Effects of growth temperature and winter duration on leaf phenology of Erythronium japonicum,a forest spring geophyte

The effects of growth temperature and winter duration on the leaf phenology of Erythronium japonicum were examined in two experiments. Bulbs wintered in the field were cultivated at 10 and 20° C and the bulbs were cultivated at 15° C after chilling treatment at 3° C for 60 and 120 days and without chilling in winter. The plants cultivated at 20° C showed significantly earlier leaf emergence, a more rapid rate of leaf extension and shorter leaf longevity than those cultivated at 10° C. The decrease in the leaf longevity at 20° C resulted from the decreases in the durations of all of the developmental, mature, and senescent phases. The bulbs without chilling treatment did not sprout leaves and those with chilling treatment sprouted leaves. The increase in the length of chilling treatment from 60 to 120 days affected leaf phenology in same manner as the increase in the growth temperature from 10 to 20° C.     

Non-destructively predicting leaf area,leaf mass and specific leaf area based on a linear mixed-effect model for broadleaf species

Based on a linear mixed-effect model, we propose here a non-destructive, rapid and reliable way for estimating leaf area, leaf mass and specific leaf area (SLA) at leaf scale for broadleaf species. For the construction of the model, the product of leaf length by width (LW) was the optimum variable to predict the leaf area of five deciduous broadleaf species in northeast China. In contrast, for species with leaf thickness (T) lower than 0.10 mm, the surface metric of a leaf (e.g., LW or width) was more suitable for predicting leaf mass; and for species with leaf thickness larger than 0.10 mm, the volume metric of a leaf (e.g., the product of length, width and thickness together, LWT) was a better predictor. The linear mixed-effect model was reasonable and accurate in predicting the leaf area and leaf mass of leaves in different seasons and positions within the canopy. The mean MAE% (mean absolute error percent) values were 6.9% (with a scope of 4.1–13.0%) for leaf area and 13.8% (9.9–20.7%) for leaf mass for the five broadleaf species. Furthermore, these models can also be used to effectively estimate SLA at leaf scale, with a mean MAE% value of 11.9% (8.2–14.1%) for the five broadleaf species. We also propose that for the SLA estimation of the five broadleaf species examined, the optimum number of sample leaves necessary for good accuracy and reasonable error was 40–60. The use of the provided method would enable researchers or managers to rapidly and effectively detect the seasonal dynamic of leaf traits (e.g., leaf area, leaf mass or SLA) of the same sample leaves in the future.     

从水力结构的角度解释生长温度对烟草叶片形状和大小的影响（英文）

叶片形状和大小在不同的生长温度下变化非常大,但少有从水力结构的角度解释其变化原因的研究。本研究测定了生长于两个不同温度下(24℃/18℃昼/夜;32℃/26℃昼/夜)的烟草叶片的解剖结构,导水率,叶片长宽比和叶面积。生长在24℃/18℃下的烟草叶片与生长在32℃/18℃的叶片相比,更狭窄,并有更小的叶柄导管直径,更低的叶脉密度和导水率。然而,在不同的生长温度下,烟草叶面积并没有显著差异。叶片导水率与叶脉密度呈正相关,但与叶片长宽比呈负相关。结果表明在不同的生长温度下叶片解剖结构和叶片导水率可能对于改变叶宽比起着重要作用。     

南京地区落叶栎林主要木本植物的展叶动态研究

 植物的展叶过程是由自身遗传因子决定的,同时又受到多种生态因子的调节,反映了植物的生活史对策和群落物种多样性的维持机制。在2001和2002年的3～6月间,不定期记录了南京地区三个落叶栎(Quercus spp.)林中主要木本植物的展叶情况,包括被标记标准枝的叶数、叶的长度、宽度、叶面积、叶干重等参数。结果表明在所调查的落叶栎林中,林冠层物种的成熟叶面积和单位叶面积干重都显著大于林下层物种;最早展叶的物种为林下层物种,但林冠层展叶顺序与林下层无显著差异。叶面积越大、单位叶面积干重越小的物种展叶越晚;林冠层物种展叶较林下层快,物种成熟叶面积越大,展叶速率越大。最后对展叶顺序和展叶速度的生态学意义作了讨论。     

利用叶色特征监测小麦叶片的碳氮状况

研究了不同土壤水氮条件下小麦 (Triticumaestivum) 抽穗后叶片碳氮状况及其比例与叶片叶色 (SPAD值 ) 的关系。结果表明, 小麦中后期叶片氮含量和可溶性糖含量与顶部 3张叶片叶色 (SPAD值 ) 均呈显著的指数正相关, 其相关程度大小为L1>L2 >L3, 但与不同叶位叶色间的差值或比值相关并不显著 ;而叶片碳氮比与各叶位叶色相关不显著, 但与顶 1叶和顶 3叶的叶色差值呈极显著直线相关, 据此建立了基于叶色特征的叶片氮含量、可溶性糖含量和碳氮比监测模型, 检验结果显示, 顶 1叶叶色和顶 1叶与顶 3叶叶色的差值可用来有效地评估小麦叶片的碳、氮含量及碳氮比状况。     

Leaf dynamics and shoot phenology of eleven warm-temperate evergreen broad-leaved trees near their northern limit in central Japan

Dynamic features of shoot phenology including leaf emergence and leaf fall, and leaf life span for eleven evergreen broad-leaved tree species were investigated in a warm-temperate rain forest in Mount Kiyosumi, central Japan. All species had periodic leaf emergence or flushing pattern, and were classified into two types; single and multiple flush and only one species, Eurya japonica, represented the latter type and the rest had single flush in spring. The single flush type can further be subdivided into two groups according to their duration of shoot growth; short and long flush. Seasonal patterns of leaf fall were categorized into four; unimodal, bimodal, broad unimodal, and multimodal type though they were not fixed pattern. The leaf emergence and leaf fall patterns were correlated for the eleven species, and five phenological types were categorized. Four of them were the single flush types, i.e., short flush of leaf emergence with unimodal leaffall (SSU) type of Castanopsis sieboldii and Quercus salicina, short flush with bimodal leaf fall (SSB) type of Quercus acuta, Machilus thunbergii, Neolitsea sericea, and Cinnamomum japonicum, long flush with bimodal leaffall (SLB) type of Myrsine seguinii, and long flush with broad unimodal leaffall (SLR) type of Symplocos prunifolia, Cleyera japonica, and Illicium anisatum. The multiple flush type is only one species, Eurya japonica, and it had multimodal leaffall pattern (MM type). The phenological pattern varied in relation to leaf life span, leaf size, and tree habit. Leaf life span ranged from 1.1 to 5.8 yr. The short flush species or SSU and SSB types were all canopy or subcanopy trees, and the former had short and the latter had long leaf life spans. The long flush species were all microphyllous small trees, and SLB type had a relatively long leaf life span in understory, SLR type had a long leaf life span in understory or in open habitat and/or forest gap as a pioneer tree. MM type had a long leaf life span and colonizing species in open habitat but they can survive in understory as well. The phenological attributes of evergreen trees were well corresponded to the ecological guild of the tree in both forest structure and successional stage, and were also constrained by phylogenetic groups.     

Leaf specific mass confounds leaf density and thickness

Summary We explored the relationship between leaf specific mass (LSM) and its two components, leaf density and thickness. These were assessed on the leaves of (a) the moderately sclerophyllous tree Arbutus menziesii distributed along a natural nutrient/moisture gradient in California, (b) eight sclerophyllous shrub species on four substrates in south-western Australia, and (c) seedlings of two morphologically contrasting Hakea species grown under varying soil nutrient, moisture and light regimes in a glasshouse experiment. Leaf area, mass, LSM, density and thickness varied greatly between leaves on the same plant, different species, and with different nutrient, moisture and light regimes. In some cases, variations in LSM were due to changes in leaf density in particular or thickness or both, while in others, density and thickness varied without a net effect on LSM. At lower nutrient or moisture availabilities or at higher light irradiances, leaves tended to be smaller, with higher LSM, density and thickness. Under increased stress, the thickness (diameter) of needle leaves decreased despite an increase in LSM. We concluded that, while LSM is a useful measure of sclerophylly, its separation into leaf density and thickness may be more appropriate as they often vary independently and appear to be more responsive to environmental gradients than LSM.     

Optimisation of spatial allocation patterns in lianas compared to trees used for support

There are only limited possibilities to study the competition between trees and lianas in the top canopy of tropical rain forests. Furthermore, the important question how the leaf traits are related to twig support is rarely studied, especially regarding growing space partitioning between the self-supporting and the climbing growth form. Our study used the hot-air balloon within the “Operation Canopee” in the Masoala National Park, Madagascar, to test the differences in spatial allocation patterns of leaves and twigs in lianas and tree parts used for support. The sampling design emphasised to obtain a common assembly of twigs and leaves from both, trees and lianas. The results from the top canopy were compared to the data from the understorey regarding biomass and nutrients in leaves and distal twigs. In the understorey the reduction in structural investment was much stronger in lianas than in trees. The results showed that lianas reduced carbon investment per volume, but increased leaf nitrogen concentration and leaf area ratio (LAR), the latter driven by a reduction in leaf mass per area (LMA). In the top canopy, lianas contributed about one third of the leaf area density of 3 m² m⁻³. For distal twigs, no relationship was found between twig biomass per volume and leaf area density for trees, but lianas balanced both structural parameters closely. The climbers benefit from the external support provided by the trees and optimise the area of assimilation tissue at low per volume investment for mechanical stability. Several traits such as low LMA and high leaf nitrogen concentrations together with higher LAR and optimised spatial investment advantage the climbing growth form and enable a fast acquisition of growing space. The results emphasize the necessity to consider spatial and structural features of growing space acquisition when dealing with plant competition. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

用回归方程法测定梨树叶面积

用回归方程法测定梨树单叶面积,以长枝、随机及比例方法取样,取样数量50至100片,采用叶长乘以叶宽的回归方程测定较为适宜。     

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.     

Reconciling the apparent difference between mass- and area-based expressions of the photosynthesis-nitrogen relationship

The relationship between photosynthetic carbon assimilation (A _max) and leaf nitrogen content (N _leaf) can be expressed on either a leaf area basis (A _area vs N _area) or a leaf mass basis (A _mass vs N _mass). Dimensional analysis shows that the units for the slope of this relationship are the same for both expressions (μmol [CO₂] g⁻¹ [N] s⁻¹). Thus the slope measures the change in CO₂ assimilation per gram of nitrogen, independent of leaf mass or leaf area. Although they have the same units, large differences between the area and mass-based slopes have been observed over a broad range of taxonomically diverse species. Some authors have claimed that regardless of these differences, the fundamental nature of the A _max-N _leaf relationship is independent of the units of expression. In contrast, other authors have claimed that the area-based A _max-N _leaf relationship is fundamentally different from the mass-based relationship because of interactions between A _max, N _leaf, and leaf mass per area (LMA, g [leaf] m⁻² [leaf]). In this study we consider the mathematical relationships involved in the transformation from mass- to area-based expressions (and vice versa), and the implications this transformation has for the slope of the A _max-N _leaf relationship. We then show that the slope of the relationship is independent of the units of expression when the effect of LMA is controlled statistically using a multiple regression. The validity of this hypothesis is demonstrated using 13 taxonomically and functionally diverse C₃ species. This analysis shows that the slope of the A _max-N _leaf relationship is similar for the mass- and area-based expressions and that significant errors in the estimate of the slope can arise when the effect of LMA is not controlled. Received: 7 May 1998 / Accepted: 19 October 1998     

Leaf architectural studies in the brassicaceae

The leaf architecture has been studied in 19 genera and 35 species of the Brassicaceae. The major venation pattern is pinnate craspedodromous with the exception ofAlyssum maritimum, Iberis amara, I. umbellata andMalcolmia maritima where it is pinnate-festooned brochidodromous. The number of secondary veins and their angle of divergence vary from species to species and even within the same species. Marginal ultimate venation is mostly looped occasionally incomplete. The areole size and shape is variable. The veinlets may be simple or once or twice dichotomously divided. The simple veinlets may be curved or hooked. The tracheids are either uni-, bi-, tri- or multiseriate and extraordinarily variable in size and shape. Isolated vein endings, isolated free vein endings, isolated tracheids and extension cells are observed. Myrosin cells have been observed inEruca vesicaria ssp.sativa andCochlearia cochlearioides.     

喀斯特地区不同类型兰科植物的叶片性状

叶片性状能够反映植物对环境的适应.认识喀斯特地区兰科植物的叶片性状及其适应意义对其科学合理的保育具有重要参考价值.本文于干季与雨季研究了广西雅长兰科植物自然保护区内落叶、常绿地生、常绿石附生三种类型共19种野生兰科植物的叶片性状及其相互关系,并比较了不同类型兰科植物之间的差异.其中18种兰科植物为C3植物,仅棒叶鸢尾兰(Oberonia myosurus)为CAM植物.相比于落叶兰,常绿兰具有较高的比叶重( LMA)和叶片碳氮比(C/N),但其叶片氮、磷含量较低.在常绿兰科植物中,石附生兰的叶片Ca含量与δ13C高于地生兰.石附生兰的叶片磷含量在雨季要高于干季,而地生兰的叶片δ13C在于季要高于雨季.该地区常绿兰科植物的N/P值＞16,表明其可能受到磷的限制.     

植物叶发育调控机理研究的进展

在植物的营养生长阶段,叶原基从植物地上部分顶端分生组织的周边区形成,在一系列细胞分裂和分化程序的指导下,最终发育成叶。近年来,通过遗传学和分子生物学研究已经鉴定和克隆了一批参与叶发育调控的关键基因,植物激素在叶原基的诱导和叶形态建成中也起十分重要的作用。目前这个领域的主要研究工作是鉴定调控叶发育的新基因并且解释叶调控基因之间的相互作用,同时了解基因调控和植物激素作用之间的关系。     

南亚热带不同演替阶段森林优势树种叶片构建成本与机械抗性的协同关系

为探究不同演替阶段森林优势种叶片资源获取策略的差异以及叶片构建成本与机械抗性的关系,对我国南亚热带不同演替阶段森林14优势种的叶片构建成本、机械抗性、角质层厚度和比叶重等结构性状进行测定。结果表明,与演替早期相比,演替晚期优势种具有更高的单位面积叶片构建成本、叶片撕裂力以及穿透力,但其叶片最大光合速率较低;同时,单位面积叶片构建成本与机械抗性呈显著正相关关系,而叶片角质层厚度、比叶重等结构性状也与叶片构建成本、机械抗性均呈显著正相关。因此,从叶片能量投资策略上反映了南亚热带森林演替进程中叶片构建成本与机械抗性的协同关系。     

Leaf structure of the cerrado (Brazilian savanna) woody plants

With the aim of recognizing the commonest leaf pattern found in the woody flora of the cerrado (the Brazilian savanna) we analyzed the leaf anatomy of 30 representative species. The leaves are mostly dorsiventral and hypostomatic and covered by trichomes and a thick layer of wax and cuticle; the vascular bundles are surrounded by a sheath of fibers. The mesophyll has a developed palisade tissue, dispersed sclerified cells and idioblasts bearing crystals and phenolic compounds. We compared the results with those reported for other species (60 species) from the same biome and for the families that the studied species belong. The present study suggests that the xeromorphism observed for the cerrado leaves is related to the evolutionary history of this biome, since its first floristic elements must have faced deficient water conditions as well as the consequent soil acidity and toxicity. Therefore we may infer that the leaf anatomical pattern here observed was already present in the first elements of the cerrado and was selected to guarantee the survival of those species in the new environment. Furthermore, the xeromorphic features present in those leaves continue nowadays to help the plants protecting themselves from the different biotic and abiotic factors they are subjected to.     

Characteristics of Encelia species differing in leaf reflectance and transpiration rate under common garden conditions

Summary The performance of coastal and desert species of Encelia (Asteraceae) were evaluated through common garden growth observations. The obectives of the study were to evaluate the roles of leaf features, thought to be of adaptive value (increased leaf reflectance and/or transpirational cooling), on plant growth in the hot, arid, desert garden versus their impact on growth under cooler, relatively more moist coastal garden conditions. E. californica native to the coast of southern California and E. farinosa, and E. frutescens, interior desert species, were grown in common gardens at coastal (Irvine, California) and interior (Phoenix, Arizona) sites under both irrigated and natural conditions. Although all species survived in both gardens during the two and a half year study period, there were large differences in their sizes. In the desert garden, leaf conductance and leaf water potential were both lower than at the coastal site. E. californica shrubs were leafless much of the time under natural conditions in the desert garden and had the smallest size there as well. Under natural conditions, E. farinosa, with its reflective leaf surface, was able to maintain lower leaf temperatures and attained a large size than the other two species in the desert garden. The green-leaved species (E. californica and E. frutescens) were not able to maintain leaves into the drought periods in the desert garden, with the exception of the irrigated E. frutescens which did maintain its leaf area if provided with supplemental watering to maintain transpirational leaf cooling. In the coastal garden, all species survived and there were few clear differences in the physiological characteristics among the three species. E. californica, the coastal native, attained a larger size in the coastal garden when compared with either of the two desert species.     

Characterising sclerophylly: some mechanical properties of leaves from heath and forest

Although sclerophylly is widespread through the world and is often the dominant leaf-form in mediterranean climates, the mechanical properties of sclerophyllous leaves are poorly understood. The term ”sclerophyllous” means hard-leaved, but biologists also use terms such as tough, stiff and leathery to describe sclerophyllous leaves. The latter term has no precise definition that allows quantification. However, each of the former terms is well-defined in materials engineering, although they may be difficult or sometimes inappropriate to measure in leaves because of their size, shape or composite and anisotropic nature. Two of the most appropriate and practically applicable mechanical properties of sclerophyllous leaves are ”strength” and ”toughness”, which in this study were applied using punching, tearing and shearing tests to 19 species of tree and shrub at Wilson’s Promontory, Australia. The results of these tests were compared with leaf specific mass (LSM) and a sclerophylly index derived from botanists’ ranks. Principal components analysis was used to reduce the set of mechanical properties to major axes of variation. Component 1 correlated strongly with the botanists’ ranks. Overall, leaves ranked as sclerophyllous by botanists were both tough and strong in terms of punching and tearing tests. In addition, tough and strong leaves typically had high toughness and strength per unit leaf thickness. There was also a significant correlation between component 1 and LSM. Although more detailed surveys are required, we argue that sclerophylly should be defined in terms of properties that have precise meanings and are measurable, such as toughness and strength, and that relate directly to mechanical properties as implicit in the term. Received: 4 March 1999 / Accepted: 22 November 1999     

Variation in rates of leaf abscission between plants may affect the distribution patterns of sessile insects

Summary At Sand Lake, Leon County, Florida, mines of Stilbosis quadricustatella, a leaf-mining moth, occur on sand live oak trees (Quercus geminata) over a broad range of densities. Some trees have fewer than 2% of their leaves mined (lightly infested), others up to 70% (heavily infested). Similar levels of infestation are maintained on the same trees year after year. There are no significant negative correlations of miner density per tree with any mortality factor that might explain miner preferences for certain trees. Nor is there a positive correlation with host leaf quality as measured by foliar nitrogen or by total or individual amino acid concentrations of host leaves. Egg-transfer experiments showed that larvae from eggs transferred to lightly infested trees were more likely to be killed by leaf abscission than were those that were transferred to and developed on heavily infested trees. This is the first demonstration that variation in rates of leaf abscission could be an important cause of the observed distribution pattern of sessile insects between conspecific host plants.