Forest Health Assessment Of Natural Larix Gmelinii In Great Xing’an Mountians Of China

The forest is called "the lungs of the earth", which keeps the balance between carbon and oxygen from the atmosphere, purities the human living environment and provides the fresh air for terrestrial biota. A healthy forest is better able to provide these services for human. On the contrary, the sustainable development of human beings will be immeasurable losses. A healthy forest ecosystem is the foundation of human heath, social stability and regional sustainable development. Forest health assessment provides a scientific and theoretical basis for forest health management and construction of demonstration area. It is a vital part of forest health research and has been received extensive attention from relevant institutions and scholars at home and abroad.The natural Larix gmelinii forest44fixed plots,4944individual trees and4474subcompartments in Pangu Forest Farm, the Great Xing’an Mountains were assessed based on forest health theory and system science theory and using entropy method, composite index method, remote sensing and geographic information system, etc. in this paper.First of all, A health assessment indicators system of individual tree was filtered out and established, which included crown transparency, crown dieback ratio, crown skewness, live crown ratio and crown overlap. The results showed that the trees in healthy gradation reached907samples, and those in sub-healthy gradation were up to3639samples, and those in mid-healthy gradation reached92samples, and and those in unhealthy gradation reached306samples. A individual tree health predition model was established by using discriminant analysis and the accuracy of the model was97.21%. Then, a health assessment indicators system of stand scale where fixed plot as the evaluation unit was filtered out in modern system science as theoretical basis, conbined with qualitative and quantitative analysis, which included underwood coverage, volume per hectare, community structure, individual tree health degree, forest fire gradation, soil erosion degree, plant diseases&insect pest degree, soil thickness, site class, near natural degree, and thickness of litter layer. Individual tree health degree as an important indicator has been integrated into the stand scale health asessment, and realize the coupling process between the individual tree scale and stand scale. To clarify forest health essence clearly through above assessment process. The results showed that the plots in healthy gradation reached2samples, and those in sub-healthy gradation were up to18samples, and those in mid-healthy gradation reached21samples, and and those in unhealthy gradation reached8samples. The most of fixed plots were judged to be sub-healthy or mid-healthy gradation. Make full use of second class investigation. Next, another health assessment indicators system of stand scale where subcompartment as the evaluation unit was established, which included underwood coverage, volume per hectare, ground coverage, forest fire grade, soil erosion degree, soil thickness, site class, thickness of humus layer and leaf area index. The results showed that the subcompartments in healthy gradation reached964(area is23086hectares), and those in sub-healthy gradation were up to1391(35199hectares), and those in mid-healthy gradation were up to1439(36179hectares), and and those in unhealthy gradation reached680(36179hectares). The most of subcompartments in Pangu Forest Farm were judged to be sub-healthy or mid-healthy gradation. More healthy and effective management measures should be taken by forest management worker to improve the the healhy gradation of natural L. gmelinii. Finally, a forest health auxiliary system was designed and developed based on C#programming language and ESRI ArcGIS Engine components using the techniques of forest management, comprehensive evaluation method and the secondary development technique of geographic information system. The common algorithms and models among comprehensive evaluation, such as forest health assessment indicators, analytic hierarchy process, entropy value method, composite index method, fuzzy comprehensive evaluation method, natural breaks and equal interval method were built in the system for users to choose and apply according to the specific situation.