从叶内生物量分配策略的角度理解叶大小的优化

叶大小的变化是许多因素综合作用的结果, 对叶大小优化机制的研究有助于我们更好地理解植物的适应进化和生活史策略。该研究通过对浙江省清凉峰常绿阔叶混交林中的19个常绿阔叶物种和30个落叶阔叶物种叶水平上的相关性状进行分析, 探讨叶内生物量分配策略对叶大小优化的限制性影响。研究结果显示: 无论叶大小用面积还是质量表示, 常绿物种和落叶物种均呈现出叶内生物量分配到支撑结构的比例随着叶大小的增加而增加的规律, 这主要是由叶柄大小与叶片大小之间显著的异速生长关系导致的。这种异速生长关系在常绿物种和落叶物种中普遍存在。然而, 由于常绿物种对叶柄具有较高的机械以及抵抗冰冻栓塞等不利环境的需求, 在某一给定的叶面积下, 常绿物种比落叶物种具有更高的叶柄生物量投资。这些结果表明: 作为整个植株支撑投资的一个重要组成部分, 叶内支撑投资所占的生物量比例对叶大小的优化具有一定的限制性影响。     

Allometric scaling relationship between above‐ and below‐ground biomass within and across five woody seedlings

Allometric biomass allocation theory predicts that leaf biomass (M_L) scaled isometrically with stem (M_S) and root (M_R) biomass, and thus above‐ground biomass (leaf and stem) (M_A) and root (M_R) scaled nearly isometrically with below‐ground biomass (root) for tree seedlings across a wide diversity of taxa. Furthermore, prior studies also imply that scaling constant should vary with species. However, litter is known about whether such invariant isometric scaling exponents hold for intraspecific biomass allocation, and how variation in scaling constants influences the interspecific scaling relationship between above‐ and below‐ground biomass. Biomass data of seedlings from five evergreen species were examined to test scaling relationships among biomass components across and within species. Model Type II regression was used to compare the numerical values of scaling exponents and constants among leaf, stem, root, and above‐ to below‐ground biomass. The results indicated that M_L and M_S scaled in an isometric or a nearly isometric manner with M_R, as well as M_A to M_R for five woody species. Significant variation was observed in the Y‐intercepts of the biomass scaling curves, resulting in the divergence for intraspecific scaling and interspecific scaling relationships for M_L versus M_S and M_L versus M_R, but not for M_S versus M_R and M_A versus M_R. We conclude, therefore, that a nearly isometric scaling relationship of M_A versus M_R holds true within each of the studied woody species and across them irrespective the negative scaling relationship between leaf and stem.     

Above- and below-ground biomass relationships across 1534 forested communities

BACKGROUND AND AIMS: Prior work has shown that above- and below-ground dry biomass across individual plants scale in a near isometric manner across phyletically and ecologically diverse species. Allometric theory predicts that a similar isometric scaling relationship should hold true across diverse forest-types, regardless of vegetational composition. METHODS: To test this hypothesis, two compendia for forest-level above- and below-ground dry biomass per hectare (M(A) and M(R), respectively) were examined to test the hypothesis that M(A) vs. M(R) scales isometrically and in the same manner as reported for data from individual plants. Model Type II regression protocols were used to compare the numerical values of M(A) vs. M(R) scaling exponents (i.e. slopes of log-log linear relationships) for the combined data sets (n =1534), each of the two data sets, and data sorted into a total of 17 data subsets for community- and biome-types as well as communities dominated by angiosperms or conifers. KEY RESULTS: Among the 20 regressions examined, 15 had scaling exponents that were indistinguishable from that reported for M(A) vs. M(R) across individual plants. The isometric hypothesis could not be strictly rejected on statistical grounds; four of these 15 exponents had broad 95% confidence intervals resulting from small sample sizes. Significant variation was observed in the y-intercepts of the 20 regression curves, because of absolute differences in M(A) or M(R). CONCLUSIONS: The allometries of forest- and individual plant-level M(A) vs. M(R) relationships share strikingly similar scaling exponents, but differ because of considerable variation in y-intercepts. These results support prior allometric theory and provide boundary conditions for the scaling of M(A) and M(R).     

白刺不同物候期的生物量分配规律

植物生物量的分配模式是植物对环境适应的结果, 并伴随着植物生活史的每一个阶段, 与植物的生长和发育息息相关。目前关于植物生物量分配的大小依赖性已有相关报道, 但关于其对物候期的响应尚鲜有报道。该研究以乌兰布和沙漠地区白刺(Nitraria tangutorum)为研究对象, 通过对其2016与2017年连续2个生长季里盛花期、盛果期与营养生长期3个物候期的根、压条、新枝、老枝、叶、繁殖器官等部分的生物量测定, 采用标准化主轴回归方程的斜率和截距的显著性比较, 分别探讨了白刺在不同物候期的异速生长的大小依赖程度和相对生物量分配比例, 特别是地上与地下部分之间、支持与同化器官之间, 在不同物候期的生物量分配规律。结果表明: 白刺的繁殖生长对生物量分配模式造成的影响主要体现在相对生物量分配比例(36.00%)而不是个体大小的依赖性程度上(16.67%), 且对新枝的影响较大, 使其不同物候期的大小依赖性程度发生了改变, 但是变化趋势不一致, 同时繁殖生长增加对叶片的相对生物量分配比例, 减少对老枝的相对生物量分配比例, 但并没有改变他们的大小依赖性程度。白刺生长过程中的地下部分生物量分配率随个体生物量的累积均增大, 而繁殖分配会在一定程度内减弱这种速率。白刺随着个体生物量的增大其生物量向支持器官分配率也越大, 但随着生长时间推移, 更倾向于将生物量分配给同化吸收器官。     

长期模拟增温对岷江冷杉幼苗生长与生物量分配的影响

川西亚高山针叶林是青藏高原东部高寒林区的重要组成部分,也是研究全球变化对森林生态系统影响的重要组成。长期模拟增温对川西亚高山森林树木的生长、物质积累及其分配格局的影响至今鲜有报道。以川西亚高山针叶林优势种岷江冷杉(Abies faxoniana)幼苗为研究对象,采用控制环境生长室模拟增温的方法,研究了模拟增温对岷江冷杉幼苗生长、物质积累及其分配格局的影响。结果表明,模拟增温(2.2±0.2)℃处理65个月后,岷江冷杉幼苗基径、株高、单株叶面积和比叶面积(SLA)均显著增加,比叶重(LMA)显著下降。增温对岷江冷杉幼苗的茎、侧枝、叶和总生物量具有显著的促进作用,对根生物量没有显著影响。岷江冷杉幼苗的叶重比(LMR)下降、枝重比(SMR)增加、根重比(RMR)无显著变化。长期增温能显著促进岷江冷杉幼苗的生长和物质积累,改变生物量分配格局,促使叶片物质向茎转移,降低光合物质投入。     

Variation in biomass allocation of Nitraria tangutorum during different phenological phases

植物生物量的分配模式是植物对环境适应的结果, 并伴随着植物生活史的每一个阶段, 与植物的生长和发育息息相关。目前关于植物生物量分配的大小依赖性已有相关报道, 但关于其对物候期的响应尚鲜有报道。该研究以乌兰布和沙漠地区白刺(Nitraria tangutorum)为研究对象, 通过对其2016与2017年连续2个生长季里盛花期、盛果期与营养生长期3个物候期的根、压条、新枝、老枝、叶、繁殖器官等部分的生物量测定, 采用标准化主轴回归方程的斜率和截距的显著性比较, 分别探讨了白刺在不同物候期的异速生长的大小依赖程度和相对生物量分配比例, 特别是地上与地下部分之间、支持与同化器官之间, 在不同物候期的生物量分配规律。结果表明: 白刺的繁殖生长对生物量分配模式造成的影响主要体现在相对生物量分配比例(36.00%)而不是个体大小的依赖性程度上(16.67%), 且对新枝的影响较大, 使其不同物候期的大小依赖性程度发生了改变, 但是变化趋势不一致, 同时繁殖生长增加对叶片的相对生物量分配比例, 减少对老枝的相对生物量分配比例, 但并没有改变他们的大小依赖性程度。白刺生长过程中的地下部分生物量分配率随个体生物量的累积均增大, 而繁殖分配会在一定程度内减弱这种速率。白刺随着个体生物量的增大其生物量向支持器官分配率也越大, 但随着生长时间推移, 更倾向于将生物量分配给同化吸收器官。     

干旱胁迫下菊芋各器官生物量及物质分配规律

以红皮和白皮菊芋为研究材料,通过设置不同的灌水梯度,研究了干旱胁迫对菊芋各器官生物量及物质分配规律的影响。试验结果表明,干旱胁迫降低了红皮和白皮菊芋各器官的生物量;其中,50%灌水条件下两种菊芋的总生物量、地上生物量和地下生物量显著高于10%、20%、30%和40%;红皮菊芋根冠比随着灌水量的减少呈现逐渐增加的变化趋势,白皮菊芋呈现"升-降-升"的变化趋势,且在相同水分处理条件下红皮菊芋茎叶比和根冠比均高于白皮;红皮菊芋随着灌水量的降低根系贡献率呈现逐渐增加的变化趋势,叶片贡献率、块茎贡献率、花贡献率、叶柄贡献率、茎秆贡献率均呈现逐渐降低的变化趋势,白皮菊芋块茎贡献率、花贡献率随灌水量的降低呈现逐渐降低的变化趋势,其他各器官的贡献率随灌水量降低没有规律可循。     

Fine root biomass in a beech (Fagus sylvatica L.) stand on Paiko Mountain,NW Greece

Abstract

Fine roots represent a small proportion of total plant biomass however they represent the most dynamic component of the root systems of woody plants. There is limited information on the beech fine root production in Mediterranean ecosystems and especially in Greece. We measured live, dead and total fine root biomass (d<2 mm) (LFRB, DFRB and TFRB, respectively) over a growing season in a beech (Fagus sylvatica L.) stand on Paiko mountain, NW Greece, in order to contribute to the generally scarce knowledge of the fine root biomass of beech stands. It was found that TFRB and LFRB increased from May to July and then decreased. LFRB decreased with soil depth while there was no pattern at the change of DFRB with soil depth.     

Influence of aluminium on biomass, nutrients, soluble carbohydrates and phenols in beech (Fagus sylvatica)

The effects of aluminium on biomass, nutrients and soluble carbohydrates and phenols were studied in beech ( Fagus sylvatica L.) seedlings. After germination, seedlings with cotyledons and the buds of the first leaf-pair developed, were preconditioned for two weeks and then grown for 31 days in nutrient solutions containing 0.1, 0.5, 1.0 or 2.0 m M A1C1₃. Aluminium did not affect the dry weights of roots but at Al concentrations ≥ 1.0 m M the development of the terminal shoot above the first leaf pair, was reduced by 80% or more. The concentrations of most nutrients (P, Ca, Mg, Zn, Cu) in the plant tissues decreased strongly even at the lowest Al levels, but K increased in the shoots. The tissue concentration of N was not affected of Al. but the distribution between the organs was changed to a higher content of N in the roots. At ≥1.0 m M Al the concentrations of starch in both the shoots and the roots were significantly increased, and at ≥ 0.5 m M the roots contained more of total phenols than untreated seedlings. The elevated concentrations and contents of starch and phenols in the seedlings may partly be related to the reduced shoot growth. The observed effects of Al were marked already at Al levels found in soil waters from beech forests in southern Sweden.     

北京地区14份柳枝稷生物量及分配差异研究

采用14份柳枝稷开展盆栽试验,研究了在北京地区条件下其生物量差异及分配规律。结果表明,低地型柳枝稷Kanlow生物量最高,其茎秆、地上部和整株生物量分别达到175.48 g/株、299.18 g/株和447.66 g/株,而高地型柳枝稷Nebraska生物量最低,其茎秆、地上部和整株生物量分别为29.86 g/株、58.08 g/株和140.51 g/株。就柳枝稷整株植株而言,Kanlow地上部生物量分配比例最高,达到63.13%,S2最低,为40.55%,Kanlow地上部营养器官生物量分配比例最高,达到48.67%,Nebraska最低,为31.88%。就柳枝稷地上部而言,Alamo、Kanlow和Trailblazer茎秆生物量分配比例及茎叶比均较高,分别为35.91%和2.75,37.09%和2.56,34.39%和2.48。起源纬度显著影响了柳枝稷的生物量及其分配,就柳枝稷整株植株而言,起源纬度与柳枝稷生物量显著负相关,与地下部生物量分配比例显著正相关,与地上部、种子和茎生物量分配比例显著负相关。就柳枝稷地上部而言,起源纬度与茎生物量分配比例及茎叶比显著负相关,与叶和鞘生物量分配比例显著正相关。生物量的差异及其分配规律反映出柳枝稷对生态环境长期适应的生殖与生长策略。本研究为柳枝稷遗传资源引种和品种选育提供了依据。     

阔叶红松林下6种早夏草本不同生长期生物量分配及模型构建

早夏草本植物作为阔叶红松林林下的一类优势物种,对整个生长季林下草本物种多样性和生物量具有重要影响,对其不同生长阶段生物量分配特征及生物量模型的研究有助于了解该类植物生存策略和碳汇储量。以吉林省蛟河地区阔叶红松林林下的白花碎米荠(Cardamine leucantha)、北重楼(Paris verticillata)、鹿药(Smilacina japonica)、美汉草(Meehania fargesii)、山茄子(Anisodus acutangulus)和紫花变豆菜(Sanicula rubriflora)6种早夏草本植物为研究对象,从4月初到8月底对其物候期进行观察记录,定期取样,从而对6种植物不同生长时期各组分生物量分配特征,地上与地下生物量相对生长关系进行分析研究,并以株高级为自变量建立5种形式(一元线性模型、一元二次模型、指数模型、幂函数模型、对数模型)的单种和混种生物量模型,选取最优模型进行验证。结果表明,6种早夏草本植物花期一般开始于4月底结束于6月中旬,果期开始于5月底结束于8月中旬,不同植物的花、果期持续时间差异较大。生长期内,随着植物生长,株高、生物量和根冠比(R/S)变化明显,但变化趋势不一致。不同物种各组分生物量分配存在差异,用于繁殖的生物量分配比例较小,通常不超过5%。所有物种AGB和BGB间均具有明显的相对生长关系(P0.0001),且均表现为异速生长(相关生长指数a≠1)。根据R~2和SEE选取最优生物量模型,其中幂函数模型形式最常用,其次是一元二次和指数模型。所有最优模型的R~2均较高且SEE较低,拟合效果较好,其中AGB和TB的最优模型要优于BGB,单种模型优于混种模型;通过验证,除混合模型BGB的RMA(30.679%)稍大于30%外,所有模型的RS、EE和RMA均小于30%,P值均大于80%,说明所建立的最优模型能够用来对该地区阔叶红松林林下早夏草本植物生物量进行估算。     

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.     

青藏高原东部高寒灌丛生物量分配对模拟增温的响应

植物生物量分配特征的变化反映了不同环境条件下植物的适应策略,全球气候变暖正在改变青藏高原高寒生态系统植被动态和生物量分配格局。然而,到目前为止,有关青藏高原高寒灌丛生物量分配特征对气候变暖的响应研究较少。为了探究气候变暖对高寒灌丛生物量分配的影响,以青藏高原东部典型的窄叶鲜卑花高寒灌丛为研究对象,分析了高寒灌丛灌木层、草本层和群落水平生物量分配特征对开顶式生长室（OTC）模拟增温的响应。研究结果表明：整个生长季节,模拟增温使空气温度和表层土壤温度分别升高0.6℃和1.2℃,使表层土壤水分含量下降2.7%。模拟增温使草本层和群落地上生物量显著增加57.8%和7.2%,使灌木层、草本层和群落根系生物量显著增加42.5%、105.6%和45.6%。然而,模拟增温没有显著影响灌木层地上生物量。同时,模拟增温使灌木层、草本层和群落总生物量显著增加25.6%、85.7%和28.4%,使灌木层、草本层和群落根冠比显著增加33.2%、30.4%和36.0%。由此可见,模拟增温在促进高寒灌丛生物量生产的同时将显著提高向地下根系部分的分配比例。Pearson相关分析表明,高寒灌丛生物量分配与空气温度、土壤温度和土壤硝态氮含量呈显著正相关关系;多元线性回归分析结果也表明,空气温度、土壤温度和土壤硝态氮含量解释了高寒灌丛生物量分配变异的50.8%以上。这些结果表明,青藏高原东部高寒灌丛植被能够通过调节生物量分配模式应对未来气候变暖。     

Growth of Fagus sylvatica saplings in an old-growth forest as affected by soil and light conditions

Abstract. Studies were conducted on 41 five yr-old common beech (Fagus sylvatica) saplings collected in an old-growth beech wood (Fontainebleau forest, biological reserve of La Tillaie, France), under varying humus and light conditions, following gypsy moth (Lymantria dispar) caterpillar injuries. Aerial and subterranean parts of each sapling were described by means of 34 parameters and environmental conditions at the microsite, where each sapling was excavated, were characterized by 23 parameters. The development of beech saplings is strongly affected by microsite conditions. An increase in sapling size was associated with darkness of the A-horizon, typical of zones with poor mineralization of organic matter. Light conditions were more important in influencing the development of the root system than that of the aerial parts. Rooting depth was shallower and rate of mycorrhiza development by the black ascomycete Cenococcum geophilum was lower in microsites receiving incident light during the morning than in those never receiving incident light during this period. Results are discussed in the frame of survival of young beech individuals in varying environmental conditions, when submitted to competition by other vegetation and adverse climate conditions.     

施氮和减水对中亚热带壳斗科三种幼树生物量及其分配的影响

土壤氮素和土壤含水量是森林生态系统中限制植物生长的重要因子。为探讨常绿阔叶树种对模拟氮沉降增加和降水减少的响应,以同质园中自然生长的壳斗科(Fagaceae)丝栗栲(Castanopsis fargesii)、大叶青冈(Cyclobalanopsis jensenniana)和麻栎(Quercus acutissima)五年生幼树为对象,比较了对照(CK)、施氮(+N,施氮60 kg hm~(-2) a~(-1))、减水(-W,减少自然降水的50%)以及施氮和减水(+N-W,施氮60 kg hm~(-2) a~(-1)和减少自然降水的50%)对总生物量、各器官生物量及其生物量分配的影响。研究表明:(1)施氮显著增加了三种幼树的总生物量及各器官生物量(P0.05)。(2)减水未引起三种幼树的总生物量及各器官生物量的显著下降(P0.05)。(3)除麻栎树叶生物量、树枝生物量外,施氮和减水交互作用对三种幼树总生物量及各器官生物量没有明显影响(P0.05)。(4)施氮显著提高了丝栗栲幼树的干重比、大叶青冈幼树的干重比和枝重比(P0.05),降低了大叶青冈的叶重比和根重比(P0.05)。(5)减水导致丝栗栲幼树和麻栎幼树的根重比、麻栎幼树的根冠比显著增加(P0.05),引起丝栗栲幼树的枝重比、麻栎幼树的叶重比、枝重比和干重比显著降低(P0.05)。(6)施氮和减水交互作用显著提高了丝栗栲幼树的根重比(P0.05),降低了麻栎幼树的干重比(P0.05)。     

Counteractive biomass allocation responses to drought and damage in the perennial herb Convolvulus demissus

Herbivory and water shortage are key ecological factors affecting plant performance. While plant compensatory responses to herbivory include reallocation of biomass from below‐ground to above‐ground structures, plant responses to reduced soil moisture involve increased biomass allocation to roots and a reduction in the number and size of leaves. In a greenhouse study we evaluated the effects of experimental drought and leaf damage on biomass allocation in Convolvulus demissus (Convolvulaceae), a perennial herb distributed in central Chile, where it experiences summer drought typical of Mediterranean ecosystems and defoliation by leaf beetles and livestock. The number of leaves and internode length were unaffected by the experimental treatments. The rest of plant traits showed interaction of effects. We detected that drought counteracted some plant responses to damage. Thus, only in the control watering environment was it observed that damaged plants produced more stems, even after correcting for main stem length (index of architecture). In the cases of shoot : root ratio, relative shoot biomass and relative root biomass we found that the damage treatment counteracted plant responses to drought. Thus, while undamaged plants under water shortage showed a significant increase in root relative biomass and a significant reduction in both shoot : root ratio and relative shoot biomass, none of these responses to drought was observed in damaged plants. Total plant biomass increased in response to simulated herbivory, apparently due to greater shoot size, and in response to drought, presumably due to greater root size. However, damaged plants under experimental drought had the same total biomass as control plants. Overall, our results showed counteractive biomass allocation responses to drought and damage in C. demissus. Further research must address the fitness consequences under field conditions of the patterns found. This would be of particular importance because both current and expected climatic trends for central Chile indicate increased aridity.     

呼伦贝尔草原植物叶片大小与数量的权衡关系及其内在机制

叶片大小与数量的权衡关系是植物生长策略的基础,研究叶片大小与数量权衡关系的内在机制对于深刻理解植物生长策略具有重要意义.本研究以单个叶片干重表示叶大小,以单位茎上的叶片数量表示出叶强度,采用标准主轴回归分析方法研究呼伦贝尔草原植物叶片大小与数量的权衡关系以及内在机制.结果表明:陈旗嵯岗(典型草原)和陈旗八一(草甸草原)...     

The effect of nutrient availability on biomass allocation patterns in 27 species of herbaceous plants

We investigated allocation to roots, stems and leaves of 27 species of herbaceous clonal plants grown at two nutrient levels. Allocation was analyzed as biomass ratios and also allometrically. As in other studies, the fraction of biomass in stems and, to a lesser extent, in leaves, was usually higher in the high-nutrient treatment than in the low-nutrient treatment, and the fraction of biomass in roots was usually higher under low-nutrient conditions. The relationship between the biomass of plant structures fits the general allometric equation, with an exponent 1 in most of the species. The different biomass ratios under the two nutrient conditions represented points on simple allometric trajectories, indicating that natural selection has resulted in allometric strategies rather than plastic responses to nutrient level. In other words, in most of the species that changed allocation in response to the nutrient treatment, these changes were largely a consequence of plant size. Our data suggest that some allocation patterns that have been interpreted as plastic responses to different resource availabilities may be more parsimoniously explained as allometric strategies.