Carrying Capacity TEACHER COPY Organisms need certain resources to survive. Water Food Space/ shelter Resources are LIMITED Cannot sustain growing populations indefinitely (forever) Limiting factors: Environmental factors that prevent/limit populations from growing any larger LIMITING FACTORS Can be food, water, space, number of predators, disease, pollution, hunting Example! For example, 10 rabbits may live in a habitat that has enough water, cover and space to support 20 rabbits, but if there is only enough food for ten rabbits, the population will not grow any larger. In this example, food is the limiting factor. Limiting factors (Amount of resources)determine the carrying capacity Carrying capacity: maximum numbers of organisms an area can support without depleting the resources of that area What do we notice ? Can overshoot (exceed) the carrying capacity but only for a short period of time The population will then begin to decrease due to the limiting factors Starvation, disease, pollution, hunting, lack of water or space Exceeding the CC will use resources faster than they can be replenished Exceeding the carrying capacity can permanently damage the habitat this lowers the carrying capacity for the habitat (fewer organisms can survive there compared to before) St. Paul & St. Matthew Island Human Carrying Capacity Unknown but estimating it to be around 9-10 billion people. Currently, were around 7 billion. Human Growth Limited Resources on Earth Little available freshwater Much of our crops go to feeding livestock (inefficient energy transfer) Space Things to Think About People in different areas use different amounts of resources (1 st world vs 3 rd countries) Technology allows us to develop new food and water supply methods (although these methods often destroy habitats). Increased populations generate more potential geniuses who can bring new ideas to the table. Spreading education and empowerment actually lowers fertility rates. Future Technologies Chinas Solution : One Child Policy- 1980s Purpose: Reduce Chinas rapidly growing population Limited every family to having one child Provided incentives (money) for sterilization & made contraceptives widely available Over time, those who did not comply were sometimes the subject of forced abortions and sterilization Problems Skewed the sex ratio: More males then females Families did not want females (cannot inherit the family property Caused an increase in abortions of female fetuses, abandonment of female children and even infanticide Now the population is struggling because there are more elderly members with few younger members to take care of them Second or third born children were hidden from authorities difficulty finding employment or education Have recently announced that the program will end in 2016: Families will be allowed to have two children