Principles Of Ecology Quiz #2

Question 1

Resilience

Answer 1

Capacity of an ecosystem to respond to a perturbation or disturbance, by resisting damage and recovering quickly

Question 2

Buzz Holling resilience quote

Answer 2

“The amount of change that a system can undergo before it crosses a threshold and flips to an alternative stability regime of that system”

Question 3

How is resilience measured

Answer 3

By the magnitude of disturbance that can be absorbed before the system changes its structure

Question 4

How is an Alternative stable state created in relation to resilience

Answer 4

The amount of resilience an ecosystem possesses relates to the magnitude of disturbance required to disrupt the system causing a shift to a new stable state or an alternate stable state that is controlled by a different set of processes, to occur. Example is a forest to a grassland

When resilience is lost, as ecosystem is more vulnerable to shift to an alternate stable state

Question 5

What is a gradual shift in ecosystems

Answer 5

Gradually changing conditions, e.g., nutrient loading, climate change, habitat fragmentation, etc., can also surpass threshold levels, triggering an abrupt ecosystem response

Question 6

When is an ecosystem at high risk of changing state

Answer 6

When resilience is lost or significantly decreased, an ecosystem is at high risk of shifting into a qualitatively different state controlled by a different set of processes

*The amount of resilience an ecosystem possesses relates to the magnitude of disturbance required to fundamentally disrupt the system

Question 7

Relationship between resilience and vulnerability of an ecosystem

Answer 7

Reduced resilience increases the vulnerability of an ecosystem to withstand smaller disturbances that it could previously cope with

Question 8

What type of disturbances contribute to a stable system

Answer 8

Few or small disturbances

Question 9

What frequency and magnitude of disturbances contribute to an unstable ecoystem

Answer 9

Many or large disturbances

Question 10

Define Ecosystem Stability

Answer 10

Stability is the property of the ecosystem, and the degree of fluctuation around specific states is the result. It is the actual disturbances a system faces

Question 11

Management should focus on..

Answer 11

• Maintaining resilience and NOT preventing disturbance
• Sustaining a LARGE stability domain
• Slowly changing variables: land-use, nutrient stocks and biodiversity

Question 12

Two fundamentals to improving performance at a site (management side)

Answer 12

Long term monitoring and adaptive management

Question 13

Disturbance

Answer 13

Ecologically, disturbance can been defined as any relatively discrete event in time that disrupts population, community and ecosystem structure

Question 14

How is diversity measured (2)

Answer 14

• Richness: refers to the number of species in the community

* Evenness: the relative abundance of species

Question 15

What is the non-equilibrium model

Answer 15

Describes communities as constantly changing after being buffeted by disturbance

Question 16

What is the Intermediate Disturbance Hypothesis

Answer 16

this hypothesis states that the highest levels of diversity are supported at intermediate levels of disturbance (frequency or intensity)

Question 17

What traits do ecosystems with intermediate levels of disturbance have

Answer 17

-high diversity, greatest resiliency, and thus lowest stability

Question 18

How is resilience degraded

Answer 18

Can be degraded by a large variety of factors including: loss of biodiversity 
toxic pollution 
overharvesting 
climate change
habitat fragmentation
drought

Question 19

What is the key to restoring resilience and why

Answer 19

Biodiversity b/c it provides functional redundancy with increases resilience

Question 20

What are 4 keys to biodiversity and functional redundancy

Answer 20

1. Habitat complexity (native)
2. Habitat connectivity
3. ‘Normal’ harvest and/or predation rates
4. Minimal pollution

Question 21

What is a keystone species

Answer 21

A keystone species is a species that has a disproportionate effect on its environment relative to its abundance.
these species play a critical role in determining the types and numbers of various others species/structure of an ecological community, helping maintain a higher species diversity.
their impact on the community is greater than would be expected based on its relative abundance or total biomass

Question 22

Why are keystone species important

Answer 22

Keystone species stabilize the entire biological community
The LOSS or DECLINE of a keystone species has serious consequences for the continued productivity, structure and function of the ecosystem
Even if that species was a small part of the ecosystem by measures of biomass or productivity, an ecosystem may experience a dramatic shift if remove

Question 23

Why are salmon a keystone species in the PNW

Answer 23

supports 137 different species