1. Ecosystems and Biomes G.2.1-G.2.5

2. Primary Production in Ecosystems
Energy hits the earth in the form of solar radiation.
A small percentage of this light is absorbed by plant pigments and used for photosynthesis.
Photosynthesis is the conversion from solar energy (light) chemical energy (sugars)

3. Biomass
The total dry mass of organic matter in organisms or ecosystems in a certain place at a certain time.
Primary production is the amount of new biomass added in a given period of time.

4. Factors that control primary production
Light (intensity and duration)
Nutrients/soil quality
Temperature
Rainfall/moisture
Density of plant populations
Crucial nutrients are used in productivity, so need to be replaced for ecosystem to continue = Limiting Nutrient

5. Gross & Net Primary Production
Gross Primary Production (GPP): The total of organic material produced by plants (including that lost to respiration).
Net Primary Production (NPP): The amount of biomass that is available to consumers at subsequent trophic levels.
NPP = GPP – R
(R = energy used by 1° producers for respiration)

6. Energy Pyramids
The lowest bar on an energy pyramid illustrates the amount of energy flowing through the producers in an ecosystem. This is called gross production.
G.P. does not need to be measured directly as it can be measured from net production and plant respiration.

7. Energy Pyramids
The energy content per gram of food does not diminish as you move up the food chain.
Instead, the food seems to get richer in energy per gram.
The total amount of energy available is lower at the higher trophic levels, and therefore can support less organisms.

8. Difficulties in Classifying organisms into trophic levels
Classifying organisms into trophic levels in a community can be difficult because many organisms can fill several different trophic levels in a food web
Euglena (uses chloroplasts for photosynthesis, but also takes in food via endocytosis)
Chimpanzees eat fruit and other plant matter, but also eat termites and some other monkeys