Geographic Variation in the Petiole–Lamina Relationship of 325 Eastern Qinghai–Tibetan Woody Species: Analysis in Three Dimensions

Abstract

The petiole–lamina relationship is central to the functional tradeoff between photosynthetic efficiency and the support/protection cost. Understanding environmental gradients in the relationship and its underlying mechanisms remains a critical challenge for ecologists. We investigated the possible scaling of the petiole–lamina relationships in three dimensions, i.e., petiole length (PL) vs. lamina length (LL), petiole cross sectional area (PCA) vs. lamina area (LA), and petiole mass (PM) vs. lamina mass (LM), for 325 Qinghai–Tibetan woody species, and examined their relation to leaf form, altitude, climate, and vegetation types. Both crossspecies analysis and meta-analysis showed significantly isometric, negatively allometric, and positively allometric scaling of the petiole–lamina relationships in the length, area, and mass dimensions, respectively, reflecting an equal, slower, and faster variation in the petiole than in the lamina in these trait dimensions. Along altitudinal gradients, the effect size of the petiole–lamina relationship decreased in the length and mass dimensions but increased in the area dimension, suggesting the importance of enhancing leaf light-interception and nutrient transport efficiency in the warm zones in petiole development, but enhancing leaf support/protection in the cold zones. The significant additional influences of LA, LM, and LA were observed on the PL–LL, PCA–LA, and PM–LM relationships, respectively, implying that the single-dimension petiole trait is affected simultaneously by multidimensional lamina traits. Relative to simple-leaved species, the presence of petiolule in compound-leaved species can increase both leaf light interception and static gravity loads or dynamic drag forces on the petiole, leading to lower dependence of PL variation on LL variation, but higher biomass allocation to the petiole. Our study highlights the need for multidimension analyses of the petiole–lamina relationships and illustrates the importance of plant functional tradeoffs and the change in the tradeoffs along environmental gradients in determining the relationships.

Patterns of Leaf and Fruit Morphological Variation in Marginal Populations of Acer tataricum L. subsp. tataricum

“…This deviation in petiole length might be due to adjustments in phyllotaxy, directed towards better light capture efficiency [ 42 ], and due to the fact that plants tend to display longer petioles on more productive habitats [ 43 ]. Adjustments in the petiole length can also be stimulated for better nutrient transport efficiency and leaf support and protection [ 44 ]. Such adaptations in petiole length are enabled through differences in the total number of cells, individual cell size, or both [ 45 ].…”

Trade-offs between petiole and lamina of different functional plants in Xiao Hinggan Mountains, China

“…)。叶作为植物能量获取的主要器官, 其性状决 定了植物的许多生态功能, 如光合作用、蒸腾作用、 对极端温度的适应能力以及对叶内各结构的生物量 投资等。另外, 叶功能性状还可以反映植物自身生 物量的分配格局及其对环境的适应能力 (Li et al, 2008;杨冬梅等, 2012;Li et al, 2021), 如"收益递 减"假说认为随着叶大小增加, 植物叶面积增长速 率慢于叶生物量, 表明植物拦截光的结构成本随着 叶面积增加增长得更快 (Niklas et al, 2007), 并且这 种异速生长关系会随环境条件发生变化 (Zhu et al, 2019)。 光合固碳是植物碳收益的主要来源, 叶作为主 要的光合器官, 其光合收益与必要支撑结构(如小 枝)的生物量分配关系是近年来生态学与全球变化 研究的重点 (Westoby & Wright, 2003;Yan et al, 2013;Smith et al, 2016;Wang et al, 2019;Zhu et al, 2019;尹凤娟等, 2021) (Niklas, 1999;祝介东等, 2011), 因此柄叶结构之间可能存在典型的权衡关 系 (Niinemets et al, 2007b;Li et al, 2021)。受温度、 水分、光照等外界因素的影响, 叶片大小常呈现有 规律的变化趋势 (Bazzaz & Carlson, 1982;Wright et al, 2017), 叶柄也会表现出相应的适应性特征, 如 生长在高海拔的同种植物通常会投入更多生物量给 叶柄 (Li et al, 2008); 在强光照与强风环境中, 叶柄 所占的生物量比例往往会增加 (Niinemets & Kull, 1999;Niklas, 1999); 不同习性植物(常绿和落叶)叶 内生物量分配比例也常常不同, 在给定叶柄干质 量下, 常绿植物的叶片面积小于落叶植物, 但叶片 生物量反而高于落叶植物 (Li et al, 2008)。柄叶关 系是研究植物光合效率和支持/保护成本之间功能 权衡的核心 (Li et al, 2021), 上述结果均表明叶片 与叶柄性状之间存在显著的相关关系, 充分了解 叶内各结构的权衡关系对探讨植物对环境的适应 性, 揭示植物的生长策略及资源分配模式具有重 要意义。 目前关于叶片与叶柄生物量分配关系的研究大 多局限在乔木 (Li et al, 2008;潘少安等, 2015), 但 不同生活型植物生活史对策通常不同 (Niinemets et al, 2007a;祝介东等, 2011), 因此针对不同生活型 植物的柄叶权衡关系开展研究十分必要。此外, 有 研究发现相较于植物小枝, 复叶的叶柄作为一次性 (每年更换茎状叶柄)的支撑结构, 可以降低叶子着 生的结构成本, 帮助植物以尽可能低的成本获取光 源 (Malhado et al, 2010)。目前关于叶型对植物功能 性状影响的实验主要集中于乔木 (Li et al, 2008;Song et al, 2018) (Poorter, 2009;Meng et al, 2015); 二是"碳增益假 说", 支持者认为耐阴植物为了适应昏暗环境, 会采 取提高光截获能力、 降低呼吸消耗的策略 (Valladares & Niinemets, 2008;Meng et al, 2015) In order to make the leaf trait data from differen...…”