In some alternate universe people have to add new rungs to the tree house ladder every year. "No trespassing" signs and woodland trail markers are posted exclusively on dedicated sign posts. Pruning ground level branches on a young tree will greatly impact the tree crown as it matures and people frequently do so for both practical and aesthetic reasons. Species of fungi evolve to go to spore every 50 years so spores fall on saplings, remain dormant as the sapling grows tall and go to spore again after being vaulted to great height as that sapling grew. By doing so their spores spread over great distance.
As per tradition, the treehouse is built for each child at ground level after they take their first steps and youngsters jump from it to the ground at each birthday celebration. Each year they must learn to fall safely from increasing heights until their 17th birthday when they are considered to enter adulthood. It is also traditional to carefully water and fertilize the tree's of your siblings and friends so they have the greatest opportunity for challenge and self betterment. Upon reaching your 60th birthday tradition dictates that you climb to your platform for the last time and jump to your death.
Those who's trees died or those who are too weak to climb to the platform are doomed to live into their old age and die of natural causes in shame and exile as suicide by any other method is unacceptable. Those who's trees did not reach necessary height are doomed to live out their lives in shame and exile while bearing the injuries of their fall. This is most often the fate of those who did not foster friendship in youth. Communities of the exiled elderly have no communication with the outside world but whispered rumors sometimes suggest that they live quite well on the 10% GDP rations they are provided.
Some who fear death enough will risk life imprisonment by poisoning their own trees to escape the death ritual. These cowards, if caught and sentenced, receive no prison rations following their 60th birthday.