In a certain year, the number of tourists in the five cities of Jicheng, Yucheng, Xucheng, Yancheng, and Qingcheng was more than in previous years. These cities have different geographical environments and tourism resources: precipitous mountains, dense forests, flat grasslands, vast seas and secluded river valleys. The number of tourists who visited the above five cities in that year were: 120,000, 270,000, 320,000, 440,000, and 650,000. It is known that: (1) The cities in the grasslands are the least attractive to tourists. The most popular tourist destination is the forest. (2) Xucheng is in the mountains and the transportation is not convenient, but many people come here to travel. (3) Jicheng has more tourists than Yancheng. (4) The number of tourists in Yancheng is 440,000, a record high. (5) There are more tourists to Yucheng than Qingcheng, but not as many as Xucheng.
Based on the above conditions, dense forests can be introduced as the characteristic tourism resources of Qingcheng.