowers that grow on the forest floor.
the overlapping crowns of the tallest trees that make up the roof of the forest.
shade-tolerant shrubs or saplings of larger trees that sometimes form a lower canopy.
D
The forest layer that gets the most sunlight is the:
canopy.
emergent layer.
forest floor.
understory.
B
Explain why many forest wildflowers emerge and bloom in early spring, before the trees “leaf out.”
This is the time when the forest floor gets the most sunlight, allowing the wildflowers to grow quickly, reproduce (bloom) and then settle down for the rest of the summer in the shade of the trees that leaf-out shortly thereafter.
3
What ecosystem services do forests provide?
INFOGRAPHICS 28.3 AND 28.4 AND TABLE 28.1
True or False: The forest biome that stores the most carbon is the boreal forest.
FALSE
How does deforestation contribute to loss of drinking water in Haiti?
Without trees, the eroded soil clogs drinking water pipes.
The loss of forest habitat fragments aquatic ecosystems that provide water to the local villages.
Without the trees, the water rushes away rather than soaking into the ground to recharge groundwater supplies.
Clearing the forest for crops means increased irrigation, which reduces drinking water supplies.
C
What is an “ecosystem service”? Describe three ecosystem services provided by forests.
Ecosystem services are resources (like fertile soil and clean drinking water) and processes (like decomposition and nutrient cycling) supplied by natural ecosystems that support life and make economic activity possible. Tree roots anchor soil and slow down the flow of rainwater, thus reducing flooding as well as recharging groundwater. Trees store a lot of carbon, making forests one of the largest carbon sinks in the world, and thus playing an important role in climate regulation. Trees provide many economic goods such as fuel, food, building materials, etc. (Other ecosystem services listed in Infographic 28.3, explained in the context of forests, would be acceptable.)
Why might it be useful to put a monetary value on the ecosystem services of forests, even if we know this value is not accurate?
By putting a price on the economic value of ecosystem services we acknowledge that they are, in fact, valuable and we get an idea of what it would take to replace them (for those that are replaceable). This can guide us to make better decisions about how to use our resources. For example, if we don’t have pollinators to freely pollinate our crops, what would it take in manpower to do the job ourselves, and could we do it as well? Maintaining healthy ecosystems that provide the pollinators to us for free thus appear to be a much better option.
4
What is the current state worldwide of forest resources? What threats exist?
INFOGRAPHIC 28.5
Which of the following is not a cause of deforestation in Haiti?
Palm oil plantations for biofuel production
Coffee and sugar plantations for export crops
Wood charcoal production for the domestic energy market
Timber harvesting for commercial sale
A
How is the current status of forests different in developing countries than in developed countries? What factors account for these differences?
Developed countries (like the United States) harvested their forests to support their industrialization in the past. Today many of these countries have fewer stands of forests than developing countries but they have more stringent regulations in place to protect the forests that are left. As a result deforestation is being kept in check and forests are in fact re-growing. In addition, funding and technical expertise also enable developed countries to practice more effective forestry management along principles of sustainable and multiple-use.
On the other hand, developing countries (like Brazil, Indonesia, and Mexico) have far greater stands of forests but are experiencing serious deforestation. While some of this deforestation is the result of domestic demand for forest resources (like charcoal in Haiti), much of it is driven to supply markets in the developed world with wood, or with agricultural commodities (like beef, sugar, and palm oil) raised on cleared forests. Poverty makes many developing countries desperate for income and they often see no other alternative than to exploit their forests. The resulting weak enforcement or lack of regulations makes it easy for multinational corporations to gain access to forests in the developing world and use them for the benefit of markets in the developed world.
5
How can we protect and sustainably manage forest resources?
INFOGRAPHIC 28.6 AND TABLE 28.2
The timber-harvesting system that would be most likely to cause disruption to the ecosystem services provided by a forest is:
shelterwood harvesting.
strip harvesting.
clear-cutting.
selective harvesting.
C
Which of the following activities will not simultaneously protect forests and provide for long-term economic well-being of local people in developing countries?
Pricing ecosystem services provided by the forest and paying landowners to maintain their trees
Clear-cutting the forest and planting fast-growing trees for charcoal production
Promoting the harvesting and selling of wood that is certified by the Forest Stewardship Council
Translating the intrinsic value of a forest into ecotourism enterprises
B
How can we sustainably use forest resources?
One approach is to put a price on all ecosystem services that forests provide, select those with the highest value, and pay to maintain them. For example, we could maintain rainforests for their role in the water cycle by charging a water protection tax and using the money to pay landowners not to cut down trees.
Another approach would be to promote the availability of sustainable forest products by certifying products from forests that use harvesting techniques that maintain the integrity of the forest ecosystem.
A third approach is to take advantage of the intrinsic value of intact forests ecosystems for non-extractive economic enterprises such as ecotourism. This type of tourism allows for the generation of income in a way that is directly tied to maintaining forest ecosystems.
What is the reforestation strategy employed by the Haitian kombit? Explain the rationale behind the approach and discuss whether it can be successful.
The kombit strategy focuses on planting three main categories of trees. They first plant fast-growing, multi-purpose trees like the moringa. As a nitrogen-fixing plant, the moringa helps re-fertilize the soil, and because it grows quickly, it can provide a sustainable source of food (its leaves are edible and packed with protein) and fuel wood. Next, they plant fruit trees like mango and avocado. While these trees take longer (3-5 years) to be ready to harvest, they put down roots thus stabilizing the soil in just a few months, and because they are fruit trees people are less tempted to harvest them. The last trees planted are the slow-growing timber trees, which don’t provide any immediate benefits to the farmers but may be sustainably and profitably harvested in the future.
The goal is to create a stable system that can provide money and food throughout the seasons and across the years. But deforestation is not easy to solve when charcoal produced from wood is the only energy source people have. Furthermore, charcoal is the fuel of the poor, and unless Haitians can escape the poverty trap, they won’t stop using it. If charcoal can be harvested sustainably (with practices such as harvesting only fast-growing trees for charcoal and pruning branches to encourage more growth) it will help, but will not be enough to meet the intensive energy needs in urban areas. For that Haitians will have to first find alternatives to charcoal such as the jatropha, a fast growing plant whose seeds show promise as a biofuel source.
28-23