Abstract:

【Objective】 The area of bamboo forests dominated by Phyllostachys edulis in the primary production region is expanding continually due to inadequate management strategies or abandonment, which poses as a serious challenge to the sustainable development of China’s regional bamboo industry and environmental conservation. Negligence or abandonment leads to a positive succession of vegetation in the understory of bamboo forests; however, the adaptive mechanisms and variations in the leaf construction costs of P. edulis and dominant tree species remain unclear.【Method】This study investigated bamboo forests undergoing vegetation succession in the understory at 0, nine and 21 years following neglect or abandonment using One-way ANOVA, Duncan analysis of variance, and redundancy analysis (RDA). The one-and two-degree bamboo plants and dominant tree species, including Schima superba, Lithocarpus harlandii, and Castanopsis sclerophylla, were studied herein. The leaf functional traits, element contents, and calorific values were analyzed, and the association between significant differences in leaf construction costs and the functional traits of Moso bamboo and dominant tree species was determined to explore the energy utilization and growth adaptation strategies of bamboo and dominant tree species. 【Result】The progression of vegetation succession in the understory altered the leaf functional traits of Moso bamboo and dominant tree species, indicating inter-species differences among the dominant tree species and age-related variations in Moso bamboo. The dominant tree species of different diameter classes were mainly S. superba and L. harlandii, with changed in specific leaf area (SLA), while bamboo mainly showed changes in nitrogen content (Nmass), The SLA of S. superba and L. harlandii decreased significantly, while the Nmass of bamboo plants in the 9-year successional bamboo forest was significantly lower than that of bamboo plants in the 21-year successional forest and pure bamboo forest. Understory vegetation succession significantly affected the leaf carbon concentration per unit area (CCarea) of the dominant tree species across different diameter classes, which was especially evident in the increased foliar CCarea of the large and medium diameter S. superba and L. harlandii trees; however, a reverse trend was observed for the medium and small diameter C. sclerophylla trees. The foliar CCarea of the one-degree bamboo plants in the nine-year successional bamboo forests was significantly higher than that in the 21-year successional bamboo forest the pure bamboo forest. Overall, the leaf carbon concentration per unit mass (CCmass) of bamboo and the dominant tree species did not differ significantly. The results of RDA indicated that SLA is a primary indicator that influenced leaf construction costs in dominant tree species, while both the SLA and ash free caloric value (AFCV) were the major indicators that influenced leaf construction costs in bamboo. The correlation analysis revealed that the SLA and CCarea were significantly negatively correlated in both bamboo and the dominant tree species, while AFCV and CCarea were significantly positively correlated in the dominant tree species, but incorrelate to bamboo. Altogether, the findings revealed that dominant tree species and bamboo adapt to changes in resource acquisition and investment strategies during understory succession by adjusting the leaf functional traits, construction costs, and their interrelationships. 【Conclusion】The succession of understory vegetation gradually shifts the roles of dominant tree species and Moso bamboo in forest stands. Dominant tree species and Moso bamboo can adapt to habitat changes caused by the succession of understory vegetation by adjusting the leaf functional traits, construction costs, and their relationships to modify resource acquisition and investment strategies. This study advances the understanding of the dynamics of bamboo forest ecosystems, and provides a scientific basis for the development of effective management and conservation strategies.

Key words: Phyllostachys edulis, dominant tree species, understory vegetation succession, leaf construction cost, resource investment strategy