关键词: 退化林, "三北"工程, 退化林修复；防护林

Abstract:

Since the inception of the Three-North Shelter Forest Project (also known as the Great Green Wall Project, GGWP) in 1978, extensive tracts of artificial shelter forests and public welfare forests have been established. This initiative has been instrumental in fortifying the ecological security barrier in northern China. In the early phases of the GGWP, certain shelterbelts constructed therein have undergone degradation. In response, the Chinese government has commenced the allocation of tasks related to the restoration of these degraded plantations within the project framework. The overarching objective is to ensure the continued efficacy of the ecological protection functions of the ecosystem in the GGWP area. In light of the scientific issues emerging from the research on the degradation of shelterbelts during the sixth phase of the GGWP, this paper undertakes a comprehensive and meticulous analysis of the definition, scope, causative factors, and restoration strategies pertaining to the problem of degraded plantations. It further presents an overarching systematic approach and corresponding countermeasures. The degraded plantations within the GGWP area, as defined in this study, are artificial plantations (including shrubs) that exhibit pronounced growth decline and a substantial reduction in ecological functions, such as windbreak and aeolian sand fixation. The restoration of degraded plantations not only needs to address the overt degradation of plantations but also needs to address the underlying systematic land degradation. The fundamental cause of this systematic degradation is attributed to inadequate post-construction management. This deficiency, in turn, leads to the deterioration of both soil and water conditions. In this region, water emerges as the most limiting factor for post-construction management. This study conducts an in-depth and exhaustive analysis of the natural, disaster-related, physiological, design-related, and anthropogenic factors that instigate the degradation of plantations in the GGWP area. Given the vast expanse of the GGWP area, the restoration of degraded plantations should commence with a classification, grading, and zoning process based on the characteristics of natural endowments, followed by the implementation of targeted and precise measures. Regarding the restoration of degraded plantations in the GGWP, the traditional degradation assessment index system, which predominantly relies on the visual appearance of vegetation, should be gradually transitioned into a system that integrates the functional attributes of vegetation with appearance-related indicators. The article also suggests to categorize the degradation degree into mild, moderate, and severe levels, and to implement distinct levels of enclosure protection, replanting, or resowing restoration strategies accordingly. Finally, this paper aims to enhance the management and protection of plantations throughout full-cycle. Additionally, it advocates for the establishment and refinement of a comprehensive full-cycle management and protection system for plantations. This study is expected to offer valuable insights and reference points for China’s endeavors in the restoration of degraded plantations within the GGWP and the formulation of relevant technical measures and regulations.

Key words: degraded plantations, the Great Green Wall Project, restoration of degraded plantations; shelterbelt