Ecosystem health research, together with its assessment theory and technique, is one of the important work and urgent tasks of environment and ecosystem Science in 21(st) century. A new practical and easily operational assessment method, integrated composed index (ICI), on forest ecosystem health had been put forward to in this paper by modifying composed index (CI) and adding biomass factors. Based on plant community field investigation data on original old-growth broadleaved and Korean pine mixed forest, viewed as a health benchmark, and various disturbed conifer-broadleaved mixed forests, secondary birch forests and larch plantation forests as well, the vertical structure of stand was divided into four layers by tree height, namely, upper canopy overstory (Hgreater than or equal to8m), subdominant overstory (18greater than or equal toHgreater than or equal to10m), succession-layer (10mgreater than or equal toHgreater than or equal to2.5m) and regeneration-layer (H<2.5m), ICI of each layer was calculated and analyzed to express the relationship between disturbance, secession and health. The ICI of overstory strata (i.e. upper canopy overstory and subdominant overstory) was bigger than that of understory strata (i.e. of succession-layer and regeneration-layer). The range was from 0.28 to 0.31 in distance for original old-growth forests. This result suggested community structure was symmetrical and steady. Overstory strata were composed of Pinus koraiensis, Tilia amurensis, Abies nephrolepis, Acer mono and so on, which had high climax adaptation value and could remain its dominant status. The understory strata were composed of species with medium climax adaptation value, and some other species with low climax adaptation value. The index distance between overstory and understory will decrease by increasing of the understory TO value when the health forests suffered some disturbances. Self-regeneration process will expand the distance of health benchmark (0.28-0.31). The disturbance extent and self-regeneration ability of original health community can be achieved according to the distance value. Different disturbance intensity and manners of cutting will affect the degree of ecosystem health. If the intensity increases, both overstory and understory index value decrease, the greatly decrease on overstory strata. The increasing disturbance intensity resulted in the coming of overlap between the overstory strata and understory strata at 11.8 on index value, and then the understory's index value exceeded that of the overstory's index value. Compared with the original broadleaved and Korean pine mixed forest, the base health forest type, distance value of each disturbed type were as following: structure switched stand (at 0.64) < structure destroyed stand (at 0.75) < structure reserved stand (at 0.85) < heavy destroyed stand (at 1.95) < birch stand (at 2.07) < larch plantation (at 2.89). The stronger stress on ecosystem, the bigger distance value, the lower degree of ecosystem health is. ICI can not only involve in the destroy extent of disturbance on forest quality, but also synthetically express many parameters of forest ecosystem health, such as structure of status quo, anti-disturbance, resilience, tree adaptability, competition relationship of tree species, secondary succession progress and mechanism, and describe the destroy extent of disturbance and health restoration process of ecosystem health as well. Thus, ICI is an effective method to analyze the effect of disturbance intensity and manners on ecosystem health of Korean pine and broadleaved mixed forest.
