Ecosystems Flashcards
What is an ecosystem?
A system formed by the interaction of all living organisms. Within an ecosystem, all of these elements are interacting with each other all of the time. All energy is coming from the sun. `
What are diverse ecosystems?
- a result of unique biophysical interactions at varying scales, the interaction of the biotic and abiotic elements result in diverse ecosystems
- e.g. coastal dunes, freshwater wetlands, intertidal wetlands, coral reefs, arid areas, alpine, rainforests
How are diverse ecosystems shaped?
- spatial patterns of these ecosystems depend on 4 spheres (bio, litho, hydro, atmo)
- result of climactic factors (temperature + precipitation)
- hydrologic processes (surface water flow, snow melt, ocean currents)
- geomorphic processes (aspect, altitude, gradient, soils)
How and what is ecosystem functioning
Ecosystem functioning = the ability of an ecosystem to capture, store and transfer energy, nutrients and water throughout the system
This depends on 2 key processes: energy flows and nutrients cycling
What are energy flows
Energy flows through an ecosystem from the sun to the plants (producers, producing energy via photosynthesis) and animals through the trophic levels.
Energy is lost as heat is produced at each level of consumption - there are fewer organisms at the top of the chain.
How does latitude impact energy flow
Equatorial ecosystems receive more regular and stronger daily insolation –> more energy available.
therefore tend to have higher biodiversity
What are the trophic levels
Top - bottom: Tertiary consumers (large carnivores) Secondary consumers (small carnivores) Primary consumers (herbivores) Producers
(greatest number found at the bottom)
What are nutrients cycles
- nutrients are central to the functioning and growth of organisms
- fixed supply of nutrients, continually cycles through biosphere
- ecosystems with higher biodiversity have higher amounts of nutrients as the amount of matter that decomposers affects the amount of nutrients that can be recycled
- net primary productivity
- nitrates, carbon, sulfur, phosphorus, water and oxygen
Net primary productivity
based on the biodiversity and nutrients cycled - the amount of material that an ecosystem produces.
Tropical rainforests = 1800g/m2/year (similar to kelp forests)
Deserts = 80g/m2/year
Optimal Functioning - Climax Communities
- ecosystems go through stages of development
- successions
- climax community = an ecological community that has reached the final stage of ecological succession and cannot support additional flora and fauna, it is highly functional
Succession
- succession: process that begins after a significant disturbance or extinction of existing community, can occur in areas that have never been colonised b4, leads to species diversity as new species adapt to change and find a niche
Disturbances preceding succession include:
Human impacts: deforestation, pollution
Natural stresses: fire, drought, tropical cyclones, tsunami
Ecosystem at risk:
- one that is subject to difficult environmental conditions (aridity, high salinity, extreme temperatures, lack of nutrients) or those slow to develop and or regenerate after change
dynamic equilibrium
a situation in which stability is achieved in an ecosystem
- all ecosystems function in a state of dynamic equilibrium or a continual state of balanced change
beyond the limits of equilibrium
a change beyond the limits means that the system as a whole cannot exist in its original state –> concept of elasticity
vulnerability
the lack of defence an ecosystem has against unforeseen changes in the environment