Assessment indicators system of forest ecosystem health based on the disturbance in Wangqing forestry

Currently,the study of forest ecosystem health,a new and controversial research field within forestry and forest ecology,provides a scientific basis for forest protection.The study of forest ecosystem health also provides a significant practical service by suggesting ways to increase the level of sustainability in forest management although the definition of forest health remains 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 used to measure ecosystem health.Several forest ecosystem health assessment systems have already been developed.For example,ecosystem health can be assessed using measures of resilience,vigor and organization and most of today's assessment systems are based on these concepts.In this research,the forest ecosystem health of 60 sample plots in Wangqing Forest was investigated.A new assessment model of forest ecosystem health based on the disturbance,H = ∑B2W2-∑B1W1,is proposed and used in this study,where H represents a measure of ecosystem health and B 1,B 2,W 1 and W 2 represent harmful sources of disturbance,forest ecosystem stability,the weights of B 1 and B 2,respectively.Based on qualitative analysis of existing data,eight indices which were divided into two categories were selected as assessment indices of forest ecosystem health in Wangqing Forest.Several harmful sources of disturbance were considered including forest diseases,forest pest species,wildfires and human-caused disturbances.Measurements of forest ecosystem stability include measurements of biological diversity,forest community structure and measurements documenting how closely a forest study plot resembles expected natural forest conditions.These types of data have frequently been used to measure ecosystem complexity and health.Additionally,two types of analysis,the Analytic Hierarchy Process and coefficient of variation analysis,were used in combination with weighted evaluation indictors to objectively evaluate the forest health of the study plots.We propose a new forest ecosystem healthy assessment model and classification system.The 60 sample plots of Wangqing Forest were divided into four health risk categories: very healthy,healthy,fairly healthy and unhealthy.By calculating a composite value for forest health,the status of forest ecosystem health of individual Wangqing Forest plots was determined.As the results showed,6,13,23 and 18(or 10%,21.67%,38.33%,and 30% of all plots) plots were categorized as very healthy,healthy,fairly healthy,and unhealthy,respectively;the health indices for these four groups of plots were measured as 0.5 ≥ 0.2,0.2 ≥ 0.1,0 ≥ 0.1,-0.5 0,respectively.Most of the forest plots with conditions resembling natural forest conditions,high levels of biodiversity and a strong ability to adjust to environmental change,such as pure natural forest,natural mixed needleleaf / broadleaf forest and mixed broadleaf forest,were categorized as healthy or fairly-healthy,while nearly all plantation forests plots which did not have conditions resembling natural forest conditions,but had low levels of biodiversity and a weak ability to adjust to environmental change were classified as unhealthy.This forest health assessment / indicator system establishes a scientific basis for conducting forest health analysis,provides a context for planning ecosystem restoration,and contributes to the understanding of the physical,biological,and human dimensions of these ecosystems.This research may enrich current theories and methods used in assessing the health of ecological systems.