武夷山不同海拔黄山松枝叶大小关系

对武夷山自然保护区不同海拔黄山松叶片面积、叶片数量、小枝长度及小枝直径等性状进行测定,分析不同海拔黄山松枝-叶大小间的权衡关系.结果表明: 随海拔升高,黄山松小枝的叶片数量、小枝长度、小枝直径、出叶强度及茎截面积逐渐增大,单叶面积呈逐渐减小趋势;不同海拔黄山松小枝出叶强度与单叶面积均呈显著负相关,不同海拔黄山松小枝茎截面积与总叶面积呈显著正相关;不同海拔黄山松小枝长度、小枝直径与出叶强度呈显著负相关,与单叶面积、叶片数量及总叶面积均呈显著正相关.为提高竞争优势或是资源利用效率,低海拔黄山松倾向于在短枝上着生量少但单叶面积大的针叶,而高海拔黄山松趋向于在长枝上着生量大但单叶面积小的针叶,这体现出不同海拔梯度黄山松小枝的资源利用策略及枝叶间生物量分配的权衡机制.     

长期增温对树线交错带岷江冷杉幼苗异龄叶大小与出叶强度关系的影响

全球气候变暖强烈影响树线交错带植物的生活史策略,异龄叶大小-出叶强度权衡关系是常绿植物生活史策略的重要内容。以川西树线交错带的岷江冷杉（Abies faxoniana）幼苗为例,研究气候变暖对异龄叶大小与出叶强度关系的影响。通过开顶箱（Open-top chamber, OTC）对川西王朗自然保护区树线交错带的岷江冷杉进行模拟增温,采用标准化主轴估计（Standardized major axis estimation, SMA）方法研究了叶大小（单叶质量、单叶面积）与出叶强度（基于茎生物量、茎体积）间异速生长关系对长期增温的响应及其年际变化。结果表明：使用不同参数表征叶大小与出叶强度得到的结果存在差异;多年生小枝上存在单叶质量-出叶强度的负等速权衡关系,共同主轴随小枝年龄增加而向下漂移;长期增温并不影响单叶质量与出叶强度的异速生长关系,不同年龄小枝的异速生长常数对增温具有差异性响应。增温处理中当年生小枝在相同单叶质量下的出叶强度更低,以换取叶片总数的增加,使小枝具有更大的可塑性而适应增温。本研究提供了岷江冷杉幼苗协调异龄叶大小与出叶强度从而适应长期增温的证据,为评估树木生长随气候变化而加速提供了理论参考。     

胡杨叶片大小与叶数量的权衡关系对地下水埋深的响应

本文以胡杨(Populus euphratica Oliv.)为研究对象,采用标准化主轴回归估计(SMA)方法探讨了种群叶片大小(单叶面积、单叶质量)与出叶强度(基于小枝质量、茎质量、茎体积)的异速生长关系对地下水埋深梯度(Groundwater depth,GWD)的响应及其变化规律.结果显示:随GWD增加,胡杨当年...     

发育阶段和海拔对岷江源区陇蜀杜鹃小枝功能性状及生物量分配的影响

本研究分析了岷江源区卡卡山典型高山灌丛植物陇蜀杜鹃不同发育阶段(花芽期和开花期)及不同海拔(3600 m低海拔和3800 m高海拔)下功能小枝和叶片性状的差异,以及空间异质性对花芽期和开花期小枝功能性状相关性及其权衡作用的影响。结果表明: 低海拔同一生长期陇蜀杜鹃小枝长度显著大于高海拔,高海拔开花期小枝的花数量和花质量显著高于低海拔。同一海拔花芽期的小枝质量、叶片数量、总叶质量、总叶面积和总叶柄质量均显著大于开花期,单叶质量和单叶柄质量均显著小于开花期。与花芽期相比,开花期叶生物量占比减少了13%,而小枝质量占比显著增加。小枝的生物量权衡表明,花芽期性状倾向于小枝质量,开花期倾向于总叶质量;花芽期的叶偏好分配于单叶质量,低海拔和高海拔开花期叶片分别偏好分配到单叶柄质量和单叶质量。低海拔开花期小枝质量与总叶面积、总叶质量均为异速生长,单叶柄质量和单叶面积为异速生长。海拔和发育阶段共同影响了陇蜀杜鹃功能小枝和叶片的性状。     

竹子扩张对阔叶林物种多样性的影响:两竹种的叠加效应

研究了不同扩张强度下毛竹和肿节少穗竹对江西武夷山常绿阔叶林群落结构和物种多样性的影响.结果表明: 毛竹、肿节少穗竹扩张都会不同程度地改变阔叶林群落结构与物种组成,两者同时高强度扩张时(毛竹30～50 ind·100 m^-2,肿节少穗竹300～500 ind·100 m^-2),群落的乔∶灌(密度比)由2∶8变成1∶9,竹∶木(密度比)由0∶10变成9∶1.毛竹、肿节少穗竹扩张对阔叶林物种多样性影响的主效应显著,毛竹主要影响乔木层,肿节少穗竹主要影响灌木层,但两种竹子的交互作用不显著.两种竹子同时扩张对群落生物多样性的影响存在叠加效应,尤其是高强度扩张使群落Shannon指数下降91.3%.毛竹与肿节少穗竹同时低强度扩张时,两者相互影响不大,但当达到一定密度后两者会相互竞争排斥.这表明,当常绿阔叶林同时遭受毛竹、肿节少穗竹扩张时,虽然二者交互作用不明显,但会通过叠加效应影响木本植物,导致阔叶林群落简单化.     

清凉峰不同海拔木本植物小枝内叶大小-数量权衡关系

权衡关系是生活史对策理论的基础, 叶大小-数量的权衡关系对理解叶大小进化具有重要的意义。该研究以单叶面积和单叶片干重表示叶大小, 用小枝干重和小枝茎干重表示小枝大小, 采用标准化主轴估计(standardized major axis estimation, SMA)和系统独立比较分析(phylogenetically independent contrast analysis, PIC)的方法, 对浙江省清凉峰自然保护区3个不同海拔落叶阔叶木本植物当年生小枝内的叶大小与数量间的关系进行研究。结果显示, 无论叶大小和小枝大小是用面积或干重表示, 在每个海拔, 叶大小与出叶强度均存在显著的等速负相关关系, 表明在落叶阔叶木本植物中发现的叶大小与出叶强度之间的权衡关系在不同生境物种中是普遍存在的, 植物在叶大小方面的种间变化, 可能不是自然选择的直接产物, 而是叶片数量变化权衡关系的一个副产物。不同海拔间的比较显示, 高海拔物种的叶面积或干重与出叶强度相关关系的y轴截距比中、低海拔物种小, 表明在出叶强度一定的情况下, 高海拔物种比低海拔物种具有更小的叶大小。与高海拔物种相比, 中海拔物种的共同斜率沿共同主轴有一个向上的位移, 表明中海拔物种比高海拔物种具有更大的叶大小, 但出叶强度更小。这些结果表明生境对叶大小-数量的权衡关系具有显著的影响, 中海拔生境具有更适宜植物生长的气候及养分条件, 而高海拔的低温等不利影响使得叶片变小。     

武夷山常绿阔叶林木本植物小枝生物量分配

小枝是木本植物的重要组成单元,研究其生物量分配策略有利于了解不同物种对环境的响应。本文以武夷山常绿阔叶林群落中19种木本植物的小枝为研究对象,采取标准化主轴回归(standardized major axis,SMA)的方法分析小枝的叶重、叶片面积、叶柄重、茎重、叶数量等性状特征,研究在群落水平上和不同生活型上,常绿阔叶林群落木本植物的小枝生物量分配格局。结果表明:群落水平上小枝重、总叶重和茎重三者间均呈等速生长关系。同样的,在乔木和灌木不同生活型分类中,茎重和总叶重也呈等速生长关系。但是,小枝重和总叶重、茎重之间的关系却不一致:小枝重和总叶重在乔木、灌木中分别呈等速生长关系和异速生长关系;小枝重和茎重在乔木、灌木中分别呈异速生长关系和等速生长关系;此外,单叶重和出叶强度在群落水平上呈负等速生长关系。然而,这种负等速生长关系并不存在于不同生活型的植物中。小枝水平上,总叶柄重和小枝重、总叶重均呈小于1的异速生长关系,即随叶的增大,小枝需要分配更多生物量用于运输组织和支撑结构(叶柄)的构建。因此,叶柄投资是限制亚热带常绿阔叶林当年生枝和叶增大的重要因素,对于小枝和叶大小的优化选择具有重要影响。     

箬竹叶片活性成分含量的季节变化

以2008年于南京地区采集的粽粑竹、美丽箬竹和阔叶箬竹竹叶为试验材料,研究了箬竹叶片中总黄酮、茶多酚和可溶性糖含量的季节变化.结果表明: 3个竹种叶片的总黄酮、茶多酚和可溶性糖含量存在显著的季节差异.不同季节叶片中总黄酮含量为1.7%～2.7%,春季粽粑竹和美丽箬竹叶片中总黄酮含量最高,冬季阔叶箬竹叶片中总黄酮含量最高;茶多酚含量为5.5%～7.6%;可溶性糖含量在1.0%～8.5%,以春季最高.在展叶后3个月内, 粽粑竹和美丽箬竹叶片中各活性成分含量随叶龄的增加而增加.12月至翌年3月为箬竹叶的最佳采叶时期. 3个竹种中,阔叶箬竹叶片的3种活性成分含量均最高,是活性成分利用潜力较大的竹种.     

亚热带常绿阔叶林植物叶小枝的异速生长

 植物生态学研究的重要内容之一是识别和定量刻画种间生态变异的主要维数,叶大小小枝大小维（谱）是其中之一,目前的研究相对比较薄弱,两者之间是异速还是等速生长关系仍存在着争论。亚热带常绿阔叶林植物叶大小-枝大小维的研究报道很少。该文以我国东部亚热带典型区域福建梅花山常绿阔叶林的68种常绿乔灌木植物为对象,进行了叶-小枝关系及其生态意义的研究。结果表明：1）小枝茎截面积与叶干重、总叶面积和单叶面积之间的SMA斜率分别为1.29、1.23和1.18,呈现异速生长关系,支持叶大小 小枝大小为异速生长的相关研究结论,但SMA斜率低于预期值,其原因及生态意义有待进一步研究;2）小枝总叶面积与单叶面积呈显著正相关,而与叶片数量不相关,反映了小枝总叶面积的增加主要是由单叶面积大小决定的,可能与这一地区湿润气候有关;而单叶面积与枝条长度呈正相关则可能反映了植物对常绿阔叶林内较弱光照环境的适应;3）叶干重同小枝干重、叶面积为等速生长关系,可能反映了植物与动物之间代谢方式的差异。     

武夷山不同海拔阔叶树叶片养分含量及再吸收效率

为揭示亚热带山地阔叶树叶片养分利用策略随海拔梯度的变化规律，本研究选取武夷山不同海拔(1400、1600和1800 m)44种阔叶树，研究成熟与衰老叶片养分含量、化学计量比及养分再吸收效率，并分析其异速生长关系。结果表明：成熟叶片氮(N)、磷(P)含量显著高于衰老叶，且均随海拔升高而升高。磷再吸收效率(PRE)与氮再吸收效率(NRE)的平均值分别为48.3%和34.9%,PRE显著高于NRE,养分再吸收效率随海拔变化无显著差异。NRE与成熟叶N含量在低海拔处(1400 m)呈正等速生长，与衰老叶N含量在高海拔处(1800 m)呈负异速生长。PRE与衰老叶片N、P含量在低海拔(1400 m处)呈负等速生长，在高海拔处(1600、1800 m)呈负异速生长。各海拔PRE-NRE异速生长指数为0.95。随着海拔的升高，成熟和衰老叶片养分含量升高，但海拔不影响养分再吸收效率，且植物偏好从衰老叶中再吸收P,高海拔养分再吸收效率会影响衰老叶片的养分状况。     

Application of leaf size and leafing intensity scaling across subtropical trees

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 ‐α (−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.     

The leaf size-twig size spectrum of temperate woody species along an altitudinal gradient: an invariant allometric scaling relationship

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. 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. 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. 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.     

Within-twig biomass allocation in subtropical evergreen broad-leaved species along an altitudinal gradient: allometric scaling analysis

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.     

The generality of leaf size versus number trade-off in temperate woody species

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.

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.

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.

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.Key words: Allometry, trade-off, leafing intensity, leaf size, leaf habit, leaf form     

The effects of leaf size,leaf habit,and leaf form on leaf/stem relationships in plant twigs of temperate woody species

Question: 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? Location: Gongga Mountain, southwest China. Methods: (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. Results: (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. Conclusions: 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.     

Testing of corner’s rules across woody plants in Tiantong region,Zhejiang Province: effects of micro-topography

Aims The size and quantity relationships between twigs and leaves can be used to describe the hydraulic properties of plants in response to environmental stresses. The objective of this study was to examine how twig-leaf relationship would vary with changes in micro-habitat conditions.
Methods The study site is located in the Tiantong National Forest Park (29.87° N, 121.65° E), Zhejiang Province. We measured twig cross-sectional area (twig size), sub-twig cross-sectional area (sub-twig size), individual leaf area, total leaf area (leaf size per twig), the number of twigs at a given twig size (twig intensity), and the number of leaves at a given twig size (leafing intensity) across individual woody plants on 10 plots in each of the convex and concave habitats within an evergreen broad-leaved forest. The standardized major axis (SMA) analysis was conducted to determine the scaling relationships between twig size and leaf size, between sub-twig size and twig intensity, and between leaf size and leafing intensity.
Important findings Significant, positive allometric relationships between twig cross-sectional area and total leaf area were found in plants in both types of micro-habitats (p < 0.001). There was no significant difference between the two micro-habitats in the slope of the regression between twig cross-sectional area and total leaf area, and the common slope of the regressions was significantly greater than 1 (p < 0.001). The intercept was significantlygreater in plants of the concave habitat than in plants of the convex habitat (p < 0.001), indicating that plants in a concave habitat support greater total leaf area at a given twig size than in a convex habitat. Significant, negative allometric scaling relationships were found between twig size and twig intensity in plants in both micro-habitats. There was also no significant difference between the two habitats in the slope of the regression between twig size and twig intensity, and the common slope of the regressions was significantly less than –1 (p < 0.001). The similar intercept in the regression relationship of twig area and twig intensity between the two habitats suggests that plants deploy similar amount of sub-twigs per twig size in both types of habitat. In addition, significant, negative allometric scaling relationships between leaf size and leafing intensity were found to be consistently conserved across micro-habitat types, with the common slope being smaller than –1. A higher value of y-intercept in the scaling relationships of leaf area vs. leafing intensity for plants in the concave habitat indicates that at a given leaf area, more leaves were supported by plants in a concave habitat than in a convex habitat. Overall, plants in a concave habitat tend to deploy more large leaves per twig size than those in a convex habitat. This study demonstrated that both the Corner’s rules and the leaf size-number trade-offs could be generalized to apply at the small local spatial scales. The magnitude and quantitative adjustment of twig-leaf deployment manifests a selection preference of hydraulic properties of plants in coping with changes in water availability between concave and convex habitats.