热岛效应下亚热带城市植被叶气孔权衡特征及其与叶功能性状的关系

叶片气孔不仅是植物平衡光合-蒸腾关系的重要门户，也是影响大气碳循环与水循环的关键结构。分析热岛效应下福州市乔木、灌木、草本3种生活型和常绿、落叶2种叶习性植物的气孔性状间的差异及其与其他叶功能性状间的权衡关系有助于探究不同类型植物在热环境下的适应策略。以福州市区的自然和半自然植被为研究对象，测定441个植物样本的气孔特征、化学计量特征和形态特征，结果表明：（1）3种生活型、2种叶习性植物的气孔长度（SL）、气孔密度（SD）差异显著（P<0.05），潜在气孔导度指数（PCI）不存在显著差异（P>0.05）。草本的SL高于灌木和乔木，乔木的SD最高，灌木次之，草本最低；落叶植物的SL高于常绿植物，SD低于常绿植物。（2）SL与SD间的权衡关系稳定存在于3种生活型和2种叶习性植物中，且随着不同生活型和落叶习性植物的生态策略而呈现各异的权衡特征，即当SL一定时，乔木的SD最大，灌木的SD最小，常绿植物的SD大于落叶植物。（3）气孔性状和叶片形态、化学计量特征紧密联系，SL与比叶面积（SLA）正相关（P<0.01），与叶面积（LA）负相关（P<0.01）；SD与叶氮含量（LNC）、叶磷含量（LPC）、SLA负相关（P<0.01），与LA正相关（P<0.01）；PCI与LNC、SLA负相关（P<0.01），与叶厚度（LT）正相关（P<0.05）。（4）复杂的环境是气孔性状变异的重要驱动因素，SL、PCI均与年均温（MAT）负相关（P<0.05）。

Trade-off characteristics of stomata of subtropical urban vegetation and its relationship with leaf functional traits under heat island effect

Stomata is not only an important gateway for plants to balance the relationship between photosynthesis and transpiration, but also a key structure affecting atmospheric carbon and water cycling. Analyzing the differences of stomatal traits among three life forms of trees, shrubs and herbs and two leaf habits of evergreen and deciduous plants in Fuzhou under heat island effect and their trade-off relationship with other leaf functional traits will be helpful to explore the adaptation strategies of plants in the thermal environment. We measured stomatal traits, stoichiometric traits and morphological traits of 441 plant samples in natural and semi-natural vegetation in Fuzhou City. The results showed that:(1) there were significant differences in stomatal length (SL) and stomatal density (SD) between the three life forms and the two leaf habit plants(P<0.05), but no significant differences in potential stomatal conductance index (PCI) between the three life forms and the two leaf habit plants(P>0.05). The SL of herbs was higher than that of shrubs and trees, and SD of trees was the highest, followed by shrubs and herbs. The SL of deciduous plants was higher than that of evergreen plants, but SD of deciduous plants was lower than that of evergreen plants. (2) The trade-off between SL and SD existed stably in the three life forms and two leaf habit plants, and showed different trade-off characteristics with the ecological strategies. When SL was constant, SD of trees was the largest, SD of shrubs was the smallest, and SD of evergreen plants was larger than that of deciduous plants. (3) The stomatal traits were closely related to leaf morphology and stoichiometric characteristics. SL was positively correlated with specific leaf area(SLA)(P<0.01) and negatively correlated with leaf area(LA)(P<0.01). SD was negatively correlated with leaf nitrogen content(LNC), leaf phosphorus content (LPC), SLA(P<0.01), and positively correlated with LA(P<0.01). PCI was negatively correlated with LNC and SLA(P<0.01), and positively correlated with leaf thickness(LT) (P<0.05). (4) The complex environment was an important driving factor for variation of stomatal traits. SL and PCI were negatively correlated with mean annual temperature(MAT) (P<0.05).