The concepts of ecological vulnerability and vicious circle were often used to describe the characteristic of ecosystem and human-land interaction respectively in past research works. The essence of ecological vulnerability and vicious circle of human-land relationship is still undefined in light of their ecological attribute and dynamic interaction process with regarding to human interference. In this paper, agro-pastoral interweaving belt in north China was adopted as a case object to analyze the transition between cultivation and grazing activity and associated land degradation. The result shows that the invasion of cultivation, positive feedback mechanism between cultivation and grazing and soaring population resulting from marginal agriculture should be responsible for the formation of vicious circle.
The new concept of ecological pitfall was suggested to compare and analyze the interaction process between human exploitation and ecosystem. Ecological pitfall is primarily defined as phenomenon and process that specific ecological attributes resonate with corresponding interference and in turn results in self-driving mechanism of human-land dynamics, leading to continuous degradation and attenuation of ecosystem. The concept of ecological pitfall implicates as follows (1) ecological vulnerability is a relative concept, i.e. relative to interference from human’s exploitation of natural resources. It is meaningless without considering outside interference. (2) the process of ecological pitfall mostly start from human’s exploitation of nature sources and then result in continuous degradation of ecosystem due to its self-driving mechanism. (3) chain reaction is main characteristic of ecological pitfall and self-driving mechanism is the function of resonance and coupling action of inertia of land use manner, irreversibility of human population in short period and long time demand for ecological rehabilitation. (4) the ecological pitfall is a scale-related concept, and interference of small scale sometime comprise normal structural component of large scale
The essence of ecological pitfall is a path-dependence of human exploiting nature resources and a low level lock-in state of human-land relationship. The new concept would contribute to management of ecosystem, ecological building and rehabilitation. From the point of this view, it is prerequisite to break down the ecological pitfall before we take action to combat desertification. In order to break down ecological pitfall, external impetus is necessary to pull out from pitfall while regulating its internal structure, involving capital investment from outside, export of population pressure, technology assistance and policy privilege. Here, with respect to the agro-pastoral interweaving belt, some suggestions were put forward on ecological rebuilding in agro-pastoral interweaving belt of north China.