The tree line can be defined as the imaginary line above which the pressure and temperature conditions are not suitable for the trees to grow. As a result of the decreased temperature, pressure and lack of moisture, the trees stop growing at the tree line. This results in the formation of forest with a canopy (closed).
This closed canopy is representative of the end of the height bearing the suitable climatic and atmospheric conditions required for the growth of trees and plants.
The trees do not grow beyond the tree line because of the unsuitable temperature and pressure. The trees at the tree line form a closed canopy.
