it is allowed in fact i plan on introducing a diverse series of rental plans this week.
keep an eye out for Elemental Estates if you are interested in renting

1 other question is have you tried reproducing this in a different sim. find a sandbox and try and see if its region specific. or if you have extras just drop a new sim out and try it there.

is your rezzer rezzing temporary trees or permanent ones? if they are sprouting trees out at a fast pace one would imagine the prim counts would get very high quickly. the oldest of said temporary trees would then be the 1st to disappear after you relog into the sim as I'm sure every time the sim go...