BackgroundWild apple (Malus sieversii) is under second-class national protection in China and one of the lineal ancestors of cultivated apples worldwide. In recent decades, the natural habitation area of wild apple trees has been seriously declining, resulting in a lack of saplings and difficulty in population regeneration. Artificial near-natural breeding is crucial for protecting and restoring wild apple populations, and adding nitrogen (N) and phosphorous (P) is one of the important measures to improve the growth performance of saplings. In this study, field experiments using N (CK, N1, N2, and N3: 0, 10, 20, and 40 g m(- 2) yr(- 1), respectively), P (CK, P1, P2, and P3: 0, 2, 4, and 8 g m(- 2) yr(- 1), respectively), N20Px (CK, N2P1, N2P2, and N2P3: N20P2, N20P4 and N20P8 g m(- 2) yr(- 1), respectively), and NxP4 (CK, N1P2, N2P2, and N3P2: N10P4, N20P4, and N40P4 g m(- 2) yr(- 1), respectively) treatments (totaling 12 levels, including one CK) were conducted in four consecutive years. The twig traits (including four current-year stem, 10 leaf, and three ratio traits) and comprehensive growth performance of wild apple saplings were analyzed under different nutrient treatments.ResultsN addition had a significantly positive effect on stem length, basal diameter, leaf area, and leaf dry mass, whereas P addition had a significantly positive effect on stem length and basal diameter only. The combination of N and P (NxP4 and N20Px) treatments evidently promoted stem growth at moderate concentrations; however, the N20Px treatment showed a markedly negative effect at low concentrations and a positive effect at moderate and high concentrations. The ratio traits (leaf intensity, leaf area ratio, and leaf to stem mass ratio) decreased with the increase in nutrient concentration under each treatment. In the plant trait network, basal diameter, stem mass, and twig mass were tightly connected to other traits after nutrient treatments, indicating that stem traits play an important role in twig growth. The membership function revealed that the greatest comprehensive growth performance of saplings was achieved after N addition alone, followed by that under the NxP4 treatment (except for N40P4).ConclusionsConsequently, artificial nutrient treatments for four years significantly but differentially altered the growth status of wild apple saplings, and the use of appropriate N fertilizer promoted sapling growth. These results can provide scientific basis for the conservation and management of wild apple populations.
背景野生苹果 （Malus sieversii） 是中国的二级国家保护物种，是全世界种植苹果的直系祖先之一。近几十年来，野苹果树的自然栖息面积严重下降，导致树苗匮乏，种群再生困难。人工近自然育种对于保护和恢复野生苹果种群至关重要，添加氮 （N） 和磷 （P） 是提高树苗生长性能的重要措施之一。在本研究中，使用 N（CK、N1、N2 和 N3：分别为 0、10、20 和 40 g m（- 2） yr（- 1））、P（CK、P1、P2 和 P3：分别为 0、2、4 和 8 g m（- 2） yr（- 1））、N20Px（CK、N2P1、N2P2 和 N2P3：分别为 N20P2、N20P4 和 N20P8 g m（- 2） yr（- 1））， 和 NxP4 （CK、N1P2、N2P2 和 N3P2：分别为 N10P4、N20P4 和 N40P4 g m（-2） yr（- 1））治疗 （共 12 个水平，包括 1 个 CK） 连续四年进行。分析不同营养处理下野苹果树苗的枝条性状 （包括 4 个当年茎性状、10 个叶性状和 3 个比例性状）和综合生长性能。结果氮添加对茎长、基径、叶面积和叶片干质量有显著的正向影响，而磷添加仅对茎长和基径有显著的正向影响。N 和 P （NxP4 和 N20Px） 处理的组合在中等浓度下明显促进了茎的生长;然而，N20Px 处理在低浓度下显示出明显的负面影响，在中等和高浓度下显示出积极影响。 各处理下，比值性状 （叶强度、叶面积比和叶茎质量比） 随着养分浓度的增加而降低。在植物性状网络中，营养处理后，基部直径、茎质量和枝质量与其他性状紧密相连，表明茎性状在枝条生长中起重要作用。隶属函数显示，单独添加 N 后树苗的综合生长性能最大，其次是 NxP4 处理下（N40P4 除外）。结论因此，4 年的人工营养处理显著但差异性地改变了野苹果树苗的生长状态，适宜施氮肥促进了树苗生长。这些结果可为野生苹果种群的保护和管理提供科学依据。

Malus sieversii (wild apple trees) is a tertiary relict tree species and a key ancestor of the cultivated apple trees today. In recent years, serious growth decline and individual death have occurred for M. sieversii. Whether growth decline would lead to the change in twig (composed of leaves and one-year stem) functional traits and their associations of wild apple trees remains unclear. Two long-term monitoring plots (1 hm(2)) for severely declined and relatively healthy wild apple trees, respectively, were set up in Yili Valley, China. Based on two-year investigations, the differences in tree functional traits and interrelations between the two plots and the influencing factors were analyzed. The crown projective cover, dead branch percentage, and fruit yield were markedly different between two sites and two years. Leaf nitrogen and phosphorous concentrations of declined trees were generally less than healthy trees, although the soil of the former was more fertile. The nitrogen was more susceptible to the stressing, especially for declined trees. Concentrations of stem nitrogen, phosphorous, and potassium and leaf potassium were relatively stable in both plots. The plant trait network analysis indicated that leaf nitrogen (per unit area) that promoted plant growth was the hub trait (meaning that it is correlated with most traits) for healthy trees, while leaf potassium (per unit mass) that related to resistance enhancement became the hub trait for declined trees. Meanwhile, the covariant characteristics of twig traits between the two plots differed obviously, and the soil-trait and growth-trait correlations became more negative for declined trees than healthy trees, indicating that intra-trait and environment-trait associations had changed greatly when trees declined. The ordination analysis revealed that total and available soil nitrogen, phosphorous, and total potassium, pH and plant growth parameters significantly influenced twig traits. Our results demonstrated that twig functional traits and their interrelations of wild apple trees can indicate tree decline trend. We strongly recommend that managers should take measures to prevent the decline of healthy wild apple trees as soon as possible to realize the sustainable existence of this precious germplasm resource. The results provide a theoretical support for scientific management of wild apple populations in the Tianshan Mountains in Central Asia.
Malus sieversii（野生苹果树）是第三纪孑遗树种，也是当今栽培苹果树的关键祖先。近年来，M. sieversii 的生长严重下降和个体死亡。生长下降是否会导致野生苹果树枝（由叶子和一年生茎组成）功能性状的变化及其关联尚不清楚。在中国伊犁河谷建立了两个严重衰退和相对健康的野生苹果树长期监测样地 （1 hm（2））。在两年调查的基础上，分析了树木功能性状的差异、两样地之间的相互关系及其影响因素。树冠投影覆盖率、枯枝百分比和果实产量在 2 个地点和 2 年之间存在显著差异。衰落树木的叶片氮和磷浓度通常低于健康树木，尽管前者的土壤更肥沃。氮更易受到压力的影响，尤其是对于衰落的树木。两个样地茎氮、磷、钾和叶钾的浓度相对稳定。植物性状网络分析表明，促进植物生长的叶氮（每单位面积）是健康树木的中心性状（意味着它与大多数性状相关），而与抗性增强相关的叶钾（每单位质量）成为衰退树木的中心性状。同时，两样地间枝条性状的协变特征差异明显，衰退树木的土壤-性状和生长-性状相关性比健康树更负，表明当树木-树木衰退时，性状内和环境-性状关联发生了很大变化。 排序分析显示，土壤总氮、磷和全钾、pH 值和植物生长参数显着影响枝条性状。结果表明，野生苹果树枝条功能性状及其相互关系可以指示树木衰退趋势。我们强烈建议管理者尽快采取措施防止健康的野生苹果树衰退，以实现这一宝贵种质资源的可持续存在。研究结果为中亚天山地区野生苹果种群的科学管理提供了理论支持。

Premise To support large leaves, many woody plant species evolved a cost-effective way to thicken twigs. As an extension of E. J. H. Corner's rule that twig diameter increases with leaf size, we hypothesized that pith width also increases with leaf size. The benefit to the plant from the proposed relationship is that pith is a low-cost tissue that reduces the metabolic cost of large diameter twig production. Methods Leaf sizes and cross-sectional areas of bark, xylem, and pith of 81 species of trees and shrubs growing in Gainesville, Florida were measured and compared with standardized major axis regressions of pairwise species trait values and phylogenetically independent contrasts. Results Pith area increases with leaf size with or without accounting for phylogenetic relationships. In agreement with Corner's rule, overall twig diameter as well as bark and wood thickness also increase with leaf size. Thicker twigs showed more variation in relative pith, wood, and bark cross-sectional areas compared to thinner twigs. Conclusions Investments in pith, a tissue of low density found in the centers of twigs, provides a low-cost way to increase twig circumference and thereby space for attachment of large leaves while increasing the overall second moment of area of twigs, which increases their ability to biomechanically support large leaves.
前提 为了支撑大叶子，许多木本植物物种进化出一种经济高效的方法来加厚树枝。作为 E. J. H. Corner 规则的延伸，即树枝直径随叶子大小增加，我们假设髓宽也随叶子大小增加。拟议的关系对植物的好处是髓是一种低成本的组织，可降低大直径树枝生产的代谢成本。方法 测量了生长在佛罗里达州盖恩斯维尔的 81 种乔木和灌木的叶子大小和树皮、木质部和髓的横截面积，并与成对物种性状值的标准化主轴回归和系统发育独立对比进行了比较。结果 髓面积随叶子大小增加，无论是否考虑系统发育关系。与 Corner 规则一致，整体树枝直径以及树皮和木材的厚度也随着叶子的大小而增加。与较细的树枝相比，较粗的树枝在相对髓、木材和树皮横截面积上表现出更大的变化。结论对髓（一种在树枝中心发现的低密度组织）的投资提供了一种低成本的方法，可以增加树枝周长，从而为大叶子的附着留出空间，同时增加树枝总第二矩面积，这增加了它们生物力学支撑大叶子的能力。

Understanding the scaling between leaf size and leafing intensity (leaf number per stem size) is crucial for comprehending theories about the leaf costs and benefits in the leaf size-twig size spectrum. However, the scaling scope of leaf size versus leafing intensity changes along the twig leaf size variation in different leaf habit species remains elusive. Here, we hypothesize that the numerical value of scaling exponent for leaf mass versus leafing intensity in twig is governed by the minimum leaf mass versus maximum leaf mass (M-min versus M-max) and constrained to be <=-1.0. We tested this hypothesis by analyzing the twigs of 123 species datasets compiled in the subtropical mountain forest. The standardized major axis regression (SMA) analyses showed the M-min scaled as the 1.19 power of M-max and the -alpha (-1.19) were not statistically different from the exponents of M-min versus leafing intensity in whole data. Across leaf habit groups, the M-max scaled negatively and isometrically with respect to leafing intensity. The pooled data's scaling exponents ranged from -1.14 to -0.96 for M-min and M-max versus the leafing intensity based on stem volume (LIV). In the case of M-min and M-max versus the leafing intensity based on stem mass (LIM), the scaling exponents ranged from -1.24 to -1.04. Our hypothesis successfully predicts that the scaling relationship between leaf mass and leafing intensity is constrained to be <=-1.0. More importantly, the lower limit to scaling of leaf mass and leafing intensity may be closely correlated with M-min versus M-max. Besides, constrained by the maximum leaf mass expansion, the broad scope range between leaf size and number may be insensitive to leaf habit groups in subtropical mountain forest.
了解叶子大小和出叶强度（每个茎大小的叶数）之间的缩放对于理解叶子大小-小枝大小光谱中关于叶子成本和收益的理论至关重要。然而，在不同叶习性物种中，叶片大小与出叶强度沿枝叶大小变化的缩放范围仍然难以捉摸。在这里，我们假设树枝中叶片质量与出叶强度的缩放指数的数值由最小叶片质量与最大叶片质量（M-min 与 M-max）控制，并限制为 <=-1.0。我们通过分析在亚热带山地森林中汇编的 123 个物种数据集的树枝来检验这一假设。标准化长轴回归 （SMA） 分析显示，M-min 缩放为 M-max 的 1.19 次方，而 -alpha （-1.19） 与整个数据中 M-min 与叶片强度的指数没有统计学差异。在叶片习性组中，M-max 相对于叶片强度呈负向和等距缩放。对于基于茎体积 （LIV） 的叶状强度，合并数据的缩放指数范围为 -1.14 到 -0.96（对于 M-min 和 M-max）。在 M-min 和 M-max 与基于茎质量 （LIM） 的出叶强度的情况下，缩放指数范围为 -1.24 至 -1.04。我们的假设成功预测了叶片质量和出叶强度之间的缩放关系被限制为 <=-1.0。更重要的是，叶片质量和出叶强度的缩放下限可能与 M-min 与 M-max 密切相关。此外，受最大叶量扩张的限制，亚热带山地森林叶片大小和数量之间的宽范围范围可能对叶习性组不敏感。

The trade-off between leaf number and individual leaf size on current-year shoots (twigs) is crucial to light interception and thus net carbon gain. However, a theoretical basis for understanding this trade-off remains elusive. Here, we argue that this trade-off emerges directly from the relationship between annual growth in leaf and stem mass, a hypothesis that predicts that maximum individual leaf size (i.e. leaf mass, M-max, or leaf area, A(max)) will scale negatively and isometrically with leafing intensity (i.e. leaf number per unit stem mass, per unit stem volume or per stem cross-sectional area). We tested this hypothesis by analysing the twigs of 64 species inhabiting three different forest communities along an elevation gradient using standardized major axis (SMA) analyses. Across species, maximum individual leaf size (M-max, A(max)) scaled isometrically with respect to leafing intensity; the scaling constants between maximum leaf size and leafing intensity (based on stem cross-sectional area) differed significantly among the three forests. Therefore, our hypothesis successfully predicts a scaling relationship between maximum individual leaf size and leafing intensity, and provides a general explanation for the leaf size-number trade-off as a consequence of mechanical-hydraulic constraints on stem and leaf growth per year.
当年嫩芽（小枝）的叶数和单个叶子大小之间的权衡对于光拦截和净碳增益至关重要。然而，理解这种权衡的理论基础仍然难以捉摸。在这里，我们认为这种权衡直接来自叶子和茎质量的年生长之间的关系，这一假设预测最大单个叶子的大小（即叶质量，M-max 或叶面积，A（max））将与出叶强度（即每单位茎质量、每单位茎体积或每茎横截面积的叶数）呈负等距缩放。我们通过使用标准化主轴 （SMA） 分析沿海拔梯度分析栖息在三个不同森林群落中的 64 个物种的树枝来检验这一假设。在物种中，最大单片叶子大小 （M-max， A（max）） 根据出叶强度按等距缩放;最大叶长和出叶强度（基于茎横截面积）之间的缩放常数在 3 种森林中差异显著。因此，我们的假设成功地预测了最大单片叶大小和出叶强度之间的缩放关系，并为每年茎和叶生长的机械水力限制导致叶子大小-数量权衡提供了一般解释。

Background and aims: The "diminishing returns" hypothesis postulates that the scaling exponent governing the lamina area versus lamina mass scaling relationships has, on average, a numerical value less than one. Theoretically, a similar scaling relationship may exist at the twig level. However, this possibility has not been explored empirically. Methods: We tested both hypotheses by measuring the lamina area and mass, petiole mass of individual leaves, and the total foliage area and stem mass of individual current-year shoots (twigs) of 64 woody species growing in three characteristic forest community types: (1) Evergreen broad-leaved, (2) mixed coniferous and broad-leaved, and (3) deciduous. Key results: The results demonstrate that lamina area vs. mass and lamina area vs. petiole mass differ significantly among the three forest types at both the individual leaf and twig levels. Nevertheless, the scaling exponents of lamina area vs. mass were <1.0 in each of the three community types, as were the corresponding exponents for lamina area vs. petiole mass, both within and across the three community types. Similar trends were observed at the individual twig level. The numerical values of the scaling exponent for lamina area vs. petiole mass and total foliage area vs. stem mass per twig decreased with increased elevation. Conclusions: These data support the "diminishing returns" hypothesis at both the individual leaf level and at the individual twig level, phenomena that can inform future inquiries into the mechanistic basis of biomass allocation patterns to physiological (leaf) and mechanical (stem) plant organs.
背景和目标：“收益递减”假说假设控制层面积与层状质量缩放关系的缩放指数平均而言，其数值小于 1。从理论上讲，在 twig 级别可能存在类似的缩放关系。然而，这种可能性尚未得到实证探索。方法：我们通过测量生长在三种特征森林群落类型的 64 种木本物种的叶片面积和质量、单片叶柄质量以及当年单个枝条（小枝）的总叶面积和茎质量来检验这两种假设：（1） 常绿阔叶，（2） 针阔混交，以及 （3） 落叶。主要结果： 结果表明，三种森林类型的叶片面积与质量以及叶片面积与叶柄质量在单个叶片和枝条水平上都存在显著差异。然而，在三种群落类型中，叶片面积与质量的缩放指数为 <1.0，在三种群落类型内和跨三种群落类型中，叶片面积与叶柄质量的相应指数也是如此。在单个小枝水平上观察到类似的趋势。每根小枝的叶片面积与叶柄质量以及总叶面积与茎质量的缩放指数的数值随着海拔的增加而减小。结论：这些数据在单个叶子水平和单个小枝水平上都支持“收益递减”假说，这些现象可以为未来对生物量分配给生理（叶）和机械（茎）植物器官的机制基础的调查提供信息。

Relationships among twig size, leaf size and leafing intensity are essential for predicting structure and function of twigs and leaves and ability of plants to acquire different environmental resources. We aimed to test whether trade-offs between twig and leaf traits for species would be influenced by forest successional status and sampling orientation within canopy. We measured four twig and leaf traits for seven coexisting broadleaf species across successional statuses in mixed broadleaved-Korean pine (Pinus koraiensis) forests in Northeast China. The results showed that both twig and leaf traits varied with successional status and twig level explained the largest variations in traits. Slopes of regression of leaf traits (i.e. individual leaf area, total leaf area and volume-based leafing intensity) against twig cross-sectional area were late-successional species > middle-successional species > early-successional species. Relationships between twig cross-sectional area and total leaf area in upper south and lower north canopy orientations did not vary with successional status of species. However, slopes of regression of twig cross-sectional area against total leaf area varied with successional status in other four sampling orientations. Our results highlight the importance of successional status and sampling orientation within canopy in controlling variations and trade-offs between twig and leaf traits.
枝条大小、叶子大小和出叶强度之间的关系对于预测枝条和叶子的结构和功能以及植物获取不同环境资源的能力至关重要。我们旨在测试物种枝叶性状之间的权衡是否会受到森林演替状况和树冠内采样方向的影响。我们测量了东北阔叶红松 （Pinus koraiensis） 混交林中 7 种共存阔叶树种的 4 个枝叶性状。结果表明，枝和叶性状均随演替状态而变化，枝水平解释了最大的性状变化。叶片性状 （即单个叶面积、总叶面积和基于体积的出叶强度） 与枝横截面积的回归斜率为晚演替物种 > 中期演替物种 > 早期演替物种。上南和北下树冠方向的枝横截面积与总叶面积之间的关系不随物种的演替状况而变化。然而，在其他 4 个采样方向上，枝条横截面积与总叶面积的回归斜率随演替状态而变化。我们的结果强调了冠层内的演替状态和采样方向在控制枝和叶性状之间的变化和权衡中的重要性。

The relationship between leaf and stem biomass as well as the relationship between leaf biomass and stem length and diameter are important to our understanding of a broad range of important plant scaling relationship because of their relationship to photosynthesis and thus growth. To understand how twig architecture (i.e., current year leaves, and stem diameter and length) affects stem diameter and length, and leaf number and biomass, we examined the twigs of 64 woody species collected from three forest types along an elevational gradient in the Wuyi Mountains, Jiangxi Province, China. We also compared the scaling relationships we observed with biomass allocation patterns reported at the whole tree level. Our results revealed isometric relationship between leaf and stem biomass on twigs despite differences in forest communities and despite changes in environmental factors along an elevational gradient. Across the 64 species, from twigs to individual trees, leaf biomass scaled approximately as the 2.0-power of stem diameter (but not for stem length or leaf number). These results help to identify a general rule that operates at two different levels of biological organization (twigs and whole trees). The scaling relationship between leaf biomass and stem diameter in twigs is insensitive to differences in species composition, elevation, or forest type. We speculate that this rule emerges because stem diameter serves as a proxy for the amount of resources supplied per unit cross section to developing leaves and for the flow of photosynthates from mature leaves to the rest of the plant body.
叶子和茎生物量之间的关系以及叶子生物量和茎长和直径之间的关系对于我们理解广泛的重要植物尺度关系很重要，因为它们与光合作用和生长有关。为了了解枝条结构（即当年叶子、茎粗和长）如何影响茎粗和长度、叶数和生物量，我们研究了中国江西省武夷山沿海拔梯度从三种森林类型中收集的 64 种木本物种的枝条。我们还将观察到的尺度关系与整棵树水平报告的生物量分配模式进行了比较。我们的结果揭示了尽管森林群落存在差异，并且尽管环境因素沿海拔梯度发生变化，但枝条上叶和茎生物量之间存在等长关系。在 64 个物种中，从小枝到单棵树，叶生物量大约是茎直径的 2.0 次方（但不包括茎长或叶数）。这些结果有助于确定在生物组织的两个不同级别（树枝和整棵树）起作用的一般规则。小枝中叶片生物量和茎粗之间的缩放关系对物种组成、海拔或森林类型的差异不敏感。我们推测，这条规则的出现是因为茎直径代表了每单位横截面提供给发育中的叶子的资源量，以及光合产物从成熟叶子流向植物身体的其他部分。

Background and Aims Corner's rule states that thicker twigs bear larger leaves. The exact nature of this relationship and why it should occur has been the subject of numerous studies. It is obvious that thicker twigs should support greater total leaf area (A(twig)) for hydraulical and mechanical reasons. But it is not obvious why mean leaf size (A) over bar should scale positively with Atwig. We asked what this scaling relationship is within species and how variable it is across species. We then developed a model to explain why these relationships exist.
背景和目标 Corner 的规则指出，较粗的树枝结出较大的叶子。这种关系的确切性质以及为什么会发生一直是许多研究的主题。很明显，出于液压和机械原因，较粗的树枝应该支持更大的总叶面积 （A（twig））。但并不明显为什么平均叶子大小 （A） 超过 bar 应该与 Atwig 呈正比例。我们询问了物种内部的这种缩放关系是什么，以及它在物种之间的变化有多大。然后，我们开发了一个模型来解释为什么存在这些关系。

Methods To minimize potential sources of variability, we compared twig properties from six co-occurringand functionally similar species: Acer grandidentatum, Amelanchier alnifolia, Betula occidentalis, Cornus sericea, Populus fremontii and Symphoricarpos oreophilus. We modelled the economics of leaf display, weighing the benefit from light absorption against the cost of leaf tissue, to predict the optimal (A) over bar : A(twig) combinations under different canopy openings.
方法为了尽量减少潜在的变异来源，我们比较了六个同时出现且功能相似的物种的枝条特性：Acer grandidentatum、Amelanchier alnifolia、Betula occidentalis、Cornus sericea、Populus fremontii 和 Symphoricarpos oreophilus。我们模拟了叶子展示的经济性，权衡了光吸收的好处与叶组织的成本，以预测不同冠层开口下的最佳 （A） 优于 bar ： A（twig） 组合。

Key Results We observed a common (A) over bar by A(twig) exponent of 0.6, meaning that A (A) over bar and leaf number on twigs increased in a specific coordination. Common scaling exponents were not supported for relationships between any other measured twig properties. The model consistently predicted positive (A) over bar A by A(twig) scaling when twigs optimally filled canopy openings. The observed 0.6 exponent was predicted when self-shading decreased with larger canopy opening.
主要结果我们观察到 A （树枝） 指数的共同 （A） 超过 bar，指数为 0.6，这意味着 A （A） 超过 bar 和树枝上的叶子数在特定协调中增加。任何其他测量的 twig 属性之间的关系不支持公共缩放指数。当树枝以最佳方式填充树冠开口时，该模型始终预测正 （A） 超过条形 A 和 A（树枝）缩放。当自阴影随着冠层开度的增加而减小时，观察到的 0.6 指数是预测的。

Conclusions Our results suggest Corner's rule may be better understood when recast as positive A by A(twig) scaling. Our model provides a tentative explanation of observed A by A(twig) scaling and suggests different scaling may exist in different environments.
结论 我们的结果表明，当通过 A（twig） 缩放转换为正 A 时，可能会更好地理解 Corner 规则。我们的模型提供了对 A（twig） 缩放观察到的 A 的初步解释，并表明不同的环境中可能存在不同的缩放。

During the development of woody twigs, the growth in leaf may or may not be proportional to the growth in stem. The presence or absence of a synchronicity between these two phenologies may reflect differences in life history adaptive strategies concerning carbon gain. We hypothesized that sun-adapted species are more likely to be less synchronous between growths in total leaf area (TLA) and stem length compared with shade-adapted species, with a bias in growth in stem length, and that shade-adapted species are more likely to be more synchronous between increases in individual leaf area (ILA) (leaf size) and leaf number (LN) during twig development compared with sun-adapted species, giving priority to growth of leaf size. We tested these two hypotheses by recording the phenologies of leaf emergence, leaf expansion and stem elongation during twig development for 19 evergreen woody species (including five shade-adapted understory species, six sun-adapted understory species and eight sun-adapted canopy species) in a subtropical evergreen broad-leaved forest in eastern China. We constructed indices to characterize the synchronicity between TLA and stem length (alpha(LS)) and between leaf size and leaf number (alpha(SN)) and we derived the alpha values from logistic functions taking the general form of A = A(max)/[1 + exp(beta - alpha B)] (where A is the TLA or average ILA, B is the corresponding stem length or LN at a specific time, and A(max) is the maximum TLA or the maximum ILA of a twig; the higher the numerical value of alpha, the less synchronous the corresponding phenologies). Consistent with our hypotheses, sun-adapted species were higher both in alpha(LS) and alpha(SN), showing less synchronous patterns in the growths of TLA vs stem length and leaf size vs LN during twig development. Moreover, alpha(LS) and alpha(SN) were significantly positively correlated with relative growth rates of LN and leaf size across species, as indicated by both analyses of ordinary regression and phylogenetic generalized least squares. The across-species synchronies during twig development show that the temporal dynamics of the leaf size-twig size spectrum is of adaptive significance in plants. We suggest that temporal dynamics of plant functional traits should be extensively studied to characterize plant life history.
在木本小枝的发育过程中，叶子的生长可能与茎的生长成正比，也可能不成比例。这两个 Phenologies 之间存在或不存在同步性可能反映了关于碳增益的生活史适应性策略的差异。我们假设，与适应阳光的物种相比，适应阳光的物种更有可能在总叶面积 （TLA） 和茎长的生长之间不同步，在茎长的生长中具有偏差，并且与适应阳光的物种相比，适应阳光的物种更有可能在枝条发育过程中单个叶面积 （ILA）（叶大小）和叶数 （LN） 的增加之间更加同步， 优先考虑叶子大小的生长。我们通过记录华东亚热带常绿阔叶林中 19 种常绿木本植物 （包括 5 种适应阴凉的林下物种、6 种适应阳光的林下物种和 8 种适应阳光的树冠物种） 在枝条发育过程中的叶片出苗、叶片扩张和茎伸长的酚类特征来检验这两个假设。我们构建了指数来表征 TLA 和茎长 （alpha（LS）） 以及叶长和叶数 （alpha（SN）） 之间的同步性，我们从逻辑函数中得出 alpha 值，其一般形式为 A = A（max）/[1 + exp（beta - alpha B）]（其中 A 是 TLA 或平均 ILA，B 是特定时间相应的茎长或 LN， A（max） 是树枝的最大 TLA 或最大 ILA;alpha 的数值越高，相应的物候的同步性就越低）。 与我们的假设一致，日照适应物种的 alpha （LS） 和 alpha （SN） 都较高，在枝条发育过程中，TLA 与茎长和叶子大小与 LN 的生长模式不太同步。此外，alpha （LS） 和 alpha （SN） 与 LN 的相对生长速率和不同物种的叶片大小呈显著正相关，普通回归和系统发育广义最小二乘分析都表明了这一点。枝条发育过程中的跨物种同步表明，叶子大小-枝条大小谱的时间动态在植物中具有适应性意义。我们建议应广泛研究植物功能性状的时间动态，以表征植物生活史。

Understanding scaling relationships between twig size and leaf size along environmental gradients is important for revealing strategies of plant biomass allocation with changing environmental constraints. However, it remains poorly understood how variations in the slope and y-intercept in the twig-leaf size relationship partition among individual, population and species levels across communities. Here, we determined the scaling relationships between twig cross-sectional area (twig size) and total leaf area per twig (leaf size) among individual, population and species levels along a soil moisture gradient in subtropical forests in eastern China. Twig and leaf tissues from 95 woody plant species were collected from three sites that form a soil moisture gradient: a wet site (W), a mesophytic site (M), and a dry site (D). The valiance in scaling slope and y-intercept was partitioned among individual, population and species levels using a nested ANOVA. In addition, the change in the twig-leaf size relationship over the soil moisture gradient was determined for each of overlapping and turnover species. Twig size was positively related to leaf size across the three levels, with the variance partitioned at the individual level in scaling slope and y-intercept being 98 and 90%, respectively. Along the soil moisture gradient, the twig-leaf size relationship differed inter- and intraspecifically. At the species and population levels, there were homogeneous slopes but the y-intercept was W > M = D. In contrast, at the individual level, the regression slopes were heterogeneous among the three sites. More remarkably, the twig-leaf size relationships changed from negative allometry for overlapping species to isometry for turnover species. This study provides strong evidence for the twig-leaf size relationship to be intraspecific, particularly at the individual level. Our findings suggest that whether or not species have overlapping habitats is crucial for shaping the deployment pattern between twigs and leaves. (C) 2014 Elsevier Masson SAS. All rights reserved.
了解沿环境梯度的枝条大小和叶子大小的缩放关系对于揭示环境约束变化下的植物生物量分配策略非常重要。然而，人们仍然知之甚少，因为树枝-叶大小关系的斜率变化和 y 截距是如何在群落的个体、种群和物种水平之间划分的。在这里，我们确定了中国东部亚热带森林土壤水分梯度沿线枝横截面积（枝条大小）和每枝总叶面积（叶大小）在个体、种群和物种水平之间的尺度关系。从形成土壤水分梯度的三个地点收集了 95 种木本植物的树枝和叶组织：湿地 （W）、中生地 （M） 和干燥地 （D）。使用嵌套方差分析在个体、种群和物种水平之间划分缩放斜率和 y 截距的效价。此外，还确定了每个重叠和周转物种的树枝-叶大小关系随土壤水分梯度的变化。枝条大小与三个水平的叶子大小呈正相关，在缩放斜率和 y 轴截距的单个水平上，方差分别为 98% 和 90%。沿着土壤水分梯度，枝叶大小关系在种间和种内不同。在物种和种群水平上，存在均匀的斜率，但 y 轴截距为 W > M = D。相比之下，在个体水平上，三个站点之间的回归斜率是异质的。更值得注意的是，树枝-叶大小关系从重叠物种的负异速生长转变为周转物种的等距关系。 这项研究为树枝-叶大小关系是种内关系提供了强有力的证据，特别是在个体水平上。我们的研究结果表明，物种是否具有重叠的栖息地对于塑造树枝和树叶之间的部署模式至关重要。（c） 2014 年 Elsevier Masson SAS。保留所有权利。

Scaling relationships among twig size, leaf size and leafing intensity fundamentally influence the twig-leaf deployment pattern, a property that affects the architecture and functioning of plants. However, our understanding of how these relationships change within a species or between species as a function of forest succession is unclear. We determined log-log scaling relationships between twig cross-sectional area (twig size) and each of total and individual leaf area, and leafing intensity (the number of leaves per twig volume) for 78 woody species along a successional series in subtropical evergreen forests in eastern China. The series included four stages: secondary shrub (S1), young (S2), sub-climax (S3) and climax evergreen broadleaved forests (S4). The scaling slopes in each of the three relationships did not differ among the four stages. The y-intercept did not shift among the successional stages in the relationship between twig cross-sectional area and total leaf area; however, the y-intercept was greatest in S4, intermediate in S3 and lowest in S2 and S1 for the relationship between twig size and individual leaf area, while the opposite pattern was found for the twig size-leafing intensity relationship. This indicates that late successional trees have few but large leaves while early successional trees have more small leaves per unit twig size. For the relationship between twig cross-sectional area and total leaf area, there was no difference in the regression slope between recurrent (appear in more than one stages) and non-recurrent species (appear in only one stage) for each of the S1-S2, S2-S3 and S3-S4 pairs. A significant difference in the y-intercept was found in the S2-S3 pair only. In the relationship between twig cross-sectional area and individual leaf area, the regression slope between recurrent and non-recurrent species was homogeneous in the S1-S2 and S3-S4 pairs, but heterogeneous in the S2-S3 pair. We conclude that forest succession caused the shift in the intercept, but did not affect scaling slopes for relationships among twig size, leaf size and leaf intensity. For recurrent species, the invariant scaling slope in the twig-leaf size relationship between adjacent pairs of successional stages may be related to their phenotypic plasticity by adjusting their twig and leaf deployment strategy to similar to what the non-recurrent species display.
树枝大小、叶子大小和叶子生长强度之间的缩放关系从根本上影响树枝-叶子部署模式，这是影响植物结构和功能的特性。然而，我们对物种内部或物种之间这些关系如何随森林演替而变化的理解尚不清楚。我们确定了中国东部亚热带常绿林中 78 种木本植物沿演替系列的枝横截面积 （枝条大小） 与总叶面积和单个叶面积以及出叶强度 （每个枝条体积的叶数） 之间的对数-对数比例关系。该系列包括次生灌木 （S1）、幼生 （S2）、亚顶生 （S3） 和顶生常绿阔叶林 （S4） 4 个阶段。这三种关系中每一种关系的缩放斜率在四个阶段之间没有差异。在枝横截面积与总叶面积之间的关系中，y 截距在演替阶段之间没有变化;然而，对于枝条大小和单个叶面积之间的关系，Y-截距在 S4 中最大，在 S3 中居中，在 S2 和 S1 中最低，而在枝条大小-叶状强度关系中发现相反的模式。这表明晚期演替树的叶子很少但很大，而早期演替树每单位树枝大小的叶子更多。对于枝横截面积与总叶面积之间的关系，S1-S2、S2-S3 和 S3-S4 对的递归物种 （出现在多个阶段） 和非递归物种 （仅出现在一个阶段） 的回归斜率没有差异。仅在 S2-S3 对中发现了 y 截距的显著差异。 在枝横截面积与单个叶面积的关系中，S1-S2 和 S3-S4 对中循环物种和非循环物种之间的回归斜率是均匀的，而在 S2-S3 对中是异质的。我们得出结论，森林演替导致了截距的变化，但不影响枝条大小、叶子大小和叶强度之间关系的缩放斜率。对于循环物种，相邻演替阶段之间树枝-叶大小关系的不变缩放斜率可能与它们的表型可塑性有关，方法是将它们的树枝和叶子部署策略调整为类似于非循环物种所显示的。

Background and aims - The leaf size/number trade-off has been recently established as a wide-spread and highly predictable relationship associated with between-species leaf size variation. In this study, we examine whether this trade-off relationship also applies at the between-plant (within-species), and at the between-shoot (within-plant) levels associated with spatial variation in incident light availability within tree canopies.
背景和目标 - 叶子大小/数量的权衡最近已被确立为与物种间叶子大小变化相关的广泛且高度可预测的关系。在这项研究中，我们检查了这种权衡关系是否也适用于植物间（种内）和与树冠内入射光可用性空间变化相关的芽间（植物内）水平。

Methods - Replicate current-year shoots were sampled from north-facing (shaded) and south-facing (sun-exposed) canopy sides of sixteen broadleaf tree species in eastern Ontario, Canada. For each shoot, measurements were recorded for mean individual leaf dry mass, number of leaves, number of side branches, and stem length, girth, and tissue dry mass. Leafing intensity was calculated as the number of leaves produced per unit of supporting stem tissue dry mass.
方法 - 从加拿大安大略省东部 16 种阔叶树种的朝北（阴凉）和朝南（暴露在阳光下）树冠侧面取样复制当年的嫩芽。对于每个芽，记录了平均单片叶干质量、叶数、侧枝数以及茎长、周长和组织干重的测量值。出叶强度计算为每单位支撑茎组织干质量产生的叶片数。

Key results - All of the direct trait measurements had generally larger values for shoots collected from south-facing canopy sides (as expected). However, negative isometric relationships between leaf size and leafing intensity were found at the between-plant level (for Acer saccharum) and the between-shoot (within-tree) level for at least some individuals of most species. The predominant trend at the within-tree level, however, was allometric - i.e. north-facing (light-limited) shoots generally had lower individual leaf dry mass but disproportionately higher leafing intensity compared with south-facing shoots.
主要结果 - 对于从朝南的树冠侧面收集的芽，所有直接性状测量通常具有较大的值（正如预期的那样）。然而，对于大多数物种的至少一些个体，在植物间水平（对于槭树）和枝条间（树内）水平上发现叶子大小和出叶强度之间的负等距关系。然而，树内水平的主要趋势是异速生长 - 即朝北（光线受限）的枝条通常具有较低的单片叶片干质量，但与朝南的枝条相比，不成比例地高出叶强度。

Conclusions - The results confirm that there is a fundamental leaf size/number trade-off at the between-plant (within-species) level and also at the between-shoot (within-plant) level, as previously reported at the between-species level. But more specifically, the results reveal distinctly different leaf deployment strategies in response to spatial light variability within tree canopies: Under high light exposure, larger leaves are favoured (with lower leafing intensity imposed as a trade-off), but in deeply shaded portions of the canopy, smaller leaves result, we suggest, for two reasons: (i) they are favoured directly (because they minimize overlap of closely spaced adjacent leaves); (ii) they are imposed as a trade-off of selection favouring high leafing intensity, which in turn maximizes the size of the reserve bud bank (number of axillary meristems per unit of supporting stem tissue) available for initiating continued growth or reproduction in the following year.
结论 - 结果证实，正如之前在物种间水平上报道的那样，在植物间（种内）水平和芽间（植物内）水平上存在基本的叶子大小/数量权衡。但更具体地说，结果揭示了响应树冠内空间光线变化的明显不同的叶子部署策略：在强光照射下，较大的叶子受到青睐（作为权衡，施加了较低的叶子强度），但在树冠的深阴影部分，我们认为，叶子较小，原因有两个：（i） 它们直接受到青睐（因为它们最大限度地减少了紧密间隔的相邻叶子的重叠）;（ii） 它们被强加为有利于高出叶强度的选择，这反过来又使储备芽库的大小（每单位支撑茎组织的腋生分生组织数量）最大化，可用于在下一年开始持续生长或繁殖。

Plant twig characters for 82 woody species including individual leaf and total leaf mass, stem mass, individual leaf area, total leaf area and stem cross-sectional area were investigated at the twig level in different altitudes and life forms on Meihuashan Mountain in Southeastern China. The results showed that twig cross-sectional area of plant twigs were found to allometrically scale to individual leaf area and total leaf area that the twig supported, all with the common SMA (standardized major axis) slope being significantly larger than 1.0. However, the spectrum of twig leaf mass-stem mass was found to be mostly isometric and the slope had no significant deviation from 1.0, the same as the spectrum of twig total leaf area-twig leaf mass. The allometric constants (y-intercepts) of the relationships between the stem cross-sectional area and leaf area (both total leaf area and individual leaf area) were found to decrease significantly along the altitudinal gradient. Compared to deciduous broad-leaved species, the evergreen broad-leaved species were smaller in total leaf area for a given cross-sectional area or stem mass. This suggests that the species would support less leaf area at a given twig cross-sectional area with increasing environmental stress. And the life form can modify leaf-stem scaling relationship because of the difference of function.
以东南梅花山为研究对象，在枝干水平上对82个木本植物的枝条性状进行了研究，包括单叶和全叶质量、茎质量、单叶面积、总叶面积和茎横截面积。结果表明，发现植物小枝的枝条横截面积异速生长到枝条支撑的单个叶面积和总叶面积，所有共同的 SMA（标准化长轴）斜率都显著大于 1.0。但发现枝叶质量-茎质量的光谱多为等距，斜率与 1.0 无显著偏差，与枝总叶面积-枝叶质量的光谱相同。发现茎横截面积和叶面积 （总叶面积和单个叶面积） 之间关系的异速生长常数 （y-intercepts） 沿海拔梯度显著减小。与落叶阔叶物种相比，在给定横截面积或茎质量下，常绿阔叶物种的总叶面积较小。这表明，随着环境压力的增加，该物种在给定的树枝横截面积上会支持更少的叶面积。并且由于功能的不同，该生命型可以改变叶-茎的鳞片关系。

Although many hypotheses have been proposed to explain variation in leaf size, the mechanism underlying the variation remains not fully understood. To help understand leaf size variation, the cost/benefit of twig size was analysed, since, according to Corner's rule, twig size is positively correlated with the size of appendages the twig bears.
尽管已经提出了许多假设来解释叶子大小的变化，但这种变化背后的机制仍未完全清楚。为了帮助理解叶子大小的变化，分析了树枝大小的成本/收益，因为根据 Corner 规则，树枝大小与树枝所携带的附属物的大小呈正相关。

An extensive survey of twig functional traits, including twig (current-year shoots including one stem and few leaves) and leaf size (individual leaf area and mass), was conducted for 234 species from four broadleaved forests. The scaling relationship between twig mass and leaf area was determined using standardized major axis regression and phylogenetic independent comparative analyses.
对来自四个阔叶林的 234 个物种的枝条功能性状进行了广泛的调查，包括枝条（当年的芽，包括一根茎和几片叶子）和叶子大小（单个叶子的面积和质量）。使用标准化长轴回归和系统发育独立比较分析确定枝条质量和叶面积之间的缩放关系。

Leaf area was found to scale positively and allometrically with both stem and twig mass (stem mass plus leaf mass) with slopes significantly smaller than 1 center dot 0, independent of life form and habitat type. Thus, the leaf area ratio (the ratio of total leaf area to stem or twig mass) decreases with increasing twig size. Moreover, the leaf area ratio correlated negatively with individual leaf mass. The results of phylogenetic independent comparativeanalyses were consistent with the correlations. Based on the above results, a simple model for twig size optimization was constructed, from which it is postulated that large leaf size-twig size may be favoured when leaf photosynthetic capacity is high and/or when leaf life span and/or stem longevity are long. The model's predictions are consistent with leaf size variation among habitats, in which leaf size tends to be small in poor habitats with a low primary productivity. The model also explains large variations in leaf size within habitats for which leaf longevity and stem longevity serve as important determinants.
发现叶面积呈正向和异速生长，茎和小枝质量（茎质量加叶质量）的斜率显著小于 1 个中心点 0，与生命形式和栖息地类型无关。因此，叶面积比（总叶面积与茎或小枝质量的比值）随着小枝大小的增加而减小。此外，叶面积比与单个叶质量呈负相关。系统发育独立比较分析的结果与相关性一致。基于上述结果，构建了一个简单的小枝大小优化模型，从中可以假设当叶片光合能力高和/或叶片寿命和/或茎长时，大叶尺寸-小枝大小可能更有利。该模型的预测与栖息地之间的叶子大小变化一致，其中在初级生产力较低的贫瘠栖息地中，叶子大小往往较小。该模型还解释了栖息地内叶子大小的巨大变化，其中叶子的寿命和茎的寿命是重要的决定因素。

The diminishing returns in the scaling of total leaf area with twig size can be explained in terms of a very simple model on twig size optimization.
总叶面积随树枝大小缩放的递减收益可以用一个非常简单的树枝大小优化模型来解释。

This study is to examine the effect of stem architecture on biomass allocation between leaf and stem and between leaf size and number in plant twigs of woody species. We investigated leaf size, leaf number, stem length, stem diameter, and mass for 282 woody species of subtropical evergreen broad-leaved forests in southwest China. Both stem diameter and stem length were positively correlated with individual leaf mass and area but were negatively associated with leaf number per unit stem mass and leaf number per stem length. This suggests that these stem architecture traits can be a physiological mechanism underlying the leaf size versus leaf number tradeoff. The ratio of stem length to stem diameter (LDR) was negatively correlated with leaf size and leaf number per stem length, due to the difference in the strength of the effects of stem length and stem diameter on leaf size and leaf number. Similarly, both stem diameter and stem length were positively correlated with leaf mass and stem mass. LDR was negatively correlated with leaf biomass fraction (the ratio of leaf mass to twig mass), due to the difference in the strength of the effect of stem length and stem diameter on leaf mass and stem mass. This indicates that stem architecture can significantly influence biomass allocation between leaf and stem. These relationships were generally strong when expressed as correlated evolutionary divergences. In addition, LDR was generally larger in the high-rainfall habitat than in the low-rainfall site. Accordingly, LDR can be regarded as a functional trait and an important component of the leading dimension of leaf size-twig size spectrum in plants.
本研究旨在研究茎结构对木本植物植物枝条叶片与茎之间以及叶片大小与数量之间生物量分配的影响。本研究调查了中国西南地区 282 种亚热带常绿阔叶林木本植物的叶长、叶数、茎长、茎粗和质量。茎粗和茎长与单个叶质量和面积呈正相关，但与单位茎质量的叶数和每茎长的叶数呈负相关。这表明这些茎结构性状可能是叶子大小与叶数权衡的潜在生理机制。由于茎长和茎粗对叶大小和叶数的影响强度不同，茎长与茎粗的比值与叶长之比 （LDR） 与叶大小和每茎长叶数呈负相关。同样，茎粗和茎长与叶质量和茎质量呈正相关。LDR 与叶片生物量分数 （叶片质量与枝质量的比值） 呈负相关，因为茎长和茎粗对叶片质量和茎质量的影响强度不同。这表明茎结构可以显着影响叶和茎之间的生物量分配。当表达为相关的进化分歧时，这些关系通常很强。此外，高降雨生境的 LDR 通常大于低降雨地点。因此，LDR 可以被视为植物叶片大小谱的功能性状和主导维度的重要组成部分。

We studied the effects of twig size and altitude on biomass allocation within plant twigs (terminal branches of current-year shoots), to determine whether species with large twigs/leaves or living at low altitude allocate a higher proportion of biomass to laminas than their counterparts with small twigs/leaves or living at high altitude. Stem mass, lamina mass and area, and petiole mass were measured for terminal branches of current-year shoots in 80 subtropical evergreen broad-leaved species belonging to 38 genera from 24 families along an altitudinal gradient of Mt. Emei, Southwest China. The scaling relationships between the biomass allocations of within-twig components were determined using model type II regression method. Isometric relationships were found between leaf mass and twig mass and between lamina mass and twig mass, suggesting that the biomass allocation to either leaves or laminas was independent of twig mass. Petiole mass disproportionally increased with both lamina mass and twig mass, indicating the importance of leaf petioles to the within-twig biomass allocation. These cross-species correlations were consistent with those among evolutionary divergences. In addition, species at low altitude tended to have a greater leaf and lamina mass but a smaller stem mass at a given twig mass than at middle and high altitudes. This is possibly due to the high requirement in physical support and the low efficiency of eco-physiological transport for the species living at high altitude. In general, within-twig biomass allocation pattern was not significantly affected by twig size but was greatly modulated by altitude.
我们研究了小枝大小和海拔对植物小枝（当年芽的末端分支）内生物量分配的影响，以确定具有大树枝/叶子或生活在低海拔地区的物种是否比具有小树枝/叶子或生活在高海拔地区的物种向叶片分配生物量的比例更高。沿中国西南峨眉山海拔梯度，测量了 24 科 38 属 80 种亚热带常绿阔叶树种当年芽末端枝的茎质量、叶片质量和面积以及叶柄质量。使用模型类型 II 回归方法确定枝内成分的生物量分配之间的缩放关系。在叶子质量和树枝质量之间以及叶片质量和树枝质量之间发现了等长关系，这表明叶子或叶片的生物量分配与树枝质量无关。叶柄质量与叶片质量和枝条质量不成比例地增加，表明叶柄对枝条内生物量分配的重要性。这些跨物种相关性与进化差异之间的相关性一致。此外，与中高海拔物种相比，低海拔物种在给定的枝质量下往往具有更大的叶和叶片质量，但茎质量更小。这可能是由于生活在高海拔地区的物种对物理支持的高要求和生态生理运输效率低。一般来说，枝条内生物量分配模式受枝条大小不显著影响，但受海拔高度的极大调节。

Do thick-twigged/large-leaf species have an advantage in leaf display over their counterparts, and what are the effects of leaf habit and leaf form on the leaf-stem relationship in plant twigs of temperature broadleaf woody species?
粗枝/大叶物种在叶片展示方面是否优于同类物种，温度阔叶木本物种的叶习性和叶型对植物枝条的叶茎关系有何影响？

Gongga Mountain, southwest China.
中国西南部贡嘎山。

(1) We investigated stem cross-sectional area and stem mass, leaf area and leaf/lamina mass of plant twigs (terminal branches of current-year shoots) of 89 species belonging to 55 genera in 31 families. (2) Data were analyzed to determine leaf-stem scaling relationships using both the Model type II regression method and the phylogenetically independent comparative (PIC) method.
（1） 本研究对 31 科 55 属 89 种植物枝条（当年芽的顶端枝）的茎横截面积和茎质量、叶面积和叶/层质量进行了调查。（2） 使用模型类型 II 回归方法和系统发育独立比较 （PIC） 方法分析数据以确定叶茎缩放关系。

(1) Significant, positive allometric relationships were found between twig cross-sectional area and total leaf area supported by the twig, and between the cross-sectional area and individual leaf area, suggesting that species with large leaves and thick twigs could support a disproportionately greater leaf area for a given twig cross-sectional area. (2) However, the scaling relationships between twig stem mass and total leaf area and between stem mass and total lamina mass were approximately isometric, which indicates that the efficiency of deploying leaf area and lamina mass was independent of leaf size and twig size. The results of PIC were consistent with these correlations. (3) The evergreen species were usually smaller in total leaf area for a given twig stem investment in terms of both cross-sectional area and stem mass, compared to deciduous species. Leaf mass per area (LMA) was negatively associated with the stem efficiency in deploying leaf area. (4) Compound leaf species could usually support a larger leaf area for a given twig stem mass and were usually larger in both leaf size and twig size than simple leaf species.
（1） 在树枝横截面积和树枝支撑的总叶面积之间以及横截面积和单个叶面积之间发现了显著的正异速生长关系，这表明具有大叶子和粗枝的物种可以支持给定的树枝横截面积不成比例的更大叶面积。（2） 而枝茎质量与总叶面积之间以及茎质量与总叶片质量之间的缩放关系近似等距，这表明叶面积和叶片质量的部署效率与叶片大小无关。PIC 的结果与这些相关性一致。（3） 与落叶树种相比，对于给定的枝茎投资，常绿树种在横截面积和茎质量方面的总叶面积通常较小。单位面积叶质量 （LMA） 与叶面积部署的茎效率呈负相关。（4） 对于给定的枝茎质量，复合叶种通常可以支持更大的叶面积，并且通常比简单叶种的叶子大小和枝条大小都大。

Generally, thick-twigged/large-leaf species do not have an advantage over their counterparts in deploying photosynthetic compartments for a given twig stem investment. Leaf habit and leaf form types can modify leaf-stem scaling relationships, possibly because of contrasting leaf properties. The leaf size-twig size spectrum is related to the LMA-leaf life span dimension of plant life history strategies.
一般来说，粗枝/大叶物种在为给定的枝茎投资部署光合作用隔室方面没有优于同类物种的优势。叶习性和叶形类型可以改变叶-茎的缩放关系，这可能是因为叶子的特性对比鲜明。叶长-枝条大小谱与植物生活史策略的 LMA-叶寿命维度有关。

Background and Aims Trade-offs are fundamental to life-history theory, and the leaf size vs. number trade-off has recently been suggested to be of importance to our understanding leaf size evolution. The purpose of the present study was to test whether the isometric, negative relationship between leaf size and number found by Kleiman and Aarssen is conserved between plant functional types and between habitats.
背景和目标 权衡是生活史理论的基础，最近有人认为叶子大小与数量的权衡对于我们理解叶子大小的演变很重要。本研究的目的是测试Kleiman和Aarssen发现的叶子大小和数量之间的等距负相关关系在植物功能类型和栖息地之间是否是保守的。

Methods Leaf mass, area and number, and stem mass and volume of current-year shoots were measured for 107 temperate broadleaved woody species at two altitudes on Gongga Mountain, south-west China. The scaling relationships of leaf size (leaf area and mass) vs. (mass-and volume-based) leafing intensity were analysed in relation to leaf habit, leaf form and habitat type. Trait relationships were determined with both a standardized major axis method and a phylogenetically independent comparative method.
方法 测定中国西南贡嘎山 2 个海拔地区 107 种温带阔叶木本物种的叶质量、面积和数量，以及当年枝条的茎质量和体积。分析了叶大小 （叶面积和质量） 与 （基于质量和体积） 叶状强度的缩放关系与叶习性、叶型和栖息地类型的关系。性状关系是用标准化的长轴方法和系统发育独立的比较方法确定的。

Key Results Significant negative, isometric scaling relationships between leaf size and leafing intensity were found to be consistently conserved across species independent of leaf habit, leaf form and habitat type. In particular, about 99% of the variation in leaf mass across species could be accounted for by proportional variation in mass-based leafing intensity. The negative correlations between leaf size and leafing intensity were also observed across correlated evolutionary divergences. However, evergreen species had a lower y-intercept in the scaling relationships of leaf area vs. leafing intensity than deciduous species. This indicated that leaf area was smaller in the evergreen species at a given leafing intensity than in the deciduous species. The compound-leaved deciduous species were observed usually to have significant upper shifts along the common slopes relative to the simple-leaved species, which suggested that the compound-leaved species were larger in leaf size but smaller in leafing intensity than their simple counterparts. No significant difference was found in the scaling relationships between altitudes.
主要结果 发现叶大小和叶强度之间的显着负等长缩放关系在物种之间始终保守，与叶习性、叶型和栖息地类型无关。特别是，不同物种之间叶质量变化的约 99% 可以由基于质量的成叶强度的比例变化来解释。在相关的进化差异中也观察到叶大小和出叶强度之间的负相关。然而，常绿树种在叶面积与出叶强度的缩放关系中比落叶树种的 y 截距低。这表明在给定的出叶强度下，常绿树种的叶面积小于落叶树种。通常观察到复叶落叶物种相对于简单叶物种沿公共斜坡具有显着的上移，这表明复叶物种的叶子比简单同类更大，但出叶强度更小。海拔高度之间的缩放关系没有发现显著差异。

Conclusions The negative, isometric scaling relationship between leaf size and number is largely conserved in plants, while the leaf size vs. number trade-off can be mediated by leaf properties. The isometry of the leaf size vs. number relationship may simply result from a biomass allocation trade-off, although a twig size constraint may provide an alternative mechanism.
结论 叶子大小和数量之间的负等距缩放关系在植物中基本是保守的，而叶子大小与数量的权衡可以通过叶子特性来调节。叶子大小与数量关系的等距可能只是由于生物量分配权衡的结果，尽管树枝大小限制可能提供另一种机制。

1. The allometric scaling relationship between lamina and lamina support has rarely been examined, such that its significance to plant life-history strategies has not been fully explored and understood so far. We investigated the sizes of leaf lamina and petiole for 93 temperate broad-leaved woody species at two altitudes of a southwestern mountain, and analysed the scaling relationship in relation to leaf habit (evergreen vs. deciduous), leaf form (simple- vs. compound-leaved species), and habitat type (low vs. high altitude).
1. 叶片和叶片支撑之间的异速生长缩放关系很少被研究，因此迄今为止尚未充分探索和理解其对植物生活史策略的重要性。我们调查了西南山脉两个海拔高度的 93 种温带阔叶木本物种的叶片和叶柄的大小，并分析了与叶习性（常绿与落叶）、叶形（单叶与复叶物种）和栖息地类型（低海拔与高海拔）相关的缩放关系。

2. Significant allometric scaling relationships were found between petiole mass and lamina mass, and between petiole mass and lamina area, with common slopes of 0.872 and 0.742, respectively, both significantly departed from the value of 1.0. The results of phylogenetic comparative analyses were in accordance with the observed positive scaling relationships.
2. 叶柄质量与叶片质量之间以及叶柄质量与叶片面积之间存在显著的异速生长缩放关系，共同斜率分别为 0.872 和 0.742，均显著偏离 1.0 的值。系统发育比较分析的结果与观察到的正缩放关系一致。

3. The evergreen species were found to have a greater petiole mass than the deciduous at a given lamina area; whilst a contrasting pattern was observed between lamina mass and petiole mass, in which the evergreens had a greater biomass allocation to lamina for the same petiole mass relative to the deciduous.
3. 发现常绿树种在给定的叶片面积上具有比落叶叶更大的叶柄质量;同时在叶片质量和叶柄质量之间观察到对比模式，其中对于相同的叶柄质量，常绿植物相对于落叶植物具有更大的生物量分配给叶片。

4. The compound-leaved species were observed to be significantly greater in both lamina area and lamina support (including petioles, rachis and petiolules) than the simple-leaved species, whereas the former had a smaller lamina area or lamina mass at a given petiole mass than the latter.
4. 观察到复叶物种在叶片面积和叶片支撑（包括叶柄、轴和叶柄）上都明显大于简单叶物种，而前者在给定叶柄质量下的叶片面积或叶片质量比后者小。

5. The plants from the high altitude had less lamina area at a given petiole investment compared to those from the lower altitude, likely due to the large mechanic and transporting requirements of petioles in the species at high altitude.
5. 与来自低海拔的植物相比，在给定的叶柄投资下，来自高海拔的植物具有较小的叶片面积，这可能是由于高海拔物种对叶柄的机械和运输要求很大。

6. Our results indicate that petioles serve as an adverse forcing on the maximization of lamina area and lamina biomass and that the allometric relationship between lamina and lamina support varies with leaf habit, leaf form and habitat.
6. 我们的结果表明，叶柄对叶片面积和叶片生物量的最大化起着不利的强迫作用，并且叶片和叶片支撑之间的异速生长关系随叶片习性、叶型和栖息地的变化而变化。

Using a sample of 24 common deciduous angiosperm trees of the Eastern Deciduous Forest region of North America, we tested the hypothesis that leaf size variation across species can be interpreted in terms of a trade-off between individual leaf mass and the number of leaves produced.
使用北美东部落叶林地区的 24 棵常见落叶被子植物树的样本，我们检验了这样一个假设，即不同物种的叶子大小变化可以用单个叶子质量和产生的叶子数之间的权衡来解释。

The true nature of a resource allocation trade-off is detectable only if variation in the total amount of growth is accounted for. We controlled for this effect by measuring all of the components of annual growth associated with leaf production at the individual terminal shoot level. Hence, number of leaves produced was expressed as 'leafing intensity', i.e. the number of leaves produced by newly emerged (current year's) shoots, divided by the total volume of these shoots.
只有当考虑到增长总量的变化时，才能检测到资源分配权衡的真正性质。我们通过在单个顶梢水平测量与叶子生产相关的年生长的所有组成部分来控制这种影响。因此，产生的叶子数表示为“叶状强度”，即新出现的（当年的）芽产生的叶子数除以这些芽的总体积。

Ninety per cent (r(2) = 0.90) of the variation in mean individual leaf mass across species, spanning two orders of magnitude, could be accounted for by proportional variation in mean leafing intensity, i.e. representing an isometric trade-off, with a slope for log-transformed data that did not deviate significantly from -1.0.
不同物种的平均单片质量变化的 90% （r（2） = 0.90） 跨越两个数量级，可以用平均叶层强度的比例变化来解释，即代表等长权衡，对数转换数据的斜率没有显着偏离 -1.0。

We suggest that this isometric relationship may represent a generalized trade-off strategy for leaf deployment at the shoot level within temperate deciduous woody species. Following traditional interpretations, adaptation here may involve a fitness benefit associated with a particular leaf size. The present results also suggest an alternative, i.e. selection may instead favour high leafing intensity, with small leaf mass resulting not as a direct adaptation, but simply as a trade-off.
我们认为这种等距关系可能代表了温带落叶木本物种中芽水平叶片部署的广义权衡策略。按照传统的解释，这里的适应可能涉及与特定叶子大小相关的适应性益处。目前的结果还提出了一种替代方案，即选择可能反而有利于高出叶强度，小叶质量不是直接适应，而只是作为一种权衡。

According to this 'leafing intensity premium' hypothesis, the fitness benefits of higher leafing intensity are associated primarily with the fitness benefits of a larger pool of lateral meristems, because each leaf is usually associated with an axillary bud. This may in turn provide greater facility for wide phenotypic plasticity in the allocation of these meristems to vegetative vs. reproductive functions. This represents a plausible hypothesis, we suggest, in accounting for why most woody deciduous angiosperms, even some of the largest/tallest ones, have relatively small leaves.
根据这种 “换叶强度溢价 ”假说，较高换叶强度的适应度益处主要与较大的侧分生组织池的适应度益处有关，因为每片叶子通常与一个腋芽有关。这反过来可能为将这些分生组织分配给营养功能与生殖功能的广泛表型可塑性提供更大的便利。我们认为，这代表了一个合理的假设，以解释为什么大多数木本落叶被子植物，即使是一些最大/最高的被子植物，都有相对较小的叶子。

center dot Background and Aims The leaf size-twig size spectrum is one of the leading dimensions of plant ecological variation, and now it is under development. The purpose of this study was to test whether the relationship between leaf size and twig size is isometric or allometric, and to examine the relationship between plant allometric growth and life history strategies in the spectrum.
中心点 背景和目的 叶子大小-枝条大小光谱是植物生态变化的主要维度之一，现在正在开发中。本研究的目的是测试叶子大小和小枝大小之间的关系是等距还是异速生长，并检查植物异速生长与光谱中生活史策略之间的关系。

center dot Methods Leaf and stem characters-including leaf and stem mass, total leaf area, individual leaf area, stem cross-sectional area, leaf number and stem length-at the twig level for 59 woody species were investigated along an altitudinal gradient on Changbaishan Mountain in the temperate zone of China. The environmental gradient ranges from temperate broad-leaved mixed forest at low altitude, to conifer forest at middle altitude, and to sub-alpine birch forest at high altitude. The scaling relationships between stem cross-sectional area and stem mass, stem mass and leaf mass, and leaf mass and leaf area at the twig level were simultaneously determined.
中心点方法 以温带长白山为研究对象，研究 59 种木本植物在枝干水平上的叶和茎性状，包括叶和茎质量、总叶面积、单叶面积、茎横截面积、叶数和茎长。环境梯度范围从低海拔的温带阔叶混交林到中海拔的针叶林，再到高海拔的亚高山白桦林。同时确定茎横截面积与茎质量、茎质量与叶质量、枝水平叶质量与叶面积的尺度关系。

center dot Key Results Twig cross-sectional area was found to have invariant allometric scaling relationships with the stem mass, leaf mass, total leaf area and individual leaf area, all with common slopes being significantly larger than 1, for three altitudinal-zoned vegetation types under investigation. However, leaf mass was found to be isometrically related to stem mass and leaf area along the environmental gradient. Based on the predictions of previous models, the exponent value of the relationship between twig cross-sectional area and total leaf area can be inferred to be 1.5, which falls between the confidence intervals of the relationship at each altitude, and between the confidence intervals of the common slope value (1.17-1.56) of this study. This invariant scaling relationship is assumed to result from the fractural network and/or developmental constraints of plants. The allometric constants (y-intercepts) of the relationships between the stem cross-sectional area and leaf area (both total leaf area and individual leaf area) were found to decrease significantly along the altitudinal gradient. This suggests that the species would support less leaf area at a given twig cross-sectional area with increasing environmental stress.
中心点 主要结果 对于正在调查的三种海拔分区植被类型，枝条横截面积与茎质量、叶质量、总叶面积和单个叶面积具有不变的异速生长比例关系，所有共同坡度均显著大于 1。然而，发现叶质量与茎质量和叶面积沿环境梯度呈等距相关。根据前人模型的预测，可以推断出枝截面积与总叶面积关系的指数值为 1.5，它介于各海拔关系的置信区间之间，也介于本研究的共同斜率值 （1.17-1.56） 的置信区间之间。这种不变的缩放关系被认为是由植物的分形网络和/或发育约束引起的。发现茎横截面积和叶面积 （总叶面积和单个叶面积） 之间关系的异速生长常数 （y-intercepts） 沿海拔梯度显著减小。这表明，随着环境压力的增加，该物种在给定的树枝横截面积上会支持更少的叶面积。

center dot Conclusions This study demonstrated that plants respond to the environmental gradient by changing the y-intercepts of the relationship between leaf size-twig size, while keeping the exponent value of the allometric relationship as an invariant constant. The allometric growth in the twig size-leaf size spectrum is related to many other components of plant life history strategy, including the well established life history trade-off between efficiency and safety in the hydraulic transport of water.
中心点 结论 本研究证明，植物通过改变叶子大小-小枝大小之间关系的 y 轴截距来响应环境梯度，同时保持异速生长关系的指数值为不变常数。树枝大小-叶子大小光谱的异速生长与植物生活史策略的许多其他组成部分有关，包括水力运输中效率和安全性之间公认的生活史权衡。

1. The leaf size-twig size spectrum is an important spectrum of variation between species, although the costs and benefits of larger vs smaller leaf size are poorly understood. This study quantified the dry mass costs of deploying leaf area in relation to leaf size, across 70 species from four sites contrasted on the basis of rainfall and soil nutrients in east-temperate Australia.
1. 叶子大小-树枝大小谱是物种之间变化的一个重要谱系，尽管人们对较大叶子与较小叶子大小的成本和收益知之甚少。这项研究量化了部署叶面积与叶子大小相关的干质量成本，根据澳大利亚东温带地区的降雨量和土壤养分，来自四个地点的 70 个物种进行了对比。

2. Leaf mass fraction beyond 10 mm(2) of conductive cross-section (LMF10) varied threefold and was strongly positively correlated with leaf size, both across all species and within each habitat. This and other key correlations were significant both across species and as evolutionary divergences.
2. 导电横截面 （LMF10） 超过 10 mm（2） 的叶质量分数变化了 3 倍，并且与所有物种和每个栖息地内的叶子大小呈强正相关。这种相关性和其他关键相关性在物种之间和进化差异中都显著。

3. An LMF10 advantage for larger-leaved species should translate into a proportional advantage in dry mass acquisition, yet species with small leaves persist and sustain populations. This raises the question as to what factors might counterbalance an LMF advantage associated with larger leaf size.
3. 较大叶子物种的 LMF10 优势应转化为干质量获取的比例优势，但小叶子的物种会持续存在并维持种群数量。这就提出了一个问题，即哪些因素可能会抵消与较大叶子尺寸相关的 LMF 优势。

4. Within some sites, specific leaf area (SLA) decreased with leaf size, which counterbalanced the LMF10 advantage. Within other sites, and across all sites, SLA did not decline with leaf size. In these comparisons other factors, such as avoidance of overheating, must counterbalance the LMF10 advantage to larger-leaved species.
4. 在一些地点，比叶面积 （SLA） 随着叶子大小而减小，这抵消了 LMF10 的优势。在其他站点内以及所有站点中，SLA 不会随着叶大小而下降。在这些比较中，其他因素，例如避免过热，必须抵消 LMF10 对较大叶子物种的优势。

5. Wood density was negatively correlated with leaf size. However, the relationship was weaker within sites in the lower rainfall zone, and species in these sites had generally higher wood density. Sapwood cross-sectional area per unit leaf area (Huber value) varied approximately ninefold across all species, and was correlated with both leaf size and SLA across all species, but not within sites.
5. 木材密度与叶子大小呈负相关。然而，在降雨量较低的地点内，这种关系较弱，并且这些地点的物种通常具有较高的木材密度。所有物种每单位叶面积的边材横截面积（Huber 值）变化约 9 倍，并且与所有物种的叶大小和 SLA 相关，但在地点内则无关。

There is a spectrum from species with narrow, frequently branched twigs carrying small leaves and other appendages, to species with thick twigs carrying large leaves and appendages. Here we investigate the allometry of this spectrum and its relationship to two other important spectra of ecological variation between species, the seed mass-seed output spectrum and the specific leaf area-leaf lifespan spectrum. Our main dataset covered 33 woody dicotyledonous species in sclerophyll fire-prone vegetation on low nutrient soil at 1,200 mm annual rainfall near Sydney, Australia. These were phylogenetically selected to contribute 32 evolutionary divergences. Two smaller datasets, from 390 mm annual rainfall, were also examined to assess generality of cross-species patterns. There was two to three orders of magnitude variation in twig cross-sectional area, individual leaf size and total leaf area supported on a twig across the study species. As expected, species with thicker twigs had larger leaves and branched less often than species with thin twigs. Total leaf area supported on a twig was mainly driven by leaf size rather than by the number of leaves. Total leaf area was strongly correlated with twig cross-section area, both across present-day species and across evolutionary divergences. The common log-log slope of 1.45 was significantly steeper than 1. Thus on average, species with tenfold larger leaves supported about threefold more leaf area per twig cross-section, which must have considerable implications for other aspects of water relations. Species at the low rainfall site on loamy sand supported about half as much leaf area, at a given twig cross-section, as species at the low rainfall site on light clay, or at the high rainfall site. Within sites, leaf and twig size were positively correlated with seed mass, and negatively correlated with specific leaf area. Identifying and understanding leading spectra of ecological variation among species is an important challenge for plant ecology. The seed mass-seed output and specific leaf area-leaf lifespan spectra are each underpinned by a single, comprehensible trade-off and their consequences are fairly well understood. The leaf-size-twig-size spectrum has obvious consequences for the texture of canopies, but we are only just beginning to understand the costs and benefits of large versus small leaf and twig size.
范围从带有小叶子和其他附属物的狭窄、经常分枝的物种，到带有大叶子和附属物的粗树枝物种。在这里，我们研究了该光谱的异速生长及其与物种之间生态变化的另外两个重要光谱的关系，即种子质量-种子输出光谱和比叶面积-叶寿命光谱。我们的主要数据集涵盖了澳大利亚悉尼附近年降雨量为 1,200 mm 的低营养土壤硬叶火灾植被中 33 种木本双子叶植物。这些被系统发育选择为贡献 32 个进化分歧。还检查了两个较小的数据集，年降雨量为 390 毫米，以评估跨物种模式的普遍性。在研究物种中，树枝横截面积、单片叶子大小和树枝上支撑的总叶面积存在 2 到 3 个数量级的变化。正如预期的那样，与树枝较细的物种相比，树枝较粗的物种叶子更大，分枝频率更低。支撑在小枝上的总叶面积主要由叶子大小而不是叶子的数量驱动。总叶面积与枝横截面积密切相关，无论是在当今物种之间还是在进化差异中。常见的对数-对数坡度 1.45 明显比 1 陡峭。因此，平均而言，叶子大 10 倍的物种每个树枝横截面支撑的叶面积大约多三倍，这必然对水关系的其他方面具有相当大的影响。在给定的树枝横截面上，位于低降雨量地点的物种在浅质粘土上或高降雨地点的物种所支持的叶面积大约是其一半。 在地点内，叶子和枝条的大小与种子质量呈正相关，与特定叶面积呈负相关。识别和理解物种之间生态变化的主要光谱是植物生态学的一项重要挑战。种子质量-种子输出和比叶面积-叶寿命光谱都以单一的、可理解的权衡为基础，它们的后果相当容易理解。叶子大小-树枝-大小的光谱对树冠的质地有明显的影响，但我们才刚刚开始了解大树叶和树枝大小的成本和收益。