Unit 1: The Living World (Ecosystems) 1.7-1.8

Energy ___ matter ____ through ecosystems

-Flows, cycles

Producer/autotroph

-(plants, algae, and bacteria) that convert solar energy into usable forms of energy.

Primary productivity

-The rate of converting solar energy into organic compounds over a period of time.

gross primary productivity

-The measure of energy from the sun converted

by photosynthesizers

-Kcal/m2/year and in kg C/m2/year

Net primary productivity

NPP = GPP - respiration by producers (R)

-Kcal/m2/year and in kg C/m2/year

Biomass

-The total mass of all living matter in a specific area

-Mass of organism * # of all organisms

-Largest = bottom of pyramid

Standing Crop

-The amount of biomass at a given time

Net Primary Productivity Efficiency

-NOT efficient.

-NPP of most ecosystems range from 25% to 50% of GPP.

Aquatic Ecosystem energy absorption

-Aquatic ecosystems only allow certain wavelengths of visible light through.

-Because of these differences, algae at different depths have evolved differences in energy absorption: red light is mainly absorbed near surface, blue light at deepest depths.

Ecosystem Productivity

-Those with warmer temperatures and better access to water and nutrients tend to be most successful.

-Colder, drier, and darker ecosystems (+ near the bottom of the sea) are less productive than others.

-Most productive = tropical rainforest, swamp and marshes

Consumers/heterotrophs

-Obtain energy through consumption of others

herbivores/primary consumers,

consumers that eat producers/plant eaters

carnivores/secondary consumers

animals that eat other animals

tertiary consumers

carnivores that eat other carnivores

trophic levels

The successive levels of organisms consuming one another

Scavenger/Detritivores

An organism that uses dead organic waste as food and digests it (ex. crab, vultures, hyena)

Decomposers

-Fungi and bacteria that chemically break down organic matter.

10% rule

-Between each trophic level along a food chain, energy is lost --> Laws of Thermodynamics!!

-The proportion of consumed energy passed from one trophic level to another is called the ecological efficiency.

-This tends to be anywhere from 5% to 20%, with an average of 10%. This is known as the 10% rule!

-This rule can be demonstrated through biomass, numbers, and energy through trophic pyramids.

Food chain vs web

-Food chain is a basic network that shows the linear flow of nutrients and energy from one trophic level to another.

-Food web is a multitude of interconnected food chains at many trophic levels.

Feedback loops in ecosystems

-Because of the interconnected food webs, changes in one level will have impacts on the other levels of the food web.

-This can lead to positive and negative feedback loops within the ecosystem.