The Study On Quality Assessment Indicator System Of Timber Forest And Its Methods At Subcompartment Level

Forest is considered to be one of the most important terrestrial-ecosystem on the earth, which is also an irreplaceable resource and treasure for human’s survival and development. The concept of forest quality is basically described as "the significance and value of all ecological, social and economic components of the forest", and this concept is brought up to draw attentions from more people to protect the forest and promote its production and service. The forest quality issues deserves more attention both in the perspectives of global ecological balance and local forest management. Assessing the forest quality will help the forest owner better understand the status of forest resource, and it can also provide improtant guidelines or references in establishing the forest management plan to steadily sustain the forest production and service.This research is about the forest quality assessment in the level of subcompartment. A review of the subject of forest quality was summarized in the first part, including the origin of forest quality theory, the exsisting relevant studies, and their methods and results. There are similiar research subjects such as forest sustainability and forest health, all of these three subjects are derived from the subject of sustained yield of forest. The similarities and differences in both indictors and methods among these different subjects were analysed in detail, and the disadvantages of present research were revealed. It is believed that with a more comprehensive and convenient data source, and more scientific and quantitative quality judgement methods, the forest quality research area will have more achievements.As the second part of this research, the fundamental concepts, definitions, connotations and assessment process of forest quality assessment were fully introduced and explained. Among the theory and these knowledge,6 principles of forest quality assessment were particularly discussed, including the indicators’ representativeness, standardability, economic feasibility, quantitative comparability, practicability and the indicator system should have a reasonable and hierarchy structure. The application process of 6 common forest quality judgement methods were also introduced and analysed in this part.The third part described the methods of building the forest assessment indicator system in subcompartment level, as one of the most important results of this research. According to the principles of forest quality assessment, this study chose the forest inventory data as the data source of assessment. The Quantification and normalization formula for forest inventory data were put forward, as well as the grade classification standard for both indicators’value and quality assessment results, In order to reduce the high subjectiveness of the analytic hierarchy process, the method of factor analysis was introduced and combined to the analytic hierarchy process to build a more reasonable indicator system and calculate the indicators’weights. The final subcompartment level forest quality assessment indicator system contains 5 criteria and 15 indicators and could be used to assess the timber quality and the land quality of timber forest,In the fourth part, different qualiy judgement methods were introduced and be applied to the subcompartment data. The research discovered that the quality assessment results under different quality judgement methods of one subcompartment object are not always the same, a further observation find out these results may not be the same but they have showed a same trend. According to the trend of results, the concept of "average forest quality grade" was proposed to describe the actual forest quality which was supposed to be measurable. Based on the average forest quality grade, the concepts of distinction degree, agreement rate and the methods accuracy were proposed to study the performance of different quality judgement methods. The results showed that the matter-element analysis has the best accuray of 86% when assessing the forest quality of subcompartments. At the same time, the model of back propagation neural network (BPNN) was used to learn and stimulate the process of calculating the average forest quality grade, the the accuracy of BPNN has reached 79.2%. A case study of Jiangle national forest farm of Fujian indicated that the subcompartments of Mingtoushan area were better than Yufang area in each age groups, and its detailed analysis results could provide references for the forest management plan in the future.In the last part of this study, using the theory of modern forest resource management, the management information system of forest quality was designed and built. An fundamental function of this system was the data exchange between different forest resource management system, and it could calculate the forest quality grade by using the quality judgement methods mentioned in this study. The system could optimize the phase of data processing of forest quality assessment and promote the efficiency of forest quality assessment, it would help more people to realise the quality of forest and accelerate the related researches.