2.1 BIOTIC, ABIOTIC FACTORS, AND TROPHIC LEVELS
BIOTIC FACTORS• Biotic factors are the living components that shape an ecosystem; any organism that affects another organism.• Biotic components are: – Animals – Plants – Bacteria – Fungi
ABIOTIC FACTORS• Abiotic factors are the non-living components of an ecosystem, affecting the life of organisms.• Abiotic factors can be harmful to the ecosystem.• Abiotic components are: – Temperature, light, water, soil, rocks, and human influence.
WATER Water is one of nature’s most important things is life. Essential to life, an organism’s survivaldepends an water. Water isnecessary for digestion and absorption of food; helps maintain proper muscletone-, supplies oxygen andnutrients to the cells; rids the body of water; and serves as a natural air conditioning system.
SUNLIGHTThe sun provides light and warmth and it is the energy source for almost all ecosystems on Earth. Sunlight powers photosynthesis by plants, the main producer in mostterrestrial ecosystems.
TEMPERATURE Most life exists within a fairly narrow range oftemperatures, from about 0 C to about 50 C. Feworganisms can maintain anactive metabolism below 0 C for long, and most organisms’ enzymes aredenatured (they lose their shape and stop working) above 50 C. However,extraordinary adaptations enable certain species to live at extreme temperatures.
SOIL Soil is the product of abiotic forces (such as ice, rain, andwind) and the actions of living things (such as microorganisms, plants, andearthworms) on the rocks andminerals of Earth’s crust. The structure and chemicalmakeup of soil and rock in anarea affect the types of plants that grow there. In aquatic environments as well, the characteristics of underlyingsand and rock affect the type of plants and algae that can grow. This in turn affect theother organisms found there.
OXYGEN Oxygen is animportant component of life. Most living things consume oxygen in different forms and quantities. Most of the oxygen that is used inrespiration is to obtain chemical energy from the fats and carbohydrates in our food.
WIND Many plants use the help of the wind to disperse seeds over long distances.Organisms disperse tofind new habitats rich in needed resources. Strong winds can be very destructive.
TROPHIC LEVELS• There are trophic levels within an ecosystem; these are the feeding positions that biotic components occupy on the food chain.• The word trophic derives from the Greek trophe referring to food or feeding.• A food chain represents a succession of organisms that eat another organism and are, in turn, eaten themselves.
TROPHIC LEVELS• Trophic levels in a food chain are: – Trophic level 1 – primary producers – Trophic level 2 – herbivores or primary consumers – Trophic level 3 – predators, carnivores which eat herbivores or secondary consumers – Trophic level 4 – carnivores which eat other carnivores or tertiary consumers – Trophic level 5 - apex predators which have no predators, at the top of the food chain The path along the chain forms a one-way flow along which energy travels in the form of food.
TROPHIC LEVELS1. Producers - (autotrophs) are typically plants or algae. Plants and algae do not usually eat other organisms, but pull nutrients from the soil or the water and manufacture their own food using photosynthesis. In this way, it is energy from the sun that usually powers the base of the food chain. – An exception occurs in deep-sea hydrothermal ecosystems, where there is no sunlight. Here primary producers manufacture food through a process called chemosynthesis.
TROPHIC LEVELS2. Consumers - (heterotrophs) cannot manufacture their own food, and need to consume other organisms. They are usually animals. Animal that eat primary producers, such as plants, are called herbivores. Animals which eat other animals are called carnivores, and animals which eat both plant and other animals are called omnivores.
TROPHIC LEVELS3. Decomposers (detritivores) break down dead plant and animal material and wastes and release it again as energy and nutrients into the ecosystem for recycling. Decomposers, such as bacteria and fungi (mushrooms), feed on waste and dead matter, converting it into inorganic chemicals that can be recycled as mineral nutrients for plants to use again.
TROPHIC LEVELS• In real world ecosystems, there is more than one food chain for most organism, since most organisms eat more than one kind of food or are eaten by more than one type of predator. A diagram which sets out the intricate network of intersecting and overlapping food chains for an ecosystem is called its food web.
FIRST TROPHIC LEVEL The plants in this image, and the algaeand phytoplankton in the lake, are primary producers. They takenutrients from the soil or the water, and manufacture their own food byphotosynthesis, using energy from the sun.
SECONDTROPHIC LEVEL Rabbits eatplants at the first tropic level, sothey are primary consumers.
THIRD TROPHIC LEVEL Foxes eat rabbits at thesecond trophic level, so theyare secondary consumers.
FOURTH TROPHIC LEVELGolden eagles eat foxes at the thirdtrophic level, so they are tertiary consumers.
DECOMPOSERSThe fungi or the earthworms feed on dead matter, converting itback to nutrients that primary producers can use.