杉木人工林下原生与引入树种叶性状变异特征

叶性状在表征植物资源利用和生存策略方面具有重要作用。构建异龄复层林是改造人工纯林的有效措施,探究引入与原生树种叶性状变异有利于林下伴生树种的筛选。研究了引入乔灌木树种(如闽楠、蚊母树等13个树种)与原生乔灌木树种(苦槠、红紫珠等6个树种)的叶片形态、光合色素、碳氮磷生态化学计量和非结构性碳水化合物特征。结果表明:(1)总体上引入与原生乔木和灌木树种的叶形态性状差异较小,原生乔木的叶长和比叶面积显著小于引入树种与原生灌木。引入与原生树种间光合色素具有显著差异,引入乔木叶绿素含量显著高于原生乔木,不同功能群植物的比叶面积.叶绿素关系格局存在策略位移现象。引入树种叶碳含量显著大于原生树种,叶氮和叶磷含量显著大于原生乔木;引入树种和原生灌木的碳、氮、磷养分含量的变异系数较大;引入与原生树种叶碳氮磷生态化学计量没有一致变化规律。引入灌木叶可溶性糖含量、原生灌木淀粉含量均显著高于乔木树种,灌木的非结构性碳水化合物总量也显著高于乔木。(2)引入与原生树种叶性状呈显著协同变化趋势。所有叶性状中,比叶面积、叶绿素含量、叶氮含量、叶磷含量在乔木和灌木中均呈极显著正相关关系。主成分分析显示,引入乔木和灌木树种的叶性状接近,引入树种与原生灌木之间叶性状差异相对较小,但与原生乔木间的叶性状差异较大。总体上引入树种的叶性状与原生树种具有趋同适应特征,但不同生活型植物叶性状在林下弱光环境中仍产生一定分异,引入灌木可能比引入乔木更适应杉木林下生境。

Variations in leaf traits of native and introduced tree species in Cunninghamia lanceolata plantations

Leaf traits of plants play crucial roles in determining resource utilization and survival strategies. Single-layered monoculture plantations are converted to multi-layered mixed plantations is an effective measure to improve plantation quality. To study the variation of the leaf traits of introduced and native species is beneficial to select the associated tree species under forest. This study assessed the traits of leaf morphology, photosynthetic pigments, carbon, nitrogen and phosphorus ecological stoichiometry, and non-structural carbohydrates of introduced arbors and shrubs species (such as Phoebe bournei and Distylium racemosum) and native arbors and shrubs species (such as Castanopsis sclerophylla and Callicarpa rubella). The results showed that leaf length and specific leaf area of native arbors were significantly smaller than those of the introduced species and native shrubs, and the other leaf morphological traits were little difference between introduced and native species. Photosynthetic pigment content differed markedly between the introduced and native species, and the chlorophyll content of native arbors was significantly lower than that of the introduced arbors. The relationship of specific leaf area and chlorophyll varied among different functional groups. The leaf carbon content of the introduced tree species was distinctly higher than that of the native tree species, and the leaf nitrogen and phosphorus contents were significantly higher than those of the native arbors. The coefficients of variation of nutrient contents of the introduced species and native shrubs were higher than that of the native arbors. The variations in leaf carbon, nitrogen, and phosphorus eco-stoichiometry differed in the introduced and native tree species. The soluble sugar content in the introduced shrubs and the starch content in the native shrubs were markedly higher than those of arbors, and the content of the non-structural carbohydrates in the shrubs was distinctly higher than that in the arbors. The leaf traits of the introduced and native tree species showed a significant synergistic change. For the arbor and shrub species, there was a marked positive correlation among the leaf area, chlorophyll content, and leaf nitrogen and phosphorus contents. Based on principal component analysis (PCA), the leaf traits were similar between the introduced arbors and shrubs. The differences of leaf traits were relatively smaller between introduced tree species and native shrubs, while there was a large difference between introduced tree species and native arbors. The leaf traits of introduced and native tree species showed convergent adaptation. However, the leaf traits of different life forms still had some differences in the low-light environment. The introduced shrubs may be more suitable for the understory environments in Cunninghamia lanceolata.