Moss Tea
Karl looked at how the moss grew, down the top of the logs, and the one side, but not the bottom or the other side. If he wanted it to keep growing, he had to leave enough in the right spots that it didn't ruin the moss bed too badly.
So, he cut diagonal stripes across the log, removing thin strips amounting to half of the moss on each log, while leaving the rest securely attached. That should grow back over, he assumed, and then it could be harvested again.
"Where did you learn that?" Dana asked as Karl cut the careful strips from the moss.
"I'm actually just guessing here by the way that it grows. But I'm only taking half, and leaving the other half in the way that looks like it will grow back the fastest. Moss spreads from the edges, you see, and only grows well on the sunny side. So, if I only take half and leave as many good edges as possible, then it looks like this.