Exponential Growth

• When a species does not have any limitations brought about by food, predators or disease, that species will experience exponential growth. The species grows purely based on the birth rate of the organism. Growth can accelerate very rapidly as offspring reach reproductive age, creating a continuous multiplier effect. This can result in overcrowding, which in turn causes the organisms to consume too many resources. If they consume plants or animals faster than those food sources can reproduce, the rapidly growing species can experience mass die-offs as they suddenly do not have any food. These die-offs can either wipe out the entire species or simply bring the species down to a very low level.
  
  

Logistics Growth

• When a species has predators, disease or limited food that can prevent exponential growth, the species instead experiences logistic growth as the environment in which the species resides eventually reaches a carrying capacity. At this point, the limiting factors will kill off any excess population.
  
  

Physical Population

• Physical population growth models are designed to help people understand complex changes in population. Researchers take statistics and transform them into graphical representations. For example, researchers might produce a map that color-codes the planet based on population densities, with the most populated areas having certain colors and less populated areas having other colors.
  
  

Mathematical Growth Model

• Mathematical population growth models help researchers predict how much a particular population will grow over a particular period of time. Various factors tend to consistently influence population growth. For example, a particular plant species might be influenced by the weather. Human population growth is often influenced by the quality of life. Some mathematical equations are too difficult for humans to figure out, but fortunately computer simulation programs can take very complex variables and use these variables to perform calculations that can effectively depict population growth.
  
  

Stochastic Models

• Models are either deterministic or stochastic. Stochastic models examine population growth in which there are variations, such as when the population is influenced by weather. Deterministic population growth models do not take into consideration variables and are useful when the population is not influenced by any changing variables.