Upload
myra-tucker
View
220
Download
0
Tags:
Embed Size (px)
Citation preview
ENERGY FLOW & ECOLOGICAL PYRAMIDS
NOTES
ECOLOGY DEFINITIONS
Ecology – study of organisms and their interactions with the environment
ECOLOGY DEFINITIONS
Biosphere – region of the Earth that supports life (includes all the land, water and air in which organisms live)
ECOLOGY DEFINITIONS
Ecosystem – all the organisms that live in a particular place, together with their physical environment
Both biotic and abiotic factors interacting
Abiotic Factors (nonliving)Ex: air, temp, water, rocks
Biotic factors (Living)Ex: all plants and animals, bacteria, algae, fungi
Ecosystems
Biotic Factors:
Moose, Bird, Rabbit,
Tree
grassAbiotic Factors:
Water, clouds, rocks
POPULATION DEFINITIONS
Species – a group of organisms so similar to one another that they can breed and produce fertile offspring (smallest level)
Population – all the members of a single species that live in one area
Niche – a particular role a population plays in the community (“its job”); ex. Honeybee pollinates flowers; hawks prey on mice
Community – all the populations that live and interact in one environment
Energy
The main source of energy for life on earth is sunlight
Autotrophs (like plants) go through photosynthesis to produce usable energy (ATP).
ENERGY FLOW DEFINITIONS
Producer (Autotroph) – organism that makes its own food (ex. Plants)
Consumer (Heterotroph) – organism that gets its energy directly or indirectly from producers (ex. Animals)
Decomposer – organism that breaks down and obtains energy from dead, organic matter (ex. Fungi and Bacteria)
FOOD CHAINS
Food Chain – a series of organisms through which food energy is passed in an ecosystem
Example of a Food Chain:
Sunflower Caterpillar Robin Fox (producer) (primary (secondary (tertiary
consumer) consumer) consumer)
FOOD WEBS
Food web – interconnecting and overlapping food chains
Name Producer Primary Consumer
Secondary Consumer
Tertiary Consumer
Oak Trees
Moths
Voles
Weasels
Shrews
Name Producer Primary Consumer
Secondary Consumer
Tertiary Consumer
Oak Trees X
Moths X
Voles X X
Weasels X X
Shrews X X
Energy Flow
Energy & nutrients are recycled by decomposers.
Definitions
A trophic level is the position occupied by an organism in a food chain.Trophic levels can be
analyzed on an energy pyramid.
Biomass is the total mass (amount of living tissue) of all the organisms within a given trophic level
Biomass
Total mass (amount of living tissue) of all the organisms within a given trophic level
Only a small fraction of the biomass from one trophic level moves to the next
2 Reasons for this:Many organisms are not consumed by
organisms at the next trophic level – energy is not available for transfer
Some of the biomass at each level consists of materials consumers won’t eat – bones, teeth, beaks, claws, shells, wood
ECOLOGICAL PYRAMID
Shows the relationships between producers and consumers at the trophic levels in an ecosystem
Plants (grass & flowers)
Rabbits, mice
Snakes
Owls 3rd consumers
Producers
1st consumers
2nd consumers
10 PERCENT LAW
Energy available at each trophic level is about 1/10 the energy available from the level below
producers
1st consumers
2nd consumers
3rd
consumers
20,000 kJ
2,000 kJ
200 kJ
20 kJ
WHY A PYRAMID SHAPE?
In most food chains fewer organisms occupy each higher trophic level (lots of producers, many primary (1st) consumers, fewer secondary (2nd) consumers and very few tertiary (3rd) or quaternary (4th) consumers)
WHY A PYRAMID SHAPE?
The greatest amount of energy is found at the base of the pyramid.
The least amount of energy is found at top of the pyramid.
BIOLOGICAL MAGNIFICATION
The buildup of a pollutant in organisms at higher tropic levels in a food chain
The concentration of a pollutant (like DDT) multiplies as it passes up the food chain from producers to consumers, so the amount of DDT in top-level consumers can be magnified nearly 10 million times
Biological Magnification
The tertiary consumers eat many of the 2nd consumers so they eat even more of the toxin
The secondary consumers eat many of the 1st consumers so they eat more of the toxin
The tiny primary consumers eat a little bit of the toxin.
At every level the amount of toxin increases!
Most toxin
Least toxin