Population Growth


***The following notes are taken directly from –Population Growth Chapter 11 of  Ecology:  Concepts and Applications, 5th edition, by Manuel C. Molles Jr.***

*Given suitable environmental conditions, aquatic and terrestrial populations will manifest their great capacity for growth.

*Sizes of populations fluctuate in terrestrial, as well as aquatic environments.

*In the presence of abundant resources, populations can grow at geometric or exponential rates.

*Geometric population growth is growth by any population.

*Exponential population growth is growth by a population in which the reproduction is nonpulsed, and a continual process.n with pulsed reproduction; successive generations differing in size by a constant ratio.

*The per capita rate of increase attained by a species under ideal environmental conditions–where birth rates, death rates, and age structure are constant is called the intrinsic rate of increase.

*As resources are depleted, populaton growth rate slows and eventually stops; this is known as logistic population growth.

*The environment limits population growth by changing birth and death rates.

*Biotic factors which effect population density are called density-dependent factors. –Examples include desease and predation.

*Abiotic factors can exert their influences independently of populatoin density and so are called density-independent factors.  –Examples include flooding and extreme weather conditions.

*Most of the significant environmental problems on earth today trace their origins to the effects of the human population on the environment.

*The human species is virtually everywhere on the planet; we occupy every continent.

*Within continents, human populations attain their highest densities in eastern, southeastern, and southern Asia.

*In 2008, 60.6% of the global population, or about 4 billion people, were concentrated in Asia.

*While the populatoins of many developed countries are either stable or declining, those of most developing countries are growing, and the trend for the entire global populatoin is continued growth.


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