Forestry course: community forests group work

I think this case might be the least learner-centered and also the most tiring for the instructor as he himself acknowledges it from the very beginning. One first and obvious thing that comes to mind is to let students propose the topic the will work themselves rather than handing them out a pre-made list. The way in which the instructor organizes the groups is not clear but also sounds very burdensome. I wonder which other better ways to organize students to work in group exist. And thank you Vincent for including the questions in your answer, that was very helpful! ;-)