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Chapter 2 – Introduction to Ecology. Section 1: Organisms and Their Relationships. Ecology. Ecology the study of the interactions between organisms and the biotic and abiotic components of their environment. The Biosphere. The biosphere is the portion of Earth that supports life.
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Chapter 2 – Introduction to Ecology Section 1: Organisms and Their Relationships
Ecology Ecology • the study of the interactions between organisms and the biotic and abiotic components of their environment
The Biosphere • The biosphere is the portion of Earth that supports life. • “bio” means life • “sphere” refers to the shape of our planet that resembles a ball • “The ball of life” • Includes our atmosphere, landmasses, bodies of freshwater and saltwater, and locations below the Earth’s surface that supports life.
The Biosphere Cont. • Biotic Factors • All of the LIVING things in an organism’s environment. • Abiotic Factors • All of the NONLIVING things in an organism’s environment • Includes temperature, air currents, sunlight, rainfall, soil type and available nutrients
A Key Theme in Ecology • No single organism is isolated!! • The interconnectedness or interdependence of all organisms is central to the study of ecology • The survival of organisms depends on their interactions with their surrounding environment • Ex: Humans cannot live without the plants that produce food and oxygen
The Biosphere • Biosphere: the broadest and most inclusive level of organization • The Earth and its atmosphere make up our biosphere • Extends from 8 to 10 km (5-6 miles) above the Earth’s surface to the deepest parts of the ocean
Ecosystems • The biosphere is comprised of smaller units called ecosystems • Includes all of the organisms and the abiotic environment found in a specific place • Ex: Pond Ecosystem • Abiotic components: water temperature, amount of dissolved oxygen and carbon dioxide, the pH level • Biotic components: insects, fish, algae, aquatic plants, turtles • Some ecosystems can be considered the habitat of an organism.
Chapter 18 Ecosystem
The Niche • Niche • the role an organism plays in its environment • Includes: • Range of conditions the organism can tolerate • Methods by which it obtains resources • Interactions with its environment such as reproduction
Community Interactions • Community • all of the interacting organisms living in an area • Ex: All of the fish, turtles, insects, plants and algae make up the community of a pond • Competition occurs when more than one organism uses a resource at the same time. • Ex: Lions and hyenas compete for the same food sources. • Predation is the act of one organism consuming another for food.
Chapter 18 Community
Symbiotic Relationships • Most species survive because of relationships called symbiosis • Mutualism: • Both organisms benefit • Ex: The Egyptian plover takes insects from the backs of buffaloes, giraffes and rhinos
Symbiotic Relationships • Commensalism: • One benefits; the other is not affected • Ex: Sea anemone and the clown fish. • Parasitism: • One benefits at the expense of the other • Ex: Deer tick and mammal
Chapter 2 – Principles of Ecology Section 2: Flow of Energy in an Ecosystem
Energy in an Ecosystem • Autotrophs: • primary producers • make their own food • Use energy from sunlight or inorganic substances • Foundation of all ecosystems • they make energy available for all of the other organisms • Ex: Plants
Energy in an Ecosystem • Heterotrophs: • get energy by consuming other organisms • Called “consumers” • Herbivores • eat only plants • Carnivores • eat others
Energy in Ecosystems • Heterotrophs Cont: • Omnivores • eat both plants and animals • Detrivores • eat dead/decaying material • Decomposers are similar to detrivores • Break down dead organisms by releasing digestive enzymes (fungi) • Important because they make nutrients available for all other organisms
Models of Energy Flow • Ecologists use food chains and food webs to show energy flow in ecosystems • Trophic level • Each step in a food chain or food web • Autotrophs are the first trophic level in ALL food chains and food webs!
Important Terms for Food Chains and Food Webs • Primary producers: make their own food • Primary consumers: eat the primary producers • Secondary consumers: eat the primary consumers • Third-level consumers: eat the secondary consumers
Food Chains • Food chains:a simple model that shows how energy flows through an ecosystem • Arrows show one-way energy flow • Each organism uses some of the energy from the organism it eats • The remaining energy is lost to the surrounding environment
Food Webs • Food webs: models that represent the interconnected food chains in which energy flows through a group of organisms
Ecological Pyramids • Diagrams that show the relative amounts of energy, biomass or numbers of organisms at each trophic level • Biomass is the total mass of living matter at each trophic level • Approximately 90% of all energy at a tropic level is NOT transferred to the level above it
Cycles of the Biosphere • Energy is notrecycled in a ecosystem • Matter (biomass) is recycled in a ecosystem • Nutrient: a chemical substance that an organism needs from its environment. • Nutrient cycling involves both the biotic and abiotic portions of an ecosystem. • These are called the biogeochemical cycles.
The Water Cycle: more of a physical process than a chemical one.
The Water Cycle • Key Terms: • Evaporation: water returning to the atmosphere from oceans, lakes, and rivers • Transpiration: water returning to the atmosphere from the surface of plants • Precipitation: water returning to the earth from the atmosphere • Percolation: water running through the soil • Runoff: water running on the surface of the earth.
The Carbon Cycle • Two natural processes help to cycle carbon through the ecosystem. • Photosynthesis: • autotrophs • take in CO2 and produce organic compounds • Make them available then for consumers. • Cellular Respiration; • both autotrophs and heterotrophs • convert energy rich organic compounds into ATP • powers cellular functions.
The Carbon Cycle • Deposition • dead materials: • converted to peat, coal, oil or gas deposits (carbon stored as fossil fuel) • carbon is released when fossil fuels are burned • Carbonate in sediments: • shells, coral, algae fall to bottom of ocean creating limestone rock. • Carbon is released in the form of bicarbonates
Brain Break Try to count the number of black dots on the image below... There are none!
The Nitrogen Cycle • Nitrogen enters ecosystems through two natural pathways. • Nitrogen fixation, where certain bacteria convert N2 to minerals that can eventually be used by plants to produce nitrogenous organic compounds.
The Nitrogen Cycle • Chemical nitrogen fixation - lighting bolts change nitrogen gas to nitrates or nitrogen is added to the soil by chemical fertilization. • Some bacteria break down detritus and animal waste producing ammonium through Ammonification • Certain bacteria convert ammonium into nitrate, a process calledNitrification. • Nitrate can be used by plants.
The Nitrogen Cycle • Some bacteria take oxygen from the nitrate and release N2 back into the atmosphere called Denitrification.
Phosphorus cycle • Needed for growth and development • Short term- cycled from soil to producers and producers to consumers • Long term-Phosphorus comes from weathering and erosion of rocks
Rates of nutrient cycling • Decomposition rates largely determine the rates of nutrient cycling • The rate at which nutrients cycle in an ecosystem depends on the rate of decomposition. • Decomposition can take up to 50 years in the tundra, while in the tropical forest, it occurs much faster. • Quantities of nutrients in the soil of different ecosystems also varies, depending on the rate of absorption by the plants.
Nutrient cycling is strongly regulated by vegetation • In a terrestrial ecosystem most of the mineral nutrients cycle within the ecosystem. • In addition to the natural ways, nitrogen-containing fertilizer contributes to the total amount of nitrogen materials in ecosystems.
