Community Ecology and Human Impact

1. Accelerated Bio Ecology Part II Chapter 20: Community Ecology Chapter 22: Humans in the Environment

2. 20-1 Species Interactions of Communities Communities contain interacting populations of many species. 3 major types of interactions between species: • PREDATION: predator eats all or part of an individual  the prey • Predators survival depends on ability to capture food • Adaptations of predators: venom, flesh-cutting teeth, sticky webs, speed • Prey’s survival depends on ability to avoid capture • Adaptations of prey: camouflage, chemical defenses (plants & animals), mimicry (resembles another species) , thorns, spines

3. 2) COMPETITION • limited resources force competition among living things in same niche. • among same species = intraspecific competition • between different species = interspecific competition • all competition almost always produces a winner and a loser (dies out) • ex: two species of paramecium kept in same culture…one species out competed the other. • the competitive exclusion principle: no two species can occupy the same niche at the same time. • dividing resources can be a “truce” in the competition for resources • ex: one spruce tree can provide for three different niches of warbler birds feeding on high, middle, and low branches • ** by dividing resources, competition helps determine the number and types of species in a community AND the niche each species occupies

4. Predation, Herbivory and Keystone Species • predator-prey: predators affect the amount ofprey and where prey can live and feed • herbivore-plant: herbivores affect both the size and distribution of plants and determine where those plants can grow • keystone species: a change in one species can have drastic effects on many other species in the community • ex: Pacific NW: sea urchins eat giant kelp stalks. Sea otters eat sea urchins. • Otters are a keystone species- they keep the sea urchin population in check • Over hunting of the otters allowed urchin population to explode giant kelp forests destroyed by urchin activity • with no kelp, many animals were without a habitat • otters are now protected species, urchin population is under control and kelp forests have rebounded

5. 3) Symbiotic Relationships • symbiosis = “together living”. • any relationship where 2 species live in close association with each other. • 3 main types of symbiotic relationships: A) mutualism(“win-win”): Both benefit. ex: sea anemone and clown fish. Clown fish gets a protected home and the anemone gets a defender when attacked B) parasitism (“win-lose”): One benefits at the harm of the other (host) ex: tapeworm inside a human. Tapeworm absorbs digested food of host, the host’s cells starved for nutrition. C) commensalism(“win-no harm/help”): One benefits while the other is neither harmed nor helped ex: barnacles on a whale. Barnacles benefit by motion of whale and the movement of food particles over them. No benefit or harm comes to the whale.

6. 20-2 Ecological Succession: Primary and Secondary • Succession: a progressive, predictable ecological change in a community over time • In 1833, volcanic island of Krakatau completely destroyed by an eruption – left completely barren. • 2 years later, grasses are present • 14 years later, 49 plant species and lizards, birds, insects, and bats • by 1929, a forest with 300 plant species were present. • today the island is a mature rainforest • HOW?: Primary Succession: • begins with no remnants of the previous community • pioneer species are first to colonize barren land • ex: lichen (fungus and algae) turn rock into soil, turn N2 gas into useful nitrogen forms, and add organic material to the soil • certain grasses are also pioneer species

7. Secondary succession: occurs after a major event disturbs a community (fire, flood, earthquake, hurricane) • SOIL survives the disturbance • plants re-colonize the area faster than in primary succession • can also follow human activities like forest clearing and farming • once plants are established, herbivores can move in and make use of the food supply. Then, carnivores can move in • if ecosystem is healthy, it may be restored to its natural state prior to disturbance (the “climax” community) • sometimes the human impact is so traumatic, a full recovery through succession is not possible

8. Chapter 6:Human Environmental Impact Humans: Rely on Earth’s life-support systems Affect our environment when we: Obtain food Eliminate waste products Build places to live “Humans affect regional and global environments through agriculture, development, and industry in ways that have an impact on the quality of Earth’s natural resources, including soil, water, and the atmosphere.”

9. The Effect of Human Activity Agriculture - Supplies a dependable food source that can be stored for later use Positives Enabled human settlements that ultimately led to modern civilization Negatives Impacts natural resources as >7 billion people!!! need Food Fresh water Fertile soil Fossil fuels (fertilizer & farm equipment) Development - Trend to move to suburbs & cities Positives High standard of living Negatives Produce lots of waste that affect air, water, & soil resources Uses up farmland Divides natural habitats into fragments

10. The Effect of Human Activity Industrial Growth – Industry & scientific know-how Positives Modern conveniences of life Comfortable homes, clothes, electronic devices Negatives Require energy and consume power Need to burn fossil fuels (coal, oil, & natural gas) Wastes discarded into air, water, & soil

11. Sustainable Development Renewable and Nonrenewable Resources Renewable – can be renewed or replaced by a healthy ecosystem A single southern white pine Nonrenewable – natural processes cannot replenish them in a reasonable amount of time Fossil fuels (formed from buried organic material over millions of years) A whole forest of white pines

12. Sustainable Development Sustainable Resource Use Sustainable development Provides for human needs & wants Preserves the ecosystems that produce natural resources What does it look like? Does not cause harm to the soil, water, and climate Consumes as little energy and material as possible Flexible to survive environmental stress/disasters Takes into account human economic systems as well as ecosystem goods and services SURVIVE AND IMPROVE

13. Using Resources Wisely: Soil Why is it needed? When healthy, supports agriculture and forestry Topsoil – absorbs/retains moisture but allows water to drain What are we doing to destroy it? Allowing soil erosion – nutrients are washed away with rain Desertification – over-plowing, overgrazing, allowing land to be barren between plantings Deforestation – loss of forests Forests help to hold soil in place, absorb CO2, absorb freshwater • How can we protect it? • Leaving stems and roots in place between plantings • Crop-rotation • Contour Plowing and Terracing – creating steps to • prevent water and soil from flowing downward • Creating tree farms (makes trees a renewable resource)

14. Using Resources Wisely: Freshwater Why is it needed? Drinking water Industry Transportation Energy Waste Disposal What are we doing to destroy it? Overuse (Ogallala aquifer – took 1 million years to collect) Pollution factories, oil spills Industrial/Agricultural Chemicals Biomagnification – pollutants (like DDT, PCBs, heavy metals) magnify as they move through the food chain from primary producers to primary consumers, etc. Residential Sewage ()

15. Freshwater Resources How can we protect it? Protection of natural resources involved in water cycle Plants can filter out pollutants Watershed conservation – protecting all inter-connected bodies of water Pollution control Sewage treatment Decrease pesticide use Use biological controls instead of poisonous sprays Water conservation Drip irrigation

16. Using Resources Wisely: Atmospheric Why is it needed? Oxygen Absorption of UV radiation Regulation of global temperature What are we doing to destroy it? Pollution (Industry, Burning Fossil Fuels) Smog - Ground Level Ozone Causes respiratory diseases Acid Rain – nitrogen and sulfur oxides mixing with precipitation Damages plants, releases toxic elements from soil Greenhouse Gases – burning of fossil fuels releases CO2, CH4 and H2O Releases carbon dioxide into the air, contributes to global warming and climate change Particulates – microscopic particles of ash and dust released by industry Can be inhaled and cause respiratory problems How can we protect it? Emission standards Clean-air regulations Unleaded gasoline

17. Biodiversity:totalof all the genetically-based variation in all organisms in the biosphere Value of Biodiversity Ecosystem Diversity - variety of habitats, communities, and ecological processes in that biosphere 1.8 million species already identified! 30 million more estimated yet to be discovered!! Species Diversity - number of different organisms in a particular area Genetic Diversity – sum total of all different forms of genetic information carried by a particular species Benefits of Biodiversity Sources of medicines Genetic diversity used to increase pest resistance Keystone species (if removed) can change entire ecosystem

18. Biodiversity Threats to Biodiversity Altering habitats Hunting Introducing Invasive Species Releasing Pollution Contributing to Climate Change Conserving Biodiversity Protect Individual Species Preserve Habitats and Ecosystems Consider Local Interests

19. Meeting Ecological Challenges Ecological Footprint – total area of functioning land and water ecosystems needed both to provide the resources an individual or population uses and to make harmless the wastes that an individual or population generates The average American has an ecological footprint that is: 4x larger than global average 2x that of England >2x that of Japan 6x that of China

20. Ozone Layer Why is it needed? Ozone Layer – molecules of O3 At ground level = pollutant Upper atmosphere = protection against harmful UV radiation which can cause cancer, eye damage and decreased immunity What are we doing to destroy it? Primary problem is CFCs (Chloroflurocarbons) Found in refrigerants, aerosol cans and plastic foams How can we protect it? CFCs banned in the late 80’s (Montreal Protocol), however residual CFCs can remain in the atmosphere for more than 30 years!!

21. Fisheries What is the problem? Despite increased efforts and new technology, seafood catch numbers continue to decline What are we doing to destroy it? Overfishing: Fish thought to be a renewable resource Death rates (commercial fishing) surpassed the birth rates of the fish How can we protect it? Regulations put in place to limit fish catches Certain areas closed to fishing until populations recovered (Sustainable Fisheries Act) Aquaculture – farming of aquatic animals

22. Climate Change What’s the Problem? Global warming – increase in average temperature of our planet (0.74ºC between 1906 and 2005) with 11 of the 12 warmest years occurring between 1995-2006 Melting sea ice Rising seal levels What are we doing to destroy it? Enhanced Greenhouse Effect not allowing solar heat to move back into outer space Burning fossil fuels Automobile exhaust Industrial pollution How can we protect it? Alternative energy sources (water, wind, solar) Decrease our ecological footprint