中文摘要：

针对防护林衰退问题，以章古台樟子松固沙林为案例，应用生态演替、干扰、种群密度等关键性恢复生态学理论和原则，对防护林在决策层面的设计要素的科学性及其与衰退的关系进行了分析和评价，认为大面积造林与地带性顶极的不吻合（即偏离生态学原则），使防护林建设的目标、步骤、树种的组成和密度等出现了偏颇，成为防护林衰退的最深层次的原因，疏于管理和粗放经营以及频频发生的自然和人为干扰也是致衰的重要因素；据此提出深化对受损生态系统的认识、强化物质和能量的投入、建立干扰的防控体系等对策．文中还就人工植被建设目标与生态演替顶极类型的判别，以及偏途顶极在人工植被建设中的应用问题进行了讨论，一并作为对策以供参考．

英文摘要：

Aimed at the decline of protective forest in China, and applying the key principles of restoration ecology, such as ecological succession, disturbance, and population density, etc. , this paper assessed the rationality of designing elements of protective forest in decision-making level, and analyzed its relationships with the decline of the forest, taking Pinus sylvestris var. mongolica plantation in Zhanggutai sandy land as an example. It was considered that the disagreement of large-scale afforestation with succession climax in regional scale was aberrant to the ecological principles, and resuhed in the aberrancy of the objectives, steps, species composition, and stand density of protective forest establishment, being the main cause of protective forest decline. Mismanagement and frequent natural and human disturbances were also the important causes for the decline. Three strategies for preventing the decline, i. e. , better understanding damaged ecosystems, increasing material and energy input, and overcoming disturbances were put forward, and the objectives of restoring vegetation, judgment of climax for ecological succession, and application of plagioclimax in establishing artificial vegetation were discussed.