Ecosystems • An ecosystem is all the organisms that live in an area together with non-living factors of the environment.
Biotic and Abiotic Factors • Biotic factors are the living parts of an ecosystem. • Abiotic factors are non-living parts of an ecosystem such as water, sunlight, oxygen and temperature.
Organization of Living Things in an Ecosystem • Species: A group of organisms that can mate and produce offspring that in turn can produce more offspring. • Population: All the organisms of the same species that live in the same place at the same time. • Community:populations sharing the environment with other populations. (For example, populations of deer, mice, raccoons, bacteria, mushrooms and ferns form a community).
Interactions Among Organisms • The place where an organism lives, that provides them with the food, water, and shelter they need to survive, grow and reproduce, is called a habitat. A single ecosystem contains many habitats. • Every organisms has a variety of adaptations that are suited to its specific habitat. An organism’s role in the habitat, or how it makes its living, is called a niche. This includes the type of food it eats, where it gets the food, and how it interacts with other organisms. Example:5 species of warblers that occupy a different niche in a spruce tree. Each species feeds at a different level. • There are three major types of interactions among organisms: competition, predation, and symbiosis.
Competition: occurs when more than one individual or population tries to make use of the same limited resources (food, water, space). Since these resources are limited, there is not enough for every organism. Only those organisms able to get the resources they need will survive. • Predation: occurs when one animal (“predator”) captures and eats another animal (“prey”) for food. Predator-prey relationships help keep an ecosystem in balance by preventing overpopulation.
Mutualism – both species benefit. Parasitism – occurs when an organism called a parasite feeds on the cells, tissues, or fluids of another organism called the host. Commensalism – one species benefits and the other is unaffected. Symbiosis is a close relationship between two species that benefits at least one of them. The three types of symbiosis are mutualism, commensalism and parasitism.
Feeding Relationships • Producersare organisms that make their own food. • Consumersget their food by eating other organisms. herbivoreomnivorecarnivore • Decomposersfeed on the remains of waste or dead organisms
Food Chains • A food chain shows how each living thing gets its food. Each link in this chain is food for the next link. A food chain always starts with a producer and ends with a consumer. (arrows point in the direction of the energy flow)
Food Webs • A food web is a system of several overlapping food chains, that shows a more complete picture of the flow of energy in an ecosystem. Interactive food webs Food Webs & Populations
Energy Pyramid As you go up the food chain less and less energy is transferred. Only about 10% moves from one level to the next. The rest is lost as heat. The above energy pyramid shows many trees & shrubs providing food and energy to giraffes. As we go up, there are fewer giraffes than trees & shrubs and even fewer lions than giraffes ... as we go further along a food chain, there are fewer and fewer consumers. In other words, a large mass of living things at the base is required to support a few at the top ... many herbivores are needed to support a few carnivores.
Carbon Dioxide - Oxygen Cycle • Photosynthesis: plants take in carbon dioxide and release oxygen. • Respiration: organisms (plants and animals) get energy by taking in oxygen from the air and combining it with food. Carbon dioxide is released back to the environment as a waste product. • Decomposition: fungi and bacteria get energy by breaking down the waste or remains of other living things into smaller molecules. Carbon dioxide is released back in the environment.
Nitrogen Cycle • Nitrogen is one of the elements needed to build proteins that make up the cells of living things. • 78% of the earth’s atmosphere is made up of Nitrogen. • Most organisms cannot use nitrogen until it is combined with other elements to form nitrogen compounds. This is called nitrogen fixation. • At the same time, nitrogen compounds in dead organisms and waste must be broken down in order to return nitrogen gas to the air. • This constant movement between the air and living things is called the nitrogen cycle. • Bacteria play a key role because they carry out most nitrogen fixation, and they also break down the waste and dead organisms.
Water Processes • Freezing – water changes from liquid to solid • Melting – water changes from solid to liquid • Evaporation – water changes from liquid to gas • Condensation - water changes from gas to liquid • Precipitation – water falls to the earth • Collection – water stored in ponds & lakes, ice, groundwater. • Percolation – water seeps into the earth • Groundwater flow – water moves from the earth to a water storage area (ocean) • Runoff - water flows over land (rivers and streams) • Transpiration (Respiration) – living things lose water to the atmosphere by evaporation • Consumption – animals get water by eating/drinking • Absorption – matter gains water from other matter (from soil to plant roots) • Excretion – animals release water as waste
Ecological Succession • Succession is the natural process by which one community of organisms slowly replaces another as the ecosystem matures. • Succession is cycle. Natural disasters such as fires, floods, volcanoes and hurricanes can restart the process.
BIODIVERSITY • The number of different species in an area is called Biodiversity.
Environmental Issues • All around the world, biodiversity is being reduced by habitat loss, pollution, non-native species and over hunting/fishing, causing extinction of plants and animals. Habitat Loss Pollution (air, water, ground) Over Hunting/Fishing Non-Native Species
Conservation“The wise use of natural resources” • Laws such as the Endangered Species Act (1973) have passed to help save plants an animals from extinction. • Land has been set aside to protect entire ecosystems, such as national parks, and wildlife preserves. • Pollution can be limited by use of clean energy like sunlight, wind and water, instead of fossil-fuels like coal and oil. • The Reduce, Reuse, Recycle model is a powerful way to conserve resources and reduce pollution. • The Problem? The human population is growing rapidly, along with the use of natural resources.
Biomes • The part of the earth that supports life is called the biosphere. It extends several kilometers up into the atmosphere and deep down to the ocean floor. • Physical factors such as climate and geography determine what ecosystems exist in the biosphere, and which plants and animals can live in those ecosystems. • A Biome is a large region characterized as having a distinct climate and specific types of plant and animal life. Biomes exist in the ocean, on land, and in freshwater. Earth’s Major Biomes http://blueplanetbiomes.org/ http://www.teachersfirst.com/lessons/biomes/biomes.html