羌塘高原降水梯度植物叶片、根系性状变异和生态适应对策

叶片和根系是植物获取资源的最重要的器官,其性状随环境梯度的变化反映了植物光合碳获取和水分与养分的吸收能力及其对环境变化适应的生态对策。羌塘高原降水梯度带高寒草地群落叶片和根系成对性状关系研究不仅能揭示环境梯度对植物性状的塑造作用,也可为理解寒、旱和贫瘠等极端环境下植物的适应策略提供依据。为此,选择3组具有代表性的叶片和根系成对性状:比叶面积(SLA)和比根长(SRL);单位质量叶氮含量(LN_(mass))和单位质量根氮含量(RN_(mass));单位面积叶氮含量(LN_(area))和单位长度根氮含量(RN_(length)),分析不同优势植物地上、地下成对性状变异特征及其与环境因子的关系,探讨植物性状对高寒生态系统水分和养分限制因素的适应策略。研究表明,区域气候和土壤环境导致的叶片性状变异大于根系性状的变异,干旱端的植物既具有高的SRL,又具有高的叶片和根系的养分含量(LN_(mass),LN_(area)和RN_(mass))。SLA-SRL、LN_(mass)-RN_(mass)、LN_(area)-RN_(length)均表现为权衡关系,在干旱端(年降雨量MAP 400 mm)的高寒草原、荒漠草原和极湿润端(MAP 600 mm)的高寒草甸这种权衡关系更为明显,而中间区域(400 MAP 600 mm)的高寒草甸养分和水分限制不是很强烈,叶片和根系性状更多地表现出协同关系。从植物功能类群来看,苔草和禾草类植物叶片和根系成对性状之间具有更强烈的权衡关系。干旱端植物通过增加SRL和叶片、根系养分含量来提高水分和养分的吸收能力,同时通过叶片高的氮含量提高光合碳获取能力,保障了根系生长的物质来源,表现出地上和地下同时投入的策略。干旱端植物保持较高的养分含量是抵御和适应严酷的寒、旱和贫瘠的环境胁迫的重要策略。而在湿润端植物则采取增加SLA,维持地上光合生产力的生态策略。     

凝结水输入差异下狭果鹤虱幼苗的水分和光合生理

凝结水作为荒漠生态系统一种重要的补充水源,其输入量的增加或者减少都将对荒漠短命植物的生态过程产生重要影响。选择艾比湖湿地国家级自然保护区为研究区,研究模拟少凝结水(W_0)、自然凝结水(W_1)和倍增凝结水(W_2)3种不同凝结水量输入下短命植物狭果鹤虱(Lappula semiglabra)幼苗的水分和光合生理适应对策。结果表明:倍增凝结水会明显改善狭果鹤虱幼苗的水分状况,而少凝结水导致狭果鹤虱幼苗叶片的水势和含水量不同程度的降低;少凝结水致使狭果鹤虱幼苗蒸腾速率和净光合速率显著降低(P0.05),且净光合速率日走势由双峰曲线转变为单峰曲线;凝结水倍增可以延缓狭果鹤虱幼苗气孔导度的降低过程,少凝结水降低狭果鹤虱幼苗叶片气孔导度;凝结水输入差异对狭果鹤虱幼苗叶片胞间CO_2浓度无显著影响(P0.05);狭果鹤虱幼苗叶片的水分利用效率在不同凝结水量输入下无显著差异(P0.05),体现了荒漠短命植物稳定的水分利用策略。     

狭果鹤虱幼苗营养生长和生物量分配对凝结水梯度的响应

以新疆艾比湖湿地国家级自然保护区荒漠短命植物狭果鹤虱为研究对象,研究少凝结水、自然凝结水和倍增凝结水3个梯度下狭果鹤虱幼苗形态、生理响应对策及单株植物的干物质分配格局.结果表明: 随凝结水量增加,狭果鹤虱幼苗与叶片吸收水分有关的性状叶绿素相对含量、叶片水势、株高、冠幅、茎质量和叶质比均显著增高,而与根吸收和运输水分有关的性状主茎径、根长和根径无显著变化;株高和叶绿素相对含量对凝结水量的响应最迅速;不同凝结水梯度下,狭果鹤虱幼苗对茎的生物量投入比例无显著差异,但随幼苗生长,3个梯度植物的根质比均逐渐下降,少凝结水处理植株降幅相对较小.狭果鹤虱幼苗主要通过改变地上部分性状响应凝结水量的变化,叶片光合潜力和干物质比重随凝结水量增加而显著增加.     

内蒙古荒漠草原植物叶片功能性状关系及其经济谱分析

气候变化和人为干扰导致草原荒漠化加剧, 引发了严重的环境问题。因此, 对荒漠草原植物与环境变化关系的研究愈加迫切, 分析比较荒漠草原不同功能型物种叶片经济谱具有重要意义。该研究通过测定内蒙古荒漠草原生态系统不同功能型植物叶片的光合及叶绿素荧光参数、比叶面积和叶片氮素含量, 验证了荒漠草原植物叶片经济谱的存在, 明确了各功能型植物叶片性状间的关系及其在叶片经济谱中的位置。荒漠草原不同功能型植物叶片性状差异明显, 草本植物的比叶面积(SLA)、单位质量叶氮含量(N_mass)分别是灌木的2.39倍和1.20倍; 一年生植物单位面积最大净光合速率(A_area)、SLA、光合氮利用效率(PNUE)分别是多年生植物的1.93倍、2.13倍和4.24倍; C₄植物的A_area、SLA、PNUE分别是C₃植物的2.25倍、1.73倍和3.61倍。除A_area与单位面积叶氮含量(N_area)、PSII的实际光化学效率(Φ_PSII)与SLA之间不存在显著相关关系外, 叶片性状间存在广泛的相关关系, 且均达到极显著水平。这验证了叶片经济谱在内蒙古荒漠草原植物中也同样存在。进一步分析表明, 一年生植物、草本植物、C₄植物叶片在叶片经济谱中位于靠近薄叶、光合能力强、寿命短的一端; 而多年生植物、灌木、C₃植物叶片靠近厚叶、光合能力弱、寿命长的一端。这说明荒漠草原中不同功能型植物可通过权衡其经济性状间的关系而采取不同的适应策略, 对于荒漠草原生态系统管理具有重要的理论指导意义。     

准噶尔盆地东南缘多枝柽柳、白刺和红砂水分来源的异同

荒漠生态系统中, 水是植物生长最主要的限制因子。为了比较同一生境下不同荒漠植物的水分来源特征, 选取了同一生境下的多枝柽柳(Tamarix ramosissima)、白刺(Nitraria sibirica)和红砂(Reaumuria soongorica), 测定了这3种植物茎水和各潜在水源(降水、土壤水和地下水)的氢、氧稳定同位素比率(δD和δ¹⁸O)值, 并利用IsoSource软件计算了3种植物对潜在水源的利用比例。结果表明: 红砂和白刺的茎水δD和δ¹⁸O值及其水分来源有明显的季节波动特征。其中, 红砂为浅根系植物, 春季(3-5月)以表层土壤水为主要水源, 夏秋季节(6-10月)表层土壤含水量显著降低, 其主要的水分来源逐渐偏向于较深层的土壤水; 白刺的根系分布范围介于红砂和多枝柽柳之间, 在春季能够较多地利用表层土壤水, 而到了夏秋季节, 所利用的水分更多地来源于深层土壤水或地下水; 多枝柽柳为深根系植物, 其90%以上的水分来源于深层土壤水和地下水, 而且茎水δD和δ¹⁸O值及其水分来源没有季节波动特征。3种植物水分来源特征的差异与其水分利用策略密切相关, 同时, 也说明荒漠灌木可以通过自身调节向着最优(最有利)表现型发展, 从而最大限度地获取水分。     

根源信号参与调控气孔行为的机制及其农业节水意义

在土壤干旱情况下,根源信号一方面向植物地上部分的长距离传输,为地上部分提供了土壤水分获取能力的测度,另一方面调控气孔开度,抑制蒸腾作用并提高植物的水分利用效率．文中综述了根源信号参与调控植物水分利用的生理机制和理论模型,指出该模型与根系吸水模型、气孔导度模型耦合,能够更好地反映植物叶片对土壤干旱以及大气干旱的响应、评述了在根源信号参与调控植物水分关系的基础上发展的调亏灌溉(RDI)、部分根系干旱(PRD)和控制性交替灌溉(CAI)等有效灌溉手段,有助于合理配置根系层供水量,通过根土相互作用和信号物质的传输,降低蒸腾和提高水分利用效率、另外,根源信号在调控根系生长发育、延缓地上部分生长以调节根冠比例,优化资源分配以利于生殖生长等方面均有所为,为全面提高农田水分利用效率提供节水生理基础。     

生物土壤结皮对准噶尔盆地5种荒漠植物幼苗生长与元素吸收的影响

生物土壤结皮广泛分布于许多干旱和半干旱地区, 它影响土壤物理过程、水文、侵蚀和养分循环过程, 从而影响植物种子萌发与生长发育。该文以新疆准噶尔盆地腹地的古尔班通古特沙漠的生物土壤结皮为研究对象, 分析了生物土壤结皮对准噶尔盆地5种荒漠植物(白梭梭(Haloxylon persicum)、蛇麻黄(Ephedra distachya)、角果藜(Ceratocarpus arenaarius)、涩芥(Malcolmia africana)和狭果鹤虱(Lappula semiglabra))的生长及其对元素吸收的影响。结果表明: 1)相对于裸沙而言, 生物土壤结皮显著促进了荒漠植物的生长速率, 并增加了草本植物地上和地下的生物量, 但对灌木的生物量无显著影响; 2)生物土壤结皮使部分一年生草本植物的开花和结实期提前, 这可能有利于荒漠植物在有限的环境资源下快速完成生活史, 并繁衍后代; 3)生物土壤结皮能够影响荒漠植物对土壤中营养元素的吸收, 具体表现在生物土壤结皮显著促进了5种植物对N的吸收, 增加了荒漠植物在N贫乏的荒漠生态系统的适应能力, 而对P和K的吸收均没有影响。生物土壤结皮对荒漠植物对元素吸收的影响因种而异, 对不同的植物有不同的影响。荒漠植物对Mg、Mn和Cu的吸收受生物土壤结皮的影响最小。     

凝结水对干旱胁迫下羊草和冰草生理生态特征及叶片形态的影响

为了探讨凝结水对植物生长的作用,该文研究了干旱处理下模拟凝结水对羊草(Leymus chinensis)和冰草(Agropyron cristatum)生理性状和叶片表面结构的影响。试验设计了干旱无凝结水、干旱每周发生3次和5次凝结水以及正常浇水不发生凝结水4个处理,通过超声波加湿器模拟凝结水的发生,研究凝结水对两种植物叶片相对含水量、水势、净光合速率、水分利用效率、生物量以及叶片表面结构等的影响。结果表明:凝结水显著增加了干旱胁迫下两种植物的叶片相对含水量和水势(p0.05);凝结水显著提高了冰草的净光合速率、气孔导度与蒸腾速率(p0.05);而羊草的气孔导度和蒸腾速率随凝结水的变化不明显。羊草和冰草的地上生物量和根系生物量随凝结水的发生有增加的趋势,但是各处理间差异不显著。凝结水降低了羊草和冰草黄叶数与总叶数的比值,这表明凝结水对干旱胁迫下植物叶片表面结构遭到的破损有一定的保护和修复作用。该研究证实羊草和冰草的叶片可以吸收凝结水,并对其光合作用、水分生理以及生长具有正效应。     

干旱内陆河流域植物群落构建过程及其关键驱动因素

作为干旱内陆河流域水资源可利用性的决定性因素之一, 地下水位在调节植物功能性状、系统发育乃至植物群落构建方面发挥着至关重要的作用。然而地下水位变化对干旱内陆河流域植物群落构建过程相对重要性的影响, 以及这种影响在地上-地下组分间的差异尚未得到系统研究。本文以典型干旱内陆河流域下游的主要植物群落为研究对象, 结合叶片、根系功能性状与环境数据, 系统地探讨植物群落构建过程沿地下水位梯度的变化模式及其关键驱动因素。结果表明: (1)综合植物个体、平均功能性状和系统发育可知, 在整个研究区域, 叶片、根系功能多样性的标准效应值(SES.RaoQ)均小于0。大多数植物群落的功能结构(90%的功能性状)表现为聚集状态。(2)地下水与土壤因子共同解释叶片、根系SES.RaoQ 13%-39%与14%-48%的变异, 而地下水位能够单独解释叶片、根系SES.RaoQ 13%-22%与14%-36%的变异。(3)叶片、根系SES.RaoQ均随平均地下水位的降低而降低, 随地下水位季节性的增加而增加; 根系SES.RaoQ与地下水位的斜率大于叶片SES.RaoQ。总体而言, 干旱内陆河流域植物群落的构建机制整体上由确定性过程主导, 支持生态位理论, 大多数植物群落的构建机制符合生态位理论中的环境筛选作用。地下水位是调控不同群落构建过程相对重要性的主要因素, 随地下水位的降低, 功能结构由发散状态转为聚集状态。植物群落地上、地下功能结构沿地下水位梯度的变化表现出一致性, 但植物群落地下部分对地下水位的变化更为敏感。     

毛乌素沙地两种典型灌木叶片凝结水吸收能力及吸水途径

凝结水是半干旱地区生态系统重要的水源, 已有研究表明, 一些沙生植物可以通过叶片吸收凝结水以改善其水分状况。该研究以毛乌素沙地典型沙生灌木黑沙蒿(又称油蒿)(Artemisia ordosica)和北沙柳(Salix psammophila)为研究对象, 研究这两种植物的叶片是否具有吸收凝结水的能力, 并探究叶片吸水的途径及运移的通道。分别将黑沙蒿与北沙柳失水和未失水离体枝条置入人工模拟加湿室中, 使用高丰度氘水标记的凝结水进行浸润实验, 比对浸润前后枝条质量、叶片水及茎水氢同位素丰度变化, 确定黑沙蒿和北沙柳的叶片吸水能力; 并将盆栽黑沙蒿和北沙柳整株置入人工模拟加湿室, 使用荧光标记的凝结水进行浸润实验, 比对浸润前后叶片、小枝荧光显像, 确定黑沙蒿和北沙柳叶片吸收和运移凝结水的途径。结果显示: (1)黑沙蒿和北沙柳未失水枝条在浸润前后质量无显著差异, 黑沙蒿和北沙柳失水离体枝条在凝结水浸润后质量显著提高了2.04%和6.74%, 叶片水氘丰度提高了170.10‰和104.09‰, 茎水氘丰度提高了10.52‰和12.72‰; (2)荧光标记凝结水浸润后, 荧光示踪剂分布在黑沙蒿和北沙柳叶片的角质层、气孔、海绵组织、栅栏组织和维管束中, 黑沙蒿叶片的厚角组织中也发现了荧光示踪剂, 两种灌木小枝的表皮、韧皮部、木质部和髓中均观察到荧光。以上结果表明, 毛乌素沙地两种典型灌木叶片均具有吸收凝结水的能力, 水分亏缺植株的吸水能力更强; 两种灌木叶片通过气孔或角质层吸收凝结水, 并通过叶肉运移至维管束乃至小枝。黑沙蒿与北沙柳叶片具有的吸水功能可能是其适应干旱期水分亏缺的重要水分利用策略。     

Modeling soil water movement with water uptake by roots

Soil water movement with root water uptake is a key process for plant growth and transport of water and chemicals in the soil-plant system. In this study, a root water extraction model was developed to incorporate the effect of soil water deficit and plant root distributions on plant transpiration of annual crops. For several annual crops, normalized root density distribution functions were established to characterize the relative distributions of root density at different growth stages. The ratio of actual to potential cumulative transpiration was used to determine plant leaf area index under water stress from measurements of plant leaf area index at optimal soil water condition. The root water uptake model was implemented in a numerical model. The numerical model was applied to simulate soil water movement with root water uptake and simulation results were compared with field experimental data. The simulated soil matric potential, soil water content and cumulative evapotranspiration had reasonable agreement with the measured data. Potentially the numerical model implemented with the root water extraction model is a useful tool to study various problems related to flow transport with plant water uptake in variably saturated soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

黄土高原典型小流域草地群落功能性状对土壤水分的响应

植物功能性状可以响应生境的变化并决定生态系统的功能,探究植物功能性状间的关系及其随土壤有效水分梯度的变化规律,对认识不同水分条件下植被在群落水平碳水代谢关系和维持水分平衡的生理生态学机制具有重要意义。以甘肃定西典型半干旱黄土小流域草地群落为研究对象,采用排序分析和回归拟合方法,分析了30个代表性草地样地中7个植物功能性状加权均值对土壤有效水分的响应以及响应性状间的相关关系。结果显示:(1)7个性状中,除叶宽与土壤有效水分无明显相关外,叶长、株高、叶面积、比叶面积、叶厚和叶干物质含量均与土壤有效水分显著性相关,可识别为草地在群落水平对土壤水分的响应性状。(2)草地群落通过降低株高,减小叶长、叶面积和比叶面积,增加叶厚和叶干物质含量以适应土壤有效水分减少;其中叶干物质含量的解释度最大,是土壤水分的最优响应性状。(3)除叶厚与叶长无显著相关外,其余功能性状均存在显著相关,说明草地群落的功能性状在土壤水分梯度上已基本形成了一个相互权衡或协同变化的功能性状组合。     

Foliar water uptake: Processes,pathways, and integration into plant water budgets

Nearly all plant families, represented across most major biomes, absorb water directly through their leaves. This phenomenon is commonly referred to as foliar water uptake. Recent studies have suggested that foliar water uptake provides a significant water subsidy that can influence both plant water and carbon balance across multiple spatial and temporal scales. Despite this, our mechanistic understanding of when, where, how, and to what end water is absorbed through leaf surfaces remains limited. We first review the evidence for the biophysical conditions necessary for foliar water uptake to occur, focusing on the plant and atmospheric water potentials necessary to create a gradient for water flow. We then consider the different pathways for uptake, as well as the potential fates of the water once inside the leaf. Given that one fate of water from foliar uptake is to increase leaf water potentials and contribute to the demands of transpiration, we also provide a quantitative synthesis of observed rates of change in leaf water potential and total fluxes of water into the leaf. Finally, we identify critical research themes that should be addressed to effectively incorporate foliar water uptake into traditional frameworks of plant water movement.     

Diurnal Pattern of Transpiration,Water Uptake and Water Budget of Succulents with Different CO2 Fixation Pathways

The water fluxes and the CO₂ exchange of three leaf succulents, Othonna opima, Cotyledon orbiculata and Senecio medley-woodii, with different leaf anatomy, growth form and CO₂ fixation pathways (C₃, CAM) were monitored with a gas exchange cuvette which was combined with a potometric system to quantify water uptake. Measurements, which are primarily valid for plants with a sufficient water supply, were made during 6 to 10 consecutive days under constant experimental conditions. Water uptake for 24 h exceeded water loss by transpiration only for a S, medley-woodii plant with 10 expanding but only 7 mature leaves. In this case the gained water evidently is put into leaf expansion. All other plants showed balanced transpiration and water uptake rates. O. opima and C. orbiculata have a similar life form, similar water storage volumes and the same natural habitat but their diurnal water uptake patterns differ significantly. In the C₃ plant O. opima water uptake increased when the transpiration increased or transpiration rates were higher than uptake rates and vice versa. On the contrary the CAM plant C. orbiculata transpired during the dark period at constant or decreasing rates but showed steadily increasing uptake rates. Senecio medley-woodii- and C. orbiculata are CAM plants with similar diurnal water uptake patterns with its maximum in uptake during or towards the end of the CO₂ dark fixation period. Water uptake of C. orbiculata was at its minimum at the end of the light period despite transpiration being maximal. The results were discussed considering the different CO₂ fixation pathways. In the investigated CAM succulents, C. orbiculata and S. medley-woodii, the CAM influenced water uptake throughout the whole day and not only during the CO₂ dark fixation period.     

Mechanisms driving plant functional trait variation in a tropical forest

Plant functional trait variation in tropical forests results from taxonomic differences in phylogeny and associated genetic differences, as well as, phenotypic plastic responses to the environment. Accounting for the underlying mechanisms driving plant functional trait variation is important for understanding the potential rate of change of ecosystems since trait acclimation via phenotypic plasticity is very fast compared to shifts in community composition and genetic adaptation. We here applied a statistical technique to decompose the relative roles of phenotypic plasticity, genetic adaptation, and phylogenetic constraints. We examined typically obtained plant functional traits, such as wood density, plant height, specific leaf area, leaf area, leaf thickness, leaf dry mass content, leaf nitrogen content, and leaf phosphorus content. We assumed that genetic differences in plant functional traits between species and genotypes increase with environmental heterogeneity and geographic distance, whereas trait variation due to plastic acclimation to the local environment is independent of spatial distance between sampling sites. Results suggest that most of the observed trait variation could not be explained by the measured environmental variables, thus indicating a limited potential to predict individual plant traits from commonly assessed parameters. However, we found a difference in the response of plant functional traits, such that leaf traits varied in response to canopy‐light regime and nutrient availability, whereas wood traits were related to topoedaphic factors and water availability. Our analysis furthermore revealed differences in the functional response of coexisting neotropical tree species, which suggests that endemic species with conservative ecological strategies might be especially prone to competitive exclusion under projected climate change.     

Leaf water potential-leaf water deficit relationship for ten species of a semiarid grassland community

The relationship between water potential and relative water content (water content in percentage of full hydration) is a characteristic of plant tissues, that may vary with environmental conditions. It is used here to compare leaf water relations of ten species coexisting in a semiarid grassland community (Festucetum vaginatae danubiale) in Hungary. Three groups of species can be distinguished. In two of these leaf water potential changes only moderately with decreasing leaf water content. These are either short-lived, drought escaping spring plants relying on seasonally favourable water supply (group 1) or xerophytes with very deep root system having access to permanent water resources (group 2, only one species studied here). Xerophytes with moderately deep roots (group 3) display a rapid drop of leaf water potential with increasing leaf water deficit. This generates a steep water potential gradient in the soil-plant continuum that in turn enhances water uptake by roots. There is a positive correlation between the rate of water potential decline and degree of sclerophylly (proportion of dry material in the water-saturated leaf), and both variables show seasonal change in perennial species.     

PHENOPSIS, an automated platform for reproducible phenotyping of plant responses to soil water deficit in Arabidopsis thaliana permitted the identification of an accession with low sensitivity to soil water deficit

The high-throughput phenotypic analysis of Arabidopsis thaliana collections requires methodological progress and automation. Methods to impose stable and reproducible soil water deficits are presented and were used to analyse plant responses to water stress. Several potential complications and methodological difficulties were identified, including the spatial and temporal variability of micrometeorological conditions within a growth chamber, the difference in soil water depletion rates between accessions and the differences in developmental stage of accessions the same time after sowing. Solutions were found. Nine accessions were grown in four experiments in a rigorously controlled growth-chamber equipped with an automated system to control soil water content and take pictures of individual plants. One accession, An1, was unaffected by water deficit in terms of leaf number, leaf area, root growth and transpiration rate per unit leaf area. Methods developed here will help identify quantitative trait loci and genes involved in plant tolerance to water deficit.     

Rose leaf elasticity changes in response to mycorrhizal colonization and drought acclimation

Tissue elasticity can affect plant response to drought, in terms of turgor maintenance and water uptake from drying soils. The purpose of this study was to determine the effect of mycorrhizal colonization and drought acclimation on rose ( Rosa hybrida L. cv. Samantha) leaf elasticity. Bulk elasticity was characterized by the pressurevolume method using plots of the elastic modulus as a function of leaf turgor pressure, total water potential and relative water content. The treatments, arranged in a 2 × 3 factorial design, included acclimated and unacclimated plants, and either Glomus irararadices Schenck and Smith, Glomus deserticola Trappe, Bloss and Menge, or a non-mycorrhizal control. Plants with root mycorrhizal colonization showed reduced leaf elasticity (i.e. higher elastic moduli) over a broad range of leaf waler potential and water content. Both mycorrbizal colonization and acclimation facilitated the maintenance of positive values of turgor and elasticity at lower leaf water potential and water content than in controls. Mycorrhizal infections may aid plants in acclimating to water deficits through effects on leaf tissue elasticity.     

濒危植物长柄双花木(Disanthus cercidifolius var. longipes)叶功能性状随生长发育阶段的变化

对珍稀濒危植物长柄双花木(Disanthus cercidifolius var. longipes H. T. Chang)不同生长发育阶段的叶厚度(LT)、叶面积(LA)、叶含水量(LWC)、比叶面积(SLA)、叶片全氮含量(LNC)和叶片全磷含量(LPC)等叶功能性状及性状症候群的变化进行了研究。结果显示,不同发育阶段长柄双花木的叶功能性状存在显著差异,其中LT、LA随植株发育呈递增趋势,而LWC、SLA、LNC和LPC则呈递减趋势。主成分分析显示,随着长柄双花木的不断发育,性状症候群朝着LT、LA增大而LWC、SLA、LNC和LPC减小的方向变化。表明该物种的经济策略随着发育进程由快收益向慢收益转变。     

Leveraging plant hydraulics to yield predictive and dynamic plant leaf allocation in vegetation models with climate change

Plant functional traits provide a link in process‐based vegetation models between plant‐level physiology and ecosystem‐level responses. Recent advances in physiological understanding and computational efficiency have allowed for the incorporation of plant hydraulic processes in large‐scale vegetation models. However, a more mechanistic representation of water limitation that determines ecosystem responses to plant water stress necessitates a re‐evaluation of trait‐based constraints for plant carbon allocation, particularly allocation to leaf area. In this review, we examine model representations of plant allocation to leaves, which is often empirically set by plant functional type‐specific allometric relationships. We analyze the evolution of the representation of leaf allocation in models of different scales and complexities. We show the impacts of leaf allocation strategy on plant carbon uptake in the context of recent advancements in modeling hydraulic processes. Finally, we posit that deriving allometry from first principles using mechanistic hydraulic processes is possible and should become standard practice, rather than using prescribed allometries. The representation of allocation as an emergent property of scarce resource constraints is likely to be critical to representing how global change processes impact future ecosystem dynamics and carbon fluxes and may reduce the number of poorly constrained parameters in vegetation models.