Limiting Factors in Ecosystems * What are limiting factors? • An ecosystem only has a certain amount of food, water, space and shelter to support a certain number of organisms. • These are called limiting factors, or a conditions or resources that keep a population at a certain size. • Relationships between numbers of organisms and the resources available in an ecosystem is described as the balance of nature. • * What happens if there is a change? • If any limiting factors change, animal and plant populations may also change. • Some changes may cause a population to decrease others may cause a population to increase. Examples: • Giant Pandas are decreasing due to the loss of their habitat (limiting factor = SPACE) • Snow Leopard – decreasing due to loss of habitat and prey (limiting factors = SPACE and FOOD) • * Increases in Populations • Increase in populations may result in overcrowding. • May grow too large for environment to support. Examples: Plants = Animal Populations Population of Predators = Population of Prey Population of Prey = Population of __predators * Decreases in Population Sometimes limiting factors cause decreases in population. Examples: • Water decreases , then animals needing water decrease then animals eating those animals will decrease • If trees are cut down or die because of disease, then animals needing those trees will die. • If organisms no longer have enough space to survive, then they move or die. This is influenced by human impact or natural hazards. Shelter *Natural events (fire) *Human invasion Food *Competition *Predators *Disease/hunting *Decrease of prey LIMITING FACTORS that impact population sizes Space *Overcrowding *Changes in resources Water *Climate *weather changes *Drought Think About It…. A) We know that in the grasslands of Africa, wildebeests graze on the grasses but they must watch for predators like cheetahs and lions. Suppose there were no predators for the wildebeests. What would most likely happen to this population? B) If many trees in a rainforest were cut down, what would happen to the population of koala bears living in them? What would in turn happen to the population of jaguars that rely on the koala bears as a source of food? C) Drought strikes a desert. How would this limiting factor impact the small rodents living there? Would this have an impact on coyotes? Why or why not?