Leaf functional traits vary with the adult height of plant species in forest communities

Aims Within-community variation accounts for a remarkable proportion of the variation in leaf functional traits. Plant height may be used to explain within-community variances of leaf traits because different microenvironments, especially light intensity, may occur at different heights. This study determines whether or not leaf nitrogen (N) and phosphorus (P) contents as well as leaf mass per area (LMA) are interspecifically correlated with the adult height of forest woody species. We also discuss these relationships with respect to community structure and functions of the ecosystem.Methods A total of 136 dicotyledonous woody species from 6 natural forests (3 evergreen and 3 deciduous ones) in East China (18°44′–45°25′N, 108°50′–128°05′E) were investigated. For each of the 157 species–site combinations, 6 traits were measured: plant adult height relative to the forest canopy (H R), leaf N and P contents per unit area (N area and P area), N and P contents per unit dry mass (N mass and P mass) and LMA. The total variances of each leaf trait across sites were partitioned in a hierarchical manner. The relationships between leaf traits and H R within forest communities were then analyzed using both standardized major axis regression and Felsenstein's phylogenetic independent contrasts. Relationships between evergreen and deciduous forests were compared by linear mixed models.Important findings H R is a robust predictor of leaf N area, P area and LMA, explaining 36.7, 39.4 and 12.0% of their total variations across forests, respectively. Leaf N area, P area and LMA increased with H R in all of the studied forests, with slopes that were steeper in evergreen forests than in deciduous ones. Leaf N mass and P mass showed no significant relationship with H R generally. The increase in leaf N area, P area and LMA with H R across species is assumed to maximize community photosynthesis and may favor species with larger H R .     

柯-青冈常绿阔叶林优势树种叶片性状变异及适应策略

厘清叶片功能性状的变异及性状间的权衡关系,对揭示植物对环境变化的响应及适应策略具有重要意义。以中亚热带柯(Lithocarpus glaber)-青冈(Cyclobalanopsis glauca)常绿阔叶林为对象,测量了1 hm²固定监测样地内6个优势树种的叶面积(LA)、比叶面积(SLA)、干物质含量(LDMC)、叶片厚度(LT)、叶片碳(LC)、叶片氮(LN)、叶片磷(LP)含量和叶片碳氮比(LC ∶ LN)8个功能性状,采用多重比较、主成分分析(PCA)法分析了群落叶片功能性状的生活型、种内和种间变异及性状间关系。结果表明：(1)群落内叶片功能性状种内、种间差异显著,变异中等(CV： 0.02-0.59),其结构性状的可塑性较化学性状保守,变异格局符合"性状空间变异分割假说";针叶树种的LA、SLA显著低于阔叶树种,常绿树种的LC和LDMC最小,而落叶树种的SLA、LN和LP最大以及LT和LC ∶ LN最小。(2)群落叶片功能性状变异主要来源于生活型和种间变异,种内变异亦有显著贡献;生活型对多数性状的贡献率较大,其对LDMC、LC ∶ LN的贡献分别高达93.11%和91.76%;种间变异(LDMC除外)对结构性状的贡献率均高于化学性状;种内变异对LP的贡献率(23.66%)较种间变异高。(3)叶片性状之间多表现出显著相关关系,针叶树和阔叶树在PCA排序图中聚集于不同区域,叶经济型谱在柯-青冈群落中具有适用性。不同树种通过叶片结构、化学性状之间的权衡策略来适应环境变化,从而实现群落物种共存。结果可为理解森林群落物种的环境适应策略、预测群落动态变化和制定植被恢复措施提供科学依据。     

Leaf traits and herbivory rates of tropical tree species differing in successional status

We evaluated leaf characteristics and herbivory intensities for saplings of fifteen tropical tree species differing in their successional position. Eight leaf traits were selected, related to the costs of leaf display (specific leaf area [SLA], water content), photosynthesis (N and P concentration per unit mass), and herbivory defence (lignin concentration, C:N ratio). We hypothesised that species traits are shaped by variation in abiotic and biotic (herbivory) selection pressures along the successional gradient. All leaf traits varied with the successional position of the species. The SLA, water content and nutrient concentration decreased, and lignin concentration increased with the successional position. Herbivory damage (defined as the percentage of damage found at one moment in time) varied from 0.9-8.5% among the species, but was not related to their successional position. Herbivory damage appeared to be a poor estimator of the herbivory rate experienced by species, due to the confounding effect of leaf lifespan. Herbivory rate (defined as percentage leaf area removal per unit time) declined with the successional position of the species. Herbivory rate was only positively correlated to water content, and negatively correlated to lignin concentration, suggesting that herbivores select leaves based upon their digestibility rather than upon their nutritive value. Surprisingly, most species traits change linearly with succession, while resource availability (light, nutrients) declines exponentially with succession.     

尖峰岭热带山地雨林林冠层乔木某些功能性状的系统发育信号、关联性及其演化模式

热带雨林林冠层具有丰富的物种、功能和系统发育(谱系)多样性,能够显著影响生态系统生物地球化学循环,调节大气水热平衡,缓解气候变化与人为干扰的负面作用。因此热带雨林林冠层功能和谱系生态学研究是目前群落生态学研究的热点之一。选取海南尖峰岭热带山地雨林3个1 hm2样地的林冠层为研究对象,利用样地林冠树种清查数据基于APG III系统发育结构重建样地林冠层系统发育树。利用Blomber's K对和Pagel'sλ指标结合系统发育独立性比较法对组成林冠层乔木树种的结构、化学计量和水力学功能性状(11个性状)的系统发育信号、关联性和演化模式进行研究,以探讨物种亲缘关系对尖峰岭热带山地雨林林冠层多维功能性状关联性及其动态演化的影响。结果表明,有8个功能性状(叶面积、叶厚度和潜在最大高度除外)具有显著的系统发育信号(通过P0.05的显著性检验),Blomber's K值和Pagel'sλ值分别介于0.202—0.392和0.277—0.847之间,表明尖峰岭热带山地雨林林冠层功能性状普遍存在系统发育保守性。在系统发育背景下,林冠层乔木树种结构、化学和水力学功能性状在物种水平普遍存在显著关联性(P0.05),表现出趋同或趋异进化;而且林冠层乔木随物种分化其功能性状分化模式大致呈水平"漏斗"状,姐妹类群功能性状间差异性在物种分化早期(大约1亿2千万年前至6000万年前)明显小于其在中后期(大约6000万年前至今)的差异性,导致了林冠层性状空间在中后期迅速膨大。然而林冠层主要功能性状在系统发育树内部每一节点上姊妹类群分化产生的系统发育独立性比较值绝大部分与零模型随机模拟值并无显著性差异。了解系统发育背景下林冠层功能性状的权衡关系及其随物种演化的分化模式与时间动态为进一步探究热带雨林林冠生态系统功能发挥奠定基础。     

Leaf morphology of 40 evergreen and deciduous broadleaved subtropical tree species and relationships to functional ecophysiological traits

We explored potential of morphological and anatomical leaf traits for predicting ecophysiological key functions in subtropical trees. We asked whether the ecophysiological parameters stomatal conductance and xylem cavitation vulnerability could be predicted from microscopy leaf traits. We investigated 21 deciduous and 19 evergreen subtropical tree species, using individuals of the same age and from the same environment in the Biodiversity‐Ecosystem Functioning experiment at Jiangxi (BEF‐China). Information‐theoretic linear model selection was used to identify the best combination of morphological and anatomical predictors for ecophysiological functions. Leaf anatomy and morphology strongly depended on leaf habit. Evergreen species tended to have thicker leaves, thicker spongy and palisade mesophyll, more palisade mesophyll layers and a thicker subepidermis. Over 50% of all evergreen species had leaves with multi‐layered palisade parenchyma, while only one deciduous species (Koelreuteria bipinnata) had this. Interactions with leaf habit were also included in best multi‐predictor models for stomatal conductance (g_s) and xylem cavitation vulnerability. In addition, maximum g_s was positively related to log ratio of palisade to spongy mesophyll thickness. Vapour pressure deficit (vpd) for maximum g_s increased with the log ratio of palisade to spongy mesophyll thickness in species having leaves with papillae. In contrast, maximum specific hydraulic conductivity and xylem pressure at which 50% loss of maximum specific xylem hydraulic conductivity occurred (Ψ₅₀) were best predicted by leaf habit and density of spongy parenchyma. Evergreen species had lower Ψ₅₀ values and lower maximum xylem hydraulic conductivities. As hydraulic leaf and wood characteristics were reflected in structural leaf traits, there is high potential for identifying further linkages between morphological and anatomical leaf traits and ecophysiological responses.     

海南岛霸王岭热带云雾林木本植物功能性状的分异规律

研究植物功能性状的分异,有助于理解植物适应环境的方式和策略,也能为预测物种分布和环境变化提供依据。以海南霸王岭热带云雾林为对象,建立21个20 m×20 m固定样方,划分为336个5 m×5 m小样方;测定胸径在5cm以上所有乔灌木植物个体的功能性状(叶面积LA;叶干重LDW;比叶重LMA;叶绿素含量Chl;叶厚度LTh;木材密度WD)和土壤养分含量,通过方差分解分析植物功能性状在个体、种内、种间、群落水平的分异大小,探究土壤养分对功能性状分异的影响。结果表明,LA、LDW、LMA、CHl、LTh、WD在个体、种内、种间、群落水平的解释方差范围分别为0.06—0.47、0.09—0.35、0.35—0.72、0—0.07,在个体、种内、种间、群落层次上,种间水平的功能性状分异最大,而群落水平的分异最小。逐步回归分析表明,不同尺度的功能性状变化与土壤有机质、氮和磷含量都有密切关系。     

漓江河岸带木本植物功能性状跨尺度变异研究

研究植物功能性状变异,有助于揭示植物对环境的适应策略以及群落构建机制。以漓江河岸带木本植物为研究对象,利用广义线性模型和"varcomp"函数对漓江河岸带主要木本植物的3个叶功能性状（比叶面积SLA;叶面积LA;叶厚度LTH）跨不同尺度（样方、物种、个体、叶）变异进行方差分解,分析各尺度的相对贡献及变异的主要来源。结果表明：（1）植物功能性状在4个巢式尺度的解释方差规律较一致,均表现为物种（0.51-0.70） > 个体（0.21-0.22） > 叶和残差（0.09-0.20） > 样方（0-0.07）;（2）4个功能性状种间尺度的解释方差均最大（SLA、LA和LTH分别为64%、70%和51%）;其次种内尺度的解释方差（SLA、LA和LTH分别为34%、30%和42%）仅次于种间。（3）样方尺度的解释方差很小甚至为零。发现：（1）植物功能性状变异主要由种间变异驱动;（2）种内性状变异是功能性状变异的重要且不容忽视的来源;（3）生境过滤并非直接作用于群落间物种组成,而可能是通过直接作用于植物功能性状的总体分布来影响植物群落构建过程,基于功能性状的生境过滤可能在漓江河岸带植物群落构建中起重要作用。     

长白山阔叶红松林主要树种凋落叶分解速率及其与叶性状的关系

阔叶红松林是我国东北地区地带性顶级森林群落,对维持区域生态系统稳定性具有重要作用。对阔叶红松林内主要树种凋落叶分解过程及影响因素进行研究,有助于增加长白山阔叶红松林生态系统的基础数据,为明确阔叶红松林的养分循环和物质流动提供依据。选取了长白山阔叶红松林内30个常见乔灌树种和16个凋落叶性状,采用野外分解袋法和室内样品分析等方法研究了长白山阔叶红松林内主要树种凋落叶分解速率及其与凋落叶性状的关系。1年的野外分解实验表明,30个树种的凋落叶重量损失率表现出较大差异。不同树种凋落叶的重量损失率在20.56%—92.11%之间,以红松(Pinus koraiensis)质量损失率最低,东北山梅花(Philadelphus schrenkii)质量损失率最高。不同生活型树种的凋落叶在质量损失率上存在显著差异,以灌木树种凋落叶的质量损失率最高,小乔木次之,乔木树种质量损失率最低。Olson模型拟合结果表明,不同树种凋落叶的分解速率k以红松最低,瘤枝卫矛(Euonymus verrucosus)最高,分别为0.24和1.64。不同树种分解50%和95%所需的时间分别在0.43—2.86年,1.83—...     

Leaf traits from stomata to morphology are associated with climatic and edaphic variables for dominant tropical forest evergreen oaks

热带森林优势种青冈叶片气孔、解剖和形态性状与气候、土壤因子的关联 了解优势树种叶片多水平的功能性状沿海拔梯度的变化及其内在关联,有助于预测优势种应对气候变化的响应与适应。本文研究了青冈属树种叶片气孔、解剖和形态性状沿海拔梯度的变化及其与环境调控因子的关联,探究了其生态策略是否随海拔发生改变。在海南尖峰岭热带森林,沿海拔梯度(400–1400 m)采集了6种常绿青冈：竹叶青冈(Cyclobalanopsis bambusaefolia)、雷公青冈(C. hui)、托盘青冈 (C. patelliformis)、饭甄青冈(C. fleuryi)、吊罗山青冈(C. tiaoloshanica)和亮叶青冈(C. phanera)叶片,用于气孔、解剖和形态性状的测定。研究结果表明,随海拔升高,青冈树种叶片气孔密度、气孔孔隙度指数和叶面积显著增加,但海绵组织厚度比和干物质含量则显着降低。叶片气孔、解剖和形态性状沿海拔梯 度的变化主要受年均温、年降水量和土壤pH 值调控。在低海拔和高海拔处,青冈属采取“耐受”和“竞 争”策略,而在中海拔处,则是“竞争”策略。土壤磷含量和土壤pH 值随海拔的变化可能是驱动其生态 策略转变的主要原因。该结果揭示,热带森林优势树种青冈可通过从气孔细胞-组织解剖结构-叶片水平功能性状的改变来响应环境变化。     

Variations of plant functional traits and adaptive strategy of woody species in a karst forest of central Guizhou Province,southwestern China

性状变异反映了植物的生活史对策。该研究以贵州普定县天龙山10种木本植物为对象, 通过分析枝叶和根系9个功能性状的种间与种内变异, 揭示植物对喀斯特生境的适应策略。结果表明: (1) 9个性状变异程度不同, 细根组织密度的种间和种内变异系数最大, 分别达96.47%和51.44%, 小枝干物质含量的种间与种内变异最小, 分别为11.67%和6.83%。(2)种间水平的细根组织密度在不同物种中没有显著的差异, 比根长、叶厚度、叶面积、比叶面积、叶干物质含量、叶组织密度、小枝干物质含量和小枝组织密度均表现出显著的差异。在种内, 比叶面积差异显著, 其他性状差异不显著。(3)绝大多数叶和枝性状间显著相关, 比根长与比叶面积显著负相关, 其他根系性状与枝叶性状相关性不显著。总之, 与同纬度非喀斯特地区植物相比, 普定喀斯特地区植物具有较小的叶面积和比根长度, 较大的叶干物质含量、叶组织密度等一系列有利于减小蒸腾和储存养分的功能性状组合, 这可能是其适应干旱贫瘠的喀斯特环境的主要生态策略。     

黔中喀斯特木本植物功能性状变异及其适应策略

性状变异反映了植物的生活史对策。该研究以贵州普定县天龙山10种木本植物为对象, 通过分析枝叶和根系9个功能性状的种间与种内变异, 揭示植物对喀斯特生境的适应策略。结果表明: (1) 9个性状变异程度不同, 细根组织密度的种间和种内变异系数最大, 分别达96.47%和51.44%, 小枝干物质含量的种间与种内变异最小, 分别为11.67%和6.83%。(2)种间水平的细根组织密度在不同物种中没有显著的差异, 比根长、叶厚度、叶面积、比叶面积、叶干物质含量、叶组织密度、小枝干物质含量和小枝组织密度均表现出显著的差异。在种内, 比叶面积差异显著, 其他性状差异不显著。(3)绝大多数叶和枝性状间显著相关, 比根长与比叶面积显著负相关, 其他根系性状与枝叶性状相关性不显著。总之, 与同纬度非喀斯特地区植物相比, 普定喀斯特地区植物具有较小的叶面积和比根长度, 较大的叶干物质含量、叶组织密度等一系列有利于减小蒸腾和储存养分的功能性状组合, 这可能是其适应干旱贫瘠的喀斯特环境的主要生态策略。     

Size‐dependent and environment‐mediated shifts in leaf traits of a deciduous tree species in a subtropical forest

AimsUnderstanding the joint effects of plant development and environment on shifts of intraspecific leaf traits will advance the understandings of the causes of intraspecific trait variation. We address this question by focusing on a widespread species Clausena dunniana in a subtropical broad‐leaved forest.MethodsWe sampled 262 individuals of C. dunniana at two major topographic habitat types, the slope and hilltop, within the karst forests in Maolan Nature Reserve in southwestern China. We measured individual plant level leaf traits (i.e., specific leaf area (SLA), leaf area, leaf dry‐matter content (LDMC), and leaf thickness) that are associated with plant resource‐use strategies. We adopted a linear mixed‐effects model in which the plant size (i.e., the first principal component of plant basal diameter and plant height) and environmental factors (i.e., topographic habitat, canopy height, and rock‐bareness) were used as independent variables, to estimate their influences on the shifts of leaf traits.Key ResultsWe found that (1) plant size and the environmental factors independently drove the intraspecific leaf trait shifts of C. dunniana, of which plant size explained less variances than environmental factors. (2) With increasing plant size, C. dunniana individuals had increasingly smaller SLA but larger sized leaves. (3) The most influential environmental factor was topographic habitat; it drove the shifts of all the four traits examined. Clausena dunniana individuals on hilltops had leaf traits representing more conservative resource‐use strategies (e.g., smaller SLA, higher LDMC) than individuals on slopes. On top of that, local‐scale environmental factors further modified leaf trait shifts.ConclusionsPlant size and environment independently shaped the variations in intraspecific leaf traits of C. dunniana in the subtropical karst forest of Maolan. Compared with plant size, the environment played a more critical role in shaping intraspecific leaf trait variations, and potentially also the underlying individual‐level plant resource‐use strategies.     

亚热带常绿落叶阔叶混交林植物功能性状的种间和种内变异

不同物种间的功能性状差异是自然生态系统中物种共存的基础, 而物种内个体间的性状变异对物种的共存和分布同样具有重要作用。本文以湖北星斗山自然保护区亚热带常绿落叶阔叶混交林内28种主要树种(通过物种多度排序获得, 其中常绿和落叶树种各14种)为研究对象, 探讨不同叶习性树种的4种功能性状(比叶面积、叶干物质含量、叶面积和比茎密度)在种间和种内的差异程度。结果表明: (1)常绿和落叶树种在4种功能性状上均存在显著差异, 常绿树种的比叶面积和叶面积显著低于落叶树种, 但叶干物质含量和比茎密度则显著高于落叶树种; (2)比叶面积的变化主要来源于叶习性(57.49%), 叶面积变化主要来源于种间(66.80%)和种内变异(27.52%), 叶干物质含量的变化主要来源于种间(38.12%)和种内(33.88%)变异, 但比茎密度的变化主要来源于种内变异(51.50%), 其次为种间变异(32.52%); (3)常绿和落叶树种种间水平的性状相关性可能掩盖各功能性状之间的相关性。种内变异能够显著影响群落间的植物功能性状差异, 但不同功能性状的种内变异程度存在差异。     

Contrasting leaf chemical traits in tropical lianas and trees: implications for future forest composition

Lianas are an important growthform in tropical forests, and liana abundance and biomass may be increasing in some regions. Explanations for liana proliferation hinge upon physiological responses to changing resource conditions that would favour them over trees. Testing a chemical basis for such responses, we assessed 22 foliar traits in 778 lianas and 6496 trees at 48 tropical forest sites. Growthform differences in chemical allocation occurred on a leaf mass and area basis. Light capture-growth and maintenance-metabolism chemicals averaged 14.5 and 16.7% higher mass-based concentration in lianas than in trees globally, whereas structure and defence chemicals averaged 9.0% lower in lianas. Relative differences in chemical allocation by lianas and trees were mediated by climate with peak differences at about 2500 mm year(-1) and 25 °C. Differences in chemical traits suggest that liana expansion could be greatest in forests undergoing increased canopy-level irradiance via disturbance and climate change.     

Differences in leaf thermoregulation and water use strategies between three co‐occurring Atlantic forest tree species

Given anticipated climate changes, it is crucial to understand controls on leaf temperatures including variation between species in diverse ecosystems. In the first study of leaf energy balance in tropical montane forests, we observed current leaf temperature patterns on 3 tree species in the Atlantic forest, Brazil, over a 10‐day period and assessed whether and why patterns may vary among species. We found large leaf‐to‐air temperature differences (maximum 18.3 °C) and high leaf temperatures (over 35 °C) despite much lower air temperatures (maximum 22 °C). Leaf‐to‐air temperature differences were influenced strongly by radiation, whereas leaf temperatures were also influenced by air temperature. Leaf energy balance modelling informed by our measurements showed that observed differences in leaf temperature between 2 species were due to variation in leaf width and stomatal conductance. The results suggest a trade‐off between water use and leaf thermoregulation; Miconia cabussu has more conservative water use compared with Alchornea triplinervia due to lower transpiration under high vapour pressure deficit, with the consequence of higher leaf temperatures under thermal stress conditions. We highlight the importance of leaf functional traits for leaf thermoregulation and also note that the high radiation levels that occur in montane forests may exacerbate the threat from increasing air temperatures.     

Neither species geographic range size,climatic envelope,nor intraspecific leaf trait variability capture habitat specialization in a hyperdiverse Amazonian forest

Many plant species exhibit strong association with topographic habitats at local scales. However, the historical biogeographic and physiological drivers of habitat specialization are still poorly understood, and there is a need for relatively easy‐to‐measure predictors of species habitat niche breadth. Here, we explore whether species geographic range, climatic envelope, or intraspecific variability in leaf traits is related to the degree of habitat specialization in a hyperdiverse tropical tree community in Amazonian Ecuador. Contrary to our expectations, we find no effect of the size of species geographic ranges, the diversity of climate a species experiences across its range, or intraspecific variability in leaf traits in predicting topographic habitat association in the ~300 most common tropical tree species in a 25‐ha tropical forest plot. In addition, there was no phylogenetic signal to habitat specialization. We conclude that species geographic range size, climatic niche breadth, and intraspecific variability in leaf traits fail to capture the habitat specialization patterns observed in this highly diverse tropical forest.