Lesson 2 - Transfer of energy

what is the definition of stability of ecosystems?

what is the definition of stability of ecosystems?

The ability to maintain its structure and function over time despite changes or disturbances.

What factors affect the stability of ecosystems?

1. Supply of energy

2. Recycling of nutrients

3. Genetic diversity

4. Climatic variables remaining within tolerance levels. 

what are some examples of stable ecosystems?

• Tropical rainforests

• Coral reefs 

what are tipping points?

The critical threshold that, when crossed leads to irreversible changes to the ecosystem. 

what is an example of a tipping point?

Rainforest and palm oil.

What are mesocosms?

they act as a model for a larger ecosystem. 

What are some advantages of mesocosms?

• Effects of several environmental factors can be tested. 

• Food webs can be established

• Contamination influence can be evaluated

what are some disadvantages of mesocosms?

• Does not fully capture the complexity of real-world ecosystems.

• It is a closed system while most ecosystems are opened.

• Very hard to completely replicate the ecosystems.

What are keystone species?

A species that has a disproportionately large effect on the community. 

What is an example of a keystone species?

sea otters

In what ways do sea otters act as keystone species?

• Sea otters control the population of sea urchins which can overgraze on vegetation. 

What does a sustainably harvested resource mean?

one which is replaced as rapidly as it is harvested. 

What factors affect the sustainability of agriculture?

• Soil erosion

• Agrochemicals

• Water use

• Biodiversity 

• Greenhouse gas emissions

what is eutrophication?

Excessive nutrients in a water body causing overgrowth of algae.

How do fertilisers lead to eutrophication?

• Fertilisers contain nitrogen, phosphorus and potassium that can leach into water bodies. 

• Excessive nutrients causes algae to grow rapidly (eutrophication)

• When it dies large amounts of organic matter accumalate.

• Bacteria breaks down the dead material and oxygen is needed. 

• Oxygen depletion can lead to death of fish and habitat degradation.

what is biomagnification of pollutants?

The increase in concentration of pollutants with ascending trophic level.

What is the definition of Bioaccumalation

the gradual accumulation of substances, in an organism.

What size are microplastics?

less than 5 mm

What are macroplastics?

 visible to the naked eye.

What are the effects of plastic pollution?

• Disruption of marine food webs (biomagnification and accumulation of pollutants)

• Chemical pollution (toxic chemicals) 

• Wildlife entanglement and ingestion

• Habitat degredation

What are some different types of rewilding projects?

• Species reintroduction

• Habitat restoration

• Rewilding urban areas

• Rewilding rivers and waterways 

• Ecological management e.g. banning intense farming or insecticides

What is an ecological succession?

the process of an ecosystem changing over time due to changes in abiotic factors

What is primary succession?

changes that occur on newly formed/exposed land

What are the steps in primary succession?

1. bare rock

2. colonised by pioneer species (moss)

3. decomposition creates a layer of topsoil

4. grasses grow and displace the pioneer species

5. more nutrients in soil allows for shrub growth

6. increase in soil depth allows for growth of trees

What is secondary succession?

occurs where soil is present but no plant or animal species are present.

What are the steps in secondary succession?

1. established climax community (final stage of succession)

2. disturbance destroys the community

3. biota (living things) removed but the soil remains

4. fast growing plants initially dominate

5. eventually climax community is re-established

What is cyclical succession?

A continuous cycle of change and regeneration.

What are the features of climax communities?

• stable

• few dominant plants + animals species

• not very diverse