23.1 Ecosystems Flashcards
What is an ecosystem?
- All the living organisms which interact with one another in a defined area.
- And the physical factors present in that region.
What are biotic factors? Give examples.
- Living factors.
- e.g. competition (intraspecific within species/interspecific between species), predation
What are abiotic factors? Give examples.
- Non-living factors
- e.g. temperature, light intensity, CO2 concentration, rainfall, pH, humidity
What is a habitat?
An area in which organisms live within an ecosystem.
What is a population?
A group of animals or plants of the same species living in the same habitat.
What is a community?
All the populations of living organisms in a particular habitat.
What is a (ecological) niche?
The role of an organism in its community.
What are producers?
Organisms which convert light energy into chemical energy by photosynthesis.
What are primary consumers?
Obtain energy by feeding on producers?
What are secondary consumers?
Obtain energy by feeding on primary consumers.
What are tertiary consumers?
Obtain energy by feeding on secondary consumers.
What are decomposers?
Break down dead organisms, releasing nutrients back into the ecosystem.
How does pH affect an ecosystem?
- Affects the organisms that can live in water, disrupts balance of ecosystem by damaging organisms or inhibiting growth and reproduction
- Changes in soil pH affect availability of soil nutrients
How does humidity affect an ecosystem?
- Promotes growth and reproduction of pathogens causing plants to die
- Low humidity leads to increased rate of transpiration which can cause uncontrolled water loss and wilting
How does temperature affect an ecosystem?
- Mostly affects enzymes controlling metabolic reactions
- Plants and ectothermic animals develop more rapidly in warmer climates
- Changes in temp can trigger migration/hibernation of animals
- Can trigger leaf-fall/dormancy/flowering in plants
How do pollutants affect an ecosystem?
Certain pollutants can have specific impacts:
- Ozone damages tree leaves
- Excess sulfur leads to excess acid in lakes and streams, and damages trees and forest soils.
How does light intensity affect an ecosystem?
- Required for photosynthesis - in general greater light availability leads to greater success of plant species
- Plants adapt to cope with different light intensities, e.g. plants in lower LI may have larger leaves or photosynthetic pigments requiring less light
How does water availability affect an ecosystem?
- Lack of water leads to water stress, can lead to death
- In plants may lead to wilting as water is required to keep cells turgid
- Required for photosynthesis of plants
- Leads to domination of xerophytes
How does oxygen availability affect ecosystems?
- Affected by flow of water, which carries O2
- Beneficial to have fast-flowing cold water - contains high conc of oxygen.
- If water is too warm/flow rate is too slow, O2 concentration drops and aquatic organisms suffocate
- In waterlogged soil, air spaces between soil particles are filled with water, reducing O2 available for plants
How do edaphic (soil) factors affect ecosystems?
Different soil types have different particle sizes, affecting organisms living in them:
- Clay - fine particles, so is easily waterlogged and clumps when wet
- Loam - different sized particles, which retain water but does not become waterlogged
- Sandy - coarse, well-separated particles that allow free draining
Why are ecosystems described as dynamic?
They are constantly changing as a result of living organisms present and environmental conditions.
