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Systems A system is a collection of related parts that interact in some organized way. Materials, energy and information that enter the system from outside are Inputs. Materials, energy, and information that leave are outputs A system can be: • made up of many sub-systems • be part of a larger system. • E.g. An automobile is a system made up many smaller systems like the engine system, brake system and a fuel system. • Each of these systems are connected to one or more other systems. • A change in one system will affect the others. Earth Systems • • • • • • Earth-Universe Biosphere Cryosphere Atmosphere Hydrosphere Solid Earth Biosphere: This is the area occupied by living organisms. • In resent years this has expanded with the finding of life deep underground. • The biosphere has played a major role in the shaping of our planet and still has a major impact on climate, erosion and weather patterns. What is ecology? (oikos = house or place to life; logos = study of Ecology is the study of the way living things interact with each other and their physical surroundings. It looks at the ways an organism is molded by its surroundings, how they make use of these surroundings, and how the area is altered by the presence and activities of organisms. These interactions involve energy and matter, which must flow through the organism if it is to stay alive. An organism is any form of life. Organisms can be classified into species - groups of organisms that resemble one another in appearance, behavior, chemistry, and genetic code. They are the same species if they can reproduce sexually to produce live, fertile offspring. A population consists of all the members of the same species living in a specific area at the same time. The place where a population lives is known as its habitat . Populations of all the different species occupying and interacting in a particular place make up a community. An ecosystem is a community of different species interacting with one another and their no-living environment of matter and energy. All the Earth’s ecosystems make up what is called the ecosphere or biosphere Climate is the main factor that determines whether a given species will thrive in an area. Biologists have divided the terrestrial (land) portion of the biosphere into biomes . These are large regions with a distinct climate and specific life forms. E.g. Desert, grassland. Each biome may have many ecosystems with communities adapted to the changes in soil, climate and other factors throughout the biome. The marine and freshwater portions of the biosphere are divided into aquatic life zones. Biodiversity is the genetic diversity, species diversity and ecological diversity that are so important to life on this planet. It is the result of adaptations that have evolved over billions of years due to environmental changes in the Earth’s past. Trophic Levels tertiary consumer secondary consumer Primary consumer Producer Energy and the Food Chain • If 10% of the energy can be transfered from one trophic level to the one above it, each trophic level must have 10x the energy as the one above it. • The number of trophic levels depends upon the primary producers Primary Producer plant/ algae autotrophs Primary consumer herbivores heterotrophs 99% Secondary consumer primary carnivore Tertiary consumer top carnivore Usually no more than 5 links in a food chain. Why? Detritivores, scavengers, and decomposers Detritivores: consume litter, debris, and dung Scavengers: clean-up dead carcasses Decomposers: microorganisms that complete final breakdown of organic matter Energy Pyramid Food Chain Food Web There is limit to the number of trophic levels in an ecosystem - maximum 3 or 4 because of this energy loss - a consequence of the 2nd law of thermodynamics. For example it takes a large population of zebras and wildebeests to support a small population of lions (1000 to 1!!!) Humans eat steak and hamburger at a great cost in energy. Nutrient Cycles •Again, nutrients (the basic chemical building blocks of all life) are recycled in a living system. •The key nutrients are Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus. These constitute 95% of all living matter. Carbon Cycle Nitrogen Cycle Phosphorus Cycle Hydrogen and Oxygen (Water) Cycle Video Cycles in Nature • Click the image to play the video segment.