The population density is influenced by many factors, see population dynamics .
There are different approaches to measuring population density.
If there is a spatial distribution, the population density can usually be related to a volume unit (individuals per liter, per cubic meter, etc.). Measurements are made using random samples, which can be quantified for the entire room if the number of samples remains the same. Examples of this are the population density of bacteria in a tank, the density of plankton organisms or fish in a lake, and the density of soil organisms .
If there is no vertical distribution, the population density can be related to the area (individuals per square meter, per hectare, etc.). Examples of this are the number of trees in a forest area or the average density of a mammal herd. Organisms from a certain area are weighed and counted and the results are quantified.
With the return method , stocks of mobile animals can be determined using markings. In doing so, selected individuals are marked and their percentage approach is assumed in later populations as exemplary for the total population. When the density changes rapidly, marking methods don't work well.
Total counts of all populations of a species are possible for conspicuous or large organisms as well as for organisms that live in manageable colonies.
- Eugene P. Odum : Ecology. Basics, locations, application. 3. Edition. Stuttgart / New York 1999, p. 196.
- Eugene P. Odum: Ecology. Basics, locations, application. 3. Edition. Stuttgart / New York 1999, p. 195.