Introduction to the Pinus sylvestris forest (Green National Gate): Located in the northwest of Aershan City, near the border between China and Mongolia, it is the largest preserved Pinus sylvestris forest belt in my country, with dense trees and neat forests. On the forest road leading from the Halaha River to Dashan Mine, there are two King Pinus sylvestris trees that require three hands to embrace. Even the original giant pine trees that are limited to this day stand on both sides of the road in the shape of a door. The pine branches The connection is like a corridor building with a roof covered with green curtains, so it is known as the "door pine".