栎类天然混交林是我国亚热带森林资源的重要组成部分，但多为低质低效林、经营水平不高，迫切需要开展其系统经营理论与技术研究；而森林立地质量评价和生长量预估研究是开展森林经营工作的基础和前提，对于天然混交林，其立地质量评价及生长量预估，一直是林业研究中的难点。基于此科学问题，本项目以亚热带栎类天然混交林为对象，主要开展：（1）天然混交林立地质量评价模型和方法研究。拟以林分优势高和蓄积生长量为评价指标，将立地类型和优势树种组成作为混合效应或哑变量，采用非线性回归分析方法构建基础模型，进行生产潜力预估与评价研究；（2）天然混交林蓄积/断面积生长量预估与评价研究。分析混交林年龄、密度、树种组成和立地条件对林分生长量的影响；采用含混合效应或哑变量的非线性回归分析方法构建生长预估模型，用以预估不同林分发育阶段和立地条件下的生长量。研究结果对于改进天然林立地质量评价方法和提高栎类森林经营水平均具有重要意义。

Natural mixed forest of Quercus spp is an important component of subtropical forest resources of China. However, most parts of natural mixed forest of Quercus spp are in low-quality and low-benefit under poor management, in order to solve the above problems, a project of studying systematical and technological management of natural mixed forest of Quercus spp is imperative. In study of forestry, researches on site quality evaluation and stand growth increment predicttion of forest are the foundation work for forest management. As for natural mixed forest, how to evaluate its site quality and predict its stand growth increment is still a focal point and difficult point in the study of forestry. In this study, subtropical natural mixed forest of Quercus spp is naturally chosen as the studying subject. Researches will be carried out as following: Firstly, researches on assessment model and approach of site quality of natural mixed forest: In this study, non-linear mixed effect stands growth model or dummy variable stands growth model will be constructed on condition that dominate height and volume increment taken as evaluation index, whose independents including site type and dominate species groups. And then the model will be used to predict and assess the potential productivity of natural mixed forest. Secondly, researches on predicting and assessing the volume or basal area growth increment of natural mixed forest. In this study, influence of the age, density, species composition and site condition of natural mixed-forest on growth increment will be analyzed; and then non-linear mixed effect stands growth model or dummy variable stands growth model will be used to construct growth prediction model. Then，the growth prediction model will be used to predict growth increment in different stand statement and site condition. Finally, the results of the researches will be conducive to improve site quality evaluation of natural mixed-stand and enhance forest management for Quercus spp.