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目前很少有直接的证据证明经营措施（特别是收获技术）导致了立地质量下降，并使人工林立地生产力下降。直接依据的缺乏，主要是由于专门研究这一问题的设计完善的试验林的不足。为了提高人们对森林生态系统功能的认识并使研究结果具有推广应用价值，开展设计完善的长期田间试验和过程研究势在必行。虽然立地分类系统和计算模型能够综合现有的知识以表达立地生产力的高低，但它们本身不能用作立地生产力下降或提高的依据。因此，建立长期田间试验是准确预测长期立地生产力变化的唯一途径。
At present, there is very little direct evidence that management practices (especially harvesting techniques) lead to a decrease in the quality of the site and a decrease in the productivity of plantations. The lack of direct evidence is mainly due to the inadequacy of a well-designed pilot forest that specializes in this issue. In order to enhance people’s understanding of the functions of forest ecosystems and make the research results have the value of popularization and application, it is imperative to conduct well-designed long-term field experiments and process studies. Although site classification systems and computational models can synthesize existing knowledge to express the level of site productivity, they can not by themselves be used as a basis for the reduction or enhancement of site productivity. Therefore, establishing long-term field trials is the only way to accurately predict long-term changes in on-site productivity.