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1.
Photosynthesis-nitrogen relations in Amazonian tree species   总被引:18,自引:0,他引:18  
The relationships between leaf nitrogen (N), specific leaf area (SLA) (an inverse index of leaf thickness or density), and photosynthetic capacity (Amax) were studied in 23 Amazonian tree species to characterize scaling in these properties among natural populations of leaves of different ages and light microenvironments, and to examine how variation within species in N and SLA can influence the expression of the Amax-to-N relationship on mass versus area bases. The slope of the Amax-N relationship, change in A per change in N (mol CO2 gN-1 s-1), was consistently greater, by as much as 300%, when both measures were expressed on mass rather than area bases. The x-intercept of this relationship (N-compensation point) was generally positive on a mass but not an area basis. In this paper we address the causes and implications of such differences. Significant linear relationships (p<0.05) between mass-based leaf N (Nmass) and SLA were observed in 12 species and all 23 regressions had positive slopes. In 13 species, mass-based Amax (Amass) was positively related (p<0.05) with SLA. These patterns reflect the concurrent decline in Nmass and SLA with increasing leaf age. Significant (p<0.05) relationships between area-based leaf N (Narea) and SLA were observed in 18 species. In this case, all relationships had negative slopes. Taken collectively, and consistent in all species, as SLA decreased (leaves become thicker) across increasing leaf age and light gradients, Nmass also decreased, but proportionally more slowly, such that Narea increased. Due to the linear dependence of Amass on Nmass and a negative 4-intercept, thicker leaves (low SLA) therefore tend, on average, to have lower Nmass and Amass but higher Narea than thinner leaves. This tendency towards decreasing Amass with increasing Narea, resulting in a lower slope of the Amax-N relationship on an area than mass basis in 16 of 17 species where both were significant. For the sole species exception (higher area than mass-based slope) variation in Narea was related to variation in Nmass and not in SLA, and thus, these data are also consistent with this explanation. The relations between N, SLA and Amax explain how the rate of change in Amax per change in N can vary three-fold depending on whether a mass or area mode of expression is used.  相似文献   

2.
魏海霞  霍艳玲  周忠科  张治国 《生态学报》2022,42(20):8343-8351
叶功能性状与植物的生长对策及资源利用效率密切相关,研究叶功能性状沿气候梯度的变异特征能为理解植物对气候变化的响应机制提供一种简便可行的测定指标。以我国西北荒漠地区广泛分布的唐古特白刺(Nitraria tangutorum)为研究对象,对其比叶面积(SLA)、单位质量和单位面积叶氮含量(Nmass、Narea)、单位质量和单位面积叶建成成本(CCmass、CCarea)进行测定,分析这些叶功能性状及性状相关关系沿气候梯度的变异特征。结果表明,唐古特白刺叶功能性状(CCarea除外)在气候梯度下存在显著差异,其中,温度是决定唐古特白刺SLA变化的主要因子,SLA随着温度的增加而增加;降水和温度对唐古特白刺Nmass、Narea和CCmass均有显著影响,Nmass和Narea随着降水和温度的增加而降低,而CCmass呈增加趋势。沿气候梯度,唐古特白刺SLA-Nmass、CCmass-Nmass和CCarea-Narea的线性正相关关系发生平移,导致在相同SLA、CCmass和CCarea下,降水和温度较低的地区具有更高的Nmass和Narea。这一结果表明唐古特白刺能通过调节叶功能性状之间的关系来适应气候的变化,并形成性状间的最佳功能组合。  相似文献   

3.

The present study was carried out to analyze the leaf functional traits of co-occurring evergreen and deciduous tree species in a tropical dry scrub forest. This study also intended to check whether the species with contrasting leaf habits differ in their leaf trait plasticity, responding to the canopy infestation by lianas. A total of 11 leaf functional traits were studied for eight tree species with contrasting leaf habits (evergreen and deciduous) and liana-colonization status (with or without liana). In the liana-free environment (L), evergreen trees had significantly higher leaf tissue density (LTD) and total chlorophyll (CHLt) than the deciduous species. Whereas the deciduous trees had higher specific leaf area (SLA) and mass-based leaf nitrogen concentration (Nmass). The leaf trait-pair relationship in the present study agreed with the well-established global trait-pair relationships (leaf thickness (LT) vs. SLA, Nmass vs. LT, SLA vs. Nmass, and LDMC vs. SLA). There was a significant difference between L+ and L individuals in leaf area (LA), petiole length (PL), SLA, LDMC, and CHLt in the deciduous species. On the other hand, evergreen species showed marked differences across LT, SLA, LTD, Nmass, and chlorophyll components between L+ and L individuals of the same species. The results revealed the differential impact of liana colonization on the host trees with contrasting leaf habits. The deciduous species with the acquisitive strategy can have a competitive advantage over evergreen species in the exposed environments (L), whereas evergreen species with shade-tolerant properties were better acclimated to the shaded environments (L+). Therefore, liana colonization can significantly impact the C-fixation strategies of the host trees by altering their light environment and further, the magnitude of such impact may vary among species of different leaf habits. The result also indicated the patterns of convergence and divergence in some of the leaf functional traits between evergreen and deciduous species explaining the patterns of species co-existence.

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4.
We investigated leaf physiological traits of dominant canopy trees in four lowland Panamanian forests with contrasting mean annual precipitation (1,800, 2,300, 3,100 and 3,500 mm). There was near complete turn-over of dominant canopy tree species among sites, resulting in greater dominance of evergreen species with long-lived leaves as precipitation increased. Mean structural and physiological traits changed along this gradient as predicted by cost–benefit theories of leaf life span. Nitrogen content per unit mass (Nmass) and light- and CO2-saturated photosynthetic rates per unit mass (Pmass) of upper canopy leaves decreased with annual precipitation, and these changes were partially explained by increasing leaf thickness and decreasing specific leaf area (SLA). Comparison of 1,800 mm and 3,100 mm sites, where canopy access was available through the use of construction cranes, revealed an association among extended leaf longevity, greater structural defense, higher midday leaf water potential, and lower Pmass, Nmass, and SLA at wetter sites. Shorter leaf life spans and more enriched foliar 15N values in drier sites suggest greater resorption and re-metabolism of leaf N in drier forest. Greater dominance of short-lived leaves with relatively high Pmass in drier sites reflects a strategy to maximize photosynthesis when water is available and to minimize water loss and respiration costs during rainless periods. Overall, our study links coordinated change in leaf functional traits that affect productivity and nutrient cycling to seasonality in lowland tropical forests.  相似文献   

5.
It is still unclear to what extent variations in foliar δ13C and nitrogen can be used to detect seasonal changes in canopy productivity. We hypothesize that in a wet and cloudy fir forest, seasonally higher litterfall and lower leaf area index (LAI) are correlated with higher mass-based leaf nitrogen (N mass) and net primary productivity (NPP), while foliar δ13C may change with specific leaf area (SLA), area-based leaf nitrogen (N area), and/or starch concentration. In order to test our hypotheses, stand-level litterfall and the means of δ13C, N mass, N area, SLA, and starch concentration of canopy needles for a wet and cloudy Abies fabri forest in the Gongga Mountains were monthly measured during the growing season. Seasonal estimates of LAI were obtained from our previous work. A conceptual model was used to predict seasonal NPP of the fir forest. Seasonal mean δ13C and N mass and climatic variables were used as inputs. The δ13C across 1–7-year-old needles increased from May to September associated with decreasing SLA and increasing N area. There were no significant differences in seasonal starch concentration. With increasing litterfall and decreasing LAI, seasonal mean N mass increased, while the δ13C varied little. The simulated NPP increased with increasing litterfall and related traits of N mass and N area. Our data generally supported the hypotheses. The results also suggest that in the forest with relatively moist and cloudy environment, the largest fraction of annual carbon gain may occur in the early part of the growing season when higher litterfall results in higher N mass of canopy leaves.  相似文献   

6.
以漓江水陆交错带为研究区,分两个条带分别量测了适生植物的5个叶性状指标:最大净光合速率(A_(max))、比叶重(LMA)、单位质量叶片全氮含量(N_(mass))、单位质量叶片全磷含量(P_(mass))、单位质量叶片全钾含量(K_(mass))。研究重度淹没带与微度淹没带不同功能型植物叶性状间的差异,分析并讨论重度淹没带叶性状间的关系与全球尺度是否存在差异,探究重度淹没带植物对水淹生境的生理响应机制。结果如下:(1)重度淹没带植物叶片的A_(mass)、N_(mass)、P_(mass)显著高于微度淹没带。(2)乔木、灌木叶片的LMA均显著高于草本植物,而A_(mass)、PPUE均显著低于草本植物。(3)重度淹没带草本叶性状指标的N_(mass)、P_(mass)、PNUE均显著高于微度微度淹没带,而乔木、灌木的叶性状在两个条带的差异则不显著。(4)重度淹没带植物叶性状关系与全球尺度基本一致,其植物叶片具有低LMA,高A_(mass)、Nmas s、P_(mass)。分析可知,重度淹没带植物在出露期提高叶片光合效率及相关营养水平可能是其适应水淹胁迫特殊生境的关键策略之一;不同功能型植物对同一环境的适应能力存在一定的差异,草本对于水淹环境的响应更为积极,适应能力更好;重度淹没带也存在叶经济谱,其植物在经济谱中属于"快速投资-收益"型物种。  相似文献   

7.
Few studies have examined leaf-trait relationships in the distribution of individual species along an environmental gradient. Here we address the issue by testing for the leaf-trait relationships of Quercus liaotungensis, a dominant deciduous woody species in northern China, along an altitudinal gradient in Dongling Mountain, Beijing. These leaf traits included specific leaf area (SLA), leaf dry matter content (LDMC), and leaf nitrogen, phosphorus, and potassium concentration on mass basis (Nmass, Pmass and Kmass, respectively). Along the altitudinal gradient, negative relationships between SLA and LDMC and Nmass were found, and Nmass, Pmass and Kmass correlated with each other positively. Relationship between Nmass and Pmass was stronger than the ones between Nmass and Kmass, and between Pmass and Kmass. The weak and negative relationship between SLA and Nmass might result from trade-offs that limit photosynthesis and water use efficiency along the altitudinal gradient, suggesting many environmental factors of local site being the collective forcing of drivers. Out of our expectations, Nmass and Pmass related very weakly to soil N and P, and no significant relationship between Kmass and soil K was found along elevation. These relationships could be used to predict the productivity of the population with changing environment in this region.  相似文献   

8.
西藏紫花针茅叶功能性状沿降水梯度的变化   总被引:4,自引:0,他引:4       下载免费PDF全文
 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(Nmass, Narea)、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-Nmass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Nmass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Nmass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Narea增加, 而干旱半干旱区的叶厚度增加并没有造成Narea的显著变化, 导致Narea沿降水梯度没有显著变化; 4)紫花针茅地上生物量与Narea具有显著正相关关系, 表明Narea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Narea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。  相似文献   

9.
Questions: How are leaf attributes and relative growth rate (RGR) of the dominant tree species of tropical deciduous forest (TDF) affected by seasonal changes in soil moisture content (SMC)? What is the relationship of functional attributes with each other? Can leaf attributes singly or in combination predict the growth rate of tree species of TDF? Location: Sonebhadra district of Uttar Pradesh, India. Methods: Eight leaf attributes, specific leaf area (SLA); leaf carbon concentration (LCC); leaf nitrogen concentration (LNC); leaf phosphorus concentration (LPC); chlorophyll concentration (Chl), mass‐based stomatal conductance (Gsmass); mass based photosynthetic rate (Amass); intrinsic water use efficiency (WUEi); and relative growth rate (RGR), of six dominant tree species of a dry tropical forest on four sites were analysed for species, site and season effects over a 2‐year period. Step‐wise multiple regression was performed for predicting RGR from mean values of SMC and leaf attributes. Path analysis was used to determine which leaf attributes influence RGR directly and which indirectly. Results: Species differed significantly in terms of all leaf attributes and RGR. The response of species varied across sites and seasons. The attributes were positively interrelated, except for WUEi, which was negatively related to all other attributes. The positive correlation was strongest between Gsmass and Amass and the negative correlation was strongest between Gsmass and WUEi. Differences in RGR due to site were not significant when soil moisture was controlled, but differences due to season remained significant. The attributes showed plasticity across moisture gradients, which differed among attributes and species. Gsmass was the most plastic attribute. Among the six species, Terminalia tomentosa exhibited the greatest plasticity in six functional attributes. In the step‐wise multiple regression, Amass, SLA and Chl among leaf attributes and SMC among environmental factors influenced the RGR of tree species. Path analysis indicated the importance of SLA, LNC, Chl and Amass in determining RGR. Conclusion: A mass, SMC, SLA and Chl in combination can be used to predict RGR but could explain only three‐quarters of the variability in RGR, indicating that other traits/factors, not studied here, are also important in modulating growth of tropical trees. RGR of tree species in the dry tropical environment is determined by soil moisture, whereas the response of mature trees of different species is modulated by alterations in key functional attributes such as SLA, LNC and Chl.  相似文献   

10.
陈静  庄立会  沐建华  周建松 《生态学报》2020,40(11):3706-3714
植物叶脉特征和叶氮含量的变化影响着叶片经济谱的形成,为验证叶片结构中叶脉网络构建提供了理论依据。该文以单位质量叶氮含量(N_(mass))和单位面积叶氮含量(N_(area))分别表示叶氮含量,采取主成分分析、线性回归分析的方法,研究了云南文山石漠化区旷地(Ⅰ)、林缘(Ⅱ)和林下(Ⅲ)3种自然生境下车桑子的叶脉密度(Vein density,VD)与N_(mass)和N_(area)的异速关系。结果表明:从乔灌群落的旷地到林下,车桑子的比叶面积、叶绿素总含量、光能利用率和N_(mass)逐渐增大,光饱和点、光补偿点、水分利用效率、VD、N_(area)逐渐减小,净光合速率、蒸腾速率、气孔导度呈先增大后减小的趋势。VD与叶氮含量呈不同程度的相关性,在生境I和III,VD与N_(mass)和N_(area)分别具有显著的负相关(P0.05)和正相关(P0.05);在生境Ⅱ,VD与N_(mass)和N_(area)分别呈不显著负相关(P0.05)和正相关(P0.05)。车桑子在旷地强光生境,高VD的叶片含有低N_(mass)高N_(area),而林下荫蔽生境偏向于相反的配置模式,反映了石漠化区植物较强的叶脉可塑性及其与氮利用性状的权衡机制。  相似文献   

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