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1.3 ENERGY AND EQUILIBRIA (Resilience of systems (Factors affecting…
1.3 ENERGY AND EQUILIBRIA
Energy in Systems
1st law of thermodynamics
energy is neither created nor destroyed
total energy in isolated system is constant
principle of conservation of energy
2nd law of thermodynamics
entropy of an isolated system not in equilibrium will tend to increase over time
entropy is a measure of disorder of a system and it refers to the spreading out or dispersal of energy
more entropy = less order
over time, all diff. in energy in universe will be evened out until nothing can change.
energy conversation never 100% efficient
energy always dissipated as waste heat
Complexity and stability
ecosystems are complex
a more stable system
withstand stress and change better
another pathway can take over if one is removed
Tundra ecosystems (simple ecosystem) - populations may fluctuate widely
monocultures - vulnerable to sudden spread disease
Equilibrium
tendency of system to return to an original state following disturbance
open systems tend to exist in stable equilibrium
types
steady-state equilibrium
continuous inputs and outputs of energy and matter, system as a whole remains constant (climax ecosystem)
negative feedback
stabilise it
self-regulation
static equlibrium
no change over time
new equilibrium is produced if disturbed
can be stable and unstable
Feedback Loops
positive mechanisms
change a system to a new state
destabilising as they increase change
negative mechanisms
return to its original state
stabilising as the reduce change
positive feedback
a further increase or decrease in output that enhances the change in the system
may be stopped abruptly by an external force
destabilised and pushed to a new state of equilibrium
Resilience of systems
how it responds to disturbance
more resilient, more disturbance it can deal with
ability of a system to return to its initial state after a disturbance
low resilience, it will enter a new state
Factors affecting
diversity and complexity
species of biodiversity of ecosystems
genetic diversity within a species
species that can shift their geographical ranges
climate
rate at which a species can reproduce
humans removing or mitigating the threat to the system
tipping points
ecosystem experiences a shift to a new state in which there are significant changes to the biodiversity and the services it provides.
characteristics
involve positive feedbacks
changes long lasting
changes hard to reverse
significant time lag, creating great difficulties in ecological management
examples
lake eutrophication
extinction of a keystone species
coral reef death