人工林长期立地生产力研究的现状和前景

Current Situations and Prospects on LongTerm Site Productivity Research of Plantations

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。

Abstract During the past 20 years a number of studies have showen that current and intensified levels of forest management may have signficant effects on longterm productivity of forest ecosystems. However, there is little direct evidence that forest harvesting practices have reduced site quality and led to a decline in productivity. The lack of evidence is largely because few studies have been done that adequately address this problem. Welldesigned, longterm field trials, together with appropriate processorientated studies, are required to improve the understanding of forest ecosystem functions, and to enable extrapolation of trial results to other site. Site classification systems and computer models can integrate knowledge but they, of themselves, cannot be used as evidence for productivity decline or increase. Longterm research trials are the only means to validate the predictions of productivity change. This paper briefly summarizes the current situations, future research required and some recommendations in China.