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Populations and the Use of Natural Resources. Chapter 26.1. Exponential Growth - occurs when the individuals in a population reproduce at a constant rate under ideal conditions with unlimited resources. Graph of population over time shows characteristic “J” curve. Carrying Capacity
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Populations and the Use of Natural Resources Chapter 26.1
Exponential Growth - occurs when the individuals in a population reproduce at a constant rate under ideal conditions with unlimited resources. Graph of population over time shows characteristic “J” curve.
Carrying Capacity - the largest number of individuals that a given environment can support. - as resources become less available the birth rate decreases and/or the death rate increases. Population growth of Bacteria Growth rate equals zero. AKA – Logistic Growth Graph of population over time shows characteristic “S” curve.
Limiting Factors - factors that cause population growth to decrease. Common Limiting Factors Density-dependent factor Density-independent factor competition Human disturbances predation Drought & climate extremes Parasitism & disease
Density - Dependent Limiting Factors 1. Competition - organisms compete for food, water, space and other essentials. 2. Predation - predators can prevent populations from growing too large. 3. Parasitism & Disease - can keep population growth in check by increasing death rate.
Density - Independent Factors 1. Drought - long dry periods. 2. Natural disasters - floods, forest fires, volcanic eruptions, landslides, tsunami, etc. 3. Human activities - damming rivers, de-forestation, pollution, construction projects, etc.