Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences,,Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences,,,
气孔是陆生植物与外界环境进行水分和气体交换的主要通道,控制着植物的光合作用和蒸腾过程。植物往往通过多种性状的组合来适应变化的环境,叶片功能性状之间的紧密关系已经在不同尺度得到证实。然而,植物气孔特征与叶片其它功能性状是否存在关联性以及这种关联性是否会受到环境变化梯度的影响仍鲜少报道。沿长白山北坡6个海拔梯度,测定了150种植物的气孔特征和叶片功能性状。结果发现,气孔密度(SD)与比叶面积(SLA)负相关,与单位面积的叶氮含量(Narea)正相关;除了SLA和Narea外,气孔长度(SL)与SLA、叶片厚度(LT)和单位质量的叶氮含量(Nmass)均存在显著的相关性(P < 0.05)。然而,气孔特征与叶片功能性状的相关性只在部分海拔梯度存在。此外,发现SD与SL之间存在稳定一致的负相关关系。这些结果表明,植物气孔特征与叶片形态和化学特征对环境变化的适应存在一定的协同变异性,但这种关系不具有普适性,主要与气孔特征和叶片功能性状的选择压力存在差异以及物种分布范围相关。未来仍需要在更多物种和不同区域内来验证气孔特征与植物功能性状之间的关联关系。
Stomata, small pores on the surfaces of plant leaves and stalks, act as turgor-operated valves to control gas (e.g. water vapor and carbon dioxide) exchange between plant tissues and the atmosphere. Stomata therefore play a major role in the regulation of water and carbon cycling. Generally, plants adapt to changing environments through the combination of multiple traits. The strong relationships between leaf morphological, chemical, and physiological traits have been documented within and across plant species, biomes, and even globally. Despite the importance of leaf stomata, little is known about interspecific covariation in stomatal traits and their relations with other leaf functional traits on a large scale, partly due to a lack of data on leaf stomata in most studies. In the present study, we measured stomatal and leaf functional traits, including stomatal density (SD), stomatal length (SL), specific leaf area (SLA), leaf area (LA), leaf thickness (LT), and nitrogen content (mass- and area-based, Nmass and Narea) of 150 plant species along an altitudinal gradient (540-2357 m) in Changbai Mountain, China. Our results showed that, for all species, the average values of SD and SL were 155.91 stomata/mm2 and 34.51 μm, respectively; the average values of SLA, LA, and LT were 33.58 m2/kg, 3291.30 mm2, and 0.14 mm, respectively; the mean values of Nmass and Narea were 24.48 g/kg and 1.07 g/m2. There were significant relationships between stomatal traits and other leaf functional traits (P < 0.05). Specifically, SD was negatively correlated with SLA, and positively correlated with Narea (P < 0.05); SL was negatively correlated with LA and Nmass, and positively correlated with LT (all P < 0.05). Additionally, SL was negatively correlated with SD (P < 0.05). Standardized major axis (SMA) analysis showed that these significant relationships between stomatal traits and morphological and chemical traits of leaves differed among different altitudes. However, the strong relationship between SD and SL was observed at all altitudes. Furthermore, although no significant difference (P > 0.05) was found among these slopes of SD-SL relationships, the y-intercepts differed significantly (P < 0.05), in which the maximum occurred at 1286 m, and the minimum at 2357 m, indicating plants with larger stomata (higher SL) at any given SD occurred at 1286 m than those with smaller stomata (lower SL) at 2357 m. These findings suggest that there is a covariation between stomatal traits and leaf morphological and chemical traits. However, this may not be universal for all plants due to different stress responses between stomata and other leaf structures. Moreover, the narrow taxonomic range at each altitude may also restrict the expression of bivariate relationships. Future research needs to verify the relationships between stomatal traits and plant functional traits in more plant species from different areas. Finally, our findings highlight the trade-off between SD and SL, which regulates the short-term (plastic) and long-term (evolutionary) strategies in plant adaptation to the external environment. These data provide a basis for revealing adaptation strategies in plants, and help us predict their responses to future climate changes.