立地质量评价是森林经营的一项基础性工作，是研究森林生长规律、预估森林生长收获和科学制定森林经营措施的重要基础。自上世纪20年代起，立地质量评价受到世界各国的广泛重视，迄今已提出了较多评价方法。然而实际应用时，发现现有方法存在2个主要缺陷：第一、这些方法大多数仅局限于人工林纯林，对于天然林立地质量评价尚未适用；第二、尽管部分学者对天然林立地质量评价进行了研究，但由于天然林中各林木种类和年龄大小不一、林分结构复杂以及树高通常呈现不规则的年龄结构等因素使得当前尚未有被广泛认同的立地质量评价指标和生产力预估方法。森林生物量是森林生态系统的最基本数量特征，是评价立地质量和森林生产力的重要指标之一。因此如何结合森林生物量有效提出一套适用于任意天然林林分的立地质量评价方法成为目前森林经营上亟需解决的一项基础理论研究。为此，本项目将重点解决该基础问题。研究成果将为我国森林质量精准提升提供重要理论依据。

Site quality assessment is a basic work of forest management. It is an important basis for studying the law of forest growth, estimating the harvest of forest growth and formulating forest management measures scientifically. Since the 1920s, site quality assessment has attracted worldwide attention, and many methods have been put forward so far. However, in practical application, two main shortcomings were found in the existing methods: first, most of these methods were limited to pure plantations, and the evaluation of natural forest site quality was not yet applicable; second, although some scholars have studied the evaluation of natural forest site quality, because of the different types and ages of natural forests, complex stand structure and tree height，irregular age structure and other factors，there is no widely accepted evaluation index of site quality and productivity prediction method. Forest biomass is the most basic quantitative characteristics of forest ecosystem, and one of the important indicators to evaluate site quality and forest productivity. Therefore, how to effectively put forward a set of site quality evaluation methods suitable for any natural forest stand in combination with forest biomass has become a basic theoretical research that needs to be solved urgently in forest management. To this end, this project will focus on solving this basic problem. The research results will provide an important theoretical basis for the precise improvement of forest quality in China.