1. Introduction to Ecosystem EcologyPP

2. Ecosystem Ecology
Ecosystems are the interactions of different populations (communities) and the abiotic factors of the environment
Species  Population  Community  Ecosystem  Biosphere

3. LOGISTIC MODEL review

4. Models the growth of a population over time
Starts off exponential (b> d) but levels off as the population reaches carrying capacity (K)
Carrying capacity (K) is the maximum number of individuals an environment can sustain
K is when b rates equals d rates or zero population growth
Limited by factors that increase in pressure as the population density increases (density-dependent factors)
EX. predation, pollution, disease, resources, mates

6. PREY: SEA URCHINS
Prey
PREDATOR: SEA
STARS
Predator

7. Predation Example One species eats (predator) another species (prey)
The relationship is cyclic in nature – ↑ in prey leads to ↑ in predators, ↓ in prey leads to ↓ in predators, and so on
The size of the predator population is always changing or fluctuating around a set point called carrying capacity

8. FEEDBACK MECHANISMS IN ECOLOGY
Process that uses the conditions of one component to regulate the state of the another

9. Negative feedback results when the a change occurs in one element that affects the other in the opposite direction
The net result produces a stable system where different forces are counterbalancing each other out creating some equilibrium.
Negative Feedback

10. Positive Feedback
Positive feedback is responsible for sudden or rapid changes within ecosystems
When part of the system increases, another part of the system also changes in a way that makes the first part increase even more.
Positive feedback is self-reinforcing and a source of instability that can drive the ecosystem outside of its normal operating parameters.

11. QUESTION:
Is the population model of the predator-prey relationship an example of negative feedback or positive feedback?
Cite one reason for your choice.

12. Stability and Change
Ecosystems are constantly changing and fluctuating around a set point
Ecosystems are characterized by both stability and change
Change can be a healthy component of the ecosystem but also unhealthy when influenced by human impact

13. TASK:
Provide 2 pieces of evidence for stability or change from the Pika video.