Week 5 - 4b

Question 1

Why is it important to focus on the ‘why’ question rather than the ‘how’ question?
Why is this particularly important when combining results from studies at different scales?

Answer 1

• Difficult to apply broad scale measurements/principles to a small scale
• Vice versa
  i. Focus on studies that include information on the fundamental, mechanistic explanations of why animals are in their habitats and absent from others,
  ii. these are more powerful than those that draw correlations between animal abundance and a list of habitat factors.

Question 2

What are two concerns about using density as a baseline to evaluate habitat quality?

Answer 2

• can vary widely depending upon the spatial scale of the study
• density (or indices of) for one scale cannot reliably be extrapolated to larger scales

Question 3

One should be cautious when using results/measures from other studies; why?
What should you look for in these publications before you rely on them?

Answer 3

• most studies of habitat use occur where previous knowledge that the species of interest is in adequate abundance,
   typical study focus - home range or a finer-scale activity location (e.g., foraging or nest site),
   restorationist must then extrapolate results to their project area,
   such extrapolations are tenuous at best;
• animals and their habitat are not uniformly distributed across the landscape

o carefully evaluate the rationale given for:
 location and size of the study area(s),
 sampling methods used, and
 how the data were analyzed.

Question 4

Vegetation floristics and structure have different levels of application; when should vegetation floristics be emphasized in habitat assessment versus vegetation structure?

Answer 4

• floristics become increasingly relevant when determining the mechanisms responsible for breeding success & body condition of animals,
  i. relatively simple presence-absence studies of animals at regional or broader scales likely do not require a floristics analysis of vegetation.

Question 5

state the four criteria that can help guide the selection of fine-scale habitat variables for measurement.

Answer 5

Selecting variables that:

Major: Are suspected to influence the distribution and local abundance of the species

Major: Have biological relevance to the species – measured as fecundity, survival, and carrying capacity.

Minor: are quickly and precisely measurable with non-destructive sampling

Minor: have intraseasonal variation that is small relative to interseasonal variation,

Important: describe the environment near animals

Question 6

When should restorationists measure broad-scale or fine-scale habitat resources?

Answer 6

Depends on study

Question 7

What is the primary assumption and point of caution of the ‘focal-animal’ approach?

Answer 7

• Measurements indicate the animals’ habitat preferences
• are these the most important variables?

Question 8

Contrast the use of transects and circular plots for habitat sampling.

Answer 8

 Circular plots are easy to establish, mark, measure, and relocate, and
* estimates of animal numbers within plots can be statistically related to vegetation data in a straightforward manner.
 Transects cover relatively large areas and thus make it difficult to relate specific animal observations (or abundances) to particular transect sections.
* transects are, however, widely used to describe the vegetation of entire study areas.