Ecology

Chapter 3: The Biosphere

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What is Ecology?

• Ecology – the study of interactions among organisms and between organisms and their environment

• Levels of Organization– Biosphere – the largest of the areas of the

earth containing the portion of the planet that life exists, including land, water and air (atmosphere)

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Levels of Organization

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Levels of Organization• Individual – similar organism (can mate)• Population – group of individuals that live in the

same area• Community – populations that live together is a

defined area• Ecosystem – all the organisms that live in a

similar area along with the nonliving material• Biome – group of ecosystems (similar climate)• Biosphere – entire earth

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Ecological Methods• Scientists use 3 basic methods to conduct

ecological research– Observing – qualitative and quantitative

observations– Experimenting – used to test hypotheses, can

set up artificial environments and manipulate conditions

– Modeling – models are made to study events that have occurred over large time periods, or are large in scale

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Interactions Among Organisms

• Sunlight is the main energy source for life on Earth

• Producers – autotrophs (make their own energy (using the sun)–Photosynthesis – using light to

produce energy / food–Chemosynthesis – using inorganic

molecules to produce energy / food

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Interactions (continued)• Consumers – heterotrophs (cannot make

their own energy)– Herbivores – consume plants– Carnivores - consume meat– Omnivores – consume both– Detritovores – dead or decaying matter

(earthworms, mites, crabs (animals)– Decomposers – dead or decaying matter

(bacteria & fungus)

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Energy Transfer / Feeding Relationships

• Food Chain / Food Web – series of steps of energy transfer (web = connected food chains)

• Trophic Levels – each step in a food chain

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Ecological Pyramids

• Diagram that shows relative amounts of energy or matter contained within each trophic level in a food chain or food web.

• Energy Pyramid – energy available at each trophic level (10% rule)

• Biomass Pyramid – amount of living tissue

• Pyramid of Numbers - # of individuals

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Examples of Pyramids

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Biogeochemical Cycles

• Water Cycle– Evaporation, precipitation, condensation,

transpiration, run-off, ground water

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Biogeochemical Cycles• Carbon Cycle – carbon fixation, CO2• Photosynthesis,

respiration• Fossil fuels• Human Activites

– Mining, cutting forests, burning fossil fuels

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Biogeochemical Cycles• Nitrogen cycle – nitrogen fixation

(bacteria), denitrification

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Nutrient Limitation

• Primary Productivity – rate of production of organic matter by producers

• Limiting Nutrients – nutrient that limits productivity

• Aquatic ecosystems – large input of limiting nutrient can cause an increase of algae or producers = algal bloom

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