1. in what type of ecosystem can monkeys population be found?

2. how might the monkey population suddenly increase? how might this affect the ecosystem?

3. what might happen to the ecosystem if the monkeys population were removed?

I, thank you for posting your question here at .

Here are the answers to your questions:

1. Monkeys live in tropical rainforest ecosystems.
2. Animals should be left alone in nature to take part in the balance of the ecosystem, and not upset it. A sudden increase of monkey population, probably due to destruction of rainforests which lead to lesser area of living for them. 
3. Monkeys take a huge part in seed dispersal among flesh fruit plants. Without them, it will greatly affect the conservation of the forests.

You can find results and justify them? you can test your hypothesis