Chapter 3 The Biosphere

3-1 What is Ecology? Ecology – study of the interactions between organisms and their environment

Levels of Organization (smallest to largest) Species (Individual) Population Communities Ecosystem Biome Biosphere (entire planet)

Levels of Organization Biosphere Biome Ecosystem Community The study of ecology ranges from the study of an individual organism to populations, communities, ecosystems, biomes—and, finally, to the entire biosphere. The information that ecologists gain at each level contributes to our understanding of natural systems. Population Individual

Ecological Methods Scientists conduct research for ecology in three ways: Observing Experimenting Modeling

3-2 Energy Flow Energy flow is extremely important in determining a system’s capacity to sustain life.

Producers Sunlight is the main source of energy for living things. Some organisms can also use inorganic chemical compounds for energy. Autotrophs/Producers – organisms that use energy from the sun or chemicals to produce its own food. (PLANTS)

Photosynthesis – autotrophs that use solar energy to make carbohydrates. Chemosynthesis – autotrophs that use chemical energy to make carbohydrates.

Consumers Heterotrophs/Consumers – organisms that get their energy from the foods they eat. Herbivores – eat plants Carnivores – eat animals Omnivores – eat plants and animals Detritivores – feed on dead matter Decomposers – break down organic matter

CARNIVORES HERBIVORES DECOMPOSERS OMNIVORES DETRITIVORES

Feeding Relationships Energy flows through an ecosystem from the sun or chemical compounds, to autotrophs, and then to heterotrophs.

Trophic Levels – each step in a food chain or food web. Food Chain – a series of steps in an ecosystem where organisms transfer energy by eating and being eaten (see figure 3-7) Food Web – complex interactions of feeding relationships among various organisms in an ecosystem. Trophic Levels – each step in a food chain or food web. Producers = 1st level Consumers = 2nd, 3rd, or higher levels

Feeding Relationships In some marine food chains, the producers are microscopic algae and the top carnivore is four steps removed from the producer. Small Fish Zooplankton Squid Food chains show the one-way flow of energy in an ecosystem. In this marine food chain, energy is passed from the producers (algae) to four different groups of consumers. Shark Algae

Ecological Pyramids A diagram that shows the relative amounts of energy or matter at each trophic level. 3 Pyramids Energy Biomass Pyramid of numbers

Energy Pyramid – shows the amount of energy passed from one level to the next. Only about 10% of the energy in one level is available to organisms in the next level. 0.1% Third-level consumers 1% Second-level consumers 10% First-level consumers Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue. 100% Producers

Biomass – total amount of living tissue within a trophic level. Biomass Pyramid – shows the amount of food available for each trophic level. Biomass – total amount of living tissue within a trophic level. 50 grams of human tissue 500 grams of chicken 5000 grams of grain Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue.

Pyramid of Numbers – the number of organisms at each trophic level. Ecological pyramids show the decreasing amounts of energy, living tissue, or number of organisms at successive feeding levels. The pyramid is divided into sections that represent each trophic level. Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one tenth the amount of living tissue.