as we have learned every environment has a maximum number of individuals it can sustain called the caring capacity it's important to understand the use of the word sustain because populations can grow over the caring capacity but the environment will not be able to support these large numbers over time because the resources will be used up a lot faster than they can be renewed again so another way to think of caring capacity is the point at which the rate of resource use is equal to Resource renewal so carrying capacities aren't set because it is tied to Resource availability so any factors that change resource Supply will cause a shift to the carrying capacity and variables that limit resources and thus limit population growth are called limiting factors and these are discussed in more detail in the next video here's a basic example of how the carrying capacity might change a population of deer is happily living in an with plenty of resources let's oversimplify and say that all they need is grass and they have a lot of it so they're happy and so this population grows exponentially so it starts down here it grows kind of slow but then there's a lot of grass and they rapidly reproduce and it shoots up like that at first it's all good but sooner or later this population starts to grow out of control because the birth rate is a lot higher than the death rate so it it will keep growing exponentially and grow beyond the carrying capacity and when it does that it is said to have overshot so the population of deer is overshooting and there's still enough grass in the beginning but very soon the grass begins to thin from overg grazing and a lot of trampling and that's when it becomes a really serious problem because now as the grass gets thinner and thinner food competition is greater and as deer more and more deer can't find food they start to die from competition and from starvation so the deer population begins to drop but it doesn't just return back to the original caring capacity level because now there's a new caring capacity and it plummets down to this new caring capacity and starts to fluctuate around here why is there this new caring capacity that's because there's so much damage that has been done to the grass by the deer from overg grazing that there is not the same amount of grass anymore as before so this caring capacity is rendered Obsolete and there's a new caring capacity to reflect the new amount of grass over time the grass can rejuvenate and the carrying capacity will be restored however this does take a lot of time and during that time the deer population is best to just stay down here and fluctuate around this new caring capacity otherwise it risks the consequences of overshooting once again