hreaded Discussion 6: Deforestation For this activity we will discuss that probl

Question

hreaded Discussion 6: Deforestation

For this activity we will discuss that problem of global deforestation. Please read the following articles and then use the prompts provided to contribute to the discussion.

Please read "Photosynthesis, Global Warming and Tropical Rain Forests" on page 188 in your textbook

KEY THEME: ecology

Reading from the book- (page 188) Photosynthesis, Global Warming, and Tropical Rain Forests

In much the same way that the windows of your car trap heat during the summer, carbon dioxide in our atmosphere traps radiation from the sun, which helps keep our planet warm. Without CO2 and other greenhouse gases, the temperature on earth would be about 33°C (60°F) cooler than it is now. Conversely, increasing the concentration of these gases in our atmosphere can cause escalating global temperatures. For the past 1,000 years, a careful balance maintained by the oceans and photosynthetic organisms has kept atmospheric CO2 levels fairly constant at 0.028%. Since the 1850s, fossil fuel combustion and deforestation have contributed to increasing atmospheric CO2 to a current level of 0.039%. Increases in greenhouse gases such as CO2 have caused a global warming of 0.6°C (1.1°F) since 1900, and predictions suggest an overall global warming of 1.0 to 3.5°C (1.8 to 6.3°F) (or even more, according to recent estimates) by the end of the 21st century.

Billions of metric tons of carbon are converted to organic matter through carbon fixation by continental and marine ecosystems each year. Some of this carbon balance is regulated by the ability of oceans and seas to equilibrate CO2, and most scientists agree that a large amount of the CO2 is absorbed by terrestrial ecosystems. Among these ecosystems, tropical rain forests (Box Figure 10.2) are the most productive, with photosynthetic efficiencies that average 2.2 kilograms (4.8 pounds) of dry organic matter produced per square meter per year, which is almost three times the average efficiency of all other continental ecosystems. Although this superior efficiency may provide a substantial contribution to global carbon fixation, the amount of earth’s landmass covered with tropical rain forests declined from 30% in the 1950s to about 5% in 2010.

In general, as you move toward the tropics, there is an increase in the diversity of all organisms. This includes plants. Even though tropical rain forests currently occupy only 5% of the world’s land surface, they contain over half of the world’s plant and animal species. For example, Costa Rica is about one-fourth the size of Great Britain, but it has almost six times the number of plant species. Experts estimate that deforestation contributes to the extinction of over 100 plant, animal, and insect species each day. For many reasons it is unfortunate to suffer such a rapid loss of life. For example, 25% of Western drugs are derived from rain-forest ingredients, and some may contain possible cures for life-threatening diseases.

While the photosynthetic capacity of tropical rain forests may increase as a consequence of high CO2 levels in the atmosphere, this does not necessarily mean that these ecosystems are a panacea to the looming threat of global warming. Between 10 and 30 million hectares (25 and 74 million acres) of rain forest are lost every year to ranching, logging, mining, and otherwise developing areas for human needs. For each hectare (2.5 acres) of forest that is cleared and burned, about 220 metric tons (242 tons) of carbon are released, which directly increases the amount of CO2 in the atmosphere. Each year, deforestation in tropical rain forests accounts for 20% to 30% of all carbon dioxide introduced into the atmosphere. The consequences are magnified because the hectares of tropical rain forest that are lost to deforestation no longer remain to absorb excess CO2.

Some evidence suggests that, as the CO2 content in the air rises, tropical rain forests will likely increase photosynthetic capacity, thereby removing excess carbon from the atmosphere. However, increasing temperatures that accompany the accumulation of greenhouses gases may, at some point, hinder the ability of plants to increase photosynthetic efficiency. This is because plant respiration, which releases CO2, increases exponentially with increasing temperature, whereas photosynthetic rates generally increase to a temperature optimum and then decline.

The results of a study conducted from 1984 through 2000 in La Selva, Costa Rica, have shed new light on possible scenarios for changes in atmospheric CO2 concentrations during global warming. In this 16-year study, the investigators measured annual diameter increments of tree girth along with daily temperatures and atmospheric CO2 levels. Even though the tree species studied were adapted to tropical rain-forest ecosystems, the data collected demonstrated relatively lower forest productivity at higher temperatures. These findings suggest that, as temperatures rise, increased plant respiration in tropical rain forests may add to ongoing atmospheric CO2accumulation and accelerate global warming. These studies provide a compelling argument to do what we can now to slow the process of global warming before it gets out of hand.

Some countries are doing what they can to combat the problem of deforestation. In the mid-1970s, Costa Rica established a system of national parks and reserves to protect 12% of the country’s land area from degradation. The current Costa Rican government continues to promote conservation programs through the preservation of rain forests and has a goal of expanding protected areas to 25% in the near future. Similar efforts may, indeed, slow the ever-increasing threat of global warming.

Box Figure 10.2    Lush vegetation in a Costa Rican rain forest. © Joe Vogt

National Geographic: Deforestation (website)

Brazil: Cutting down on cutting down (website)

Were you surprised by the amount of damage that is being done by global deforestation?

What do you think about the suspected relationship between global warming and deforestation, stated in your textbook? Should this be the focus of future studies?

Describe the efforts in Brazil that have allowed them to have a decrease in global deforestation. Do you think that these regulations are successful? Do you think that this could work in other parts of the world? Why or Why not?

Need all questions answered in the boxes and the page 188 from book is on here it is above this box.

Were you surprised by the amount of damage that is being done by global deforestation?

What do you think about the suspected relationship between global warming and deforestation, stated in your textbook? Should this be the focus of future studies?

Describe the efforts in Brazil that have allowed them to have a decrease in global deforestation. Do you think that these regulations are successful? Do you think that this could work in other parts of the world? Why or Why not?

Need all questions answered in the boxes and the page 188 from book is on here it is above this box.

Explanation / Answer

Deforestation has obvious negative impacts on the environment, since majority of the species lives in forest deforestation leads to extinction of many species which in turn causes imbalance in the natural systems. Deforestation reduces rain by majority which has devastating effect in agriculture.

Global warming and deforestation: Climate changes was also a major impact of deforestation yas it causes loss of moisture in soils which leads to dry and heat temperatures. Cutting down of trees releases much more carbon which gets mixed up with other green house gases that increases the threat of global warming.

Efforts taken by Brazil since 2008 in the program called Reducing emissions from Deforestation and forest Degradation (REDD) has reduced global deforestation by 40percent in the year 2008 and it has planned to reduce by 80 percent by 2020 and it will possibly have reducing the effects of deforestation in the rest of the world.

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