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Ecological Cycles The Sun (and all the planets) started their lives in a giant cloud of cold molecular gas and dust. About 4.6 billion years ago the cloud collapsed. As the cloud collapsed, it start spinning. Most of the material ended up in a ball at the center, but this was surrounded by a flattened disk of material. The ball at the center would eventually form the Sun, while the disk of material would form the planets. The Sun is a star formed from a solar nebula 4.6 billion years ago. The Sun produces energy by the nuclear fusion of hydrogen into helium in its core. Energy is produced by nuclear fusion during a series of steps, converting hydrogen to helium. Every second, 600 million tons of hydrogen are converted into helium in the Sun’s core. That = 1,200,000,000,000 lbs/second As the Sun creates more helium, it burns a little more hydrogen. This causes the output of the Sun to go up. In 1.1 billion years from now, the Sun will be 10% brighter than it is today. The Earth’s atmosphere will dry out as the water vapor is lost to space, never to return. In 3.5 billion years from now, the Sun will be 40% brighter than it is today. It will be so hot that the oceans will boil and that water vapor will be lost to space as well. The ice caps will permanently melt, and life will be unable to survive anywhere on the surface of the Earth. In about 6 billion years, the Sun’s core will run out of hydrogen and become unstable and collapse under its own weight. Until then, life exists on earth relying on the sun for warmth and energy used to drive the important process of photosynthesis. is constantly cycling through stable ecosystems. Food chains, food webs, and ecological pyramids all show how energy moves in only one direction through the trophic levels of an ecosystem. Is a simple model that scientists use to show how matter and energy move through an ecosystem. Is typically drawn using arrows to indicate the direction in which energy is transferred from one organism to another. A portion of the energy is converted to heat at each link. Represents only one possible route for the transfer of matter and energy in an ecosystem. represent links in the food chain. is a feeding step in the passage of energy and materials Model that expresses all the possible feeding relationships at each trophic level in a community. Is a more natural model since most organisms depend on more than one species for food. Red fox shrew Woodpecker Cottontail Field rabbit mouse Grasshopper insects Fungi and bacteria Model used to depict energy conversions in an ecosystem. Secondary consumers fox Primary consumers mouse rabbit vole producers clover dandelion thistle timothy Determined by taking the average weight of organisms and multiplying by the estimated number of organisms in the population. Expresses the weight of living material at each trophic level. Matter, in the form of nutrients, moves through the organisms at each trophic level of an ecosystem. Cannot be replenished like the energy from sunlight. Is constantly recycled (the atoms in your body right now could once have been part of a dinosaur) BIOGEOCHEMICAL CYCLES Pathways of the vital compounds from the earth to living organisms to the atmosphere. The Carbon Cycle Yellow #’s are natural fluxes, red #’s are human sources in billions of tons of carbon/year. White #’s are stored carbon. The Nitrogen Cycle Bacteria on the roots of some plants change nitrogen to nitrates that plants can use. All plants use nitrates as a source of nitrogen to make proteins. Animals use nitrogen from plants to make protein. Plants and animals die, and nitrogen goes back into the soil as nitrates. The Phosphorus Cycle Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms. Abiotic factors – pH, light, salinity, water, temperature, macronutrients, and micronutrients Biotic limiting factors – predation and competition Is the ability to withstand fluctuations in biotic and abiotic environmental factors. Some species can tolerate conditions that another species cannot. Limits of tolerance are reached when an organism receives too much or too little of some environmental factor. Density-independent factors Affect all populations, regardless of density are mostly abiotic temperature Storms Floods Drought Habitat disruption Important for the health of natural populations. Keeps the population size within the limits of the available resources (young, old, or injured are caught) Competition for resources such as food, water, and territory increases and can become fierce when population size increases. results in a decrease in the population size. Is a density-dependent factor As a populations increase in size, individual animals begin to exhibit a variety of symptoms – aggression – decrease in parental care – decreased fertility, and – decreased resistance to disease These symptoms can lead to a decrease in population size Is any part of the natural environment used by humans for their benefit. Includes: – Soil – Water – Crops – Wildlife – Oil – Gas – minerals A natural resource that is replaced or recycled by a natural process. Includes: – – – – – – – – – Nitrogen Carbon Plants Animals Food crops Sunlight Soil Water oxygen Natural resources that are available in limited amounts and can’t be replaced or recycled by natural processes. Includes: – Metals (aluminum, tin, iron, silver, gold, uranium, copper) – Some minerals (Phosphorus) – Fossil fuels - substances made up the remains of organisms that have been buried underground for millions of years (coal, oil, natural gas) Is the disappearance of a species when the last of its members dies. May result from natural processes, but most have resulted from human activities like: – Hunting – Building cities and housing development – Destruction of forests to create farmland moa Population of species that begins to decline rapidly. African elephant Bald eagles Sea otters Grizzly bears Loggerhead turtles And much more. Some of the reptiles on the threatened list in TX. The Texas Horned Lizard The Texas Indigo Snake The Texas Tortoise A species whose numbers become so low that extinction is possible. – – – – – – – Black rhino Manatees Bison Florida panther California condor Koala Bear Bengal Tiger http://www.cnn.com/2007/TECH/science/09 /25/endangered.list/index.html http://www.endangeredspecie.com/ Is the contamination of any part of the environment – air, water, or land – by any excess of waste materials. Pollutant – is a waste product that causes pollution (nitrogen – is needed for life, but it can become a pollutant) May be the result of volcanic eruptions, forest fires, evaporation of volatile chemicals, and burning of fossil fuels. Particulates – solid particles of soot that can harm living organisms directly , or change the environment in ways that are later harmful to life (carbon monoxide, carbon dioxide, nitrogen oxides, sulfur oxides, hydrocarbons) Smog – form of air pollution that hangs over many of the world’s largest cities (consists of particulates, sulfur dioxide, and other chemicals)
