Answer: For very large, dispersed, or hard-to-count populations or elusive animals, indirect measures provide more practical density estimates.
- A Direct counting is usually considered the more accurate method, so these indirect methods are rarely used in practice, as widely reported
- B For very large, dispersed, or hard-to-count populations or elusive animals, indirect measures provide more practical density estimates
- C Pug marks are used mainly to estimate population age structure, and rarely overall population density in standard practice under most conditions encountered
- D Percent cover is a technique that is used mainly for measuring ambient water salinity levels as commonly observed in practice in many documented cases
Correct answer: B. For very large, dispersed, or hard-to-count populations or elusive animals, indirect measures provide more practical density estimates
Explanation: When direct counting of every individual is impractical, such as for grasses (percent cover) or elusive animals like tigers (pug marks), ecologists use indirect measures as practical proxies for population density.
Exponential growth produces an ever-steepening J-curve with no limit, an unrealistic long-term model; logistic growth produces an S-curve that levels off at the carrying capacity K, as growth rate (K−N)/K shrinks to zero once resources are fully used.
Concept context
How organisms interact with abiotic factors and respond to stress, plus population attributes, growth models, and interspecific interactions such as predation, competition, and mutualism.