Various studies in recent years have indicated that the so-called "prosperous age" 盛世 of the mid-Qing of the 18th century was brought to a close by the ecological limits of exploitation. In order to explore this issue historically, it is necessary to clarify the perceptions of the people at the time of the ecological limits of exploitation. The responses to the ecological limits of exploitation during the Qing dynasty were shaped by three factors pulling in different directions, i.e., the prohibition of access to natural resources, fengjin 封禁, the promotion of planned development, kaicai 開採, and the deregulation of the prohibition to the access to natural resources, chijin 馳禁. I have attempted to clarify the perceptual systems that upheld arguments for each response and their relations to the methods of administrative policy. The Tongtangshan 銅塘山 dealt with in this article was called a "prohibited mountain, " because access to its resources was prohibited during the Ming dynasty in order to preserve public peace. The policy of prohibiting development was carried on during the Qing. When the rule of emperor Qianlong commenced, even the officials of the central government became conscious of the rise in the cost of food, and the planned development of natural resources began to be advocated. Receiving these demands from the central government, Chen Hongmou 陳弘謀, who was known as a capable bureaucrat, submitted a plan for the development of Tongtangshan to the throne. He deciphered the complex geography of the mountainous region and proposed the cultivation of crops suited to each environment. The crux of Chen's development plan was to limit those who were to reclaim the land to local residents. His aim was to transform the mountainous land into sustainable property, heng-ye 恆業. Within Chen Hongmou's argument for deregulation, his writings on the mountainous areas are quite detailed. He pointed out that it was possible to develop the land according to the character of the terrain and to cultivate crops, and that much wealth could be created by choosing crops that could be introduced under mountainous conditions. Chen's argument had been supported by the methods of administration built up while he served as the provincial governor, xunfu 巡撫, of Jiangxi. He determined regional administrative policy after receiving reports of investigations of local conditions and maps that he had commissioned by the magistrates of the localities that were under his jurisdiction. The administrative methods developed in the administration of Jiangxi were fully deployed in Shaanxi，his next assignment. By comparing the categories in the reports issued shortly after his appointment to Jiangxi and those after taking office in Shaanxi, one sees that he had deepened his awareness of the development of mountainous regions while ruling in Jiangxi. It is clear, for example, that he had come to grasp the vegetation of mountainous regions and had become intensely aware of the necessity of its link to land rights. The policies that Chen issued in regard to planned development were not the traditional agronomism grounded Confucian thought. They were intended to solve the "food" problem by providing the people the power to buy and sell land in order to promote commercial activity. The development of mountainous lands was not simply aimed at increasing the volume of arable land; it was also intended to put the various resources of the forests to use in establishingindustry. The argument that Chen Hongmou advanced for planned development was, nevertheless, never put into practice. A summary of the dangers as they would have been construed by local officials in regard to the development of the mountainous regions would probably include the following. In developing mountainous regions, local financing would prove inadequate, and it would be necessary for commercial capital from outside the region to provide funding. In order to seek profit beyond a fixed level, commerc