Question

Explain with the help of an example each any three ways the ecologists use to measure
population density of different organisms rather than by calculating their absolute
number.​

Answer 1

Answer:

Population size, more technically called population density (designated as N), need not necessarily be measured in numbers only. Although total number is generally the most appropriate measure of population density, it is in some cases either meaningless or difficult to determine.

1). in an area, if there are 200 Parthenium plants but only a single huge banyan tree with a large canopy, stating that the population density of banyan is low relative to that of Parthenium amounts to underestimating the enormous role of the Banyan in that community. In such cases, the per cent cover or biomass is a more meaningful measure of the population size. Total number is again not an easily adoptable measure if the population is huge and counting is impossible or very time-consuming.

2) Sometimes, for certain ecological investigations, there is no need to know the absolute population densities; relative densities serve the purpose equally well. For instance, the number of fish caught per trap is good enough measure of its total population density in the lake.

3). The tiger census in our national parks and tiger reserves is often based on pug marks and fecal pellets.