No, weeds do not grow into trees. Weeds are typically smaller plants that grow quickly in unwanted areas, while trees are larger, woody plants that grow over a longer period of time.
You leave the process to the nature. Just plant trees on that
soil. If the trees will not grow, you select herbs or even weeds.
In long run, any soil will be converted to a fertile soil.
producers are plants. so in a woodland, the primary producer
would be the trees, followed by shrubs, weeds, flowers, etc.
Anything that would grow in a woodland