浙江天童常绿植物当年生与往年生叶片性状的变异与关联

植物叶片性状随叶龄的变化是植物生活史策略的体现, 反映了植物叶片的物质投资和分配方式。该研究通过在个体和物种2个水平, 比较浙江天童1 hm ²样地内常绿阔叶树种的平均叶面积(MLA)、比叶面积(SLA)和叶片干物质含量(LDMC)在当年生和往年生叶片间的差异和关联, 探究叶片物质分配策略在异龄叶间的变化, 并分析叶龄对植物叶片性状, 特别是叶片面积建成消耗的影响。结果显示: 1)在个体和物种水平上, MLA变异系数最大(个体: 79.5%; 物种: 66.5%), SLA次之(个体: 28.1%; 物种: 24.7%), LDMC较低(个体: 17.0%, 物种: 14.1%); 当年生叶片MLA、LDMC和SLA的变异系数均高于往年生叶片; 2)往年生叶MLA显著大于当年生叶(t = -38.53, p < 0.001), 往年生叶SLA显著小于当年生叶(t = 45.30, p < 0.001), 往年生叶LDMC显著大于当年生叶(t = -9.71, p < 0.001); 3)在个体水平, 当年生叶片MLA、SLA和LDMC值分别解释了往年生叶片MLA、SLA和LDMC变异的86%、48%和41%; 在物种水平, 当年生叶片MLA、SLA和LDMC值分别解释了往年生叶片MLA、SLA和LDMC变异的97%、83%和85%; 4) SLA在异龄叶间的变化表明, 与往年生叶片相比, 投资相同干物质, 当年生叶片可形成较大的叶面积, 其叶片面积建成消耗较小。研究认为, 植物叶性状在异龄叶间具有较大的变异性和关联性, 叶面积形成过程中生物量建成与消耗的协调可能影响植物叶片的发育。     

内蒙古锡林河流域典型草原植物叶片与细根性状在种间及种内水平上的关联

植物的叶片与细根分别作为植物体地上和地下部分重要的营养器官, 很多功能性状在二者之间存在着一定的关联性。研究这种关联有助于理解植物各性状之间的相互作用、植物生长过程中对资源的利用和分配, 以及建立细根性状的估算模型。该研究对内蒙古锡林河流域65种植物叶片与细根的氮(N)含量、磷(P)含量、N:P以及比叶面积(SLA)和比根长(SRL)进行了比较研究, 结果表明: 在种间尺度上, 叶片与细根间的N、P和N:P存在显著的相关性, 而SLA与SRL之间相关性较弱; 在种内尺度上, 叶片和细根的N、P及SLA与SRL, 在不同的物种中呈现出不同的趋势。此外, 叶片与细根性状的关联, 在不同的植物功能群之间存在差异。例如, 双子叶植物叶片与细根间的N含量显著相关, P含量不相关; 而单子叶植物二者之间的P含量显著相关, N含量无关联。该研究的主要结论是, 在相对一致的生境中, 植物叶片与细根性状的关联主要发生在不同物种之间, 在种内尺度上这种关联不明显, 这可能与植物功能性状在种内存在较小的变异幅度有关。     

Specific leaf area estimation model building based on leaf dry matter content of Cunninghamia lanceolata

随着叶片功能性状研究的不断深入, 通过简单易测量的叶片指标, 同时探究植物生活史权衡对策和估算林分生产力的研究需求日益增长, 例如叶干质量比(LDMC)和比叶面积(SLA)的相互转换。杉木(Cunninghamia lanceolata)是亚热带重要的常绿针叶树种, 基于LDMC对杉木SLA进行估算, 能够为核算SLA提供途径, 为机理解释和生产估算构建连接途径, 为小区域到大尺度、精算到估算搭建桥梁。该研究在湖南会同和河南信阳两个杉木生长区, 对处于不同小生境(坡向、坡位和冠层深度)以及不同生活史(林龄和叶龄)的叶片进行抽样和采集, 通过测得不同叶龄的单叶LDMC和SLA, 初步探究在不同因子下两个性状值的分布差异, 进一步基于LDMC构建SLA估算模型并讨论以叶龄为差分因子对模型的影响。结果表明: 1)杉木SLA平均值为(103.15 ± 69.54) cm ²·g ^-1, LDMC为0.39 ± 0.11; 2)杉木LDMC和SLA可用非线性模型进行估算, 模型符合估算要求; 3)其中一年生叶的拟合效果最好, 老叶(大于二年生叶)的拟合优度较低, 老叶较低的SLA (52.28-75.74 cm ²·g ^-1)可能暗示LDMC的变化保持相对独立性。该研究基于杉木LDMC的SLA估算模型可信且有效, 且不同叶龄对LDMC和SLA的影响可能预示着杉木叶片的响应敏感性和生活史权衡策略。     

漓江河岸带植物功能性状变异与关联

研究植物功能性状随环境梯度的变异和关联格局, 对于认识不同环境梯度下群落构建和植物适应型具有重要意义。该研究以漓江河岸带不同河段植物群落为研究对象, 调查了研究区内36个样方的物种组成, 测量了样方内42种木本植物的叶面积(LA)、比叶面积(SLA)和木材密度(WD)的功能性状值, 并运用性状梯度分析法对3个功能性状进行群落内(α组分)和群落间(β组分)组分分解及相关性分析。结果表明: (1)群落平均LA表现为中游最小且和下游差异显著, 群落平均WD则表现为中上游显著高于下游, 群落平均SLA在两两河段间均差异显著。(2)不同河段的3个植物功能性状β组分差异显著且实际观测值均小于随机模拟的零模型分布, 但α组分在河岸带不同河段均差异不显著且3个功 能性状的α组分分布范围均小于β组分, 说明在河岸带不同河段的群落构建过程中环境筛选的作用要大于群落内种间的相互作用。(3)性状SLA与LA在群落间和群落内呈现出实际观测和随机模拟的相关性均较低, 暗示了LA和SLA各自代表了植物在不同生态策略上的维度; 但SLA和WD实际观测值和随机模拟值呈现出较强的负相关关系, 暗示这2个性状对于环境筛选表现出较高的整体趋同适应性, 体现了植物功能性状对群落间环境变异的依赖性大于群落内种间相互作用的依赖性。     

不同区域针叶年龄对红松叶性状及相关关系的影响

叶龄是植株个体发育过程中性状变异的重要影响因素, 不同叶龄下的性状变异可以体现植物针对环境变化做出的响应。该研究以东北地区4个不同区域阔叶红松(Pinus koraiensis)林中的成年红松为研究对象, 测定了4个区域红松的叶寿命和不同针叶年龄叶片的比叶面积(SLA)、叶片干物质含量(LDMC)、针叶密度(ND)以及针叶体积(NV), 探讨了红松叶形态性状间的相关性, 并检验了纬度和针叶年龄对这些相关关系的影响。结果显示: (1)不同纬度下红松叶寿命存在显著差异, 随纬度增加呈单峰模式。(2)针叶年龄在性状变异解释中占比最大(34.2%-80.1%), 对4个叶形态性状均存在显著影响。SLA、LDMC和ND在当年生叶片中均表现了比所有龄级下更大的可塑性, 仅NV在所有龄级下的可塑性大于当年生叶片。(3) 4个性状间的二元相关性显著, 且在不同纬度下多有体现, 但性状间的回归斜率随纬度变化趋势存在差异。(4)不同针叶年龄性状间的相关关系依然显著但变异规律不同, 如SLA与ND的回归斜率随针叶年龄增加而减小, ND与NV则相反。研究结果表明红松叶形态性状的变异和性状间的相关关系受纬度和针叶年龄的显著影响, 性状协同应对不同纬度梯度导致的环境变化以及不同针叶年龄下叶片的资源利用策略存在差异。     

海南尖峰岭热带山地雨林不同空间尺度和径级水平的物种丰富度与个体密度关联

以海南尖峰岭热带山地雨林为研究对象, 基于尖峰岭原始林60 hm²大样地, 分析了7个不同空间尺度(5 m × 5 m、10 m × 10 m、20 m × 20 m、40 m × 40 m、60 m × 60 m、80 m × 80 m、100 m × 100 m)、3个不同径级(胸径(DBH) ≥ 1.0 cm、DBH ≥ 2.5 cm、DBH ≥ 7.5 cm)物种丰富度与个体密度之间的关联性, 以期为负密度制约效应等研究的尺度选择提供参考依据。研究结果表明, 物种丰富度和个体密度之间的关联性是基于空间尺度存在的, 并受分析植株径级大小的影响。DBH ≥ 1.0 cm时, 在4个空间尺度下(5 m × 5 m、10 m × 10 m、20 m × 20 m、40 m × 40 m), 物种丰富度随个体密度增加而增加, 但物种丰富度和个体密度两者间的相关性随取样空间尺度的增大而逐渐下降; 在其他3个空间尺度下(60 m × 60 m、80 m × 80 m、100 m × 100 m), 两者间没有显著相关性。当DBH ≥ 2.5 cm和DBH ≥ 7.5 cm时, 物种丰富度和个体密度间的相关性随空间尺度变化的趋势也与上述结果基本一致; 在60 m × 60 m的空间尺度上, DBH ≥ 1.0 cm时物种丰富度和个体密度相关性不显著, DBH ≥ 2.5 cm和DBH ≥ 7.5 cm两个径级的物种丰富度和个体密度表现出弱相关性。DBH ≥ 2.5 cm和DBH ≥ 7.5 cm时, 各空间尺度下物种丰富度和个体密度之间的决定系数几乎一致, 但高于DBH ≥ 1.0 cm时两者之间的决定系数, 说明大径级植株的个体密度和物种丰富度之间有更强的关联性, 负密度制约效应和自疏效应可能是产生这种现象的主要原因。     

西藏紫花针茅叶功能性状沿降水梯度的变化

植物叶功能性状与环境因子的关系是近10年来植物生态学的研究热点。该文以广泛分布于青藏高原干旱、半干旱草地的优势植物种紫花针茅(Stipa purpurea)为研究对象, 沿降水梯度(69-479 mm)系统测定了日土、改则、珠峰、当雄和纳木错5个调查地点紫花针茅比叶面积(SLA)、单位重量和单位面积叶氮含量(N_mass, N_area)、叶密度和厚度等叶功能性状以及土壤全氮含量等因子, 试图验证干旱胁迫地区同一物种内SLA-N_mass关系沿降水梯度的策略位移现象是否具有普遍性, 并对是否出现策略位移现象提出可能的解释。研究结果表明: 1) SLA和N_mass与生长季温度和降水以及土壤全氮含量均没有显著关系, SLA与N_mass的关系在干旱半干旱区(年降水/蒸发比< 0.11)与半湿润区(年降水/蒸发比> 0.11)之间并没有出现典型的位移现象; 2)叶密度是决定半湿润区SLA变化的主导因子, 而叶厚度则是干旱半干旱区SLA变化的控制因子, 两者与SLA均呈负相关, 随着温度增加或降水减少, 叶厚度增加而叶密度降低, 导致SLA随温度和降水变化不明显; 3)半湿润区的叶密度增加引起N_area增加, 而干旱半干旱区的叶厚度增加并没有造成N_area的显著变化, 导致N_area沿降水梯度没有显著变化; 4)紫花针茅地上生物量与N_area具有显著正相关关系, 表明N_area的增加有助于提高植被生产力。结果表明, 在干旱胁迫下, 植物通过增加叶厚度来维持不变的N_area可能有助于保持与较湿润地区相似的光合生产和水分利用效率。叶厚度和叶密度对比叶面积的相对影响在干旱半干旱区与半湿润区之间发生转变, 这为进一步检测高寒草地植被的水分限制阈值提供了新思路。     

基于叶干质量比的杉木比叶面积估算模型的构建

随着叶片功能性状研究的不断深入, 通过简单易测量的叶片指标, 同时探究植物生活史权衡对策和估算林分生产力的研究需求日益增长, 例如叶干质量比(LDMC)和比叶面积(SLA)的相互转换。杉木(Cunninghamia lanceolata)是亚热带重要的常绿针叶树种, 基于LDMC对杉木SLA进行估算, 能够为核算SLA提供途径, 为机理解释和生产估算构建连接途径, 为小区域到大尺度、精算到估算搭建桥梁。该研究在湖南会同和河南信阳两个杉木生长区, 对处于不同小生境(坡向、坡位和冠层深度)以及不同生活史(林龄和叶龄)的叶片进行抽样和采集, 通过测得不同叶龄的单叶LDMC和SLA, 初步探究在不同因子下两个性状值的分布差异, 进一步基于LDMC构建SLA估算模型并讨论以叶龄为差分因子对模型的影响。结果表明: 1)杉木SLA平均值为(103.15 ± 69.54) cm ²·g ^-1, LDMC为0.39 ± 0.11; 2)杉木LDMC和SLA可用非线性模型进行估算, 模型符合估算要求; 3)其中一年生叶的拟合效果最好, 老叶(大于二年生叶)的拟合优度较低, 老叶较低的SLA (52.28-75.74 cm ²·g ^-1)可能暗示LDMC的变化保持相对独立性。该研究基于杉木LDMC的SLA估算模型可信且有效, 且不同叶龄对LDMC和SLA的影响可能预示着杉木叶片的响应敏感性和生活史权衡策略。     

氮添加对山西太岳山天然油松林主要植物叶片性状的影响

为探讨植物性状对大气氮沉降的响应与适应机制, 该文以中国特有的、在北方温性针叶林中广泛分布的天然油松(Pinus tabuliformis)林为研究对象, 在2009-2013年开展了氮添加对植物叶片性状影响的野外控制试验, 4个氮添加浓度分别为0 kg·hm^-2·a^-1 (CK)、50 kg·hm^-2·a^-1 (低氮)、100 kg·hm^-2·a^-1 (中氮)和150 kg·hm^-2·a^-1 (高氮)。试验过程中分别测定了油松、蒙古栎(Quercus mongolica)、茶条槭(Acer ginnala)、毛榛(Corylus mandshurica)、沙梾(Cornus bretschneideri)、绣线菊(Spiraea salicifolia)、金银忍冬(Lonicera maackii)、羊须草(Carex callitrichos)、龙常草(Diarrhena mandshurica)、大火草(Anemone tomentosa)和玉竹(Polygonatum odoratum)等11种主要植物的9种叶片性状, 包括叶厚度(LT)、比叶面积(SLA)、干物质含量(LDMC)、叶氮含量(LNC)、叶磷含量(LPC)等。结果表明: 1)在氮添加影响下, 玉竹等个别物种的LT和SLA、绣线菊等部分物种的叶面积(LA)和LDMC差异显著, 上述所有物种的LNC与大多数物种的叶绿素含量(CC)、LPC显著增加, 油松等9种植物叶片N:P发生显著变化, 不同年龄、不同类型的植物叶片对氮添加的响应不同。2)叶性状之间普遍存在显著相关性, 如SLA与LNC和LPC极显著正相关, LT与LNC和LPC极显著负相关, 且相关性随氮添加强度变化。3) 11种植物的叶片特征空间分布规律与叶经济谱的描述一致, 氮添加使植物在特征空间中的位置向叶片薄、生长快、叶寿命短的“快速投资-收益型”一端发生移动; 在垂直方向上, 阔叶乔木、灌木及草本的位置与针叶乔木的移动方向相反。当环境改变时, 植物会改变生存策略, 调整资源分配, 从而保证物种间相对位置和群落整体结构的稳定性。叶经济谱的形成不依赖于环境的变化, 而是植物一种固有的属性。     

典型阔叶红松林主要树种叶性状的垂直变异及经济策略

分析不同树种叶片性状的变化有助于了解植物群落结构。该文通过对典型阔叶红松(Pinus koraiensis)林15种阔叶树种的比叶质量、叶片厚度、叶干物质含量、叶绿素含量指数、叶片碳、氮、磷含量的测定, 分析了冠层高度对叶性状及叶性状间相关关系的影响。结果表明, 水曲柳(Fraxinus mandshurica)和大青杨(Populus ussuriensis)上层的比叶质量显著大于下层, 而其他树种冠层间的比叶质量无显著变化; 叶绿素含量指数在白桦(Betula platyphylla)和春榆(Ulmus japonica)冠层间的分布分别为上层显著大于下层和上层显著大于中层; 单位质量氮含量在水曲柳的中层显著大于上层。叶片性状间存在着广泛的相关性, 比叶质量与叶片厚度、干物质含量在三层间均呈显著正相关关系, 而有些性状, 只在一或二个冠层中存在一定的相关性。山杨(Populus davidiana)和大青杨的叶片倾向于选择光合能力较低、营养浓度较低、呼吸速率较慢的一端, 而黄檗(Phellodendron amurense)和山槐(Maackia amurensis)叶片更倾向于光合能力强、营养物质浓度高的一端。不同树种对光照响应的差异可能会改变不同冠层中叶片的形态和化学性状, 从而有助于群落构建和物种共存。     

Stem diameter growth rates in a fire‐prone savanna correlate with photosynthetic rate and branch‐scale biomass allocation,but not specific leaf area

Plant growth rates strongly determine ecosystem productivity and are a central element of plant ecological strategies. For laboratory and glasshouse‐grown seedlings, specific leaf area (SLA; ratio of leaf area to mass) is a key driver of interspecific variation in growth rate (GR). Consequently, SLA is often assumed to drive GR variation in field‐grown adult plants. However, there is an increasing evidence that this is not the general case. This suggests that GR – SLA relationships (and perhaps those for other traits) may vary depending on the age or size of the plants being studied. Here we investigated GR – trait relationships and their size dependence among 17 woody species from an open‐canopy, fire‐prone savanna in northern Australia. We tested the predictions that SLA and stem diameter growth rate would be positively correlated in saplings but unrelated in adults while, in both age classes, faster‐GR species would have higher light‐saturated photosynthetic rate (A_sat), higher leaf nutrient concentrations, higher branch‐scale biomass allocation to leaf versus stem tissues and lower wood density (WD). SLA showed no relationship to stem diameter GR, even in saplings, and the same was true of leaf N and P concentrations, and WD. However, branch‐scale leaf:stem allocation was strongly related to GR in both age groups, as was A_sat. Together, these two traits accounted for up to 80% of interspecific variation in adult GR, and 41% of sapling GR. A_sat is rarely measured in field‐based GR studies, and this is the first report of branch‐scale leaf:stem allocation (analogous to a benefit:cost ratio) in relation to plant growth rate. Our results suggest that we may yet find general trait‐drivers of field growth rates, but SLA will not be one.     

干热河谷植物叶片,树高和种子功能性状比较

植物功能性状 (plant functional trait)是近年来生态学研究的热点。以云南怒江和澜沧江干热河谷36种木本植物为研究对象,选取比叶面积 (SLA)、植株高 (H) 和种子干重 (SM) 3个功能性状,研究它们的相互关系,比较其在河谷间、河谷内的差异。结果表明:1)两个河谷内36种木本植物的以上3种功能性状间没有显著的相关性 (P值分别为0.8739,0.5763,0.5517);2)河谷间的比叶面积存在显著差异 (P=0.02944),植株高和种子干重无显著差异 (P分别为0.4070, 0.8867);3)两个河谷内木本植物功能性状中,种子干重差异最大,植株高次之,比叶面积最小。     

Competition intensity at local versus regional spatial scales

Studies of competition intensity over natural (i.e. topographic) gradients often contradict the results from studies where artificial (i.e. fertilizer) gradients have been used. Why should the type of gradient matter? To explore the possibilities, we performed experiments to measure competition intensity experienced by tree seedlings from grass competitors across a natural resource gradient, and simultaneously across artificial soil nutrient (fertiliser) gradients. We measured various functional traits (i.e. specific leaf area, leaf area, leaf nitrogen content, δ¹⁵N, δ¹³C, RGR) to gain mechanistic insight into the nature of competition across these gradients. Competition intensity increased with increasing resource availability, unequivocally at the local scale (i.e. with fertilizer application) but not at the regional scale (i.e. across the natural productivity gradient). Our measurements of plant traits were generally consistent with measurements of competition intensity, and demonstrate that competition occurs even when resource levels are low. Competition mainly acted to reduce the growth of Eucalyptus seedlings. Functional (physiological) traits in the Eucalyptus seedlings were not strongly affected by competitors, with the possible exception of δ¹⁵N, which may effectively integrate information on soil nutrient, moisture and leaf processes.     

Within‐species patterns challenge our understanding of the leaf economics spectrum

The utility of plant functional traits for predictive ecology relies on our ability to interpret trait variation across multiple taxonomic and ecological scales. Using extensive data sets of trait variation within species, across species and across communities, we analysed whether and at what scales leaf economics spectrum (LES) traits show predicted trait–trait covariation. We found that most variation in LES traits is often, but not universally, at high taxonomic levels (between families or genera in a family). However, we found that trait covariation shows distinct taxonomic scale dependence, with some trait correlations showing opposite signs within vs. across species. LES traits responded independently to environmental gradients within species, with few shared environmental responses across traits or across scales. We conclude that, at small taxonomic scales, plasticity may obscure or reverse the broad evolutionary linkages between leaf traits, meaning that variation in LES traits cannot always be interpreted as differences in resource use strategy.     

Differential selection of growth rate-related traits in wild barley, Hordeum spontaneum, in contrasting greenhouse nutrient environments

Across-species comparisons show that inherent variation in relative growth rate (RGR) and its underlying traits are correlated with habitat productivity. In this study, we test the hypothesis that growth rate-related traits confer differential selective effects in contrasting nutrient environments. We specifically test whether high RGR is targeted by selection in nutrient-rich environments whereas low values of traits that underlie RGR [specific leaf area (SLA), leaf mass fraction and leaf area ratio (LAR)] confer a direct fitness advantage in nutrient-poor environments, resulting in selection of low RGR as a correlated response. We measured RGR, its underlying component traits, and estimated fitness in a range of wild barley (Hordeum spontaneum) accessions grown under high and low nutrient conditions. Selection on component traits differed between the two environments, while total selection of RGR was not significant. Using multiple regression and path analysis to estimate direct fitness effects, a selective advantage of high LAR and SLA was demonstrated only under nutrient-rich conditions. While supporting the view that observed associations between habitat richness and some RGR-component traits reflect adaptation to differing nutrient regimes, our data suggest that direct selection targets component traits rather than RGR itself.     

黄土高原子午岭不同森林群落叶功能性状

对黄土高原子午岭地区5种主要森林群落中重要值>0.1的物种叶功能性状进行了比较,结果表明:1)叶干物质含量(LDMC)与比叶面积(SLA)呈负相关;SLA与叶厚度(LT)呈负相关,但与叶氮含量(LNC)和叶磷含量(LPC)呈正相关;LT与LNC、LPC和叶钾含量(LKC)呈负相关;LNC、LPC和LKC三者之间均呈正相关。2)坡位是影响叶大小(LS)、LT、LNC和LKC的主要地形因子,海拔对LPC和SLA的影响最大,而坡向则是影响LDMC的主要因子。因此,叶功能性状之间所呈现的特征及其对立地条件的适应都表现出了植物的生态策略。3)各群落间的乔木层叶功能性状均有显著差异,灌木层的叶功能性状无显著差异,而草本层除了LDMC无显著差异(P>0.05)外,其他叶功能性状均有显著差异,说明群落的叶功能性状的大小取决于群落内物种的叶功能性状及其重要值。     

Resource economics and coordination among above- and below-ground functional traits of three dominant shrubs from the Chilean coastal desert

Aims Plant functional traits determine how plants respond to environmental factors and influence ecosystem processes. Among them, root traits and analyses of relations between above and below-ground traits in natural communities are scarce. Methods we characterized a set of above- and below-ground traits of three dominant shrub species in a semiarid shrub-steppe that had contrasting leaf phenological habits (deciduous, semideciduous and evergreen). We analysed if there was coordination among above- and below-ground resource economics patterns: i.e. patterns of biomass allocation, construction costs and lifespan.Important findings Above- and below-ground traits and their resource economics relations pointed to species-specific functional strategies to cope with drought and poor soils and to a species ranking of fast to slow whole-plant strategies in terms of resource uptake, biomass construction costs and turnover. The deciduous shrub, Proustia cuneifolia, had relatively deep and even distribution of roots, and high proportion of short-lived tissues of low C construction costs: it had high fine to coarse root and high leaf-to-stem biomass ratios, high specific leaf area (SLA), and stems of low wood density. This strategy allows Proustia to maximize and coordinate above- and below-ground resources uptake as long as the most limiting factor (water) is available, but at the cost of having relative high plant biomass turnover. The evergreen Porlieria chilensis, instead, displayed a more conservative and slow strategy in terms of resource economics. It had ~80% of the roots in the 40cm topsoil profile, low proportion of fine compared with coarse roots and low leaf-to-stem ratios, low SLA and stems of high wood density, i.e. it invested in C costly tissues that, overall, persist longer but probably at the cost of having lower plant resource uptake rates. Traits in the semideciduous Adesmia bedwellii were in between these two functional extremes. Our results revealed high functional diversity and above- and below-ground complementarity in resource economics among these three codominant species in the Chilean coastal desert.     

Natural selection and neutral evolutionary processes contribute to genetic divergence in leaf traits across a precipitation gradient in the tropical oak Quercus oleoides

The impacts of drought are expanding worldwide as a consequence of climate change. However, there is still little knowledge of how species respond to long‐term selection in seasonally dry ecosystems. In this study, we used Q_ST‐F_ST comparisons to investigate (i) the role of natural selection on population genetic differentiation for a set of functional traits related to drought resistance in the seasonally dry tropical oak Quercus oleoides and (ii) the influence of water availability at the site of population origin and in experimental treatments on patterns of trait divergence. We conducted a thorough phenotypic characterization of 1912 seedlings from ten populations growing in field and greenhouse common gardens under replicated watering treatments. We also genotyped 218 individuals from the same set of populations using eleven nuclear microsatellites. Q_ST distributions for leaf lamina area, specific leaf area, leaf thickness and stomatal pore index were higher than F_ST distribution. Results were consistent across growth environments. Genetic differentiation among populations for these functional traits was associated with the index of moisture at the origin of the populations. Together, our results suggest that drought is an important selective agent for Q. oleoides and that differences in length and severity of the dry season have driven the evolution of genetic differences in functional traits.     

松嫩草地66种草本植物叶片性状特征

植物叶片功能性状及其相互关系越来越受到关注.以松嫩草地66种草本植物为研究对象,测量叶片干物质含量、比叶面积、叶片厚度、叶片氮含量、叶片磷含量、叶绿素含量和类胡萝卜素含量,检验性状间的相互关系,比较不同功能群(多年生根茎禾草,多年生丛生禾草,多年生杂类草,1年生或2年生草本)间性状的差异性.结果表明,叶片厚度变异系数最大,比叶面积、叶片氮含量、叶片磷含量、叶绿素含量和类胡萝卜素含量之间存在显著的正相关关系;叶片于物质含量与叶片磷含量没有显著的相关关系,与其它叶片性状呈显著的负相关关系;叶片厚度只与叶片干物质含量和比叶面积呈显著的负相关关系,与其它叶片性状不相关.叶片干物质含量、比叶面积、叶片厚度、叶片氮、磷含量在4个功能群间差异显著,叶绿素含量和类胡萝卜素含量在各个功能群间差异不显著;多年生根茎禾草和多年生丛生禾草叶片的7个性状差异不显著;多年生根茎禾草和多年生丛生禾草的叶片干物质含量高于多年生杂类草和1年生或2年生草本,其它性状小于这两个功能群.