1. Human Impact on ecosystems
Chapter 16

2. AKS Standards
11d - assess and explain human activities that influence and modify the environment such as global warming, population growth, pesticide use, and water/power consumption

3. Humans in the Biosphere
The human population is still growing, but the earth is not, and this places increasing demands on Earth’s air, water, land, and living things
Understanding how humans interact with the biosphere is crucial to protecting these resources
Industry & technology give humans a strong advantage in competing w/ other species for limited resources
Human activity uses as much energy as all of Earth’s other multicellular species combined
Hunting and gathering, agriculture, industry and urban development have significantly transformed the biosphere
Human activities can change the flow of energy in an ecosystem and reduce the ability of ecosystems to recycle nutrients.

4. The Green Revolution
The green revolution was introduced in the 1950’s by the government as an effort to greatly increase the yields of rice, wheat, and other crops
Using highly productive varieties of certain crops
Using monoculture – large fields cleared, plowed, and planted with the same crops year after year
Relied on pesticides, fertilizers, and large equipment to support large growing areas
Benefits: increased food production
Problems: depletion of energy and water supplies, pest species enabled to reproduce on a vast scale, pesticides can be potentially harmful, fertilizers can interfere with food webs and biogeochemical cycles
Key Terms: green revolution, monoculture
Key Concepts/Class Activity: List three types of human activities that can affect the biosphere. For each activity, give one environmental cost and one benefit.

5. The Industrial Revolution
The era known as the Industrial Revolution was a period in which fundamental changes occurred in agriculture, textile and metal manufacture, transportation, economic policies and social structure ( ).
Dense human communities
Human waste products
Reduction in habitats
Pollution
Overuse of wildlife products

6. Earth’s human population continues to grow
Our prediction of Earth’s human carrying capacity has changed over time. Although we do not know of a fixed limit to the number of people that Earth can support, some limit must exist. As humans have modified their environment through agriculture, transportation, medical advances, and sanitation, the carrying capacity of Earth has greatly increased.

7. The growing human population exerts pressure on earth’s natural resources
Renewable Resources: those that replenish themselves quickly enough so that they will not be used faster than they can be produced.
Examples include: oil & coal
Nonrenewable Resources: natural resources that are used more quickly than they can be formed.
Examples include: wind energy, solar energy, and resource renewable through regrowth or reproduction (as long as they are not used faster than their regrowth)
Renewable resources are NOT NECESSARILY unlimited! Fresh water is renewable but can become limited by drought or overuse.
Fossil fuels form over hundreds of millions of years from deeply buried organic materials…when they are depleted, they are gone forever!!!!

8. Effective management of earth’s resources will help meet the needs of the future
Earth’s carrying capacity depends on how much land is needed to support each person on Earth. The amount of land necessary to produce and maintain enough food, water, shelter, energy, and waste is called an ecological footprint. Individuals and populations vary in their use of resources and production of waste, and therefore in the size of their ecological footprint. The average U.S. citizen’s ecological footprint covers an area larger than 24 football fields and is one of the largest in the world.

9. Critical thinking activity: Connecting concepts
The progressive increase in Earth’s human carrying capacity came from advances in technology. What density-independent and density- dependent limiting factors may prevent the human population from continued growth?
Disease, lack of food, limited water supplies (density-dependent)
Exhaustion of nonrenewable resources, medical and cultural practices (density-dependent)

10. AKS Standards
11d - assess and explain human activities that influence and modify the environment such as global warming, population growth, pesticide use, and water/power consumption

11. Pollutants Accumulate in the air
Pollution describes any undesirable factor, or pollutant, that is added to the air, water, or soil. The harmful effects of pollutants can be immediate or delayed, but these effects may add up over time and can disrupt the function of ecosystems. Smog is a type of air pollution caused by the interaction of sunlight with pollutants produced by fossil fuel emissions.

12. Acid Rain
The chemicals produced by the burning of fossil fuels become part of the ecosystem and can change the products of natural cycles. For example, nitrogen oxides and sulfur oxides from fossil fuel emissions can lead to the formation of acid rain. By decreasing pH levels in lakes and streams, acid rain threatens water supplies and species habitat.
The burning of wood and of fossil fuels, including coal and oil, releases oxides of sulfur and nitrogen that react with water in the atmosphere, forming sulfuric and nitric acid, respectively.
The acids eventually fall to Earth’s surface as acid precipitation – rain, snow, sleet, or fog that has a pH of less than 5.2.
This acid precipitation lowers the pH of streams and lakes and affects soil chemistry and nutrient availability.
The main causes of acid rain are emissions from ore smelters and electrical generating plants.

13. Ecological Effects from Acid Rain in Lake System
Changes begin to occur as soon as a lake starts to lose it natural bases or alkalinity.
A large reduction in the number of plankton & invertebrates.
The rate of decomposition of organic matter decreases
Direct effects on fishes reproductive cycles.
A calcium deficiency in fish leads to bone malformation.
Fish can suffocate as their gills become clogged with aluminum hydroxide.
Songbirds are effected by eating insects contaminated with toxic metals.

14. The Greenhouse effect
Earth’s temperatures remain within a range suitable for life because of the biosphere’s natural insulating blanket – the atmosphere
Carbon dioxide, methane, water vapor, and other gases trap heat energy and maintain Earth’s temperature range
The function of these gases is similar to glass in a greenhouse – they trap the heat energy of sunlight inside Earth’s atmosphere.
The natural situation in which heat is retained by this layer of greenhouse gases is called the greenhouse effect.
These greenhouse gases allow solar energy to penetrate the earth’s atmosphere, where much of the sunlight that hits the Earth’s surface is converted to heat energy and reflected back into the atmosphere.
The same greenhouse gases do not allow the heat to readily escape the atmosphere, but instead, trap it inside. The Earth is heating up!

15. Global warming
Human activities may be causing climate change by increasing carbon dioxide concentration in the atmosphere!
Rising atmospheric CO2 - since the Industrial Revolution, the concentration of CO2 in the atmosphere has increased greatly as a result of burning fossil fuels.
Human-produced greenhouse gases include: carbon dioxide: CO2 , methane: CH4, nitrous oxide: N2O
The predicted consequences of global warming include:
sea level rise
increased plant primary productivity
increased storm severity
changes to patterns of rainfall
changes to ocean circulation patterns

16. Animated biology: Greenhouse warming
t5/bio_ch16_0491_ab_co2fx.html

17. AKS Standards
11d - assess and explain human activities that influence and modify the environment such as global warming, population growth, pesticide use, and water/power consumption

18. Water pollution affects ecosystems
Algae are microscopic plants that are usually aquatic, unicellular, and lack true stems, roots, and leaves. Algal blooms occur in both marine and freshwater environments when an algal species outcompetes other species and reproduces rapidly. An algal bloom can still kill fish and other aquatic life by decreasing sunlight available to the water and by using up all of the available oxygen in the water. Blooms can be caused by several factors. An increase in nutrients can cause algae growth and reproduction to increase dramatically into a bloom just as fertilizing a lawn makes the grass grow faster.

19. Biomagnification causes accumulation of toxins in the food chain
In biomagnification, there is a tendency for pollutants to concentrate as they move from one link in a food chain to another…top level carnivores suffer the most harmful effects of biomagnification. Know and be able to explain how biomagnification of DDT affected the health of large birds of prey.
Dichlorodiphenyltrichloroethane (DDT):
Used as a pesticide from 1939-late 1960s; fat soluble compound - it is not broken down by metabolic processes in bacteria, plants, or animals
When DDT is picked up by organisms, they do not eliminate it from their bodies. As a result, something unexpected happens. DDT is picked up, concentrated, and stored by aquatic plants and algae.
When herbivores eat those plants, they concentrate DDT to levels ten times higher than levels found in plants! When carnivores eat herbivores, the toxic substance is concentrated further in a process called biological magnification.
The world’s production has substantially decreased since it was banned in the West
Detected in mud of deep sea and snow & ice of Antarctica

20. Interactive review: Water Quality
Complete this interactive review using your virtual textbook at home. Concept maps are an excellent way to organize your thoughts and review material!

21. AKS Standards
11d - assess and explain human activities that influence and modify the environment such as global warming, population growth, pesticide use, and water/power consumption

22. Preserving biodiversity is important to the future of the biosphere
Biodiversity is the sum total of the genetically based variety of all organisms in the biosphere
Biologists have identified ~1.5 million species and estimate that there are millions more.
Biodiversity is one of the Earth’s greatest natural resources – food, industrial products, medicines!!!!
Ecosystem diversity includes the variety of habitats, communities, and ecological processes in the living world
Species diversity is the number of different species in the biosphere
Genetic diversity is the sum total of all the different forms of genetic information carried by all organisms living on Earth today

23. Loss of habitat eliminates species
Development often splits ecosystems into pieces (habitat fragmentation). This results in remaining pieces of habitat becoming biological “islands”. Fewer species can survive here and they are more vulnerable to further disturbances or climate changes.

24. Introduced species can disrupt stable relationships in an ecosystem
One of the largest threats to biodiversity is the accidental or intentional introduction of new plants and animals to areas around the world by humans.
These can often become invasive species (a new species able to reproduce rapidly because their new habitat lacks the natural population controls they face in their old habitat).
Cane Toads in Australia
Kudzu in America
African Bees in South America
Burmese Python in Florida Everglades

25. Conserving Biodiversity
Conservation describes the wise management of natural resources
Today, conservation efforts focus on protecting entire ecosystems as well as single species
Most often, the need to protect biodiversity is greatest in countries that are least able to do so (these are known as “hot spots”) – immediate danger of extinction of species as a result of human activity
Example: rainforests are found in developing countries
In an effort to locate problem areas and set up a list of conservation priorities, conservation biologists identify “hot spots”…places where significant numbers of habitats and species are in immediate danger of extinction as a result of human activity.
Pg. 156 – hot spot photo.
Class Activity: Draw an illustration of a problem that could result if an endangered species were introduced into a nonnative habitat…you may choose from the species shown in figure 6-18.
Key Terms: biodiversity, ecosystem diversity, species diversity, genetic diversity, extinction, endangered species, habitat fragmentation, biological magnification, invasive species, conservation
Key Concepts: Why is biodiversity worth preserving? List 4 ways in which humans can decrease biodiversity. What is the current focus of conservation biologists worldwide? Explain the relationship between habitat size and species diversity.

26. Biological Hot Spots
In an effort to locate problem areas and set up a list of conservation priorities, conservation biologists identify “hot spots”…places where significant numbers of habitats and species are in immediate danger of extinction as a result of human activity.

27. Webquest: invasive species

28. DATA ANALYSIS ONLINE
ch16_frog_recovery/index.html

29. AKS Standards
11d - assess and explain human activities that influence and modify the environment such as global warming, population growth, pesticide use, and water/power consumption

30. SUSTAINABLE DEVELOPMENT MANAGES RESOURCES FOR PRESENT AND FUTURE GENERATIONS
Sustainable use is a way of using natural resources at a rate that does not deplete them
Land resources
Forest resources
Ocean resources
Air resources
Water resources
A sustainable system operates without causing long-term harm to the ecological resources on which it depends
Example: alternative methods of pest control that do not involve harmful chemicals

31. Critical thinking activity: interpreting visuals

32. Animated biology: Human effects on a food web
t5/bio_ch16_0507_ab_foodwbfx.html