1. APES Chapter 3 Mrs. Hatchett
Ecosystem Ecology
APES
Chapter 3
Mrs. Hatchett

2. Reversing the Deforestation of Haiti
This case offers us the idea that many problems can be solved by using economic principles!
Low income, people of Haiti began cutting trees to make charcoal from firewood.
As population grew, so did the demand for charcoal
1923: 60% forests
2012: less than 2% forests
Today, most trees in Haiti are cut before they grow to more than a few centimeters in diameter. This is not sustainable.

3. Clear-cut: land more susceptible to erosion
When trees are cut, their roots die and can no longer stabilize the soil. Without roots as anchors, soil erodes with heavy rains of tropical storms and hurricanes.
Rainwater runs quickly down the mountainsides, dislodging the topsoil that is so important for forest growth.
Oversaturation of the soil causes massive mudslides that can destroy entire villages.
1980’s 60 million donated trees planted, but locals can’t afford to let the trees grow because of need of charcoal and firewood.

4. Solution: plant mango trees
Mature mango tree can provide $70 to $150 worth of mangoes, providing an economic incentive to let the trees grow to maturity.
Solution: efforts to develop alternative fuel sources, such as discarded paper that is processed into dried cakes that can be burned.
Solution: president of Haiti started new program to plant 50 million trees every year, with the goal of getting 29% forest cover in 50 years.
This case study demonstrates that economic thinking can be used to solve an environmental problem. Economic concepts are essential to the decisions we make about the environment and should be threaded into everything we learn.

5. This case study reminds us that all the components of an ecosystem are interrelated.
An ecosystem is a mix of interacting biotic and abiotic components
The abiotic components of the ecosystem help determine which organisms can live there.
In this chapter we ill see that ecosystems control the movement of the energy, water, and nutrients organisms must have to grow and reproduce. Understanding the processes that determine these movements is the goal of ecosystem ecology.

6. Question? What is an ecosystem and what are its components?
Ecosystem: a natural unit distinguished by the nonliving, physical environment and the community of all organisms living in a given area.
It includes nonliving, or abiotic, components such as water, soil , and the atmosphere, as well as living, or biotic, components such as animals, plants, and microorganisms.

7. Ecosystem Boundaries are not Clearly Defined
The characteristics of any given ecosystem are highly dependent on the climate that exists in that location on Earth.
Temperature, amount of rainfall, soil water retention (high supports trees, low support only grasses)
The biotic and abiotic components of an ecosystem provide the boundaries that distinguish one ecosystem from another.
Cave = well defined ecosystem: contains identifiable biotic components (animals and microorganisms that are specifically adapted to live in a cave), distinctive abiotic components (temperature, salinity, and water that flows through the cave as an underground stream)

8. Bat feces provide energy that p asses through the relatively few animal species that live in the cave. Small invertebrate animals consume bat fees and are in turn consumed by cave salamanders.

10. A cave ecosystem is relatively easy to study because its boundries are clear.
With the exception of the bats feeding outside of the cave, the cave ecosystem is defined as everything from the point where the stream enters the cave to the point where it exits.
Many aquatic ecosystems, such as lakes, ponds, and streams, are relatively easy to define because the ecosystem’s boundaries correspond to the boundaries between land and water.
Knowing the boundaries of an ecosystem, makes it easier to identify the system’s biotic and abiotic components and to trace the cycling of energy and matter through the system.

11. In most cases, determining where one ecosystem ends and another begins is difficult. For this reason, ecosystem boundaries are often subjective.
Environmental scientists can define boundaries in different ways; the range of a particular species of interest (area where wolves roam), or topographic features (two mountain ranges enclosing a valley), national parks are defined by administrative choices rather than scientific criteria.
Ecosystems can be vast (Yellowstone) or small (water-filled hole in a fallen tree trunk). Even the tiny ecosystems include all the physical and chemical components necessary to support a diverse set of species, such as microbes, mosquito larvae, and other insects.

12. Each ecosystem interacts with surrounding ecosystems through the exchange of energy and matter.
Some organisms move across ecosystem boundaries (bats)
Some chemical elements move across ecosystem boundaries (carbon or nitrogen dissolved in water)
Changes in any one ecosystem can ultimately have far-reaching effects on the global environment.
The combination of all ecosystems on Earth forms the biosphere, which is the region of our planet where life resides.

13. How do you know when you leave one ecosystem and enter another?
Depends: Sometimes it is easy , like when you enter a body of water from land or walk into a cave. Others, there are no well defined boundaries and you may enter a transition zone when going from one to the other. This transition zone might include an overlap of biotic and abiotic components from both ecosystems, such as vegetation type, soil substrate, or topography.

14. Photosynthesis Captures Energy and Respiration releases Energy
To understand how ecosystems function and how best to protect and manage them, ecosystem ecologists also study the processes that move energy and matter within an ecosystem.
When looking at the Serengeti Plain in East Africa, there are millions of herbivores but far fewer carnivores….why???
Acording to the 2nd law of thermodynamics, when one organism consumes another, not all of the energy in the consumed organism is transferred to the consumer. Some of that energy is lost as heat.
So, the carnivores in an area contain less energy than all the herbivores in the same area because all the energy going to the carnivores must come from the animals they eat.

15. Photosynthesis

16. Nearly all of the energy that powers ecosystems comes from the Sun as solar energy, which is a form of kinetic energy.
Plants, algae, and some bacteria that use the Sun’s energy to produce usable forms of energy are called producers, or autotrophs.
Photosynthesis: use solar energy to convert carbon dioxide and water into glucose and oxygen. Glucose is a form of potential energy that can be used by a wide range of organisms.
Oxygen is produced as a waste product of photosynthesis and the producer releases this waste into the atmosphere.
Why are plants and other producers beneficial to our atmosphere? Because they produce the oxygen we need to breathe!

17. Cellular Respiration

18. Producers use the glucose they produce to store energy and to build structures such as leaves, stems, and roots.
Herbivores then eat the tissues of producers and gain energy from the chemical energy contained in those tissues.
They do this through cellular respiration: a process by which cells unlock the energy of chemical compounds.
Aerobic respiration is the opposite of photosynthesis; cells convert glucose and oxygen into energy, carbon dioxide, and water.

19. In essence, organisms conducting aerobic respiration run photosynthesis backward to recover the solar energy stored in glucose.
If organisms, like bacteria, that live where oxygen is not available, conduct anaerobic respiration: cells convert glucose into energy in the absence of oxygen.
Anaerobic respiration does not provide as much energy as aerobic respiration.
Many organisms—including producers–carry out aerobic respiration to fuel their own metabolism and growth.
Thus producers both produce and consume oxygen.

20. When the Sun is shining and photosynthesis occurs, producers generate more oxygen through photosynthesis than they consume through respiration. At night, when producers only respire they consume oxygen without generating it.
Overall, producers photosynthesize more than they respire.
The net effect is an excess of oxygen released into the air and an excess of carbon stored in the tissues of producers.

21. Complete the Concept Map
Performed by plants
Uses CO2
Produces CO2
Photosynthesis
Cellular Respiration

22. Energy Captured by Producers Moves Through Many Trophic Levels
Consumers, or heterotrophs, are incapable of photosynthesis and must obtain their energy by consuming other organisms.

23. Consumers in both terrestrial and aquatic ecosystems fall into different categories.
Consumers that eat producers are called herbivores or primary consumers.
Consumers that eat other consumers are called carnivores.

24. Carnivores that eat primary consumers are called secondary consumers.
Carnivores that eat secondary consumers are called tertiary consumers.
The successive levels of organisms consuming one another are known as trophic levels.

25. Homework
Draw the pathway of energy as it travels from the Sun to a hawk
Make sure you indicate the direction of energy flow and label the types of energy in the diagram. (if it helps you can color coordinate the energy flow (the arrows); red for solar energy and black for chemical energy)
Why does only about 10% of the energy available at a given trophic level get passed on to the next trophic level?
What happens to the energy flow beyond the hawk?

26. The sequence of consumption from producers through tertiary consumers is known as a food chain, where energy moves from one trophic level to the next.
A food chain helps us visualize how energy and matter move between trophic levels.
Species are rarely connected in such a simple, linear fashion.
A more realistic type of model is a food web.

27. A food web is a complex model of how energy and matter move through trophic levels.
Food webs illustrate that in an ecosystem, all species are connected to one another.
Not all organisms fit neatly into a single trophic level.

28. Omnivores operate at several trophic levels.
Each trophic level eventually produces dead individuals and waste products.
Three groups of organisms feed on this dead organic matter: scavengers, detritivores, and decomposers.

29. Scavengers are organisms that consume dead animals.
Detritivores are organisms that specialize in breaking down dead tissues and waste products (referred to as detritus) into smaller particles.
These particles can then be further processed by decomposers, which complete the breakdown process by converting organic matter into small elements and molecules that can be recycled back into the ecosystem.

30. Without scavengers, detritivores, and decomposers, there would be no way of recycling organic matter and energy, and the world would rapidly fill up with dead plants and animals.

31. Activity Write three different food chains within the food web.
Compare and contrast the information offered in a food chain verses a food web.

32. Some Ecosystems are More Productive Than Others