Why are you attaching a stick to that tree?
Jonathan and I spent a day and biked over to the high bridge dog park. During the arbor day celebration we planted a bunch of trees there, and went to check up on how they were doing. As part of the checkup, we removed the metal conduit poles that had been attached to some of the trees. Someone asked what the poles did, and there are a lot of answers, dependent on how old the tree is and where it is in development.
For the high bridge trees, the poles are there to act as a support while the trees develop enough roots to support their own weight. When transplanting trees they need support while developing enough roots to support themselves. Once the tree has had some time to establish itself, the pole should be removed. The conduit helps the tree stand up, but also takes away the effects of the wind on the tree. When a tree blows in the wind, the force against it tells the tree to grow stronger. This is called thigmotropism, the growth response as a result of force, and is important for tree development. Stakes also can rub into a tree repeatedly, causing lacerations in the bark.
In other circumstances, staking a tree is used to train a leader. This is the branch that is headed most vigorously towards the sky. The leader is trained to keep the tree going upwards. Trees naturally have no intention of shading bikers, picnickers and others. They are most concerned with growing just tall enough and far enough out to grow and spread their seeds. In a forest they have the job of getting through the canopy, but in an open field or park, a tree has no reason to grow taller than around 6 feet. This is why through pruning, staking, and a lot of other work, shade trees grow much taller than they naturally would.