【目的】探究疏于管理(近自然)状态下毛竹(Phyllostachys edulis)林中毛竹和优势树种叶片建成成本适应性机制及其变化规律,为毛竹林的科学管理及竹产业可持续发展提供参考。【方法】以近自然状态林下植被演替0、9、21年毛竹林为对象,运用单因素、Duncan方差分析和冗余分析法(RDA),分析1度、2度立竹和不同胸径木荷(Schima superba)、东南石栎(Lithocarpus harlandii)、苦槠(Castanopsis sclerophylla)等优势树种的叶片功能性状、碳、氮元素含量(质量分数)和热值等差异,并对立竹和优势树种叶片建成成本与功能性状的关系进行分析,探讨毛竹林中优势树种的能量利用和生长适应策略。【结果】随林下植被的演替,毛竹林中立竹和优势树种叶片功能性状发生变化,存在优势树种种间差异和立竹年龄差异,不同径级优势树种中木荷、东南石栎主要是比叶面积变化,而立竹主要是氮含量变化,优势树种木荷、东南石栎叶片比叶面积明显变小,林下植被演替9年毛竹林立竹的叶片氮含量显著小于演替21年毛竹林和毛竹纯林的含量;对不同径级的优势树种叶片单位面积建成成本产生明显影响,主要表现为大、中胸径木荷、东南石栎和大胸径苦槠叶片单位面积建成成本显著增大,而中、小胸径苦槠则相反。1度立竹叶片单位面积建成成本以演替9年毛竹林显著大于演替21年毛竹林和毛竹纯林的,立竹和优势树种的单位质量建成成本总体上无明显变化。冗余分析(RDA)表明,比叶面积是影响优势树种叶片建成成本的主要指标,比叶面积、去灰分热值是影响立竹叶片建成成本的主要指标。相关性分析表明,优势树种、立竹叶片比叶面积与单位面积建成成本均呈显著负相关,优势树种叶片去灰分热值与单位面积建成成本呈显著正相关。【结论】随林下植被演替的进行,优势树种和立竹在林分中逐渐发生“角色”转变。优势树种和立竹能够通过调节叶片功能性状、建成成本及其之间的关系来改变资源获取与投入策略,以适应林下植被演替引起的生境变化。

【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.