中药射干的化学成分研究

本学位论文由4章组成。第一章是论文的主体，报道了中药射干的化学成分研究。第二章是中药射干代用品川射干的化学成分研究，并附带报道了西番莲化学成分的研究结果。第三章是射干、川射干及西番莲提取物化学成分串联质谱分析的报道。第四章为综述，概述了射干及鸢尾属植物的化学成分和药理研究进展。 在第一和二章中分别报道了射干（Belamcanda chinensis (L.) DC.）、川射干 （Iris tectorum Maxim.）及西番莲（Passiflora incarnate L.）化学成分的分离纯化与结构鉴定。采用正、反相硅胶柱层析、凝胶柱层析、薄层制备及HPLC等各种分离方法，从三种药用植物中共分离出68个不同的化合物，其中61个的结构得 得以鉴定，另外4个化合物的结构正在鉴定中，3个由于量少且有点杂质未作进一步的鉴定。 中药射干（Rhizoma Belamcandae）为射干植物的干燥根茎，从中共分离出53个化合物，通过红外、质谱及核磁共振等波谱方法鉴定了包括12个新化合物在内的48个，结构类型分别属于iridal型三萜及其新颖的二聚体、异黄酮、黄酮及黄酮醇、香豆素、甾体、芳香酸和脂肪酸及其甘油酯等。新化合物中有两个异黄酮类化合物，其结构分别鉴定为5,7,8,4′-四羟基-6-甲氧基异黄酮和5,6-二羟基-4′-甲氧基异黄酮-7-O-β-D-吡喃葡萄糖苷；八个新的iridal型三萜化合物分别鉴定为鸢尾烯（L）、16-甲氧基鸢尾烯、16-去羟基鸢尾烯、2-(E)-16-去羟基鸢尾烯、16-去羟基鸢尾烯B、3-乙酰基-16-去羟基鸢尾烯、iristectoroneL和iristectoroneM；两个结构骨架新颖的双三萜，分别命名为射干素A和射干素B，其分离纯化的困难以及结构的新颖和复杂突显出该论文的科学意义。除这些新化合物外，还有9个已知化合物为首次从中药射干中分离得到。此外，从中药射干的代用品川射干中分离得到7个已知化合物，主要是黄酮类成分及iridal型三萜化合物，其中1个三萜化合物为从射干中分离鉴定的新成分。另外还从西番莲中分离出8个化合物，鉴定了其中的6个，主要为黄酮碳苷。 第三章是关于射干、川射干及西番莲提取物化学成分的ESI-MS-MS分析，在初步探讨了从这些植物中分离鉴定出的一些异黄酮及黄酮碳苷的质谱裂解规律基础上，通过质谱和串联质谱分析，定性和半定量地检测了射干和川射干中主要的异黄酮成分以及西番莲中的黄酮碳苷成分，为这些药材品质的快速鉴定提供了一种简便方法。 第四章概述了射干及鸢尾属药用植物的化学和药理研究进展，特别是对其中异黄酮及三萜类成分的研究进展进行了深入系统的综述。 This dissertation is composed by four chapters. The first and second chapter reports the phytochemical investigation of three medicine plants, Belamcanda chinensis (L.)DC., Iris tectorum Maxim. and Passiflora incarnate L. Sixty eight different compounds were isolated and sixty one of them were identified. The third chapter described rapid ESI-MS-MS analysis of B. chinensis, I. tectorum, and P. incarnate. The forth part is a review about the progress of studies on the chemical constituents from Belamcanda chinensis and Iris species. Fifty-three compounds were isolated from Rhizoma Belamcandae, the rhizomes of B. chinensis by the methods of column chromatography (normal and reversed phase silica gel, Sephadex LH-20), preparative TLC and HPLC. On the basis of spectroscopic methods including IR, ESI-MS, 1-D and 2-D NMR, forty eight of them were identified as seventeen flavonoids, seventeen tritepenoids, one cumarin, five steroids and some benzene derivative etc. Among them, the structures of twelve new compounds were elucidated as 6-methoxy-5,7,8,4′-tetrahydryoxyisoflavoe, 4′-methoxy-5,6-dihydroxyisoflavone-7-O-β-D-glucopyranoside, iristectorene L, 16-methoxyisoiridogermanal, 16-dehydroxyisoiridogermanal, 2-(E)-16-dehydroxy isoiridogermanal, 16-dehydroxyiristectorene B, 3-acetyl-16-dehydroxyisoiridoger- manal, iristectorone L, iristectorone M, belamcandene A and belamcandene B. Last two new compounds are dimer of triterpenoids with a novel carbon skeleton. Beside the new compounds, nine known ones were isolated from this plant for the first time. Isolation of I. tectorum yielded seven compounds. On the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples, three of them were determined as isoflavone, two of them were triterpenoids, and other two were β-sitosterol and apocynin. All of them are known compounds except one of iridal type triterpenoid, 16-dehydroxyiristectorene B, which also obtained from B. chinensis as a new compound. Isolation of P. incarnate yielded eight compounds. Six of them were determined on the basis of spectroscopic methods including ESI-MS, NMR and the comparison with authentic samples. Four of them are flavone-C-gluconside, and two are steroids. The third chapter describes the tandem mass spectrometry (ESI-MS-MS) analysis of the isoflavonoids from B. chinensis and I. tectorum, as well as C-glycosyl-flavonoide from P. incarnate, in order to explore the rapid methodology of validating the quality of the herbs. In addition, the fractionation rules of some iosflavonoids and C-glycosyl-flavonoids were discussed. The fourth chapter summarizes the research development on chemistry and pharmacology of medicine plants of B.chinensis and Iris species.

环境CO2浓度和群落密度对红桦(Betula albosinensis Burk.)幼苗碳氮吸收和分配的影响

当前大气CO2浓度升高是全球变化的主要趋势之一，CO2浓度升高还会引起全球变暖等其它环境问题，因而CO2浓度浓度升高对植物影响的研究已经成为全球变化领域的焦点。红桦是川西亚高山地区暗针叶林演替初期的先锋树种和演替后期的建群种，在群落演替过程中它对环境因子的响应决定红桦群落的演替进程。本文通过控制CO2浓度的气候室试验，研究了CO2浓度倍增环境下，不同密度水平红桦碳氮固定、分配可能发生的改变，并探讨了升高大气CO2浓度对群体内部竞争的影响。以期通过本研究明确川西亚高山地区代表性物种红桦对未来气候变化的响应，为今后采取措施应对气候变化、妥善进行森林管理提供理论依据和科学指导。主要研究结果如下： 1.升高CO2浓度对红桦幼苗生长的影响以及树皮、树干响应的不同 (1) CO2浓度升高显著促进红桦幼苗的生物量、株高、基茎的生长，同时也改变生物量在体内的分配格局，主要是增加根和主茎、减少叶在总生物量中的比重。(2)树皮和树干对升高CO2浓度的影响有差异，它们对CO2浓度升高的反应程度不同，但反应方向一致。 2.密度的副效应 (1) 增加种植密度对单株生物量、株高和基径的生长具有副效应，也降低升高CO2浓度对红桦生长的正效应。(2) 增加种植密度，显著增加红桦幼苗的群体生物量，从而使红桦群体固定更多的大气CO2气体。可见密度在决定红桦生物量及固碳能力方面具有重要意义。探索适合未来大气CO2浓度升高条件下植物生长的密度，对未来的森林经济生产、生态恢复具有重要意义。 3. 升高CO2浓度对红桦幼苗苗冠结构及冠层内部竞争的影响 (1) 冠幅、冠高、苗冠表面积和苗冠体积等树冠特征均受CO2浓度升高的影响而增加，但是受密度增加的影响而降低。(2) 单位苗冠投影面积叶片数(LDcpa)和单位苗冠体积叶片数(LDcv)均低于相应的现行CO2浓度处理，这主要是由于冠幅和冠高的快速生长所造成的。(3) LDcpa和LDcv的降低表明，红桦在升高CO2浓度的条件下，会作出积极的响应，从而缓解由于群体和个体生长的增加所引起的竞争压力的增加。 4. 升高CO2浓度对红桦幼苗养分元素吸收与分配的影响 (1) CO2浓度升高，植株各器官N、P含量降低，但单株N、P总吸收量均增加。红桦幼苗体内N、P浓度的下降是由于生物量迅速增加引起的稀释效应造成的。(2) CO2浓度升高，N、P向主茎和根的分配增加，向叶片的分配减少，主要是由于前者在总生物量中的比重增加，而后者减少了。(3) CO2浓度升高，氮磷利用效率(NUE和PUE)提高，氮磷累积速率(NAcR和PAcR)显著增加。而NUE和PUE的提高可以有效缓解CO2浓度升高后，亚高山和高山地区森林土壤中养分元素不足对森林生产力的限制。 5. 升高CO2浓度对红桦幼苗群体碳平衡的影响 (1) 升高CO2浓度对植物的光合作用、呼吸速率和生长均具有促进作用。(2) 土壤有机碳含量在实验前期迅速增加，后期积累速率下降。(3) 升高CO2浓度以后，土壤呼吸显著增强；土壤呼吸还具有明显的季节变化。(4) 红桦群体日固碳量受到升高CO2浓度的促进作用。结果(1)-(4)说明所研究群落的碳动态对现行的气候波动是敏感的；所研究群落在作为大气CO2气体的源-汇关系方面至少存在季节间的源汇飘移。(5)种植密度的升高显著增加了群体固碳量。 6. 升高CO2浓度对红桦幼苗生长后期叶片衰老的影响 升高CO2浓度有利于减缓红桦幼苗叶片生长季节末期的衰老。生长季节末期，随着CO2浓度的升高光合速率和可溶性蛋白含量均呈上升趋势，同时MDA（丙二醛）含量下降，保护酶SOD（超氧化物岐化酶）、CAT（过氧化氢酶）活性升高。由此说明，升高CO2浓度有利于减缓生长季节后期叶片的衰老，使叶片维持较高的光合速率，也从生理学的角度支持了本文及前人有关CO2浓度升高促进植物光合和生长的假说及结果。 The increased CO2 concentration is one of the most important problems among global changes. The increase of CO2 will also cause other environmental problems, such as global warming, etc. So the effects of elevated CO2 on plant have drawn sights of many scientists in the research field of global change. Red birch (Betula albosinensis) usually emerges as the pioneer species in initial stage and as constructive species in later stages of forest community succession of the dark coniferous forests in Western Sichuan, China. It’s response to elevated CO2 may determine the succession process of the community where it lives in. By controlling CO2 at the ambient and twice as the ambient level (ambient + 350 umol mol-1) using enclosed-top chambers (ETC), possible effects of elevated CO2 on carbon fixation and allocation under two plantation densities are investigated. The effects of elevated CO2 on competition within canopy of red birch seedlings are also observed in the present paper. We hope to make sure of the effects of elevated CO2 on the representative species, red birch. And so that, our results could provide a strong theoretical evidence and scientific direction for forest management and afforestation under a future, CO2 elevated world. The results are as fowllows: 1. The effects of elevated CO2 on growth and the different responses of wood and bark of red birch seedlings (1) Elevated CO2 increases the growth of seedling biomass, seedling height and basal diameter of red birch. It also changed the biomass allocation in red birch seedlings. The ratio of root and main stem to all biomass is increased and the ratio of leaf is decreased. (2) Tree bark and wood show different response degree but similar response direction to elevated CO2. 2. Negative effects of planting density (1) The increase of planting density showes negative effects on the individual growth of seedling biomass, seedling height and basal diameter of red birch. It also eliminates the positive effects of elevated CO2 on growth of red birch seedlings. (2) Community biomass is increased by the elevated planting density, which means that the high density red birch community could fix more CO2 than the low density one. These results show that planting density plays an important role in determining biomass and carbon fixation ability of red birch community. Thus, exploring proper planting density becomes economically important for the future, CO2 elevated word. 3. The effects of elevated CO2 on crown architecture and competition within canopy of red birch seedlings (1) Crown width, crown depth, crown surface area and crown volume are all increased under the influence of elevated CO2. (2) Leaf number per unit area of projected crown area (LDcpa) and per unit volume of crown volume (LDcv) are lower under elevated CO2. This is resulted from the stimulated growth of tree crown features. (3) The decrease of LDcpa and LDcv indicate that plants will respond forwardly to reduce the possible increase of competition resulted from stimulated growth of individual plant and collectives in conditions of elevated CO2. 4. The effects of elevated CO2 on nutrition accumulation and allocation of red birch seedlings (1) Contents of N and P decrease due to the prompt increase of biomass of plant organs caused by elevated CO2. However, their accumulations increase under elevated CO2. (2) Elevated CO2 increases the allocation of N, P to main stem but reduced its allocation to leaf for that dry weight of the former increased but the dry weight of the later decreased. (3) Using efficiencies of N, P (NUE and PUE) and their accumulation rates (NAcR and PAcR) are found to increase under elevated CO2. Soil nutrition contents are always the limiting factors for plant growth at subalpine and alpine region. The increased NUE and PUE are helpful to eliminate the nutrition limitation in this area in the future world, when CO2 concentration doubles the ambient. 5. The effects of elevated CO2 on carbon balance of red birch communities (1) Net photosynthetic rates (Pn), dark respiration rates (Rd) and growth are all stimulated by elevated CO2. (2) Content soil organic carbon increases sharply at the primary stage of experiments and then the increasing rates decrease to a low level at later stages. (3) Soil respiration rates increase significantly with the elevation of CO2 concentration. (4) The daily carbon fixations of whole community are heightened by elevated CO2. The results (1)-(4) suggest that, the community being studied are sensitive to current climate change; the studied community, as a sink of atmospheric CO2, is pool-sink alternative between seasons. (5) The carbon fixations are increased along the increase of planting densities. 6. The effects of elevated CO2 on physiological features of leaf senescences of red birch seedlings at the later stage of growing season Elevated CO2 helps to postpone the leaf senescences of red birch at the end of the growth season. CO2 enrichment increases the photosynthetic rates, contents of soluble proteins and photosynthetic pigments. And meanwhile contents of malondialdehyde (MDA) decreases and activities of superoxide dismutase (SOD) and catalase (CAT) are both increased. These results suggest that the senescences of red birch leaves are delayed by elevated CO2, which keep the photosynthetic rates at relatively high levels. Our results lend supports to hypothesis and results on stimulated photosynthetic rates and growth from both other researchers and the present paper.

川西亚高山森林生态系统辐射传输研究

辐射传输研究是贯穿森林生态系统的纽带，太阳辐射为植物的生长发育提供光合能量、适宜的环境温度以及发育信息。一方面，气候变化使到达地面辐射能的质和量发生变化，影响到植被的生长发育，改变森林的结构，而森林结构的变化又会影响林冠内辐射能的分配和质量，这些变化会进一步影响到林下土壤温度，改变森林根系活性以及土壤营养转化的效率；连锁反应的结果有可能会使森林生态系统的生产力发生变化，改变碳素和氮素源库的调节方向，从而反馈影响地球气候系统。另一方面，人类作为生态系统的成员，必然需要森林生态系统为其提供更多的原材料和更好的生态服务功能，如何实现这些目标，就需要人类适度调整干预方式和频度，达到预期的目的。本文在建立适合于川西亚高山森林的叶面积测量技术、光照辐射模型和土壤温度变化模型的基础上，对川西亚高山地带森林生态系统的辐射传输特征进行了分析，并从森林结构的角度探讨了林分内的辐射分布以及对土壤温度的影响。主要成果如下： 1. 提出了一种照相法测量叶面积的方法。通过对摆放在平面上的叶片照相，利用投影变化，把非正射图像转化为正射图像，然后经过计算机图像处理得到每一片叶片的面积、周长、长度、宽度等信息。这种方法可使用户以任意方向和距离拍摄处于平面上的叶片，能同时处理大量的叶片，适于野外离体或活体叶片测量。叶片面积分辨率可调，分辨率可以与常用的激光叶面积仪相近甚至更高，而且叶片图像可以存档查询。 2. 提出一种模拟林内光照变化的模型。利用林冠半球照片，记录视点以上半球内的林冠构件空间分布，作为林冠子模型；天空辐射子模型采用国际照明委员会(CIE)的标准晴天和阴天以及插值模型。该模型能够模拟林下某一位点处的实时光斑变化。 3. 提出一种土壤温度变化模型。把土壤视为具有容量和阻力性质的结构，利用电阻和电容器件构建土壤能量分布模型。外界太阳辐射能经过植被以及其它一些能量分配器后进入土壤，其中有一部分转化为土壤势能，即土壤温度。土壤温度的变化类似于电池的充放电过程。在已知模型参数的情况下，可以从太阳辐射计算土壤温度的变化。在模型参数未知的情况下，通过输入和输出值推算模型的参数，而模型参数中的时间常数与土壤组成和含水量有关，这样就可以知道土壤水分的变化情况。 4. 从王朗亚高山森林典型样地林分结构的测量获得林地三维结构图、树冠形态、叶面积密度等参数，这些参数输入到Brunner (1998)开发的tRAYci 模型中计算出一段时间内林分任意位置处的光照值。与林下辐射计测量值以及半球照片计算结果的比较，该模型基本上能够满足对林分光环境了解的要求。 5. 从川西亚高山森林生产力的角度，探讨了森林生产力研究的方法以及川西地区的研究历史和成果，发现了其中的一些规律和问题，特别是在叶面积测量上，还没有使用标准的叶面积指数定义。综合来看，川西地区针叶林叶面积指数(单位土地面积上植物冠层总叶面积的一半) 应在4-5 之间。降雨丰富的华西雨屏带是川西地区森林生产力最高的地区，而向西北森林生产力逐渐降低。川西地区云冷杉林森林生产力平均约为600 gDM m-2 a-1，但是根据辐射能计算的潜在生产力则达到1800 gDM m-2 a-1。实际与潜在森林生产力的巨大差异说明其它因子对生产力的影响。 6. 王朗亚高山3 个典型森林林分中，白桦林样地(BF) 林下草本以糙野青茅、牛至、紫菀等喜阳性物种为主，林下透光度较高；冷杉林样地(FF) 林下透光度最低，以喜阴性物种水金凤、蟹甲草、囊瓣芹等为主；而云杉林样地(SF)林分林龄最大，林下透光度介于冷杉林和白桦林之间，草本层仍然以喜阴性物种东方草莓、紫花碎米芥、酢浆草等为主。冷杉林和云杉林的灌木层也很丰富，卫矛属、五加属、茶藨子属、忍冬属植物很丰富，而在白桦林则以栒摘要子属、榛子属、鹅耳枥属等植物为主。藓类植物在云杉林中最丰富，并且形成毯状层，其它两个林分则很稀少。3 个样地林分结构与林下光环境有很强的相关性，从光环境特征可以在一定程度上推测林分的结构。各样地单纯从乔木层材积推算的NPP 排列顺序为BF>FF>SF，与林下辐射透射率和林分年龄的顺序相同，暗示辐射对群落演替过程的驱动作用。 7. 用半球照相法测得BF、FF 和SF 3 个样地的有效叶面积指数以SF 样地最高，BF 最低。如果考虑针叶树叶片在小枝上的丛聚分布，利用北方针叶林的数值进行校正，则SF 样地LAI 显著增加(达到89%)，其它样地的LAI 基本不变甚至有所下降。校正后的数值与文献中地面测量的结果较相近，说明在使用半球照相法测量川西亚高山针叶林LAI 时必须加以校正。 8. 在3 个样地中，白桦、岷江冷杉和方枝柏种群为丛聚分布，紫果云杉在FF和SF 样地中基本上为随机分布。3 个物种出现丛聚分布的最短距离约为2m，在最短距离以内则为随机分布。最短距离可能与树冠大小有关，种子传播特征以及对光照的需求状况可能是造成这种分布格局类型的原因。 Radiative transfer plays a key role in forest ecosystems. Solar radiation providesenergy for photosynthesis, appropriate ambient temperature and development informationfor plants. However, quality and quantity of radiation reaching land surface are affected byweather and subsequently influence the growth and development of plants, which in turnchanges the budget of radiation in forest. Soil temperature changes with the variation ofradiation under forest canopy and influences the activity of roots and rate of nutrientturnover. Thus, any changes of radiation will induce chain reactions in the entireecosystem and display in the value of net primary productivity which will possibly shiftthe relationship between carbon source and sink at local or regional scale and feed back tothe global climate system. On the other hand, as a component of ecosystems, humanbeings of course need to demand more materials and better service from ecosystems. Forthese purpose, man must adapt their pattern and frequency of interference to ecosystems.This paper aims to research on the canopy structure, the radiation distribution and theirinfluence on soil temperature from the process of radiative transfer in subalpine forestecosystem of western Sichuan. The main results are: 1 Present a new photogrammetric method for leaf area. The main idea is to convertnon-vertically taken images of planar leaves to orthoimages through projectivetransformation. The resultant images are used to get leaf morphological parametersthrough image processing. This method enables users to take photos at almost anyorientation and distance if only the leaves are placed on same plane, and to processlarge quantity of leaves in a short time, which is suitable for field measurement. Theresolution of leaf area is adjustable to fit for special requirement. 2 A model using hemispherical photos combining with solar tracks and radiation courseis provided to simulate light variation in forest. The hemispherical photos of canopyrecord the real spatial distribution of each element of plants viewed from a point. Skyradiance is simulated with CIE standard clear sky or cloudy sky model. This modelcan be used to simulate real time light variation under canopy. 3 Present a soil temperature model. Soil could be regarded as a body of resistor andcapacitor. Some of the budget of solar radiation in soil body is transformed into soilpotential energy, the soil temperature. Variation of soil temperature is driven by solarradiation, vegetation, soil properties, etc. This model has two parameters, one of whichis time constant and is related to soil water content. The inversed model can be used tosimulate the variation of soil water. 4 By using model tRAYci developed by Brunner (1998), the 3-D distribution of light inthree subalpine forest stands of Wanglang Nature Reserve has been simulated andvalidated with value of radiometers in these stands. This model can basically satisfythe need for understanding light regimes of these stands. 5 Present some principles and questions of NPP (net primary of productivity) researchesin western Sichuan. The standard leaf area index (LAI) defined by Chen and Black(1997) has not been used in this region. Total leaf area and projected leaf area indexare still used in NPP researches which may differ around 1-fold in magnitude. Thestandard LAI which is a half of total leaf area above unit land area should be between4 and 5 for typical subalpine coniferous forest of western Sichuan concluded fromliteratures. The maximum forest NPP occurs in West China rain belt and decreasesnorthwestwards. Average NPP of spruce-fir forest in western Sichuan is about600gDM m-2 a-1, which is below the potential NPP of 1800gDM m-2 a-1 based onmeasured radiation in this region. The significant difference between potential and realNPP suggests that other factors influence the growth of stands. 6 In the three subalpine forest stands of Wanglang Nature Reserve, herbage layer ofAbstractbirch stand (BF) with age of 40 is dominated by heliophytes of Deyeuxia scabrescens,Origanum vulgare, Aster tongoloa etc.. However, both of the other two stands aredominated by shade tolerent species, such as Impatiens noli-tangere, Impatiensdicentra, Cacalia deltophylla and Pternopetalum tanakae etc. in fir stand (FF) withage of 180 and Fragaria orientalis, Cardamine tangutorum and Oxalis corniculata etc.in spruce stand (SF) with age of 330. Shrub species in the latter two stands arerelatively rich, typical dominant genera being Euonymus, Acanthopanax, Ribes andLonicera. Birch stand has relatively sparse shrubs dominated by genera of Cotoneaster,Corylus and Carpinus. Mosses are significant only in spruce stand. The canopystructure controls the light regime of stand, which influence the composition of herblayers beneath the canopy. This light regime-community structure relationship can beused to infer the herb community from canopy structure. The NPP derived from timbervolume of arbor layer of the three stands decreases from BF to SF, which is in thesame order of transmitted total radiation under canopy and age of these stands,suggesting the driving effect of radiation in the succession of community. 7 The highest effective LAI of the three stands obtained by hemispherical photos is inplot SF and lowest in plot BF. After rectification of the clumping effect of leaves onshoot, the real LAI in plot SF increases significantly (89%) and approximate to theaverage LAI of coniferous forest in western Sichuan. Therefore, the LAI obtainedfrom hemispherical photos needs rectification for clumping effect. 8 Spatial distribution pattern for Betula platyphylla, Abies faxoniana and Sabinasaltuaria is clumpy, but Picea purpurea almost random in plot FF and SF. The shortestdistance for clumpy distribution for Betula platyphylla and Sabina saltuaria is 1.5m,and 2m for Abies faxoniana. And random pattern for these trees is exhibited within thisrange which almost coincides with the diameter of crown. Seed dispersalcharacteristics and light requirement may be the reason for different spatial pattern.

增温对川西亚高山针叶林不同光环境下几种幼苗生长的影响

由于人类活动所引起的地球大气层中温室气体的富集已导致全球地表平均温度在20 世纪升高了0.6 ¡æ，并预测在本世纪将上升1.4-5.8 ¡æ。气候变暖对陆地植物和生态系统产生深远影响，并已成为全球变化研究的重要议题。位于青藏高原东部的川西亚高山针叶林是研究气候变暖对陆地生态系统影响的重要森林类型。森林采伐迹地和人工云杉林下作为目前该区人工造林和森林更新的两种重要生境，二者截然不同的光环境对亚高山针叶林不同物种更新及森林动态有非常重要的影响。 本文以青藏高原东部亚高山针叶林几种主要森林树种为研究对象，采用开顶式增温法（OTCs）模拟气候变暖来研究增温对生长在两种不同光环境下（全光条件和林下低光环境）的几种幼苗早期生长和生理的影响，旨在从更新角度探讨亚高山针叶林生态系统不同树种对气候变暖在形态或生理上的响应差异，其研究结果可在一定程度上为预测气候变暖对亚高山针叶林物种组成和演替动态提供科学依据，同时也可为未来林业生产管理者提供科学指导。 1、与框外对照相比，OTCs 框内微环境发生了一些变化。OTCs 框内与框外对照气温年平均值分别为5.72 ¡æ和5.21 ¡æ，而地表温度年平均值分别为5.34 ¡æ和5.04 ¡æ，OTCs 使气温和地表年平均温度分别提高了0.51 ¡æ和0.34 ¡æ；OTCs框内空气湿度年平均值约高于框外对照，二者分别为90.4 %和85.3 %。 2、增温促进了三种幼苗生长和生物量的积累，但增温效果与幼苗种类及所处的光环境有关。无论在全光或林下低光条件下，增温条件下云杉幼苗株高、地径、分支数、总生物量及组分生物量（根、茎、叶重）都显著地增加；增温仅在全光条件下使红桦幼苗株高、地径、总生物量及组分生物量（根、茎、叶重）等参数显著地增加，而在林下低光条件下增温对幼苗生长和生物量积累的影响效果不明显；冷杉幼苗生长对增温的响应则与红桦幼苗相反，增温仅在林下低光条件下对冷杉幼苗生长和形态的影响才有明显的促进作用。 增温对三种幼苗的生物量分配模式产生了不同的影响，并且这种影响也与幼苗所处的光环境有关。无论在全光或林下低光环境下，增温都促使云杉幼苗将更多的生物量分配到植物地下部分，从而导致幼苗在增温条件下有更高的R/S 比；增温仅在林下低光条件下促使冷杉幼苗将更多的生物量投入到植物叶部，从而使幼苗R/S 比显著地降低；增温在全光条件下对红桦幼苗生物量分配的影响趋势与冷杉幼苗在低光条件下相似，即增温在全光条件下促使红桦幼苗分配更多的生物量到植物同化部分—叶部。 3、增温对亚高山针叶林生态系统中三种幼苗气体交换和生理表现的影响总体表现为正效应（Positive），即增温促进了几种幼苗的生理活动及其表现：（i）无论在全光或林下低光环境下，增温使三种幼苗的光合色素含量都有所增加；（ii）增温在一定程度上提高了三种使幼苗的PSII 光系统效率（Fv/Fm），从而使幼苗具有更强的光合电子传递活性；增温在一定程度使三种幼苗潜在的热耗散能力（NPQ）都有所增强，从而提高幼苗防御光氧化的能力；（iii）从研究结果来看，增温通过增加光合色素含量和表观量子效率等参数而促进幼苗的光合作用过程。总体来说增温对幼苗生理过程的影响效果与幼苗种类及所处的光环境有关，增温仅在全光条件下对红桦幼苗光合过程的影响才有明显的效果，而冷杉幼苗则相反，增温仅在低光条件下才对幼苗的生理过程有显著的影响。 4、增温对三种幼苗的抗氧化酶系统产生了一定的影响。从总体来说，增温使几种幼苗活性氧含量及膜脂过氧化作用降低，从而在一定程度上减轻了该区低温对植物生长的消极影响；增温倾向表明使三种幼苗体内抗氧化酶活性和非酶促作用有所提高，从而有利于维持活性氧代谢平衡。但增温影响效果与幼苗种类所处的光环境及抗氧化酶种类有关，增温对冷杉幼苗抗氧化酶活性的影响仅在林下低光环境下效果明显，而对红桦幼苗抗氧化酶活性的影响仅在全光条件下才有明显的效果。 总之，增温促进了亚高山针叶林生态系统中三种幼苗的生长和生理表现，但幼苗生长和生理对增温的响应随植物种类及所处的光环境不同而变化，这种响应差可能异赋予了不同植物种类在未来气候变暖背景下面对不同环境条件时具有不同的适应力和竞争优势，从而对亚高山针叶林生态系统物种组成和森林动态产生潜在的影响。 Enrichment of atmospheric greenhouse gases resulted from human activities suchas fossil fuel burning and deforestation has increased global mean temperature by 0.6¡æ in the 20th century and is predicted to increase it by 1.4-5.8 ¡æ. The globalwarming will have profound, long-term impacts on terrestrial plants and ecosystems.The ecoologcial consequences arising from global warming have also become thevery important issuses of global change research. The subalpine coniferous forests inthe eastern Qinghai-Tibet Plateau provide a natural laboratory for the studying theeffects of climate warming on terrestrial ecosystems. The light environment differssignificantly between clear-outs and spruce plantations, which is particularlyimportant for plant regeneration and forest dynamics in the subalpine coniferous forests. In this paper, the short-term effects of two levels of air temperature (ambient andwarmed) and light (full light and ca. 10% of full light regimes) on the early growthand physiology of Picea asperata, Abies faxoniana and Betula albo-sinensis seedlingswas determined using open-top chambers (OTCs). The aim of the present study wasto understand the differences between tree species in their responses to experimentalwarming from the perspective of regeneration. Our results could provide insights intothe effects of climate warming on community composition and regeneration behavior for the subalpine coniferous forest ecosystem processes, and provide scientificdirection for the production and management under future climate change. 1. The OTCs manipulation slightly altered thermal conditions during the growingseason compared with the outside chambers. The annual mean air temperature andsoil surface temperature was 5.72 and 5.34 ¡æ (within the chambers), and 5.21 and5.04 ¡æ (outside the chambers), respectively. The OTCs manipulation increased airtemperature and soil surface temperature by 0.51 and 0.34 ¡æ on average, respectively.Air relative humidity was slightly higher inside the OTCs compared with the controlplots, with 90.4 and 85.3 %, respectively. 2. Warming generally stimulated the growth and biomass accumulation of thethree tree species, but the effects of warming on growth and development variedbetween light conditions and species. Irrespective of light regimes, warmingsignificantly increased plant height, root collar diameter, total biomass, componentbiomass (stem, foliar and root biomass) and the number of branches in P. asperataseedlings; For A. faxoniana seedlings, significant effects of warming on all the tested parameters (plant height, root collar diameter, total biomass, and component biomass) were found only under low light conditions; In contrast, the growth responses of B.albo-sinensis seedlings to warming were found only under full light conditions. Warming had pronounced effects on the pattern of carbon allocation. Irrespectiveof light regimes, the P. asperata seedlings allocated relatively more biomass to rootsin responses to warming, which led to a higher R/S. Significant effects of warming onbiomass allocation were only found for the A. faxoniana seedlings grown under lowlight conditions, with significantly increased in leaf mass ratio (LMR) and decreasedin R/S in responses to warming manipulation. The carbon allocation responses of B.albo-sinensis seedling to warming under full light conditions were similar with theresponse of A. faxoniana seedlings grown under low light conditions. Warmingsignificantly decreased root mass ratio (RMR), and increased leaf mass ratio (LMR)and shoot/root biomass ratio (S/R) for the B. albo-sinensis seedlings grown under full light conditions. 3. Warming generally had a beneficial effect on physiological processes of dominant tree species in subalpine coniferous forest ecosystems: (i) Warming markedincreased the concentrations of photosynthetic pigments in both tree species, but theeffects of warming on photosynthetic pigments were greater under low lightconditions than under full light conditions for the two conifers; (ii) Warming tended toenhance the efficiency of PSII in terms of increase in Fv/Fm, which was related tohigher chloroplast electron transport activity; and enhance non-radiative energydissipation in terms of in increase in NPQ, which may reflect an increased capacity inpreventing photooxidation; (iii) Warming may enhance photosynthesis and advancephysiological activity in plants by increasing photosynthetic pigment concentration,the efficiency of PSII and apparent quantum yield (Φ) etc. From the results, theeffects of warming on seedlings’ physiological performance varied between lightenvironment and species. The effects of warming on photosynthesis performance of B.albo-sinesis seedlings were pronounced only under full light conditions, while thephysiological responses of A. faxoniana seedlings to warming were found only underthe 60-year plantation. These results provided further support for the observationsabove on growth responses of seedlings to warming. 4. Warming had marked effects on antioxidative systems of the three seedlings.Warming generally decreased H2O2 accumulation and the rate of O2- production, andalleviated degree of lipid peroxidation in terms of decreased MDA content, whichalleviated to some extent the negative effects of low temperature on the plant growthand development in this region; Warming tended to increase the activities ofantioxidative enzymes and stimulate the role of non-enzymatic AOS scavenging,which helped to create an balance in maintaining AOS metabolites for the threeseedlings. Nevertheless, the effects of warming on antioxidative defense systems werepronounced only under the 60-year plantation for the A. faxoniana seedlings. Incontrast, the marked effects of warming on antioxidative defense systems for the B.albo-sinesis seedlings were found only under the full light conditions. In sum, warming is considered to be generally positive in terms of growth andphysiological process. However, the responses of growth and physiology performanceto warming manipulation varied between species and light regimes. Competitive and adaptive relationships between tree species may be altered as a result of responsedifferences to warming manipulation, which is one mechanism by which globalwarming will alter species composition and forest dynamics of subalpine coniferousforest ecosystems under future climate change.

delta C-13 variation of C-3 and C-4 plants across an Asian monsoon rainfall gradient in arid northwestern China

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