When advanced farming practices allowed farmers to grow more food than they needed for their families Figure below , some people were then able to do other types of work, such as crafts or shop keeping.
Farming increasingly depended on machines. Rows of a single crop and heavy machinery are normal sights on modern-day farms. The next major stage in the growth of the human population was the Industrial Revolution , which started in the late s Figure below.
This major historical event marks when products were first mass produced and when fossil fuels were first widely used for power. Early in the Industrial Revolution, large numbers of people who had been freed from food production were available to work in factories.
Every major advance in agriculture has allowed global population to increase. Irrigation, the ability to clear large swaths of land for farming efficiently, and the development of farm machines powered by fossil fuels allowed people to grow more food and transport it to where it was needed.
The Green Revolution has allowed the addition of billions of people to the population in the past few decades. The Green Revolution has improved agricultural productivity by:. The Green Revolution has increased the productivity of farms immensely. A century ago, a single farmer produced enough food for 2.
The Green Revolution is credited for feeding 1 billion people that would not otherwise have been able to live. What is the flip side of this? The flip side is that for the population to continue to grow, more advances in agriculture and an ever increasing supply of water will be needed.
The question is, even though we have increased the carrying capacity of the planet, have we now exceeded it Figure below? Are humans on Earth experiencing overpopulation? There is not yet an answer to that question, but there are many different opinions. In the eighteenth century, Thomas Malthus predicted that human population would continue to grow until we had exhausted our resources.
At that point, humans would become victims of famine, disease, or war. This has not happened, at least not yet. Some scientists think that the carrying capacity of the planet is about 1 billion people, not the almost 7 billion people we have today. The limiting factors have changed as our intelligence has allowed us to expand our population.
Can we continue to do this indefinitely into the future? The Green Revolution has brought enormous impacts to the planet. Natural landscapes have been altered to create farmland and cities. Already, half of the ice-free lands have been converted to human uses Figure below.
Forests and other landscapes have been cleared for farming or urban areas. Rivers have been dammed and the water is transported by canals for irrigation and domestic uses. Ecologically sensitive areas have been altered: wetlands are now drained and coastlines are developed. Similar to the biomes map in the Climate chapter, this map shows human ecosystems. Modern agricultural practices produce a lot of pollution Figure below.
Some pesticides are toxic. Dead zones grow as fertilizers drain off farmland and introduce nutrients into lakes and coastal areas. Farm machines and vehicles used to transport crops produce air pollutants. Pollutants enter the air, water, or are spilled onto the land. Moreover, many types of pollution easily move between air, water, and land. As a result, no location or organism — not even polar bears in the remote Arctic — is free from pollution. The increased numbers of people have other impacts on the planet.
Humans do not just need food. They also need clean water, secure shelter, and a safe place for their wastes. These needs are met to different degrees in different nations and among different socioeconomic classes of people. For example, about 1. The percentage of people in the world that live in abject poverty is decreasing somewhat globally, but increasing in some regions, such as Sub-Saharan Africa. A large percentage of people expect much more than to have their basic needs met.
For about one-quarter of people there is an abundance of food, plenty of water, and a secure home. Introduction to Population Demographics. Population Dynamics of Mutualism. Population Ecology Introduction. Population Limiting Factors. The Breeder's Equation. Global Atmospheric Change and Animal Populations. Semelparity and Iteroparity. Causes and Consequences of Dispersal in Plants and Animals.
Disease Ecology. Survivorship Curves. The Population Dynamics of Vector-borne Diseases. Population Limiting Factors By: W. Citation: Edwards, W. Nature Education Knowledge 3 10 Aa Aa Aa. Introduction to Population Growth Limitation. Populations Cannot Grow Without Limit. Density Dependant Limitation. Density Independent Limitation. A Phosphorus load decreased toward the target annual load 11 ktonnes. References and Recommended Reading Blaustein, A.
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Other Topic Rooms Ecology. Student Voices. Creature Cast. Simply Science. Green Screen. Green Science. Bio 2. Carrying Capacity is the total frequency of individuals within a community a habitat can sustain. Limiting Factors are biotic or abiotic factors which limit the carrying capacity. For example, within a population of foxes, there is enough space and water for 20 individuals. However, the population of rabbits has decreased and now can only sustain 15 individual foxes. In this circumstance, the limiting factor is the available food rabbits for the foxes, and thus the carrying capacity is 15 foxes.
How are carrying capacity and limiting factors related? What letter is used to refer to the shape of an exponential growth curve? What are the four density-dependent limiting factors? Which is a density independent factor?
Which of the following is an example of density-independent factor? What is the definition of a density-dependent factor? Is exponential growth density-dependent? Previous Article What is the ultimate goal of the United Nations? Next Article Where can I ask a question and get a quick answer?
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