Have an older Monkey Tree (Monkey Puzzle Tree?) approximately 30 feet high with 20 foot base spread. Over the past year limbs started turning brown and dying from the base and working slowly up toward the top but presently stopped leaving only top third green. Info found on Google/Wikipedia showed pictures of very tall mature trees in South America with only the top third with limbs, the bottom 2/3rds or more bare; limbs stripped or having fallen off. Appears to be growing wild and not part of a mancured estate. Shorter trees were pictured separately having full green limbs to ground as ours was. Is this then normal? Could another large evergreen about 40 feet away be interfering with its roots? Can anything be done? If tree was poisoned, how would one know?