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Flashcards in Landres1999 Deck (16)
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1
Q

Title

A

Overview of the use of natural variability concepts in managing ecological systems

2
Q

Natural resource managers have used natural variability concepts since?

A

Early 1960’s

3
Q

Natural variability concepts are being used for?

A
  • Maintaining biological diversity
  • Restore altered ecosystems
  • Benchmarks for assessing anthropogenic change
4
Q

Management use of natural variability relies on 2 concepts

A
  • Past conditions and processes provide context and guidance for managing ecological systems today
  • Disturbance-driven spatial and temporal variability is a vital attribute of nearly all ecological systems
5
Q

Natural variability can be defined by a specific time period or spatial extent, T or F?

A

False

- No a priori time period or spatial extent should be used in defining natural variability

6
Q

What are the drivers for selecting a relevant time period and spatial extent for defining natural variability?

A
  • Specific goals
  • Site-specific field data
  • Inferences derived from data collected elsewhere
  • Simulation models
  • Explicitly stated value judgement
7
Q

What must always be explicit parts of the definition and use of natural variability concepts?

A
  • Clearly defined goals, objectives, assumptions, value judgements, and spatial and temporal bounds
8
Q

Wide-ranging, legally-protected species must be evaluated at what scale?

A
  • The scale of their range, even if it extends beyond local planning area
9
Q

Range is often used to describe what? But?

A
  • Natural variability and to evaluate when current conditions are beyond the bounds of natural conditions
  • But, rare extreme events define these bounds and spatial and temporal limits usually are not defined in sufficiently explicit terms
10
Q

What is a spike descriptor and what does it include?

A
  • Spike descriptors quantify short-term, extreme, or high magnitude changes caused by discrete disturbance events and the relatively short term ecological responses to these events
  • Include rate of change, severity, seasonality, and size and severity frequency distributions
11
Q

When does the natural variability approach have little utility?

A
  • When historical relationships between ecosystem components and their functions cannot be determined or restored
12
Q

What needs to be done when the size, intensity, or effect of a disturbance on socio, political, or endangered ecosystem components (species) is so great as to be unacceptable?

A
  • Other approaches to landscape management need to be employed that are outside of the historical regime/natural variability
13
Q

What are the significant concerns that remain about the use of natural variability concepts?

A
  • Relevance of the concepts to environments that are different today from what they were
  • Amount and quality of information and understanding about natural variability may be insufficient
  • Difficult of managing dynamic ecological systems, especially at large enough scales to be meaningful
14
Q

What are 3 primary criticisms against natural variability?

A
  • Native and contemporary people altered natural systems so that there are no pristine areas left, making info from the past irrelevant or difficult to interpret
  • Dominant climate patterns continually change, past patterns and processes are largely irrelevant today or in future
  • Management goals using natural variability see to recreate past envrs and maintain them in a static condition, not the dynamic of nature
15
Q

What uncertainty in long-term trends makes analysis of trends difficult

A
  • few data available further back in time
  • Rare events increase with longer time frames, and skew data b/c intense and impacts longer lasting
  • Earlier times limited info available about disturbance processes and interactions with dominant driving variables such as climate
16
Q

Applying natural variability concepts multiple sources of info are needed such as?

A
  • Site-specific
  • Simulation models
  • Expert opinions and judgements
  • Data from sites that are both similar and different from the target area to get necessary spatial and temporal context