【摘要】 为探究热带次生林林下植物叶片对长期氮(N)、磷(P)添加的响应,阐明热带森林植物对土壤低磷环境适应的生理生态机制,基于华南热带次生林长达9年的氮、磷添加实验,测定两种分布较广的林下乡土树种大青(Clerodendrum cyrtophyllum)和紫玉盘(Uvaria microcarpa)的叶片基本属性、叶绿素含量及氮磷元素含量等指标.结果显示:(1)两种植物叶片的基本属性及光合色素存在显著的种间差异(P <0.05);氮和磷添加提高了大青叶片的比叶面积(35%-38%),对两个树种叶片的叶长、叶宽、叶面积等无显著影响;(2)氮添加显著影响两种植物叶片叶绿素a和总叶绿素含量(P=0.036和P=0.043),而磷添加对光合色素含量无显著影响;(3)对照处理下,大青和紫玉盘叶片的N:P分别为28.71与21.75,大于16,表明两个树种仍受到较强的磷限制;磷添加显著提高了两种植物叶片的磷含量,并降低N:P值;(4)相关性分析表明叶片基本属性、光合色素与氮磷元素含量三者之间的相关性关系较弱.综上,热带森林植物叶片氮和磷元素含量对氮磷添加的响应较敏感,叶绿素a和总叶绿素对氮添加的响应较敏感,而其他属性对氮磷添加的响应较小;因此,在热带森林土壤磷长期缺乏的情况下,植物叶片的生理功能对环境变化具有较好的适应性,其蕴含的生物学机制仍需要进一步的探讨.(图3表2参31)更多还原

【Abstract】 The goal of this study was to investigate the response and adaptation of plant leaves to long-term N and P addition,clarifying the physiological and ecological mechanisms of tropical forest plants to lower soil P availability in southern China.Based on an N and P addition experiment in the secondary tropical forest of southern China, the foliar traits, photosynthetic pigment, and N and P concentrations of two widely distributed tree species, Clerodendrum cyrtophyllum and Uvaria microcarpa were measured. The results obtained were as follows: 1) Inter-species differences were noted in foliar trait,photosynthetic pigment, and N and P concentrations(P < 0.05)—N and P addition increased the specific leaf area(SLA) of C. cyrtophyllum(35%–38%), whereas there was no significant effect on leaf length, width, or area for the two species; 2) N addition significantly influenced the chl a and chl(a + b) concentrations(P = 0.036 and P = 0.043, respectively), whereas P addition had no significant effects on photosynthetic pigment levels; 3) In the CK treatment, the N:P ratios of C. cyrtophyllum and U. microcarpa were 28.71 and 21.75, respectively, and both were higher than 16, indicating that the two tree species were strongly limited by P availability—P addition significantly increased foliar P concentrations and decreased N:P ratios of the two species; 4) Relatively weaker correlations were noted among foliar traits, photosynthetic pigment, and N and P concentrations.Thus, the foliar N and P concentrations were sensitive to N and P addition, and chl a and chl(a + b) were also sensitive to N addition, whereas other foliar traits were slowly responsive to N and P addition in this tropical forest. With the long-term lower soil availability, tropical forest plant leaves are well adaptive to environmental change, although the underlying biological mechanism is yet to be elucidated.更多还原