CHAPTER 12
ECOSYSTEMS AS RESOURCES

I. Why Do We Want to Use Resources Sustainably?

A. Resources provided by ecosystems sustain life.
B. There are a limited number of resources in an ecosystem.
C. Ecosystems are limited in their ability to cycle resources.

II. Ecosystems and Their Goods and Services

A. The Goods (Resources)
a. Wood: buildings, paper, furniture
b. Food: meat, grains, vegetables, fruits, oils
c. Minerals: phosphorus and nitrogen (for farming), copper (electrical wire),
aluminum (cans, cars), iron, silver, gold, platinum, titanium
d. Fuel: wood, petroleum, dung, alcohol
e. Clothing: cotton, rayon, nylon, polyester, fur, leather
f. Plastics: petroleum, trees (rayon)

B. The Services

1. Maintenance of Hydrologic Cycle: water infiltrates soil and is absorbed
by plants.
Water evaporates from soil or evapotranspires from plants. Evaporated water
condenses in the atmosphere and falls to the earth as precipitation. Flooding is
prevented by the functioning of dynamic ecosystems because precipitation is
absorbed by the ecosystem and slowly released.
2. Modification of Climate: Water absorbs a considerable amount of energy
from the sun as it evaporates. This energy is released when the water condenses.
Heat is moved around the planet in water.
3. Erosion Control and Soil Building: Plant and detritus control erosion by
absorbing the impact of precipitation, and make a greater surface area available
for the absorption of water. Plants, animals, and microorganisms found in
terrestrial ecosystems create soil.
4. Maintenance of  Oxygen and Nitrogen Cycles: Photosynthesis releases
oxygen. Nitrogen fixing microorganisms in the soil maintain soil fertility.
5. Waste Treatment: Water is a universal solvent. Many water-soluble pollutants
(sediments, excess nutrients) are removed from the water in wetlands.
6. Transformation of Toxic Chemicals: Microorganisms transform many toxic
chemicals, both organic and inorganic, into harmless products. [The opposite is
true also. The Minamata Bay disaster resulted when inorganic mercury was
released in industrial effluent and transformed by microorganisms into organic
mercury.]
7. Pest Management: Predators for the organisms we consider pests exist. When
predators are maintained, pest management is provided by ecosystems.
8. Carbon Storage and Maintenance of the Carbon Cycle: Carbon is cycled
through the atmosphere, biomass, and soil. The biomass of the forest contains 500
billion metric tons of carbon  more than is found in the atmosphere. Even more
          carbon is found in the organic matter of soil
Fig. 12.4 Worth more than $100,000 a year for just one acre, these services are lost when wetlands are bulkheaded and converted for vacation homes.
B. Monetary Benefit of Ecosystems

1. A 1997 study estimated that the world's ecosystems provide $33 trillion worth of
goods and services per year.
2. One acre of wetlands does the equivalent of $100,000 per year of water purification
and fish propagation services.
3. We undervalue the services of ecosystems because their services are provided free
of charge.
4. We notice the services when they are gone:
a. The eutrophication of Chesapeake Bay is a result of wetland loss and an increase
in the added nutrients within its watershed.
b. Flooding in Bangladesh is a result of deforestation in India; consequently, the
monsoons cause great loss of human life and devastation of crops.

III. Patterns of Use of Natural Ecosystems

A. Consumptive versus Productive Use
1. In consumptive "people harvest natural resources in order to provide for their
needsfor food, shelter, tools, fuel and clothing."
2. "Productive user refers to the exploitation of ecosystem resources for economic
gain."

B. "A natural ecosystem will receive protection only if the value society assigns to its
natural function is higher than the value the society assigns to exploiting its natural
resources."
1. This is a conflict between individual gain from and societal loss of the goods and
services provided by an ecosystem.
2. This conflict also occurs between those who use public land for private gain
(ranchers, loggers, miners, etc.) and those who want the ecosystem conserved in a
way that produces the greatest good for the largest number of organisms (humans
included.)

C. Maximum Sustained Yield (MSY): "The highest possible rate of use that the
system can match with its own rate of replacement or maintenance."

1. How does MSY works?
At low population size the rate of population growth will increase because the
environmental resistance factors are low.
At low population size, the rate of population growth will increase until
environmental resistance factors begin to limit population size. This point is MSY.
As the population size becomes larger than the MSY, the rate of growth population
decreases and the number of individuals that can be extracted does not increase.

2. MSY is the point where the highest rate of recruitment can occur. The highest
rate of harvesting can occur at the point where the highest recruitment occurs.

3. The difficulty with MSY is determining it. We typically do not know the point at
which the highest recruitment occurs.

4. For example, North Sea cod were overfished because we do not understand
           MSY.
Fig. 12.8 Maximum sustainable yield occurs not at the maximum population level, but rather at a lower, optimal population level.
Fig. 12.12 This figure shows the global fish catch and fish farming equals world total for 1950-97
Fig. 12.10 In the U.S. only 17% of wood is used for fuel.
Fig. 12.14 This method of harvesting groundfish has been compared to clear-cutting forests because of degradation of the bottom.
D. Tragedy of the Commons: When a resource is held in common or by no one, it is
known as a commons.
1. Grasslands (grazing, mining)
2. Coastal and open ocean (fishing, mining)
3. Groundwater (urban and agricultural use)
4. Woodlands and forests (logging, mining)

IV. Ecosystems Under Pressure

A. Forests and Woodlands
1. Threat: Total Removal
2. Consequences: loss of biomass, reduced productivity, reduced biodiversity, soil
erosion, changed hydrologic cycle, loss of carbon dioxide sink

B. Ocean Ecosystems
1. Threat: Overexploitation
2. Consequences: Reduced productivity and reduced biodiversity

C. Grasslands
1. Threat: Total Removal
2. Consequences: Loss of biomass, reduction in biodiversity, loss of carbon dioxide
sink, changed hydrologic cycle, and soil erosion
V. Solutions

A. Private Ownership of Land
B. Regulation of Commerce (national parks and wildlife refuges, etc.)
C. Land Trusts
D. Preservation
E. Conservation

VI. When We Have Gone Too Far  Restoration Ecology

A. Restoration Ecology: Repairs a damaged ecosystem so that normal functioning
returns and the native flora and fauna are again present.

B. Difficulties
1. Lack of Knowledge
2. Disturbed Soils
3. Accumulated Pollutants
4. Exotic Species Have Achieved Dominance

C. Examples:
1. Prairie Restoration at Fermi Labs, Illinois
2. Wetlands Restoration at Stone Lake on the Consumnes River, California
3. Riparian Habitat Restoration by the Nature Conservancy along the Sacramento
River, California

VII. Public and Private Land in the United States

A. Federal, State and Local Land
1. What do they provide us?
2. Who benefits from them?
3. Why do we have them?

B. Private Land
1. Land Trusts
2. Individual Owners
3. Corporate Owners
Fig. 12.16 Because the East and Midwest were settled first, federally-owned lands are concentrated in the West and Alaska.
Fig. 12.17 The National Park is the center of a much larger ecosystem receiving attention from the Greater Yellowstone Coalition.
Fig. 12.13 This figure shows cod landings from Georges Bank, 1982-96.