Population Dynamics and DTM PDF

Population 1 Population: The number of people living in a geographic area. The study of population is demography. In population geography, the main focus of study is the human population. Population Size is the number of individuals in a population. The number...

Population 1 Population: The number of people living in a geographic area. The study of population is demography. In population geography, the main focus of study is the human population. Population Size is the number of individuals in a population. The number of population in Bangladesh is 165 millions (2022). 2  Population Distribution Distribution of population refers to the way people are spaced over the surface of the earth. The distribution may be linear, dispersed or agglomerated. Population Density The term ‘Density of Population’ refers to the number of persons per sq. kilometer. In other words, density of population indicates the man-land ratio. 3 Factors Affect Population Distribution and Density Climate Geographical location Natural vegetation Relief (configuration of land) Fertility of Soils Availability of rivers and water supply Natural resources Industry Political condition/government policy 4  Migration ✓ Distance ✓ Cost ✓ Lack of qualifications 5 Population of Bangladesh Total Population: 165 Million Female: 83.4 Million Male: 81.6 Million Source: BBS, 2022 6 Factors Affecting Population Growth 7  Population Dynamics Population dynamics is the study of the fluctuations of a population’s size over time, as observed through rates of birth, death, immigration, and emigration. 8 Population Dynamics observes the changes in the static physical properties of populations. Here are the main observable characteristics of populations: 1. Size 2. Density 3. Dispersion 4. Sex distribution 5. Age distribution 9 1. Size Size is the count of individuals within a population. This count represents a specific and unique point in time. When observing population dynamics, we thus need at least two data points at time A and time B. In population ecology, the common symbol for population size is the uppercase letter 'N'. 2. Density Density is the number of individuals of a population per region. For example, a very dense population of squirrels may have one individual per square meter, whereas a more scattered population may have one individual per square km. The denser the population, the higher the level of competition. The multiple squirrels in the square meter may all have to struggle for the same acorn. Density is strongly correlated with biotic factors affecting population growth. 10 3. Dispersion Dispersion describes the geographic distribution, or clustering, of the individuals in a population. 4. Sex Distribution Sex distribution is used to describe the quantity of individuals in a population who are male and female. In population dynamics, counting individuals of each sex are in a population can help determine the maximum potential birth rate. By extrapolating the number of breeding females, population growth can be predicted. 5. Age Distribution Age distribution is used to describe the quantity of individuals of a population within a specific age group, as sorted in classes, or cohorts. A cohort is a group of individuals in a population born within the same time frame. Population dynamics uses cohorts to observe whether a population is young or old, booming or busting. 11 Young People in Bangladesh (10-24 Years) in Bangladesh (in Million) Source: Bangladesh Population Census, UN Population Projection 12  Korail Slum in Dhaka 13 Source: Peter Kim Streatfield, 2008  Demographic Transition Model (DTM) ✓ The Demographic Transition Model was initially proposed in 1929 by American demographer Warren Thompson. The DTM’s function is to demonstrate the natural sequence of population change over time, depending on development and modernization. ✓ This can help geographers, and other scientists examine the causes and consequences of fertility, mortality, and natural increase rates. ✓ Though controversial, the DTM is used as the benchmark for forecasting human population growth regionally and globally. ✓ The DTM is effective in understanding the relationships between economic development and human population. ✓ This model has four stages: pre-industrial, urbanizing/industrializing, mature industrial, and post-industrial. 14 Stage 1 Stage 2 Stage 4 Stage 3 15 Stage 1: Low Growth Rate ❑ People have lived in the first stage of the Demographic Transition Model for most of human existence. ❑ In this first stage, Crude birth rates (CBRs) and Crude death rates (CDRs) fluctuated significantly over time because of living conditions, food output, environmental conditions, war, and disease. ❑ However, the natural increase of the world was pretty stable because the CBRs and CDRs were about equal. ❑ However, around 8,000 BC, the world’s population began to grow dramatically due to the first agricultural revolution. ❑ During this time, humans learn to domesticate plants and animals for personal use and became less reliant on hunting and gathering for sustenance. ❑ While this transition allowed for more stable food production and village populations to grow, War and disease prevented population growth from occurring on a global scale. 16 Stage 2: High Growth Rate ❑ In mid-1700s, global populations began to grow ten times faster than in the past for two reasons: The Industrial Revolution and increased wealth. ❑ The Industrial Revolution brought with it a variety of technological improvements in agricultural production and food supply. Increased wealth in Europe, and later North America, because of the Industrial Revolution, meant that more money and resources could be devoted to medicine, medical technology, water sanitation, and personal hygiene. Sewer systems installed in cities led to public health improvements. ❑ All of this dramatically caused CDRs to drop around the world. At first, CBRs stayed high as CDRs decreased; this caused populations to increase in Europe and North America. Over time, this would change. ❑ Africa, Asia, and Latin America moved into Stage 2 of the demographic transition model 200 years later for different reasons than their European and North American counterparts. The medicine created in Europe and North America was brought into these emerging nations, creating what is now called the medical revolution. 17 Stage 3: Moderate Growth Rate ❑ Today, Europe and North America have moved to Stage 3 of the demographic transition model. A nation moves from Stage 2 to Stage 3 when CBRs begin to drop while CDRs simultaneously remain low or even continue to fall. ❑ It should be noted that the natural rate of increase in nations within Stage 3 is moderate because CBRs are somewhat higher than CDRs. The United States, Canada, and countries in Europe entered this stage in the early 20th Century. Latin American nations entered this stage later in the century. ❑ Advances in technology and medicine cause a decrease in IMR and overall CDR during Stage 2. Social and economic changes bring about a reduction in CBR during Stage 3. Nations that begin to acquire wealth tend to have fewer children as they move away from rural-based development structures toward urban-based structures because more children survive, and the need for large families for agricultural work decreases. ❑ Additionally, women gain more legal rights and chose to enter the workforce, own property, and have fewer children as nations move into Stage 3. 18 Stage 4: Low Growth Rate ❑ A nation enters Stage 4 of the demographic transition model when CBRs equal to or become less than CDRs. When CBRs are equal to CDRs, a nation will experience zero population growth (ZPG). ❑ It should be noted that sometimes a nation could have a slightly higher CBR, but still experience ZPG. This occurs in many countries where girls do not live as long before they reach their childbearing years due to gender inequality. ❑ When a country enters Stage 4, the population ages, meanwhile fewer children are born. This creates an enormous pressure on the social safety net programs of a country as is tries to support older citizens who are no longer working and contributing to the economy. ❑ Most of Europe has entered Stage 4. The United States would be approaching this stage if it were not for migration into the country. 19 The 5th Stage of the Demographic Transition Model and Beyond ❑ The original DTM anticipates four stages of changing birth, death, and population growth rates. ❑ By stage 4, birth and death rates are equally low, and population growth stabilizes. Many demographers now suggest that a stage 5 follows the original 4 stages of the DTM. ❑ In stage 5, birth rates fall below death rates, and total population declines. Japan may be in this stage. ❑ If the DTM is meant to predict future population trends, then it does not serve a purpose for countries like Japan that are currently in the final stage. Stage 6 is hypothetical at this point, and even stage 5 isn’t completely agreed upon. 20 ❑ In summary, the demographic transition model is a model that helps human geographers understand and predict the demographics of individual nations. ❑ In essence, the demographic transition model argues for economic development to help reduce crude death rates. It is assumed that access to medicines, safe drinking water and sanitation, and information about disease, will help improve human health. ❑ In Stage 1, CBR and CDR are very high and thus produce a low natural increase. In Stage 2, a nation’s CBR stays relatively high, but the CDR drops dramatically, producing the highest growth in population. In Stage 3, CDR stays low; however, changes in social customs and economic conditions result in a moderately low CBR. ❑ Finally, nations in Stage 4 have nearly equal CBR and CDR (sometimes higher CDR), creating a drop in natural increase. ❑ While the demographic transition model still is a useful tool to predict trends, like all models, it has some limitations. 21  Criticism ❑ A primary criticism of demographic transition theory is that it may oversimplify and generalize the complex process of population change. ❑ The DTM is based on data from Western Europe and the U.S. leading up to the 1920s. In the modern world, with globalization, climate change, and a diverse range of cultural, political, and social influences flowing across country borders, the DTM can be less accurate to describe and predict actual demographic trends in various places around the world. ❑ It is suggested that, as the less economically developed countries (LEDCs) are not following the same pattern of development, they do not fit the DTM. ❑ Because the DTM is only a model, it cannot necessarily predict the future, but it does suggest an underdeveloped country's future birth and death rates, together with the total population size. Most particularly, of course, the DTM makes no comment on change in population due to migration. ❑ The model assumes that all countries must follow the stages sequentially which is not always true. 22  Criticisms Cont…. ❑ Newly Industrialised countries such as Malaysia and South Korea are advancing much faster than the early industailsed countries did causing the timescale of the model to be shortened. ❑ In less developed countries the advancement is and has been slow. Most LEDCs are still stuck in stage 2. ❑ The sharp (rapid) decline in birth rate in stage 3 is not always as fast. Most countries (except where policies to decrease birth rate) show a slow decline in birth rate. ❑ The DTM does not take into account large-scale global challenges like pandemics or climate change. These events disrupt industrialization and have critical impacts on birth, death, and migration trends. Countries may find themselves moving backwards to an earlier stage of the model, or shifting forwards faster than they might otherwise progress. 23