Which of the following best describes the Lincoln Index?

The Lincoln Index is a specific method used for estimating the population size of mobile organisms, such as animals that can move across a landscape. This index operates on the principle of mark-recapture, where a sample of the population is captured, marked, and then released back into the environment. After a certain period, a second sample is taken. The proportion of marked individuals in the second sample provides insight into the total population size. This technique is particularly effective in ecological studies and wildlife management, as it allows researchers to estimate not just how many individuals are present, but also to monitor changes over time and make informed decisions regarding conservation strategies.

Contextually, the other options do not accurately describe the Lincoln Index. Sampling stationary organisms does not align with the concept of mobility that the Lincoln Index is designed to address. Soil nutrient levels are assessed using different methods such as soil testing, which is unrelated to population estimation. Evaluating habitat quality involves a range of other techniques that focus on biotic and abiotic factors in an area, rather than directly estimating organism populations. Thus, the correct identification of the Lincoln Index as a tool for estimating population size in mobile organisms reflects the index's intended application and the methodologies it employs.