Leaf adaptation strategy of non-tree plants altered by community structure implies vegetation degradation risk in alpine rocky desertification areas.

In alpine rocky desertification areas, environmental stress poses challenges to vegetation restoration and protection. Merely observing the changes in specific leaf area driven by environmental factors may overlook the risk of non-tree vegetation degradation. The leaf resource allocation strategies of non-tree plants need to be focused on. In the alpine rocky desertification areas of the Jinsha River Basin, three vegetation types were investigated. The leaf traits, vegetation coverage, species diversity of non-tree plants, and soil total nitrogen, rock bareness degree were measurement. An increase in altitude led to a decrease in vegetation coverage and an increase in species diversity. In grasslands with exceeded 35% rock bareness degree, the increase in species diversity intensified competition pressure, resulting in a decrease in the specific leaf area. In forests with less than 20% rock bareness degree, the species of shrubs have become homogeneous, resulting in a decrease in vegetation coverage but an increase in the specific leaf area. But due to environmental stress, the leaf resource allocation of different species may have favored leaf dry weight (allometric index < 1.0). An increase in soil total nitrogen alleviated environmental stress, causing leaf resources to be allocated to both leaf dry weight and leaf area (allometric index ≁1.0). However, it enhanced the above-ground competitiveness of few dominant species, squeezing out the living space of auxiliary species, and vegetation degradation risk increased. Species with similar specific leaf areas can have different leaf resource allocation strategies. By combining the changes in specific leaf area with leaf resource allocation strategies, the development of vegetation under environmental stress can be accurately revealed.