1. Energy in Ecosystems

2. The source of all energy for ecosystems is the SUN
Of the energy released by the Sun, only about one billionth reaches Earth – after a journey of about 150 million kilometers
Of the energy that gets into the atmosphere
30% is reflected by clouds or the surface
70% warms the surface of the planet (causes water to evaporate, generates the water cycle and weather)
Only approximately 0.023% is used by producers for photosynthesis
Photosynthesis – the process by which green plants use sunlight energy to produce carbohydrates (sugars)

3. The Albedo Effect
Albedo is the measurement of the percentage of light that an object reflects
The higher the albedo, the greater the object’s ability to reflect sunlight.

4. Energy Movement
Trophic level – a way of categorizing living things according to how they gain their energy; first trophic level contains autotrophs, and each higher level contains heterotrophs
Autotrophs – organisms that can make their own food from basic nutrients and sunlight, or some other non-living energy source (Plants, algae, some bacteria); producers
Primary consumers – second trophic level; organisms that feed on producers or autotrophs
Secondary consumers – animals in the third trophic level
Heterotrophs – cannot make their own food, must obtain energy/food from autotrophs or other heterotrophs

5. Energy and Food Chains
Food chains are a way of showing the step-by- step sequence of who eats whom in an ecosystem; one way flow, arrows show the direction of energy

6. Food Webs
Each individual organism is involved in many food chains. They all interlock with each other to form a feeding relationship called a food web

7. Limits on Energy Transfer
Only about 10% of the energy in an organism is passed on to the next trophic level
Some is eliminated in the waste (feces)
Energy is lost during chemical transformation of digestion
Some used to maintain body temperature
Lost to surrounding environment
Pyramid of Energy
Largest amount of energy in the producers, this energy decreases as we move up the food chain
Pyramid of Numbers
Number of producers is greater than the trophic level above it

8. Pyramid of Energy

9. Pyramid of Numbers

10. Pyramid of Biomass
Pyramid of biomass is the measure of the dry mass (after water has been removed) of the dry tissue in the plants and animals

11. Human Use of Energy in Ecosystems
Hunting and Gathering
Humans survived by collecting edible plants and animals
Energy demands were limited to two sources (wood for fuel, food)
Agriculture
10,000-12,000 years ago: agricultural revolution
Nomadic existence  farm life
Planting of crops, domestication of animals allowed people to remain in one place
Trees were cut for lumber for housing, forests were cleared so the land could be cultivated
Farms produced more food energy so populations could grow, but they also made greater demands on the ecosystem
Humans began to take a larger share of the energy budget
Industry
energy in ecosystems was used to power machines
Products helped to increase food production and improve the health of humans
Although each individual industrial improvement allowed the local ecosystem to support a greater population of humans, an increasing population places greater demands on the ecosystem

12. Roles in Ecosystems
Ecological Niche – the organism’s place in the food web, its habitat, breeding area, and the time of day it is most active are all part of its ecological niche; includes everything it does to survive and reproduce; an organisms “role” in the ecosystem
Read pages 40 – 44 about ecological niches
Do questions 1-3 on page 44
Discuss with your table partner