Chapter 13: Principles of Ecology

Ecology = the study of interactions among organisms and between organisms and their surroundings Ecologists study nature on different levels 1. Organism – a single living thing 2. Population – a group of the same species that live in the same place, at the same time

3. Community – different populations that live in the same place, at the same time 4.Ecosystem– includes the living & nonliving things in a given area 5.Biome– a group of ecosystems that have the same climates/communities

Ecological research methods include: 1. Observation (field work) 3. Modeling 2. Experimenting

Biotic factors = living factors Living and nonliving factors help shape ecosystems Abiotic factors = physical/nonliving factors Ex. Animals, trees, insects, bacteria Ex. Temp, precipitation, soil, wind, sunlight, humidity

Biodiversity – the variety of living things in an ecosystem Changing 1 factor can affect many others Keystone Species – a species that has an unusually large effect on its ecosystem

All organisms need energy; some make it and some obtain it Producers = make their own food Aka: Autotroph Most use sunlight to make food (photosynthesis) Some use other chemical compounds (chemosynthesis)

Consumers = must eat to get their food Aka: Heterotroph There are several different types of consumers 1. Herbivores – eat only plants 2. Carnivore – eat only meat

3. Omnivores – eat both plants and animals 4. Detritivores – eat dead organic matter 5. Decomposers – breakdown organic matter

Energy flows through ecosystems in one direction; sun/inorganic compounds  autotrophs  heterotrophs

The arrows show the direction the energy is flowing A food chain shows the flow of energy by showing feeding relationships Only a small amount of energy makes it to the top level of a food chain

Producers are the 1 st trophic level Trophic level = each step in a food chain Consumers are the higher trophic levels

A food web shows the complex network of interactions within an ecosystem Link food chains together Can be very complex because some organisms have multiple feeding relationships

Ecological pyramids model energy or matter in an ecosystem 1. Energy pyramid – shows the amount of energy available at each trophic level Only about 10% of the energy gets passed from one level to the next Why?

2. Biomass pyramid – shows the total amount of living mass (biomass) in each trophic level Units of g/m 2 Shows the amount of food at each level 2. Numbers pyramid – shows the number of individuals for each trophic level Helps to show it takes many producers to support the top consumers

Energy only flows 1 way, but matter cycles in and out of ecosystems  it changes forms, but does not disappear 1. Water cycle – all living things need water! Evaporation Transpiration Condensation Precipitation

Biogeochemical cycles show the movement of chemicals and nutrients through ecosystems 2. Carbon cycle – carbon is the building block of life Carbon can be found in solids, liquids, and gases  Fossil fuels  Bicarbonate dissolved in water  CO 2 in the atmosphere  Carbonate rocks  Organic matter (dead or alive)

3. Nitrogen cycle– about 78% of the atmosphere is nitrogen Most organisms don’t use the nitrogen from the air  it gets converted by bacteria Nitrogen is needed to form amino acids and proteins

4. Phosphorus cycle– does not include the atmosphere Phosphate is usually stored in rock Human activities can increase the amount of phosphorus in an ecosystem Phosphorus is needed to form DNA/RNA

Grand Lake on July 1 st, 2011