Minimum amount of saplings left at /warp farm

I believe there should be some minimum amount of saplings left at /warp farm. Just before writing this, I went to there to farm some dark oak. I found 5 dark oak saplings. This is too little for anything useful. I've seen the signs of leaving saplings and unwanted items behind but it doesn't seem like that is enough. I suggest making it mandatory to leave behind some amount of saplings, of course more than 5, seeing as encouraging is simply not enough.

- Rassi_