While many people would think that slash and burn have a negative feedback, controlled slash and burn have a positive feedback on the earth, for example:
1) Nutrients: Nutrients that were located in the plant & animals (which becomes remains) become ashes, which hold high amount of nutrients, allowing plants to grow quickly
2) Clearing: Controlled slash and burn can help clear large amounts of land in a relatively short amount of time, allowing for the creation of farms and cities.
hope this helps, Senpai