How Population Size and Density are Calculated
Quadrat method
A quadrat method is an ideal tool for the study of ecology, particularly biodiversity. Generally, a sequence of squares (quadrats) of a set size are arranged in a habitat of interest, and the species within those quadrats are pinpointed and recorded.
The passive quadrat method (accomplished without removing the organisms found within the quadrat) can be either done by hand, with researchers carefully sorting through each particular quadrat or, efficiently, can be done by taking a picture of the quadrat for future analysis.
Mark and recapture
A quadrat would not function for animals moving around. So to define the population size of more migrating organisms, scientists use a method called mark and recapture.
In this situation, individual animals are captured and labeled with a tag, band, paint, or something similar. The animal is released back into its environment. Then, another group of animals is captured, which may contain those already marked and unmarked animals.
The result of capturing both marked and unmarked animals provides researchers with a ratio to use, and from that, they can estimate the estimated population size.
Population Ecology – Definition, Characteristics, Importance, Effects
Ecologists study how organisms interact with their surroundings on earth. Population ecology is a more specific field of study of how and why the populations of those organisms transform over time. As the human population rises in the 21st century, the information gleaned from population ecology can help with planning. It can also help with measures to preserve other species.
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