Energy in Ecosystems

Food Web:• a group of food chains

showing all of the feeding relationships in an ecosystem.

• Trophic level — a layer in the feeding relationship of an ecosystem, one link in the food chain/web.

• Biomass — total amount of organic material present in a trophic level.

Organic = is currently living or lived in the past

So, all producers are at the same trophic level and all primary consumers are at the

next trophic level.

All Food Webs:

• Original Energy (SUN)

• Producers

• Consumers

• Decomposers

• Soil

• Arrows showing energy flow!

Energy/Ecological Pyramids

• Another way to look at trophic levels.

• a diagram showing the relative amounts of energy/biomass in the different trophic levels.

• Lowest trophic levels are at the bottom: Producers have the greatest biomass.http://www.earthforce.org/files/

1284_image2_Energy_Pyramid_for_Galvbay.jpg

http://www.vtaide.com/png/foodchains.htm

Example of an Energy Pyramid

MAN

FOX

RABBIT

100 % of the sun’s energy 10%

1%

0.1%

10%

10%

10%

1 MAN

10 FOXES

100 RABBITS

1000Bunches ofGRASS90%

90%

90%

Energy Lost during

conversion to heat, waste….

Grass

Rabbit

- The decreasing size of the pyramid shows that each level of the pyramid has a smaller and smaller number of those organisms.

Carrying Capacity:

• The maximum population a community can tolerate for extended periods of time. Usually determined by abiotic factors …

Community = the plants and animals found

in an area

Population: How many of a specific species

can live in an area?

Abiotic Factors = non-living characteristics of the environment.

For example:

-Sunlight

-Moisture

-Space

-Pollution

-Landscape/Terrain

An extended period of time … the

environment remains healthy and future

generations of organisms are able to continue to live

within the community

Limiting Factors:

• Anything that keeps a population from over-growing the resources available.

• Consider how changing the factors that affect carrying capacity can alter the population size of a species.

Disease

Parasites

Accidents

Fire

Floods

StormsStarvation

Hunting

Predation

Habitat Loss

Drought

Pollution

Shade