太岳山典型阔叶乔木冠层叶片性状的分布格局

以太岳山4种阔叶乔木不同冠层高度的叶片为研究对象,用LI-3000A叶面积仪和Li-6400便携式光合作用测定系统分别测定了这4种乔木不同冠层高度叶片的叶面积大小和单位面积的叶光饱和速率(Aarea);同时测定了其叶氮含量;计算了其比叶面积(SLA)、单位面积叶氮含量(Narea)、单位重量叶氮含量(Nmass)、单位重量的叶光饱和速率(Amass)和光合氮素利用效率(PNUE),对植株不同冠层高度叶片的SLA、叶氮和光合特性的空间分布格局进行了比较研究,结果表明:Aarea、Amass、Nmass、PNUE、SLA和Narea在树冠上层、中层和下层的差异均达到了极显著水平(P<0.001),表明树冠不同高度的叶片性状参数差异较大;在相同SLA下,Nmass和Narea在冠层中的分布均表现为中层>上层>下层,并出现平行位移现象;Aarea和Nmass都以中层值最大,表明冠层光合能力分布格局以中层相对较高。     

不同功能型植物叶氮含量与光合特性的关系研究

在山西南部的霍山七里峪林场,确定乔木、灌木和草本物种共26个,用Li-3000A叶面积测定仪测量了叶面积的大小、用Li-6400便携式光合作用测定系统测定了叶光饱和速率（A_area）,计算了比叶重（LMA）、单位重量的光饱和光合速率（A_mass）、单位面积叶氮含量(Narea)、单位重量叶氮含量(N_mass)及光合氮利用效率(PNUE),研究了它们之间的不同和相互作用关系。结果表明：不同功能型植物的N_mass、A_area、A_mass、N_area和PNUE差异显著(p<0.05),植物叶片氮含量与植物光合生理特性具有显著相关关系,N_mass与A_area、A_mass和PNUE呈线性显著的正相关(p<0.05);N_area与A_area、A_mass、PNUE之间呈极显著的负相关(p<0.01)。     

Effect of nitrogen supply on growth,allocation and gas exchange characteristics of two perennial grasses from inland dunes

Summary We studied the effects of nitrogen supply on growth, allocation, and gas exchange characteristics of two perennial grasses of dry, nutrient-poor inland dunes: Corynephorus canescens (L.) Beauv. and Agrostis vinealis Schreber. C. canescens invests more biomass in leaves and less in roots, but has less leaf area and more root length per unit plant weight than A. vinealis. A. vinealis invests more nitrogen per unit leaf weight, but less per unit leaf area, despite a similar relative nitrogen investment in leaves and plant nitrogen concentration. Between-species differences in the rate of net photosynthesis, transpiration and shoot respiration are positively related to leaf nitrogen content per unit leaf area. The rate of net photosynthesis per unit plant weight is higher for A. vinealis at both levels of nitrogen supply, due to differences in leaf area ratio (LAR), and despite the reverse differences in the rate of net photosynthesis per unit leaf area. The water use efficiency of the two species is similar and increases significantly with an increase in nitrogen supply. The photosynthetic nitrogen use efficiency on the other hand is not affected by nitrogen supply, while at both low and high nitrogen supply A. vinealis has a 10% higher photosynthetic nitrogen use efficiency than C. canescens.     

Carbon and nitrogen economy of four Triticum aestivum cultivars differing in relative growth rate and water use efficiency

We investigated physiological and morphological traits underlying variation in relative growth rate (KGR) among wheat cultivars. Subsequently, we determined whether higher RGR is correlated with higher water demand and lower plant water use efficiency (WUE_p). Further, the correlation between water use efficiency and leaf nitrogen concentration was examined. For this purpose we chose lour cultivars contrasting in RGR or WUE_p. Gas exchange of shoots and respiration of roots were measured on intact plants over a 24 h period, and total carbon and nitrogen concentrations of all plant parts were determined. The highest RGR was achieved by the cultivars with the highest leaf area ratio. WUE_p was strongly dependent on photosynthetic water use efficiency and was highest for the cultivars with the highest rate of photosynthesis, which achieved higher rates of photosynthesis per unit leaf nitrogen. We found no evidence for a functional or genetic link between the physiological traits underlying differences in RGR (specific leaf area and leaf area ratio) and those causing variation in water use efficiency (photosynthetic rate and transpiration rate). These results indicate that, in wheat, it may be possible to select simultaneously for traits associated with a high WUE_p and a high RGR.     

黄土高原油松和刺槐叶片光合生理适应性比较

以黄土高原地区由南向北分布的杨凌、永寿、富县、安塞、米脂、神木等县为研究地点，研究不同地区油松和刺槐的光合特性与叶结构性状间的关系.结果表明，不同地区油松针叶和刺槐叶片的净光合速率（P_n）、光合氮利用效率（PNUE）、水分利用效率（WUE）、比叶质量（LMA）、氮含量（N_mass）和叶绿素相对含量（Chl）差异均达极显著水平（P＜0.001）,说明不同地区油松和刺槐的光合能力和叶结构性状参数差异很大.由南向北，油松的P_n、WUE和PNUE呈略微增加趋势，而刺槐则呈显著降低趋势，表明油松在干旱生境下仍能维持较高的光合能力，而刺槐光合能力明显受到抑制；油松和刺槐的LMA均呈略微上升趋势，而N_mass和Chl均呈略微下降趋势，且刺槐的变化幅度高于油松，说明油松从生理代谢和叶结构性状上对干旱环境的适应能力均强于刺槐.相关分析表明，不同地区油松和刺槐的LMA与N_mass整体上呈极显著负相关；P_n、PNUE与LMA、N_mass相关不显著，与Chl呈极显著正相关；WUE与LMA呈显著负相关（P＜0.05），与N_mass呈显著正相关.     

中国东部南北样带森林优势植物叶片的水分利用效率和氮素利用效率

通过测定中国东部南北样带主要森林生态系统中10种优势植物(兴安落叶松、蒙古栎、水曲柳、紫椴、色木槭、红松、杉木、木荷、马尾松、锥栗)叶片的碳氮含量(Cmass、Nmass)、同位素丰度(δ13C、δ15N)以及光合响应曲线,分析了不同优势植物叶片的水分利用效率和氮素利用效率之间的差异及其相互关系.结果表明： 不同生活型植物叶片的Nmass和δ15N差异显著,表现为阔叶植物>针叶植物,落叶植物>常绿植物;最大光合速率(Pn max)表现为针叶植物>阔叶植物,落叶植物>常绿植物;植物叶片的瞬时水分利用效率(WUEi)和长期水分利用效率(WUE)均表现为阔叶植物>针叶植物,常绿植物>落叶植物;植物叶片的瞬时氮素利用效率(NUEi)和长期氮素利用效率(NUE)则表现出相反的规律,且常绿植物和落叶植物叶片的NUE差异显著;WUEi和WUE之间相关性不显著,而NUEi和NUE之间呈显著正相关.植物叶片的水分利用效率与氮素利用效率显著负相关.两种资源利用效率均受植物生活型的影响,并且存在一定的制约关系.     

Plant biodiversity in a larch plantation from the view point of photosynthetic nitrogen use efficiency in northeast China

Forest floor of larch species often provides growth habitat for many kinds of understory species because of relatively sparse structure in a larch canopy. A rich flora of forest understory species may play an essential role in maintaining fertility of a larch stand. An attempt was made to evaluate photosynthetic nitrogen use efficiency (PNUE) of many understory and overstory species according to their Raunkiaer lifeform. By studying 72 perennial deciduous species in a larch plantation in northeast China, marked photosynthetic differences between phanerophytes (Ph) and other three lifeforms of chamaephytes (Ch), hemicryptophytes (He), and cryptophytes (Cr) were found, with marginal differences found among Ch, He, and Cr. Ph species had much lower PNUE, and much lower values of rate of nitrogen allocation to chlorophyll (Chl./N) and nitrogen allocation to carboxylation processes (V _cmax/N) were concurrently observed in Ph compared with the other three lifeforms. Ph had much lower leaf nitrogen per unit of projection area (N _area) and specific leaf area (SLA, cm² g^–1). At lower SLA, for Ph species the change of PNUE with SLA was small, but these changes became very large at higher SLA for Ch, He, and Cr species. Our findings indicate that leaf morphological change is important for clarifying photosynthesis differences among species with different lifeform.     

塔里木沙漠公路防护林3种植物光合特性对干旱胁迫的响应

利用Li-6400光合作用系统在沙漠腹地测定分析塔里木沙漠公路防护林植物梭梭(Haloxylon ammodendron)、多枝柽柳(Tamarix ramosissima)和乔木状沙拐枣(Calligonum arborescens)光合特性对干旱胁迫的响应,探讨了水分亏缺对防护林植物光合积累的影响作用。结果显示:沙拐枣的净光合速率、蒸腾速率、水分利用效率、光能利用效率及潜在光合作用能力对水分亏缺最敏感,而柽柳则最不敏感;不同处理下3种植物光合特性变化的差异表明,不同植物对水分亏缺有着不同的响应变化和适应方式;此外,干旱胁迫未提高3种植物的水分利用效率,反而降低了其光能利用效率;C3植物多枝柽柳在干旱高温条件下保持着比C4植物梭梭和沙拐枣更为稳定的光合积累和水分利用效率,说明部分C3植物具备不弱于C4荒漠植物的干旱耐受适应能力;虽然水分亏缺对3种植物的光合作用能力均存在不同程度抑制作用,但未对其光合积累造成不可逆转的影响。可见3种植物都有很强的干旱适应与耐受能力,这种能力表明沙漠公路防护林的灌溉管理还有进一步的节水空间。     

Relationship between maximum leaf photosynthesis,nitrogen content and specific leaf area in balearic endemic and non-endemic mediterranean species

Gas exchange parameters, leaf nitrogen content and specific leaf area (SLA) were measured in situ on 73 C3 and five C4 plant species in Mallorca, west Mediterranean, to test whether species endemic to the Balearic Islands differed from widespread, non-endemic Mediterranean species and crops in their leaf traits and trait inter-relationships. Endemic species differed significantly from widespread species and crops in several parameters; in particular, photosynthetic capacity, on an area basis (A), was 20 % less in endemics than in non-endemics. Similar differences between endemics and non-endemics were found in parameters such as SLA and leaf nitrogen content per area (Na). Nevertheless, most of the observed differences were found only within the herbaceous deciduous species. These could be due to the fact that most of the non-endemic species within this group have adapted to ruderal areas, while none of the endemics occupies this kind of habitat. All the species-including the crops-showed a positive, highly significant correlation between photosynthetic capacity on a mass basis (Am), leaf nitrogen content on a mass basis (Nm) and SLA. However, endemic species had a lower Am for any given SLA and Nm. Hypotheses are presented to explain these differences, and their possible role in reducing the distribution of many endemic Balearic species is discussed.     

Effects of N-supply on the rates of photosynthesis and shoot and root respiration of inherently fast- and slow-growing monocotyledonous species

Are there intrinsic differences in the rates of photosynthesis, shoot- and root-respiration between inherently fast- and slow-growing monocotyledons at high and low nitrogen supply? To analyze this question we grew 5 monocotyledons, widely differing in their inherent relative growth rate at high and low nitrogen supply in a growth room. Nitrate was exponentially added to the plants, enabling us to compare inherent differences in plant characteristics, without any effect of species differences in the ability to take up nutrients. At high nitrogen supply, the fast-growing species from productive habitats had a higher photosynthetic nitrogen use efficiency and rate of root respiration than the slow-growing ones from unproductive habitats. Only minor differences were observed in their rates of photosynthesis and shoot respiration per unit leaf area. At low nitrogen supply, the rates of photosynthesis and shoot- and root respiration decreased for all species, even though there were no longer any differences in these processes between inherently fast- and slow-growing species. The photosynthetic nitrogen use efficiency increased for all species, and no differences were found among species. Differences in the photosynthetic nitrogen use efficiency among species and nitrogen treatments are discussed in terms of the utilization of the photosynthetic apparatus, whereas differences in respiration rate are discussed in terms of the energy demand for growth, maintenance and ion uptake and their related specific respiratory energy costs. It is concluded that the relatively high abundance of slow-growing species compared to fast-growing ones in unproductive habitats is unlikely to be explained by differences in rates of photosynthesis and respiration or in photosynthetic nitrogen use efficiency.     

Relationships between photosynthetic activity and silica accumulation with ages of leaf in Sasa veitchii (Poaceae, Bambusoideae)

BACKGROUND AND AIMS: Bamboos have long-lived, evergreen leaves that continue to accumulate silica throughout their life. Silica accumulation has been suggested to suppress their photosynthetic activity. However, nitrogen content per unit leaf area (N(area)), an important determinant of maximum photosynthetic capacity per unit leaf area (P(max)), decreases as leaves age and senescence. In many species, P(max) decreases in parallel with the leaf nitrogen content. It is hypothesized that if silica accumulation affects photosynthesis, then P(max) would decrease faster than N(area), leading to a decrease in photosynthetic rate per unit leaf nitrogen (photosynthetic nitrogen use efficiency, PNUE) with increasing silica content in leaves. METHODS: The hypothesis was tested in leaves of Sasa veitchii, which have a life span of 2 years and accumulate silica up to 41 % of dry mass. Seasonal changes in P(max), stomatal conductance, N(area) and silica content were measured for leaves of different ages. KEY RESULTS: Although P(max) and PNUE were negatively related with silica content across leaves of different ages, the relationship between PNUE and silica differed depending on leaf age. In second-year leaves, PNUE was almost constant although there was a large increase in silica content, suggesting that leaf nitrogen was a primary factor determining the variation in P(max) and that silica accumulation did not affect photosynthesis. PNUE was strongly and negatively correlated with silica content in third-year leaves, suggesting that silica accumulation affected photosynthesis of older leaves. CONCLUSIONS: Silica accumulation in long-lived leaves of bamboo did not affect photosynthesis when the silica concentration of a leaf was less than 25 % of dry mass. Silica may be actively transported to epidermal cells rather than chlorenchyma cells, avoiding inhibition of CO2 diffusion from the intercellular space to chloroplasts. However, in older leaves with a larger silica content, silica was also deposited in chlorenchyma cells, which may relate to the decrease in PNUE.     

A model of the acclimation of photosynthesis in the leaves of C3 plants to sun and shade with respect to nitrogen use

A model of leaf photosynthesis of C₃, plants has been developed to describe their nitrogen economy. In this model, photosynthetic proteins are categorized into five groups depending on their functions. The effects of investment of nitrogen in each of these groups on the maximal rate of photosynthesis and/or the initial slope of the light-response curve are described as simple equations. Using this model, the optimal pattern of nitrogen partitioning which maximizes the daily rate of CO₂ exchange is estimated for various light environments and leaf nitrogen contents. When the leaf nitrogen content is fixed, the amount of nitrogen allocated to Calvin cycle enzymes and electron carriers increases with increasing irradiance, while that allocated to chlorophyll-protein complexes increases with decreasing irradiance. For chlorophyll-proteins of photosystem II, the amount of light-harvesting complex II relative to that of the core complex increases with decreasing irradiance. At any irradiance, partitioning into ribulose bisphosphate carboxylase increases with increasing leaf nitrogen content Taking the total leaf nitrogen content and the daily CO₂ exchange rate as ‘cost’ and ‘benefit’, respectively, the optimal amount and partitioning of nitrogen are examined for various conditions of light environment and nitrogen availability. The leaf nitrogen content that maximizes the rate of daily carbon fixation increases with increasing growth irradiance. It is also predicted that, at low nitrogen availabilities, low leaf nitrogen contents are advantageous in terms, of nitrogen use efficiency. These trends predicted by the present model are largely consistent with those reported for actual plants. The differences in the total amount of leaf nitrogen and in the organization of photosynthetic components that have been reported for plants from different environments would therefore be of adaptive significance, because such differences can contribute to realization of efficient photosynthesis. These results are fürther discussed in an ecological context.     

Growth, gas exchange and water use efficiency of the facultative hemiparasite Rhinanthus minor associated with hosts differing in foliar nitrogen concentration

The facultative hemiparasitic angiosperm Rhinanthus minor was grown on 11 different host species, and in the absence of a host. The height of R. minor parasitising the legume Trifolium pratense exceeded that of unattached plants by more than an order of magnitude, with performance on grasses and non-legume dicotlyedonous hosts between these two extremes. Light saturated rates of photosynthesis in R. minor on different hosts ranged from 1. 5 to 22. 5 μmol g⁻¹ dry weight min⁻¹, and were positively correlated with growth. Foliar nitrogen concentrations in the parasite exceeded those of the hosts. The former were positively related to light saturated rates of photosynthesis, and inversely related to photosynthetic nitrogen use efficiency. There was no relationship between leaf nitrogen concentration and water use efficiency in R. minor. The data are discussed in relation to studies of nitrogen and water use in mistletoes.     

Possible Mechanisms of Adaptive Leaf Senescence

Abstract: Availability of nitrogen almost always limits plant growth. Therefore, efficient use of nitrogen is essential for the plants. In upright plants, especially when they form dense plant stands, old, lower leaves are shaded by young, upper leaves. Nitrogenous compounds in such shaded leaves are degraded and re-allocated to the developing young, upper leaves. These processes raise efficiency of nitrogen use in photosynthetic production of the plant. For this to occur in the most effective way, leaves would need to sense their photosynthetic status in a plant and increase, maintain or decrease their photosynthetic capacity accordingly. Hypotheses that explain how a leaf can sense its photosynthetic status in the plant are reviewed. They include systems involving phytochrome, sugar-sensing, or cytokinin. Our experimental results with Helianthus annuus and Phaseolus vulgaris plants, which were subject to various shading treatments, are examined in the light of these hypotheses. Our experimental results favoured the sugar-sensing hypothesis: A leaf can sense demand of other plant parts for photosynthates produced by it and nitrogen abundance or deficiency by monitoring its sugar concentration. Problems that are to be challenged in the near future are also pointed out.     

C3和C4植物的氮素利用机制

提高植物的氮素利用效率(NUE)不仅有利于保障全球粮食安全, 也是实现农业可持续发展的重要途径。近半个世纪以来, 植物氮素利用机理研究已取得重要进展, 但NUE的调控机制仍不明确, NUE的提高仍然十分有限。高等植物集光合碳素同化和氮素同化于一体, 只有碳氮代谢相互协调, 才能维持植物体内的碳氮平衡, 保证植物正常生长发育。由于C₃和C₄植物的光合氮素利用率(PNUE)存在差异, 对氮素的利用效率也会存在差异。为了更有效地提高作物的NUE, 须更全面地了解C₃和C₄植物对氮素吸收、转运、同化和信号转导等关键因子的功能和调控机制。此外, 面对大气CO₂浓度增高和全球气候变暖条件下的植物碳氮同化及其机理的研究也不容忽视。该文综述了C₃和C₄植物氮素利用关键因素的差异及其调控机制, 并对提高C₃禾本科作物氮素利用效率的遗传改良途径进行了展望。     

A test of the generality of leaf trait relationships on the Tibetan Plateau

Leaf mass per area (LMA), nitrogen concentration (on mass and area bases, N(mass) and N(area), respectively), photosynthetic capacity (A(mass) and A(area)) and photosynthetic nitrogen use efficiency (PNUE) are key foliar traits, but few data are available from cold, high-altitude environments. Here, we systematically measured these leaf traits in 74 species at 49 research sites on the Tibetan Plateau to examine how these traits, measured near the extremes of plant tolerance, compare with global patterns. Overall, Tibetan species had higher leaf nitrogen concentrations and photosynthetic capacities compared with a global dataset, but they had a slightly lower A(mass) at a given N(mass). These leaf trait relationships were consistent with those reported from the global dataset, with slopes of the standardized major axes A(mass)-LMA, N(mass)-LMA and A(mass)-N(mass) identical to those from the global dataset. Climate only weakly modulated leaf traits. Our data indicate that covarying sets of leaf traits are consistent across environments and biogeographic regions. Our results demonstrate functional convergence of leaf trait relationships in an extreme environment.     

Gas exchanges of three co-occurring species of Cypripedium in a scrubland in the Hengduan Mountains

Gas exchanges and related leaf traits of three co-occurring species of genus Cypripedium (C. yunnanense Franch., C. guttatum SW., and C. flavum P.F. Hunt et Summerch.) were investigated in a scrubland at 3 460 m a.s.l. in the Hengduan Mountains. The considered species had similar photosynthetic responses to photosynthetic photon flux density (PPFD) and air temperature. The photosynthetic capacity (P _max), carboxylation efficiency (CE), apparent quantum efficiency (AQE), PPFD-saturated rate of electron transport (J_max), respiration rate (R _D), and leaf nitrogen content per unit area (LNC) of C. guttatum were higher than those of C. yunnanense and C. flavum. The highest P _max of C. guttatum was related to the highest LNC and the lowest ratio of intercellular CO₂ concentration to atmospheric CO₂ concentration (C _i/C _a). However, no significant differences in stomatal conductance (g _s) and relative stomatal limitations (RSL) were observed among the three species. Hence biochemical limitation had a dominant role in P _max differences among the considered species.     

Light acquisition and use by individuals competing in a dense stand of an annual herb, Xanthium canadense

The importance of light acquisition and utilization by individuals in intraspecific competition was evaluated by determining growth and photosynthesis of individual plants in a dense monospecific stand of an annual, Xanthium canadense. Photosynthesis of individual plants in the stand was calculated using a canopy photosynthesis model in which leaf photosynthesis was assumed to be function of leaf nitrogen content and light availability. The estimated photosynthetic rates of individuals were strongly correlated with the measured growth rates. Photosynthetic rates per unit aboveground mass (RPR, relative photosynthetic rate) increased with increasing aboveground mass, suggesting asymmetric (one-sided) competition in the stand. However, larger individuals had similar RPRs, suggesting symmetric (two-sided) competition. These results were consistent with the observation that size inequality over the whole stand increased with growth, but it remained stable among the larger individuals. The RPR of an individual was calculated as the product of absorbed photon flux per unit aboveground mass (Φ_mass) and light use efficiency (LUE, photosynthesis per unit absorbed photon flux). Φ_mass indicates the efficiency of light acquisition, and was higher in larger individuals in the stand, while LUE was highest in individuals with intermediate aboveground mass. LUE depends on leaf nitrogen content. At an early stage, leaf nitrogen contents of smaller individuals were similar to those that maximize LUE. Light availability to smaller individuals decreased as they grew, while their nitrogen contents did not change markedly, which decreased their LUE. We concluded that asymmetric competition among individuals in the stand resulted mainly from lower efficiencies in both light acquisition and light use by smaller individuals. Received: 31 January 1998 / Accepted: 12 November 1998     

油蒿资源利用效率在生长季的相对变化及对环境因子的响应

为了探明西北半干旱区典型沙生植物油蒿(Artemisia ordosica)叶水平资源利用效率的相对变化及对环境因子的响应机制, 该研究于2018年5-10月, 使用LI-6400XT便携式光合仪测定了毛乌素沙地油蒿叶片的净光合速率(P_n)、蒸腾速率(E)、叶表面光合有效辐射(PAR_l)、叶表面温度(T_l)、叶表面相对湿度(RH_l), 在实验室计算叶片单位面积氮含量(N_area), 分析了叶片氮利用效率(NUE)、水分利用效率(WUE)、光利用效率(LUE)与环境因子之间的关系及NUE、WUE、LUE之间的相对变化。研究结果表明, 在充足且稳定光强下油蒿的P_n主要受温度的影响, NUE、WUE与VPD_l、T_l之间具有显著负相关关系, NUE、WUE与LUE间为正相关关系, NUE、WUE和LUE最大值分别发生在5、7和9月, 分别为9.43 μmol CO₂·g^-1·s^-1、3.86 mmol·mol^-1、0.04 mol·mol^-1, 资源利用效率的变化主要受P_n的影响。温度通过影响植物N分配来改变P_n, 进而影响着资源利用效率, WUE与LUE显著正相关, 对构建荒漠区生态系统能量交换过程模型有重要意义。     

Photosynthesis or persistence: nitrogen allocation in leaves of evergreen and deciduous Quercus species

Photosynthetic nitrogen use efficiency (PNUE, photosynthetic capacity per unit leaf nitrogen) is one of the most important factors for the interspecific variation in photosynthetic capacity. PNUE was analysed in two evergreen and two deciduous species of the genus Quercus. PNUE was lower in evergreen than in deciduous species, which was primarily ascribed to a smaller fraction of nitrogen allocated to the photosynthetic apparatus in evergreen species. Leaf nitrogen was further analysed into proteins in the water‐soluble, the detergent‐soluble, and the detergent‐insoluble fractions. It was assumed that the detergent‐insoluble protein represented the cell wall proteins. The fraction of nitrogen allocated to the detergent‐insoluble protein was greater in evergreen than in deciduous leaves. Thus the smaller allocation of nitrogen to the photosynthetic apparatus in evergreen species was associated with the greater allocation to cell walls. Across species, the fraction of nitrogen in detergent‐insoluble proteins was positively correlated with leaf mass per area, whereas that in the photosynthetic proteins was negatively correlated. There may be a trade‐off in nitrogen partitioning between components pertaining to productivity (photosynthetic proteins) and those pertaining to persistence (structural proteins). This trade‐off may result in the convergence of leaf traits, where species with a longer leaf life‐span have a greater leaf mass per area, lower photosynthetic capacity, and lower PNUE regardless of life form, phyllogeny, and biome.