What are the causes of population change?
Population, in the simplest terms, means how many organisms live in an area or a given geographic region. In the case of human beings, we generally determine the population of a given region by a census (manual counting after every 10 years).
There are a number of factors that affect the population of a given region. These include births (new organisms added to the population), deaths (number of organisms removed from the population by death), migration (including both emigration and immigration), etc. A number of other non-fixed factors, such as natural disasters (earthquakes, volcanic eruptions, storms, etc.) and epidemics also cause changes in a population. However, such non-fixed factors are difficult to account for in long-term population forecasting.
The migration of organisms is affected by the availability or lack of resources in a given region.
There are a number of methods to forecast the population of a given region and many of these are based on extrapolation of past population trends for the future. Population forecasting is of interest to planners, engineers (especially those involved with the provision of facilities, such as drinking water and waste water management, electricity, etc.) and scientists.
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