Evaluation of the stand quality of Casuarina equisetifolia in coastal shelterbelts

Coastal areas face challenges in updating and enhancing the quality of coastal shelterbelt forests due to limited soil resource utilization, the biological characteristics of tree species, and the impact of coastal storm surges. This study, based on clarifying the connotation of stand quality (SQ) for Casuarina equisetifolia (C. equisetifolia), a typical coastal shelterbelt species, integrates stand growth conditions and structure, applying the AHP-EWM method to construct an SQ evaluation model. The model identifies key factors influencing the quality of C. equisetifolia stands and explores the mechanisms driving their growth processes. The results indicate that mean tree height, mean diameter at breast height, and stand density are key indicators for assessing the SQ of C. equisetifolia stands. The SQ of C. equisetifolia coastal shelterbelt stands varies across different land-sea positions, mainly influenced by stand age and soil nutrient levels. As stand age increases, the SQ initially improves and then declines. Additionally, C. equisetifolia trees growing in nutrient-rich soils exhibit better growth and higher SQ than those in poor soils. The findings of this study provide a theoretical foundation for the management and quality enhancement of coastal shelterbelt forests.