The answer is:
How to solve? Notice first that there are:
If we then:
At this point, now that we know the encoding, we can see that there was another clue in the puzzle that I inadvertently skipped past altogether! Notice that:
This solution also explains the title, since:
Thinking about this problem in reverse is easier, i.e. think about the trees that need to remain. Find the fewest number of trees that can be arranged in five lines with 4 trees in each line. To minimise that number, we need as many trees as possible to do double duty by being part of multiple lines.
TL;DR: The answer to this puzzle is:
Explanation: Note first of all that the puzzle itself bears a resemblance to:
Note next that:
Looking familiar? Of course! Because:
So if we next:
What can we do with this now? Well, how about trying to interpret this using:
By doing so, we find that:
Which (as stated at the very top) translates to:
Notice finally ...
Wrap-up: The Making Of A Twisted Enigma
This is not a solution to the puzzle, but provides notes from its poser. This type of answer has been approved by the community.
Caution: This post may contain spoilers.
Logistical steps and resources
The detailed things I was looking for in a solution were:
That's all the ...