I thought that the forest was well-trimmed by the municipality of Sapporo but basically, the forest on the hillside of Mt. Maruyama is wild forest.
That ma be why such artistic shape was made up.
The concept of the shape seemed to be "Freedom". They seemed to have been expanding their branches to get enouhg sunshine on the leaves, competing each other.
They seemed to be performing freely under the blue sky. They were filled with vim and vigor. Needless to say, the trees will wear green leaves like flame in a month. Yes, it is the real art of the nature.