HELP! I have to write a paper on ecology.....?

I won't write your paper for you but here are some ideas.

Start by describing a selected environment; say a 100 acre meadow surrounded by a mixed hardwood and evergreen forest. There has been no human activity in the area for thousands of years. The plants and animal have reached an equilibrium and little changes from year to year.

When man arrives he changes the environment. He cuts down trees to build shelter and use for fuel. He tills the soil in the meadow to grow food. and he harvest food from plants and kill animals for food.

As time passes and life is good the population increases. Soon man the invader is man who wants it back the way he found it. There are too many people for peace and quiet. Its not as easy to find native plants and animals to eat. At times the water in the creek taste funny and is kind of murky.

Man then gets with his neighbors and talks them into creating government and rules for people moving into his neighborhood. By planning for the amount and type of development that is allowed they hope to keep their little piece of earth undamaged.

There are many ways of expanding this story to emphasize each of the points in your question.

The numbers of deer available within walking distance from the cabin changes as the population changes. Do the same for the amount of edible plants.

The water flow in the creek could begin to dry up as more people use it for agriculture. The deer population could change not only due to humting pressure but also because the forage is disapearing and farmers are fencing them from their crops. The deer population could also increase if the predators are eliminated to protect the public.

By weaving this all together, you can show how human activities can have both a positive or a negative affect on the environment depending on how they plan and regulate their activities.

hope this helps

Well, I'll give you credit--at least you're honest! I've put a few links below which hopefully will be of some help.