There are 5 factors that can limit or affect the production of an ecosystem.
Living Space
As a population grows they need more room, without space they're forced to either move or slow down reproduction
Resources
The more animals needing to be fed the more resources that need to be produced, if they aren't produced some will go hungry
Temperature/Weather
Bad weather can be really hard to put up with, some animals aren't able to survive in freezing or hot temperatures
Disease
Diseases especially deadly ones can cause an impact on a population.
Predator/Prey relationships
The more a population grows the more competition there is .and whoever is the strongest will come out on top.