Data_Sheet_5_Variations in Leaf Traits Modulate Plant Vegetative and Reproductive Phenological Sequencing Across Arid Mediterranean Shrublands.PDF

Structural and nutrient traits of a leaf are important for understanding plant ecological strategies (e.g., drought avoidance). We studied the specific leaf area (SLA), leaf carbon content (LCC), leaf nitrogen content (LNC), leaf phosphorous content (LPC), and the phenophase sequence index (PSI) in 126 Mediterranean perennial species from predesert (SMS) and semiarid (SaMS) to subalpine (SAS), alpine cushion (AcS), and oro-Mediterranean (AjS) shrublands, which represent eight functional groups (evergreen and deciduous trees, evergreen large and half shrubs, deciduous large and half shrubs, succulents and perennial herbs). We analyzed the variation and relationships between leaf traits and PSI among shrublands, functional groups, and within species with drought-avoidance mechanisms. SLA variation of 20–60% could be ascribed to differences between functional groups and only 38–48% to different shrublands increasing from the predesert to the alpine. Alpine species display low PSI and N:P and high SLA, LNC, LPC, LCC, and C:N. On the contrary, predesert and semiarid showed high PSI and low SLA. SLA mediates the vegetative and reproductive phenological plant sequencing, high SLA is often associated with the overlapping in growth and reproductive phenophases with a seasonal reduction of vegetative growth, whereas low SLA is associated with vegetative and reproductive sequencing and a seasonal extension of vegetative growth. Species with drought-avoidance mechanisms (e.g., semideciduous species) contribute to an increase in the mean values of the SLA and LNC because these species show similar leaf and phenological patterns as the deciduous (high SLA and LNC and low PSI). The N:P indicates that only the alpine shrublands could present P limitations. The positive correlations between SLA and LPC and LNC and LPC (leaf economic spectrum) and the negative correlation between SLA and C:N were consistently maintained in the studied arid Mediterranean shrublands.

叶片的结构与养分性状对于解析植物生态策略（如耐旱策略）至关重要。本研究针对来自荒漠前灌丛（predesert, SMS）、半干旱灌丛（semiarid, SaMS）、亚高山灌丛（subalpine, SAS）、高山垫状灌丛（alpine cushion, AcS）以及地中海山地灌丛（oro-Mediterranean, AjS）的126种地中海多年生植物，测定了其比叶面积（specific leaf area, SLA）、叶片碳含量（leaf carbon content, LCC）、叶片氮含量（leaf nitrogen content, LNC）、叶片磷含量（leaf phosphorous content, LPC）与物候序列指数（phenophase sequence index, PSI）。供试物种涵盖8个功能群：常绿乔木、落叶乔木、常绿大灌木、常绿半灌木、落叶大灌木、落叶半灌木、肉质植物以及多年生草本植物。本研究分析了不同灌丛类型、功能群间以及携带耐旱机制的物种内部，叶片性状与PSI的变异规律及其相互关联。SLA的变异中有20%~60%可归因于功能群间的差异，仅38%~48%可归因于不同灌丛类型的差异，且该差异自荒漠前灌丛至高山灌丛逐渐递增。高山灌丛物种表现出较低的PSI与氮磷比（N:P），以及较高的SLA、LNC、LPC、LCC与碳氮比（C:N）。与之相反，荒漠前灌丛与半干旱灌丛的物种则呈现较高的PSI与较低的SLA。SLA介导植物的营养生长与生殖物候序列：高SLA通常与生长和生殖物候重叠、营养生长季节性减弱相关，而低SLA则与营养生长和生殖物候依次进行、营养生长季节性延长相关。携带耐旱机制的物种（如半落叶物种）的SLA与LNC平均值更高，这是由于这类物种的叶片与物候模式与落叶物种相似（高SLA、高LNC与低PSI）。氮磷比（N:P）表明，仅高山灌丛可能存在磷限制。在本研究涉及的干旱地中海灌丛中，SLA与LPC、LNC与LPC间的正相关关系（即叶片经济谱，leaf economic spectrum）以及SLA与C:N间的负相关关系均稳定存在。