Ecosystems

Ecosystems

Succession
1. Net Primary Productivity (NPP) = The total amount of energy transferred from sunlight to chemical potential energy (biomass) less any used in respiration.
2. Succession = When changes to the environment causes the plant and animal species to change.
3. Primary Succession: This is where life has to re-establish from bare rock.
4. Secondary Succession: Disturbance but the soil remains. This could be due to a forest fire. Pioneer species come in, then intermediate.
5. Climax stage: What happens after succession.
Population Sustainability
1. A limiting factor is an environmental resource or constraint that limits population growth. These are abiotic and biotic factors.
2. Population growth curve - This has three stages. Stage 1 - Lag phase where a small population is reproducing. Here the birth rate is higher than the death rate. This is a period of slow growth.
3. Log phase - A period of rapid growth. The population increases exponentially. Here there are no limiting factors.
4. Stationary phase - Population growth is prevented by external constraints. Here population size is generally stable but it can fluctuate.
Competition
1. Interspecific competition - competition between different species.
2. Intraspecific competition - competition between members of the same species.
3. Interspecific competition results in the decline in resources for both populations. Therefore less energy for growth and reproduction.
4. The less adapted species will be outcompeted.
5. Intraspecific variation - The availability of the resource determines the population size. Stage 1 - When a resource is plentiful , all organisms have enough of the resource to survive and reproduce. Stage 2 - Increased population means there are many more individuals sharing the same number of resources. So population decreases in size. Stage 3 - Less competition means less competition for the same resources. So population grows again.
Ecosystems
1. Ecology: The name given to the study of relationships between organisms and their environment.
2. An ecosystem is the area where living organisms and non-living conditions interact with each other.
3. Abiotic factors: Soil pH, temperature, light intensity, humidity, oxygen and edaphic (soil).
4. Biotic factors: Disease, invasive species and reproduction.
Energy Transfer
1. 1-3% of the sun's light is captured by the plants/algae.
2. 90% if the sun's energy is reflected by dust/clouds or absorbed by the atmosphere.
3. Light may not fall on a chlorophyll molecule.
4. A factor, such as low CO2 levels will inhibit photosynthesis, therefore the sun's energy isn't used for photosynthesis.

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