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Learn about ecology, the biosphere, levels of organization, biotic and abiotic factors, energy flow, and cycles of matter in ecosystems. Discover the interconnected web of life.
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Ecology Ch. 3 – The Biosphere
3.1 - What is Ecology? • It is the scientific study of interaction among organisms and between organisms and their environment
What is the Biosphere? • The biosphere is the combined portions of the entire planet where life exists.
Levels of Organization • To understand relationships within the biosphere ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere
Levels (con’t.) • Species: a group of organisms so similar to one another that they can breed and produce fertile offspring. • Populations: a group of individuals that belong to the same species and live in the same area. • Communities: different populations that live together in a defined area.
Levels (con’t.) • Ecosystems: all the organisms that live in a particular place, together with their nonliving or physical environment. • Biomes: a group of ecosystems that have the same climate and dominant communities.
Biotic and Abiotic Factors • Biotic Factors – Any living part of the environment with which an organism might interact • Ex. – animals, plants, mushrooms & bacteria • Abiotic Factors – Any nonliving part of the environment • Ex. – sunlight, heat, water, soil, etc.
Biotic and Abiotic Factors Together • The differences between biotic and abiotic factors are not always clear and simple • Many physical factors can be strongly influenced by the activities of organisms • Ex. – pond “muck” is a combination of soil (abiotic) and leaf mold & decomposing plant material (biotic)
Ecological Methods Scientists use three basic approaches to conduct ecological research. They are: • Observing • Experimenting • Modeling
3-2 Energy, Producers, and Consumers • What happens if your car runs out of gas? • What do you need before you can play in a soccer game or run for 5 miles? • Living systems need a constant input of Energy.
Primary Producers • Autotrophs • Organisms that use energy from the environment to make complex organic compounds • Also known as producers. Why? • Two types • Photosynthesis - Energy from the Sun • Chemosynthesis - Life without Light
Primary Producers • Primary Producers • The first producers of energy-rich compounds that are later used by other organisms • Energy from the Sun • Capturing light energy and using it to convert CO2 & H2O into O2 & Carbohydrates • Energy without Light • Using chemical energy to make Carbohydrates
Consumers • Heterotrophs • Rely on other organisms for their energy and food supply. • Also known as consumers • Why?
Consumers • Types of Consumers • Herbivores • Obtain energy and nutrients by eating plant materials • Carnivores – • Kill and eat other animals • Omnivores • Eat both plants and animals • Scavengers • Consume the carcasses of dead animals • Detritivores • Feed on dead and decaying plant and animal remains • Decomposers • Chemically break down matter
Beyond Consumer Categories • These simple categories often don’t express the real complexities of nature. • Examples: • Hyenas (carnivores) will scavenge if they get a chance • Aquatic animals will eat a mixture of algae, bits of animal carcasses, and detritus
3.3 Energy Flow in Ecosystems • Energy flows through the ecosystem in one direction.
Food Chain • A series of steps in which organisms transfer energy by eating and being eaten.
Food Web • A network of many feeding interactions
Food Webs and Disturbance • Relationships in Food Webs are not simple. • Disturbances do happen and their effects can be dramatic. • Example - Marine Food Web / Krill
Trophic Levels and Ecological Pyramids • Each level in a food chain or food web is a trophic level. • Each trophic level depends on the level below it for energy.
Ecological Pyramids • Can be used to represent energy, matter or number of individuals at each trophic level
Energy Pyramid • Only 10% of the energy available at one trophic level makes it to the next level • When one organism eats another, energy is lost. Where does this energy go?
Biomass Pyramid • Represents all the living tissue (food) at each trophic level.
Pyramid of Numbers • The number of individual organisms at each trophic level usually decreases as you go up the pyramid of numbers.
3-4 Cycles of Matter • Unlike the one-way flow of energy, matter isrecycledin the biosphere. • Where does your body get the materials, such as Carbon, it needs to function? __________ • Elements , chemical compounds and other forms of matter are passed from one organism to another throughbiogeochemical cycles. Bio - ______ Geo - ______ Chemical - ______
Other Biogeochemical Cycles • Carbon Cycle - carbon is especially important because it is thekey ingredientin all living organisms. • Carbon is found in oceans, the air, and certain types of rock.
Nitrogen Cycle - All organisms require nitrogen tomake amino acidswhich are used to buildproteins.
Phosphorus Cycle - Unlike carbon nitrogen and oxygen, phosphorousdoes not enter the air, it remains mostly in rock, soil minerals, and ocean sediments. • Phosphorous is of great biological importance for molecules like DNA and RNA.
Nutrient Limitation • Primary Productivity: the rate at which organic matter is created by a producer. • Controlled by theavailability of nutrients in the environment • How can a nutrient be a limiting factor for an ecosystem? • If even a single essential nutrient is in short supply, primary productivity will be limited
Nutrient Limitation • Limiting Nutrient • the nutrient whose supply limits productivity • Ex. - If ample sunlight and water are available, the primary productivity of an ecosystem may be limited by the availability of nutrients.
Nutrient Limitation • In Soil • Growth of crop plants is limited by one or more nutrients that must be taken up by plants through their roots • That’s why farmers use fertilizers! • In Aquatic Ecosystems • Sometimes receive large amounts of a limiting nutrient (runoff from fertilized fields) • The result can be an Algal Bloom which can cover the water’s surface and disrupt the ecosystem
