Population Density Equation
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Population density
Population density (in agriculture: standing stock or plant density) is a measurement of population per unit area, or exceptionally unit volume; it is a quantity of type number density and frequently applied to living organisms, most of the time to humans. It is a key geographical term. In simple terms, population density refers to the number of people living in an area per square kilometre.
Biological population densities
Population density is population divided by total land area or water volume, as appropriate.
Low densities may cause an extinction vortex and lead to further reduced fertility. This is called the Allee effect after the scientist who identified it. Examples of the causes of reduced fertility in low population densities are:
- Increased problems with locating sexual mates
- Increased inbreeding
People per Area
What is the population of your hometown? Is it a big city or a rural farming town? Depending on how much land your town covers, the population of two such different areas could actually be the same. Population as a flat number only tells you how many people there are; it doesn’t actually look at those people in relation to the area where they live.
If you want to know how many people there are in a certain area, what you want is population density. This tells you the population as it relates to the amount of land area in which those people live. Population density helps show the difference between a small but dense city and a widely spread out town, even if the absolute population is the same.
Formula for Population Density
The formula for calculating population density is Dp= N/A. In this equation, Dp is the density of population, N is the total population as a number of people, and A is the land area covered by that population.A is usually expressed in terms of either square miles or square kilometers, especially when you’re looking at human population. However, you could use smaller units as well. For example, if you’re looking at the population density of a type of insect on a tree, you would use square feet or square meters, because kilometers would be far too large. You might also use acres if you’re looking at the population density of cattle on a ranch. The same population density formula applies to both human and non-human populations.
Population Density Example
How to calculate population density?
The following example problem outlines the steps required for calculating a population density.
First, determine a specific area that is to be analyzing. In this example, we will use the city of New York as the area.
As of 2019, the city contained 8.419 million people. Note that this is only the borough of New York City, and does not include the surrounding metropolitan area.
Next, determine the total area of the city. For this problem, New York City is found to have a total size of 302.6 square miles.
Finally, calculate the population density using the formula D = P/A = 8,419,000 / 302.6 = 27,822.20 people per square mile.
How To Calculate Population Density?
In this section, we will be solving a couple of population density examples to clear this basic term in more depth. Keep focusing!
Example # 01:
The land area of New York city is about \(783.3km^{2}\). According to a recent survey made in the year 2019, the population of this city has exceeded upto 8 million. How to find population density?
Solution:
First of all, we have:
$$ 8 million = 8000000 $$
Finding population density: $$ D = \frac{P}{A} $$ / $$ D = \frac{8000000}{783.3} $$/ $$ D = 10213 People Per Square Miles $$
Example # 02:
How is population density calculated of a particular locality of about \(23km^{2}\) in area and having a population of about 1lac?
Using the population density formula: $$ D = \frac{P}{A} $$/ $$ D = \frac{100000}{23} $$ / $$ D = 4347 people per square miles $$
Here the free population density calculator online also estimates the same population value but more precisely.
Population Density Units
In most cases, population density is present in the number of people per square mile, or the number of people per square kilometer.
These units can be expressing in per thousands of people when looking at very dense areas, such as New York, like the example above shows.
Population research methods
Counting all individuals in a population is the most accurate way to determine its size. However, this approach is not usually feasible, especially for large populations or extensive habitats. Instead, scientists study populations by sampling, which involves counting individuals within a certain area or volume that is part of the population’s habitat. Analyses of sample data enable scientists to infer population size and population density about the entire population.
A variety of methods can be using to sample populations. Scientists usually estimate the populations of sessile or slow-moving organisms with the quadrat method. A quadrat is a square that encloses an area within a habitat. The area may be defined by staking it out with sticks and string, or using a square made of wood, plastic, or metal placed on the ground.
A field study usually includes several quadrat samples at random locations or along a transect in representative habitat. After they place the quadrats, researchers count the number of individuals that lie within the quadrat boundaries. The researcher decides the quadrat size and number of samples from the type of organism, its spatial distribution, and other factors.
For sampling daffodils, a 1 m2 quadrat could be appropriate. Giant redwoods are larger and live further apart from each other, so a larger quadrat, such as 100 m2, would be necessary. The correct quadrat size ensures counts of enough individuals to get a sample representative of the entire habitat.
Scientists typically use the mark and recapture technique for mobile organisms such as mammals, birds, or fish. With this method, researchers capture animals and mark them with tags, bands, paint, body markings, or some other sign. The marked animals are then releasing back into their environment where they mix with the rest of the population. Later, a new sample is collecting, including some individuals that are marking (recaptures) and some individuals that are unmarking.
The ratio of marked to unmarked individuals allows scientists to calculate how many individuals are in the population as an estimate of total population size. This method assumes that the larger the population, the lower the percentage of tagged organisms that will be recapturing since they will have mixed with more untagged individuals. For example, if 80 deer are capturing, tagged, and releasing into the forest, and later 100 deer are capturing with 20 of them are already marking, we can determine the population size (N) using the following equation:
numbermarkedinfirstcatch×totalnumberofsecondcatchnumberofmarkedrecapturesinsecondcatchnumbermarkedinfirstcatch×totalnumberofsecondcatchnumberofmarkedrecapturesinsecondcatch
Plugging the example data into the equation, the calculation gives an estimated total population size of 400.
80×10020=40080×10020=400
Using the example data, if only 10 already-marked deer had been recaptured, the calculated total population size would be 800.
The mark and recapture method has limitations. Some animals from the first catch may learn to avoid capture in the second round. Such behavior would cause inflated population estimates. Alternatively, animals may preferentially be retrapping (especially if a food reward is offering), resulting in an underestimate of population size. Also, some species may be harming by the marking technique, reducing their survival.
A variety of other techniques have been developed, including the electronic tracking of animals tagged with radio transmitters and the use of data from commercial fishing and trapping operations to estimate the size and health of populations and communities.
What Is The Equation For Population Density?
What are the 3 methods for calculating population density?
The three methods for calculating population density are arithmetic, physiological and agricultural. The method used to calculate population density reveals different information about the pressure the population exerts on the land.
What is the formula for population?
Population formula in economics is using to determine the economic activity of the country or area. Population percentage is the formula to divide the target demographic by the entire population, and then multiply the result by 100 to convert it to a percentage.
What is population density how it can be calculated biology?
The formula for finding the population density is PD = N/S or population density = a number of organisms/area. In the formula, PD = N/S, PD stands for population density, N stands for the number of organisms, S stands for the area to get the PD, divide the number of organisms by the area.
How Population Density Calculator Works?
The population density formula calculator takes a couple of seconds to calculate the residential density in any state quickly and absolutely. Let’s find how!
Input:
- Write down the population of the area in the menu box
- After doing so, mention the residential area in the next column
- Tap the calculate button
Output:
The population distribution calculator estimates:
- The exact number of the people residing in the area per square mile.
