1. Bio 178 Lecture 19 Photosynthesis (Cntd.) Copyright: J. Elson-Riggins

2. Reading Chapters 10 & 11, P 1186, 1220 Quiz Material Questions on P 206 & 226 Chapters 10 & 11 Quizzes on Text Website (www.mhhe.com/raven7)

3. Outline Photosynthesis  Energy Cycle - Importance of Photosynthesis

4. The Energy Cycle Cellular Respiration Uses the glucose and O 2 made by photosynthesis to fuel endergonic reactions.  The energy for life is released, not produced by cellular respiration. Photosynthesis The waste products of cellular respiration are the raw materials for photosynthesis - to make glucose and O 2.

5. The Carbon Cycle

6. CO 2 Use Globally, photosynthesis uses ~10% of atmospheric CO 2 to produce organic compounds. All terrestrial heterotrophs obtain their C indirectly from photosynthetic organisms. Carbon Acquisition Decomposers recycle C in dead organisms either into the atmosphere or into aquatic sediments. CO 2 Release Heterotrophs release C back into the atmosphere through respiration. Burning fossil fuels releases C into the atmosphere.

7. The Carbon Cycle (Cntd.) Balance Between Carbon Release and Use Respiration and Photosynthesis are approximately balanced. Consumption of fossil fuels has shifted this balance. Deforestation is also shifting this balance.

8. Deforestation Copyright: J. Elson-Riggins

9. Deforestation Facts ~1/2 the original extent of the world’s tropical rainforests were left by the mid-1990s. From this, an area greater than the size of Indiana is clear-cut every year. Destruction of the Amazon rainforest reached its highest level in 10 years from Aug 03 - Aug 04 with 10,000 square miles burned and cut down. 17.3% of the Amazon rainforest has now been destroyed. If this rate continues all the tropical rainforests in the world will have gone in ~ 30 years.

10. Deforestation http://www.greenpeace.org.uk/forests/med ia/pressrelease.cfm?ucidparam=20050519 110452 http://www.telegraph.c o.uk/news/main.jhtml? xml=/news/2005/05/20 /wjung20.xml http://www.wwf.org.uk/news/n_0000001 569.asp

11. Consequences of Deforestation The Carbon Cycle Deforestation decreases global photosynthesis  increasing atmospheric CO 2. Burning forest to convert it to pastureland further increases atmospheric CO 2. Increasing atmospheric CO 2 enhances the greenhouse effect  increased global temperatures. The Hydrologic Cycle ~1/2 the precipitation that falls in the rainforest is a result of transpiration. This is also responsible for cloud formation and affects global temperatures (reduces evaporative cooling).

12. Consequences of Deforestation (Cntd.) Biodiversity Although tropical rainforests cover ~ 7% of terrestrial earth, they hold >1/2 of all the plant and animal species on earth. It is estimated that 137 species disappear globally every day ( http://earthobservatory.nasa.gov/Library/Deforestation/). Nutrient Loss In tropical rainforests most of the nutrients are present in the plants, rather than the soil. Removing the trees  removes the nutrients required for growth. Any remaining nutrients are washed away when it rains. Within 3 years the ground will no longer support crops.

13. Selective Logging (Asner et al. 2005. Science 310: 480-482) What is it? Individual trees are removed from the rainforest, rather than clear-cutting the forest. How much selective logging occurs? Due to lack of appropriate technology selective logging has been historically underestimated - logged areas of the Brazilian Amazon have been logged 60-123% (per year) more than previously estimated (1999-2002). Consequences Increases annual C flow from the Amazon 25% more than previously estimated for deforestation alone. Thins shady canopy and causes damage to undergrowth  forests are drier and more flammable.

14. The Ceiba tree is an example of a tree that is very important in the Amazon. It is much taller than the other trees and therefore can offer other organisms the opportunity to be exposed to more sunlight. Epiphytes are found on the ceiba tree, including bromeliads. These fill with water and therefore provide habitat for amphibians. Many organisms use the ceiba tree. However, the ceiba tree is also a very valuable resource for humans. It is the source of kapok, which was used historically for filling life jackets. The length of the tree also makes it valuable for making long canoes. Ceiba trees are therefore highly sought after by humans. What might be the effects on the Amazon ecosystem of cutting down a Ceiba tree?

15. Ceiba Tree Copyright: J. Elson-Riggins

16. Ceiba Tree Copyright: J. Elson-Riggins