Assessment indicators system of forest ecosystem health based on the harmful disturbance
基于有害干扰的森林生态系统健康评价指标体系的构建

Healthy forests are closely related to global ecological stability and sustainable development of human society. It is important to study forest ecosystem health including developing theories related to forest health and exploring various assessment methods. Reasonable methods lead to accurate assessments of forest ecosystem health. The definition of forest health is controversial. The concept of health is well understood as applied to humans but the human concept of health may not be appropriate for ecosystems. The difficulties of defining the optimal conditions for ecosystem health have led to a lack of universally accepted indicators to measure ecosystem health. In this paper, a healthy forest ecosystem is defined as a system having good mechanisms for self-regulation, such as beneficial mechanisms that allow an ecosystem to react to external harmful disturbances. Positive ecosystem responses to negative changes keep forest ecosystems intact, stable and sustainable. With this concept of forest ecosystem health in mind, we can discuss assessment methods which can be used to monitor forest ecosystem health. Several forest ecosystem health assessment systems already exist. For example, ecosystem health can be assessed using measures of resilience, vigor and organization. Today, most assessment systems are based on this concept. Based on the concept of forest ecosystem health presented above, a new approach is proposed, which considers four external harmful disturbances: forest fire, forest pest species, air pollution and human-caused disturbances. This method is designed to build assessment indicator systems which can be used to monitor and evaluate forest ecosystem health. It also considers beneficial disturbances in this assessment indicator system. This method includes an analysis of forest fire disturbance, which causes severe damage to forest ecosystems, followed by eight other indicators of forest health including average precipitation, average temperature, proportion of flammable species, crown density, altitude, slope gradient, slope direction and distance between the forest and the nearest road. Disturbance caused by forest pests can also be measured. These include disturbances caused by forest animals, such as rat and rabbit damage, as well as indicators like forest diseases and forest pests, the degree of damage and rate of infection in host trees. Air pollution disturbance can be measure by studying leaf damage as well as soil and contamination analysis. The study of harmful human-caused disturbances includes measurement of forest management techniques such as timber harvest and management of undergrowth vegetation. Measurements of forest ecosystem stability include measurements of biological diversity, forest community structure and measurements documenting how closely a forest is to natural conditions, with natural conditions defined as being free of human-caused disturbances. These types of measurements have been used frequently to