If you're really dead set on the land never being developed, you could always donate it to the government with the proviso that it remain parkland, or donate it

If you're really dead set on the land never being developed, you could always donate it to the government with the proviso that it remain parkland, or donate it to a non-profit land trust. You could even add a life tenancy for yourself to the deal -- you'd probably get out of paying any taxes at all.