Why did the new england colonies use slaves?

first of all if we can just put ourselves into what america must of looked like when the first settlers came to America... Unlike the new settlers the Indians did not normally change the land "drastically".. they adapted themselves to the land....

However, the new settlers wanted to cut down trees to make fields, cities, homes, shops, etc etc. Yet, their really wasn't enough of them to do all that they needed to do... so they had to look to for cheap labor.. at first they used indentured servants .. these are slaves that came from Europe and normally put themselves into servitude so that hey could come to the New World... and would become free men in 5 years. However, it was very expensive to get new indentured servants every few years... so later blacks were placed into servitude... which also in the beginning was not life long servitude... it wasn't until slavery entered into the southern stated did Africa slaves became it life long punishment.