Ecosystems: What Are They and How Do They Work? Chapter 3

3-1 What Is Ecology? Concept 3-1 Ecology is the study of how organisms interact with one another and with their physical environment of matter and energy.

3-1 What Is Ecology? Ecology is a study of connections in nature. How organisms interact with one another and with their nonliving environment.

Species Make Up the Encyclopedia of Life Organisms – individual forms of life Classified into species based on certain characteristics Species – a set of individuals that can mate and produce viable, fertile offspring 1.75 Million species identified Up to 10–14 million species not yet identified?? Insects make up most of the known species

Science Focus: Have You Thanked the Insects Today? Many times we classify insects as pests: Compete with us for food Spread human diseases Bite or sting us Can be a nuisance However, they are VERY beneficial: Pollinators Eat other insects Loosen and renew soil Estimated $57 billion/yr in ecological services

Species Make Up the Encyclopedia of Life A population is a group of interacting individuals of the same species occupying a specific area. The space an individual or population normally occupies is its habitat.

Species Make Up the Encyclopedia of Life Genetic diversity In most natural populations individuals vary slightly in their genetic makeup. These genetic diversity is crucial to the survival of the population.

Levels of Organization of Matter in Nature Populations of different species living and interacting in an area form a community. A community interacting with its physical environment of matter and energy is an ecosystem. The biosphere is where all of the Earth’s life is found A “global ecosystem”

3-2 What Keeps Us and Other Organisms Alive? Concept 3-2 Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

Natural Capital: General Structure of the Earth The biosphere consists of several physical layers that contain: Air Water Soil Minerals Life

The Earth’s Life-Support System Has Four Major Components Biosphere – All of the life on the planet Atmosphere – Membrane of air around the planet. Troposphere – lowest layer - most gas of any layer where weather occurs Stratosphere – contains ozone to filter out most of the sun’s harmful UV radiation. Hydrosphere – All the earth’s water: liquid, ice, water vapor Geosphere – The earth’s crust and upper mantle Lithosphere – hard outer crust Asthenosphere – molten interior

Three Factors Sustain Life on Earth One-way flow of energy beginning with the sun Follows the laws of thermodynamics Most is lost as heat Cycling of matter or nutrients Nutrients exist in a fixed amount Follows the law of conservation of matter Gravity

Flow of Energy to and from the Earth Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth. Natural greenhouse effect – natural process that keeps the Earth warmer than it would otherwise be

Life Exists on Land and in Water Life exists on land systems called biomes and in freshwater and ocean aquatic life zones.