Impact of abandonment on leaf morphology traits and nutrient utilization strategies of dominant tree seedlings in Moso bamboo forests

The restoration of ecological functions in abandoned Moso bamboo forests facilitates positive succession in evergreen vegetation. Nevertheless, there is a limited understanding regarding the leaf functional traits and nutrient utilization strategies of understory vegetation after abandonment. This study investigated the impact of abandonment duration (9 and 21 years) on leaf morphological traits, soluble sugars characteristics, carbon (C), nitrogen (N), phosphorus (P), and their ratios in dominant tree seedlings (Lithocarpus brevicaudatus and Schima superba) within Moso bamboo forests. Leaf sizes increased significantly, while leaf thickness and leaf tissue density consistently decreased with prolonged abandonment in both species. These morphological indices were significantly higher for L. brevicaudatus compared to S. superba (P < 0.05), and they increased with tree size. Leaf soluble sugars, C, and C: N: P ratios of both species decreased over duration abandonment, while N and P contents increased in both tree species. L. brevicaudatus exhibited elevated levels of fructose, glucose, N, and P, whereas S. superba displayed higher sucrose, C, and C: N: P ratios. Our findings reveal that both species, with extended abandonment, enlarged their leaf area and improved carbon utilization, facilitating adaptation to competitive resource habitats. Particularly, L. brevicaudatus exhibited a propensity to augment leaf sizes, N, and P contents to enhance carbon assimilation, suggesting potential benefits from additional N and P nutrient supplementation. Conversely, S. superba primarily focused on enhancing carbohydrate reserves, indicating that moderate thinning or pruning of bamboo forests could enhance sunlight intensity, along with the appropriate nutrient supplementation. These insights significantly contribute to the scientific understanding necessary for the classification and management of mixed stands in abandoned bamboo forests.