- Slides: 86
What is Ecology? n Ecology is the study of interactions of organisms and their environment.
Where does Energy Come From? n n All energy comes from the sun (either directly or indirectly). Energy flows in one direction -from the sun to producers then through consumers. Energy is not recycled! It is used or lost as heat.
Producers/Autotrophs Producer/Autotroph: Organisms that CAN make their own food through photosynthesis (Ex: plants, algae). Process of Photosynthesis n sunlight n Carbon Dioxide + Water glucose + oxygen chlorophyll
Consumers/Heterotrophs n Consumer/Heterotroph: Organisms that CANNOT make their own food. They must eat other organisms for energy. n Herbivores- feed off plants n Carnivores- feed off animals n Omnivores- eat both plants and animals n Detritivores/scavenger- feed on dead remains (ex: earthworms, vultures)
Decomposers n Organisms that break down dead organic matter and return nutrients to the soil for producers n Ex: Bacteria, mushrooms, microorganisms
Feeding Relationships n n n Food chain: series of steps in which organisms transfer energy by eating and being eaten. Food web: overlapping food chains Trophic Level- each step in the food chain/web. n n 1 st level: producer 2 nd level: primary consumer 3 rd level: secondary consumer 4 th level: tertiary consumer
Examples of Food Webs
Ecological Pyramids 1. Energy Pyramid n Shows the relative amount of energy available at each trophic level. n Organisms use about 10 percent of this energy for life processes- the rest is lost as heat.
Draw this pyramid and label (Do not include examples- grass, mouse, snake, hawk)
2. Pyramid of Numbers n Shows the relative number of individual organisms at each trophic level (draw the pyramid below).
3. Biomass Pyramid n Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid. (Draw the pyramid below).
Biomass and amount of available energy decreases as you go up the energy pyramid.
Recycling in the Biosphere n n Unlike the one-way flow of energy, MATTER IS RECYCLED through the ecosystem. Matter is recycled because systems do not use up matter, they transform it.
Water Cycle n n n What is a cycle? When rain falls on the ground, it either soaks into the soil or runs across the surface of the soil. When rainwater runs across the land, what body of water might collect the rain? From here, where might the water flow? After the rain, the sun comes out and the land dries. Where does the water that had been on the land go?
Water Cycle Water moves between the ocean, atmosphere, and land. Steps of the water cycle: n Evaporation- water changes from liquid to gas n Transpiration- loss of water from a plant through leaves. n Condensation-water vapor turns into tiny droplets n Precipitation- rain, snow, sleet, hail n Runoff- water comes from mountains, etc. n
The Water Cycle
Plants vs animals n What is the relationship between plants and animals?
Carbon-Oxygen Cycle n n n Step 1: Carbon dioxide released into atmosphere by volcanic activity, respiration, human activity (burning fossil fuels), and decomposition of matter. Step 2: Plants take in the carbon dioxide and use it to make food (photosynthesis). Step 3: Food is passed along the food chain from producer to consumers.
Nitrogen Cycle n n n Nitrogen gas makes up 78% of earth’s atmosphere- not usable to plants and animals. Bacteria that live in the soil convert nitrogen gas to a usable form for plants through nitrogen fixation. Plants take in the nitrates and pass them along the food chain to animals.
Label and Id n Look at the worksheet. Label and identify each cycle.
The Role of Climate n Climate: average, year-after-year conditions of temperature and precipitation in a particular region.
What Shapes An Ecosystem? Climate: the average, year-after-year conditions of temperature and precipitation in a particular region. Biotic Factors: anything living that affects the environment. n Predators, animals, plants, bacteria Abiotic Factors: anything non-living that affects the environment. n n Water, soil, temperature, climate, rocks Predation: one organism feeds on another Predator: the eater Prey: the food
Habitat: area where an organism lives n Ex: a tree Niche: role or position a species has in its environment. n Ex: the role of a predator feeding on its prey.
Interspecific competition: competition among populations of different species: n Example: different birds competing for a place to build a nest on a tree Intraspecific competition: competition among members of the same species n Example: two birds of the same species competing for a mate.
Relationships among Organisms Symbiosis: 2 or more organisms living together n Mutualism: both species benefit n n Commensalism: one species benefits from relationship, the other is unaffected. n n Ex: bee and flower Ex: barnacles on whales Parasitism: a parasite lives on or near the host and harms the host. n Ex: tapeworms and ticks on animals
Parasitism- tapeworm in mammal
How do Ecosystems Change? n n Ecological succession: natural changes in an ecosystem in response to disturbances (natural disasters). Two Types: Primary and Secondary
Primary Succession n Primary Succession: the formation of new land caused by volcano, avalanche, glacier. n n No soil exists Pioneer organisms -first organisms to exist after primary succession (Ex: moss and lichen)
Series of Events in Primary Succession
Bare Rock- Primary Succession
Pioneer Organisms- Lichen
Pioneer Organisms- Moss
Secondary Succession n Secondary Succession- follows the destruction of the land caused by a disturbance that leaves the soil intact. n n n Causes: fire, flood, cut land, drought, windstorm Does NOT remove soil. Climax Community: the point of growth after succession when the plants are most stable and mature (trees).
Series of Events in Secondary Succession
Click on the website below to complete the succession computer lab assignment. n http: //ilo. ecb. org/Source. Files/succession. swf
Ecological Populations n n Population – group of organisms of the same species living in the same area. Population Size/Density – Number of organisms in population Population growth –change in population over time (increase, decrease, stay same). Biotic Potential – highest rate of reproduction under ideal conditions
Factors that Affect Population Size 1) # of births 2) # of deaths 3) # of individuals entering or leaving the area: n Immigration – movement of individuals INTO an area over a given period of time. n Emigration – movement of individuals OUT of an area over a given period of time.
Exponential Growth: J-Curve n n Occurs when the individuals of a population reproduce at a constant rate. Not realistic because populations usually a limit to their resources. n At first, the number of individuals in an exponentially growing population increases slowly. Over time, however, the population becomes larger until it approaches an infinitely large size. Under ideal conditions with unlimited resources, any population can grow exponentially.
Graph is called J-Curve Doesn’t exist in many populations. Can be seen in bacteria (b/c population size doubles every 20 minutes).
Logistic Growth- S Curve n n A realistic growth curve Most populations show this curve because resources are limited. Population grows fast (exponentially) then slows or stops because it reaches its carrying capacity. Carrying Capacity: the maximum number of individuals a population can support.
Logistic Growth- S Curve Number of Yeast Cells Carrying capacity Time (hours)
Limiting Factors n n Limiting Factors - anything that keeps organisms from reaching their biotic potential Density Dependent Factor- organism is responsible for doing: n n n Competition Predation Parasitism Disease Human Impacts Density Independent Factor- organism has no control over. n Natural Disasters
Predator – Prey Population Graph 60 2400 50 2000 40 1600 30 1200 20 800 10 400 0 1955 1960 1965 1970 1975 Moose 1980 Wolves 1985 1990 1995 0
Human Population Growth Curve Industrial Revolution begins Agriculture begins Plowing and irrigation Bubonic plague
Age Distribution Graph U. S. Population Males Females Rwandan Population Males Females
Human Impacts on the Environment
What is Biodiversity? Why is it Important? n n Biodiversity: the variety of life in an area. Importance of Biodiversity: n n n Organisms need to interact with other organisms in a community. Other organisms suffer when the organism they feed upon is removed from the area or food chain. Ecosystem balance, 02 for humans, diverse diets, clothing and building materials, medicines.
Loss of Biodiversity can lead to… n n n Threatened species: when a population of a species quickly declines. Endangered Species. when numbers become so low that extinction is possible. Extinction- the disappearance of a species n Ex: African elephants went from a population of about 3 million in 1970’s to 700, 000 in the 1990’s.
Endangered Species in GA n n Purple pitcherplant—Sarracenia purpurea Loggerhead Sea Turtle—Caretta caretta
How is Biodiversity Measured? n n Measured by counting the number of species that live in an area. More biodiversity in a tropical rain forest than in a cornfield.
Causes of Biodiversity n Introduction of non-native/exotic species n n Habitat Loss n n Changing a rain forest into a pasture Habitat Fragmentation n n Introduce new species to environment on purpose or by accident can cause problems to native species. Cutting in roads across a forest area Habitat Degradation n Damage to habitat by pollution
Bioaccumulation and Biomagnification n n Bioaccumulation- the process of pollutants entering a food chain usually at producer level. Biomagnification: the tendency of pollutants to concentrate as they move from one trophic level to the next in a food chain. n Even small concentrations of chemicals in the environment can find their way into organisms in high enough dosages to cause problems.
History of DDT stands for dichloro, diphenyl trichloroethane. n n Developed and used during WWII- given to soldiers to help with lice & mosquitoes. Heavily used in US from 1940 s to 1970’s: sprayed in public areas to kill mosquitoes. Banned from US in 1972, but continues to be used in other countries. Used in Africa to kill mosquitoes and help with spread of Malaria.
Rachel Carson n n DDT a serious problem…decline in bird populations (top of food chain) and caused thin egg shells. Silent Spring written by Carson helped to bring about formation of EPA and banning of DDT Bird populations showed dramatic recovery Even today, traces of DDT have been found in every organism tested—even in human breast milk throughout world
Human Impact on Land n n n SOIL EROSION – is the wearing away of surface soil by water and wind. Overplowing removes soil. Desertification – the process of turning once productive areas into deserts from a combination of farming, overgrazing, and drought. Deforestation: loss of forest leads to erosion. n n Takes away habitats for organisms to live. Decreases the process of photosynthesis
Soil Erosion Deforestation
Solutions to Land Depletion n Contour plowing- fields plowed across the slope of the land Leaving stems and roots of the previous year’s crops in place to hold soil. Replant trees that are cut down.
Human Impact on Water Oil Spills threaten our water supply. n Improperly discarded chemicals can enter streams and rivers. n Domestic sewage entering water ways can cause an increase in bacteria growth. n Overfishing: fish stocks are harvested faster than they can reproduce. n
Water Resources n What is being done? n n n Limiting the catch of fish Certain fishing grounds have been temporarily closed Aquaculture - farming of aquatic organisms (see picture to right)
Air Resources n n Smog - a mixture of chemicals that occurs as a graybrown haze in the atmosphere The burning of fossil fuels can release pollutants that cause smog and other problems in the atmosphere. n n This leads to toxins that enter the mouth, nose and lungs causing health problems over the long term. Gases released from the burning of fossil fuels combine with water vapor to form ACID RAIN Acid rain kills plants and changes the chemistry of soils What is being done? n n Technology to control emissions from factory smokestacks Strict automobile emission standards and clean air regulations
Acid Rain n "Acid rain" : term used to describe several ways that acids fall out of the atmosphere. n n n Wet deposition (acidic rain, fog, snow) Dry depostion (acidic gases and particles). Primary Cause of Acid Rain: sulfur dioxide (SO 2) and nitrogen oxides (NOx). In the US, about 2/3 of all SO 2 and 1/4 of all NOx comes from electric power generation that relies on burning fossil fuels like coal. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. Sunlight increases the rate of most of these reactions. The result is a mild solution of sulfuric acid and nitric acid.
Air Resource Depletion
Global Warming n n Global Warming: the term used to describe an increase in the average temperature of the biosphere. Temperatures have risen 0. 5 degrees over the last 120 years. Estimated increase of 2˚C by end of 21 st century Even 1. 3˚C affects polar ice cap melting (sea level could rise 100 m, gradually going in 150 km or more)
Why is this a problem? n n n Polar ice caps will continue to melt and could rise enough to flood some low lying coastal areas. Storms and other weather disturbances could become more frequent and severe. Heat favors rodents, weeds, and insects that reproduce and spread quickly.
Sunlight Some heat escapes into space Greenhouse gases trap some heat Atmosphere Earth’s surface
Global Warming- The Cause? n Human activities such as burning fossil fuels and cutting down/burning forests has added Carbon Dioxide into the atmosphere faster than the carbon cycle can remove it. n n Possible Solutions: decrease the burning of fossil fuels and deforestation. Not all agree on the main cause and some suggest that the rise in temperatures is due to natural variations in climate.
Ozone Depletion n The stratosphere, or "good" ozone layer extends protects life on Earth from the sun's harmful ultraviolet (UV) rays. This natural shield has been gradually depleted by man-made chemicals like chlorofluorocarbons (CFCs). A depleted ozone shield allows more UV from the sun to reach the ground, leading to more cases of skin cancer, cataracts, and other health problems.
What are CFC’s (chlorofluorocarbons) n n CFC’s act as catalysts that enable UV light to break apart ozone molecules. CFC’s are chemicals that were once widely used in: n n n Aersol cans Production of plastic foams As coolants in refrigerators, freezers and air conditioners.
Where do we see the Ozone Problem? n n First problem sign of the ozone layer was a gap or hole in the layer over Antarctica during winter. Over past 20 years the hole is getting larger. Similar hole now appears over the Arctic. By 1995, the northern ozone hole had grown enough to expose parts of the US to higherthan-normal levels of UV.