Interactions of three dual-dressing effects of four-wave mixing in a five-level atomic system

We study the four-wave mixing (FWM) in an opening five-level system with two dressing fields. There are three kinds of doubly dressing mechanisms (parallel cascade, sequential cascade, and nested cascade) in the system for doubly dressed four-wave mixing. These mechanisms reflect different correlations between two dressing fields and different effects of two dressing fields to the FWM. Investigation of these mechanisms is helpful to understand the generated high-order nonlinear optical signal dressed by multi-fields.

Fast calculation technique for scattering in T-matrix method

In scattering calculations using the T-matrix method, the calculation of the T-matrix involves multiplication and inversion of matrices. These two types of matrix operations are time-consuming, especially for the matrices with large size. Petrov et al. [D. Petrov, Y. Shkuratov, G. Videen, Opt. Lett. 32 (2007) 1168] proposed an optimized matrix inversion technique, which suggests the inversion of two matrices, each of which contains half the number of rows. This technique reduces time-consumption significantly. On the basis of this approach, we propose another fast calculation technique for scattering in the T-matrix method, which obtains the scattered fields through carrying out only the operations between matrices and the incident field coefficient. Numerical results show that this technique can decrease time-consumption by more than half that of the optimized matrix inversion technique by Petrov et al. (c) 2008 Elsevier B.V. All rights reserved.

A fast-settling frequency-presetting PLL frequency synthesizer with process variation compensation and spur reduction

This paper proposes a fast-settling frequency-presetting PLL frequency synthesizer. A mixed-signal VCO and a digital processor are developed to accurately preset the frequency of VCO and greatly reduce the settling time. An auxiliary tuning loop is introduced in order to reduce reference spur caused by leakage current. The digital processor can automatically compensate presetting frequency variation with process and temperature, and control the operation of the auxiliary tuning loop. A 1.2 GHz integer-N synthesizer with 1 MHz reference input Was implemented in a 0.18μm process. The measured results demonstrate that the typical settling time of the synthesizer is less than 3μs,and the phase noise is -108 dBc/Hz@1MHz.The reference spur is -52 dBc.

SOI thermo-optic modulator with fast response

Silicon-on-insulator (SOI) technology offers tremendous potential for integration of optoelectronic functionson a silicon wafer. In this letter, a 1 * 1 multimode interference (MMI) Mach-Zender interferometer(MZI) thermo-optic modulator fabricated by wet-etching method is demonstrated. The modulator has anextinction ratio of -11.0 dB, extra loss of -4.9 dB and power consumption of 420 mW. The response timeis less than 30μs.

Stable mode-locking in an Yb:YAG laser with a fast SESAM

Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.

Splitting the Fast and Slow Motions in Molecular Dynamics Simulations Based on the Change of Cold Potential Well Bottom

The atomic motion is coupled by the fast and slow components due to the high frequency vibration of atoms and the low frequency deformation of atomic lattice, respectively. A two-step approximate method was presented to determine the atomic slow motion. The first step is based on the change of the location of the cold potential well bottom and the second step is based on the average of the appropriate slow velocities of the surrounding atoms. The simple tensions of one-dimensional atoms and two-dimensional atoms were performed with the full molecular dynamics simulations. The conjugate gradient method was employed to determine the corresponding location of cold potential well bottom. Results show that our two-step approximate method is appropriate to determine the atomic slow motion under the low strain rate loading. This splitting method may be helpful to develop more efficient molecular modeling methods and simulations pertinent to realistic loading conditions of materials.

Fast plasma sintering deposition of nano-structured silicon carbide coatings

Fast plasma sintering deposition of SiC nano-structured coatings was achieved using a specially designed non-transferred dc plasma torch operated at reduced pressure. Employing the Taguchi method, the deposition parameters were optimized and verified. With the optimized combination of deposition parameters, homogeneous SiC coatings were deposited on relatively large area substrates of Φ50 mm and 50×50 mm with a deposition rate as high as 20 μm/min. Ablation test showed that such coatings can be used as oxidation resistance coatings in high temperature oxidizing environment.

两种银莲花属植物的化学成分研究

本学位论文由5 章组成。第1 章报道了两头尖中三萜皂苷类化合物的全扫描电喷雾多级质谱分析及银莲花素A 的电喷雾质谱裂解规律；第2 和3 章报道了两种银莲花属药用植物化学成分的研究结果；第4 章报道了银莲花素A 的化学结构修饰及其对一种蛋白酪氨酸磷酸酯酶（PTP-1B）的抑制活性；第5 章综述了电喷雾质谱在皂苷类化合物结构鉴定中的应用进展。 第1 章报道了运用全扫描电喷雾多级质谱对两头尖中三萜皂苷类化合物的快速定性检测，共检测出18 个准分子离子峰，根据多级质谱数据并结合文献报道，对其中的15 个准分子离子峰进行了归属，并区分了一些同分异构体；更有意思的是，发现了3 个未见文献报道的三萜皂苷类化合物。根据它们的多级质谱数据，对其结构分别进行了初步解析。本章同时对银莲花素A 特殊的质谱裂解途径通过衍生物制备及其质谱分析进行了确认。 第2 和3 章，分别报道了两头尖和打破碗花花中水溶性多糖苷的分离纯化和结构鉴定。采用D101 大孔树脂和反复硅胶柱层析等分离手段，从两头尖水溶性部分分离得到8 个三萜皂苷类化合物，通过红外、电喷雾质谱和核磁共振等现代谱学方法，并结合传统的化学手段鉴定了它们的结构，其中4 个化合物为新化合物，分别命名为多被银莲花皂苷19、多被银莲花皂苷20、多被银莲花皂苷21和多被银莲花皂苷22。从打破碗花花水溶性部位分离得到6 个三萜皂苷类化合物，通过现代谱学手段，并结合传统的化学方法对它们进行了鉴定，其中1 个为新化合物，命名为打破碗花花苷H。 第4 章报道了以银莲花素A 及其同系物为先导化合物，进行化学结构修饰并对修饰产物进行广泛的生物活性筛选，发现在银莲花素A 及其同系物的结构中引入一些酸性基团后，其生物活性发生了变化，一些修饰产物显示出很强的PTP-1B 抑制作用，提示这些化合物有可能用于治疗II 型糖尿病。 第5 章综述了电喷雾多级质谱用于皂苷类化合物结构鉴定的研究进展。 This dissertation composes of five chapters. The first chapter elaborates the detection and qualification of the triterpenoidal saponins in Anemone raddeana by positive and negative full scan ESI-MSn. This part also reports the special fragmentation pathway of Raddeanin A by ESI-MS/MS. The second and third chapters present the phytochemical investigation of two medicinal plants from Anemone. The fourth part dwells on the structure modification of Raddeanin A and their inhibitory activity against PTP-1B. The last part is a review on the progress in the application of ESI-MSn in the structure identification of saponins. The first chapter reports the application of full scan ESI-MSn for fast analysis of triterpenoid saponins in Anemone raddeana. Eighteen quasi- molecular ion peaks were detected in the positive full scan ESI-MS and fifteen of them were identified by analysis of their tandem mass spectral data in the negative ion mode. Several isomers were differentiated. More interesting, three unreported triterpenoid saponins in this medicinal plant were detected and their structures were deduced according to the dissociation pathway of the known triterpenoidal saponins. This chapter also confirms the special fragmentation pathway of Raddeanin A by its derivative and the mass spectral analysis. The second and third chapters expatiate on the isolation and identification of the chemical constituents from A. raddeana and A. hupehensis. Eight compounds were isolated from the roots and stems of A. raddeana by methanol extraction and repeated column chromatography (including D101 and silica gel), and their structures were determined on the basis of IR, ESI-MS, NMR and chemical methods (including acid hydrolysis and alkaline saponification). Among them, four are new triterpenoid saponins and named as Raddeanoside R19, Raddeanoside R20, Raddeanoside R21 and Raddeanoside R22. Six compounds were isolated from the whole plants of A. hupehensis by the same methods as above, and their structures were also determined with the same way. One of them was confirmed to be new triterpenoid saponins and named as hupehensis saponin H. In the fourth chapter, in order to look for new active compounds, the structure of Raddeanin A and its analogs were modified. It was found that the modified products exhibited obvious inhibitory activity against PTP-1B when several acid groups were introduced. The fifth chapter summarizes the progress on the application of ESI-MSn in the structure identification of saponins.

基于RS和GIS的四川省土地利用/覆盖变化及可持续利用研究

LUCC是全球变化研究的核心主题之一，也是社会经济可持续发展的关键问题。改革开放后四川的社会经济发展非常快，在各种因素的驱动下，土地利用/覆盖发生了深刻变化。目前四川省缺乏基于实际调查数据的、全域性的、具有连续时间序列的LUCC和驱动力分析及土地可持续利用研究成果，这对我们从全局上把握全省土地利用现状、发展变化趋势，利用土地政策参与宏观调控，实现长期可持续发展目标，建设资源节约型、环境友好型社会极为不利。本研究针对这一问题，选取全川八大土地利用类型作为研究对象，研究了全省1996年到2006年的土地利用/覆盖格局和变化情况，分析了不同尺度的驱动因素，对全省农用地和建设用地的集约利用状况、潜力进行了分析评价，并提出相应的对策措施。 1．1996年-2006年10年来整个省域的土地利用/覆盖格局变化。 （1）1996年-2006年全省的土地利用/覆盖格局 1996年，全省是一个以农用地为主的土地利用/覆盖格局，林地和牧草地属于优势覆盖类型（合占69.17%），居民点及工矿用地和交通用地合占只有3%左右。 2000年的LUCC格局较为明显的特点是耕地所占比重下降0.4个百分点，水域和未利用土地所占比重有所下降，牧草地保持不变，其余地类所占比重有所上升。 与2000年相比，2004年林草地的优势格局进一步得到强化（合占比重达到70.23%）。耕地面积占幅员面积的比重下降0.83个百分点，略有下降的有未利用土地、水域和牧草地。值得关注的是在“退耕还林还草”的大背景下，牧草地占幅员面积的比重下降0.04个百分点。 到2006年，仍为林草地为主导优势的格局，二者合占上升0.15%。在城市化快速推进的背景下，居民点及工矿用地中的城市用地和建制镇用地占比重超过15%，农村居民点占比重降至76%。交通用地中农村道路占比重降至57.8%,公路用地占比重升至37.5%。五个地貌区的土地利用/覆盖格局与全省的变化基本一致。值得关注的是盆西平原区的交通用地上升幅度和盆地丘陵区的未利用土地的开发利用力度明显大于其它地貌区。 （2）1996-2006年10年间土地利用/覆盖格局的变化 1996-2000年4年间，耕地、水域和未利用地三个地类下降，年均减少0.75、0.19和0.32个百分点。其中耕地年均减少49229.0公顷，约一半流向林地，13.77%流向园地，约20%流向建设用地。另外5个地类面积增长，增长绝对量最大的是林地，年均增长40063.7公顷，交通用地增幅最大，4年年均增长达1.95%。 2001-2004年是西部大开发逐步推进、“退耕还林还草”项目全面展开和土地整理深入实施的关键期，LUCC更为深刻。耕地、未利用地、水域和牧草地四个地类面积下降，其余地类按增长幅度依次是园地、交通用地、居民点及工矿用地和林地。耕地加速下降，年均降幅达到1.59%，其减少去向主要是林地（占66.75%）和园地（占19.84%），其增加来源主要是未利用地、园地和水域。交通用地的增幅最大，为3.96%,其增加主要来源于耕地、未利用土地和林地，分别占49.96%、16.63%和13.09%。居民点及工矿用地增长幅度为3.12%。 从1996年到2006年的10年间，耕地、未利用地、水域和牧草地下降幅度分别为10.36%、3.61%、1.34%和0.26%。园地增幅达23.61%。绝对面积增长最大的则是林地，达630733.3公顷。交通用地和居民点及工矿用地增幅也较大，分别为15.00%和9.31%。 10年间年均总变化量为310326.6公顷，2000年-2004年之间变化最大（为356865.8公顷），高于平均变化量，而1996-2000年间和2004-2006年间都小于平均变化量。 （3）10年间不同地貌区的LUCC变化 盆西平原区的特点是园地大幅上升达77%，居民点及工矿用地和交通用地也大幅上升，耕地、未利用地下降幅度大，该区耕地、水域、未利用地的减少强度和园地、居民点及工矿用地、交通用地的上升强度均居五区第一；盆地丘陵区的特点是牧草地下降幅度大，为-36.89%,交通用地、园地和林地上升幅度较大，该区耕地减少、未利用地减少、林地增加、居民点及工矿用地和交通用地增加的变化强度均居五区相应地类增减的第二位；盆周山地区的特点是耕地减少较多，交通用地和园地增长较大，该区林地变化强度居各区第一位，牧草地和水域变化强度居各区第二位，耕地、居民点及工矿用地和未利用地居各区第三位；川西南山地区的特点是园地、耕地、交通用地和居民点及工矿用地变化幅度大，另外四个地类变化较小。该区减少的牧草地占全省牧草地减少的97.91%，变化强度居各个地貌区的第一位，园地相对变化强度居五区的第二位；川西北高山高原区的特点是耕地大幅下降、园地大幅上升，交通用地升幅也较大，其余地类变化不大。值得注意的是，该区牧草地和水域面积增加，与全省该地类的变化相反。其余地类的相对变化强度均是五个地貌区中最小的。 用变化强度分值考量变化强度，盆西平原区的变化强度最大，盆地丘陵区和盆周山地区的变化强度相当，川西北高山高原区的变化强度则要小得多。 （4）1996年及2006年全省土地利用/覆盖格局的景观生态学分析 全省是以自然景观占优势（占约70%）、农业景观为补充、建设用地景观居于从属地位的土地利用景观格局。景观多样性和均匀度不高。到2006年，全省总的景观格局并无大的改变。总体情况是随着时间的推移和人类活动的加强，区内景观优势度上升、多样性和均匀度变小。但斑块数减少，斑块面积和斑块孔隙度有所增大。斑块的形状指数和分维数均有所下降，表明受人为干扰有加剧的趋势。反映景观格局结构的破碎度指数有轻微下降。景观指数的变化表明全省土地利用有缓慢集中、规模聚集的趋势。 （5）三大生态建设工程对土地利用/覆盖变化的影响 1996-2006年间LUCC与三大生态建设工程实施的耦合分析，发现退耕工程对耕地、林地、牧草地等地类覆盖变化的影响最大，天保工程次之，长防工程最小。 2.四川省LUCC驱动力分析 （1）总体分析： 从整体上分析，人为因素对区域整体LUCC的影响从1996年的63.32%增加到2006年的66.99%，变得日益强烈。同时人为因素影响强度表现出明显的区域差异，地势平缓、经济区位条件好的区域其人为影响强度明显较高。 政策体制转变下的经济高速增长、快速的城市化、工业化过程和生态建设是四川省LUCC宏观尺度的驱动因素。区域的LUCC主要受到了由内向外(从城市到乡村)和由外向内(从山顶向平地)两种作用力的共同推动。局部尺度上，如距离交通线、水利线、中心城市的远近，地形凸起、大型独立项目落址、重污染项目的阻隔等，甚至一些乡规民俗等因素也会成为LUCC的驱动影响因素。在较小的尺度上,人类个体行为选择对LUCC的影响也是存在的。 　　根据驱动因子的特性作者将其划分为驱变、阻变、良性、惰性因子等类型。 （2）分地貌区的驱动因子分析 各地貌区都存在城市化、工业化、生态工程实施、自然灾害等驱动因子，但主次不一。对于盆西平原和盆地丘陵区，城市化、工业化是前两位的因子，而对另外三个地貌区，生态工程实施和产业结构调整则成为第第一、二位的驱动因子。 （3）分地类的驱动因子分析（以坡耕地为例） 分坡度的耕地变化分析发现，耕地减少主要集中在2°以下的平地、15°-25°和25°以上三个坡度级，是其它坡度级耕地减幅的三倍左右。这表明耕地减少受城市化进程和“退耕还林还草”工程驱动影响尤为巨大。 3.土地利用格局优化、集约利用评价和可持续利用及对策研究 （1）土地利用格局优化的战略选择及调整预测 土地利用格局调整的战略是农业生产用地、建设用地和生态及其他用地占幅员的比重分别稳定在13%、7%和80%左右，重点是三大类别内部二级和三级地类的合理调整。 （2）全省土地集约利用评价 全省农用地利用集约度为0.46，总体上集约度不高，处于较适度利用阶段。建设用地利用集约度为0.38，处于较适度利用阶段。集约利用提升空间较大。 农用地的潜力主要在于加强土地保育、完善利用制度、提高单产。城市建设用地的包括存量潜力、强度潜力、结构潜力，空间很大。农村居民点整理潜力可以逐步挖掘。 （3）新增建设用地集约利用的统筹安排 据测算，到2020年，四川省城市建设用地需求量在463850-492360hm2之间，城镇各业新增建设用地规模为361276.79hm2，占用耕地200565.94 hm2。2004-2020年间四川省农村居民点整理潜力33.86万hm2。农村居民点建设用地需求量为70.57万公顷。 （4）土地集约利用措施与坡耕地可持续利用战略 提出了土地集约利用的措施。在对坡耕地生态系统结构与功能分析的基础上，提出坡耕地可持续利用战略与生态恢复战略，并从技术和政策层面提出了坡耕地合理利用和生态退耕的措施和建议。 LUCC is one of the key questions of global change and sustainable development of society. After the opening and reform of China, the society and economy of Sichuan Province developed very fast ,the land-use/cover changed very strong droved by many factors .But nowadays we have no constant spatial-temporal study and driving force analysis about the whole province based on investigation. And it is lack of land sustainable utilization study based on correlative study. So we choose all the land resource in Sichuan, combine RS and GIS and field investigation, and take statistic-mathematic means and system analysis, to study the LUCC patterns and different scale driving force of different physiognomy regions, land cover types and periods; to analyze the current situation and potential of land resource intensive utilization, and gave out corresponding measurements. We found that forest and grassland are the dominant cover types of Sichuan provincial land –use/cover pattern, and becoming more and more stronger from 1996 to 2006,the natural landscape is the metric and occupy 70%,the diversity and evenness index are not high; the totally change quantity from 2000 to 2004 is the biggest; cultivated land especially steep cultivated land ,garden plot, forestry land ,settlement and industry land and traffic land changed relative stronger; among five physiognomy regions ,the changing intensity of PEN XI PING YUAN QU is the biggest, CHUAN XI BEI GAO SHAN GAO QU is smallest; under the background of policy system changing, the fast developing of economy, fast urbanization and industrialization and ecology construction are the macro-scale driving force of Sichuan provincial LUCC; to compare the impacts of “TUI GENG GONG CHENG” on LUCC especially to cultivated land ,forestry land and grassland is strongest, “TIAN BAO GONG CHENG ” is stronger,“ HANG FANG GONG CHENG” is smallest; the intensive utilization level of farmland and construction land of whole province is relative moderation, there is huge potential to excavate and fulfill the increasing demand of construction land；we must take synthetic measurements to accelerate the sustainable utilization of land resource, including administrative, economical ,technological and ecological policies.

中国卧龙自然保护区不同海拔川滇高山栎(Quercus aquifolioides)群体的遗传变异

海拔梯度造成的环境异质性，如崎岖的地形、复杂的植被结构以及花期延迟等可能会极大地影响到物种的形态和遗传变异格局。理解物种形态和遗传变异的海拔格局对于物种多样性的管理和保护是非常重要的。尽管植物群体遗传学是一个飞速发展的研究领域，然而与海拔相关的形态变异、遗传变异及群体间遗传差异的研究却很少。到目前为止，还不清楚遗传变异与海拔之间是否必然的相关性。 川滇高山栎是一种重要的生态和经济型树种，广泛分布于中国西南的四川、西藏、贵州和云南省的高海拔地区，在保持水土、调节气候方面起着十分重要的作用。尽管主要受阳光限制而仅分布于阳坡，但其海拔梯度范围较大，表明川滇高山栎对不同的环境具有很强的适应性。本文通过叶型及生理响应、微卫星分子标记和扩增性片段长度多态性方法，试图探索川滇高山栎叶沿海拔梯度的形态和生理响应及其沿海拔梯度的遗传变异格局，为川滇高山栎的保护和利用提供进一步的遗传学理论依据和技术指导。 对叶形、含氮量及碳同位素的试验结果表明，平均比叶面积、气孔密度、气孔长度和气孔指数等气孔参数随海拔的升高呈非线性变化。在海拔大于2800 m时，川滇高山栎的比叶面积、气孔长度和气孔指数都随海拔升高而降低，但是在海拔小于2800 m时，这些指标都随海拔的升高而增大。相对而言，单位叶面积的含氮量和碳同位素则表现出相反的变化模式。另外，比叶面积是决定碳同位素沿海拔梯度变化的最重要参数。本研究结果表明，海拔2800 m附近是川滇高山栎生长和发育的最适地带，在这里生长的植物叶片厚度更薄、气孔更大、叶碳同位素值更小。 利用六对微卫星引物对五个不同海拔川滇高山栎群体遗传多样性进行研究，结果表明，群体内表现出较高的遗传多样性，平均每位点等位基因数11.33个，平均期望杂合度达0.820。群体间差异较小，分化仅为6.6％。聚类分析也并没有显示出明显的海拔格局。然而低频率等位基因却与海拔呈显著性正相关(R2=0.97, P < 0.01)，表明在高海拔处，川滇高山栎以更多的稀有基因来适应恶劣的环境条件。本试验结果表明由海拔梯度形成的选择性压力对川滇高山栎群体的遗传变异影响并不明显。 为了进一步探讨川滇高山栎群体遗传变异与海拔之间的相互关系，我们还对其进行了扩增性片段长度多态性分析。结果表明：(1)随海拔的升高(从群体WL2到群体WL5)，群体内遗传变异降低，而群体间遗传差异增加；(2)低海拔群体WL1表现出最低的遗传变异性(HE = 0.181)，同时与其余四个群体间呈现出最大的遗传差异性(平均FST = 0.0596)；(3)在除去低海拔群体WL1后，Mantel检测表明群体间遗传距离与海拔距离之间表现出正相关性。另外，研究结果还表明，遗传变异受生境条件(过度的湿热环境)及人为干扰(火烧、砍伐和放牧)的影响，这一点至少在低海拔群体WL1上发生了作用。 通过叶形态、生理及DNA分子水平的研究，结果表明叶形态特征和碳同位素与海拔紧密相关，与海拔之间呈非线性变化，海拔2,800 m附近是川滇高山栎生长和发育的最适地带。海拔梯度在一定程度上会影响到川滇高山栎群体的遗传变异结构，但在这样一个狭窄的地理分布区域里，这种影响并不足以导致群体间较大的遗传分化。同时生境条件及人为干扰也是影响遗传变异的限制性因子，不容忽视。 Altitudinal gradients impose heterogeneous environmental conditions, such as rugged topography, a complex pattern of vegetation and flowering delay, and they likely furthermore markedly affect the morphological and genetic variation pattern of a species. Understanding altitudinal pattern of morphological and genetic variation at a species is important for the management and conservation of species diversity. Although plant population genetics is a fast growing field of research, there are only few recent investigations, which analyzed the genetic differentiation and changes of intra-population variation along altitudinal gradients. At present, it is still unclear whether there are some common patterns of morphological and genetic variation with altitude. Quercus aquifolioides Rehder & E.H. Wilson, which is an important ecological and economical endemic woody plant species, is widely distributed in the Yunnan and Sichuan provinces, Southwest China. Its large range of habitat across different altitudes implies strong adaptation to different environments, although it is mainly restricted to sunny, south facing slopes. It plays a very important role in preventing soil erosion, soil water loss and regulating climate, as well as in retaining ecological stability. In this paper, we tried to understand the altitudinal pattern of morphological and genetic variation along altitudinal gradients through the experiments of leaf morphological and physiological responses, microsatellite analysis and AFLP markers. In leaf morphological and physiological responses experiment, we measured leaf morphology, nitrogen content and carbon isotope composition (as an indicator of water use efficiency) of Q. aquifolioides along an altitudinal gradient. We found that these leaf morphological and physiological responses to altitudinal gradients were non-linear with increasing altitude. Specific leaf area, stomatal length and index increased with increasing altitude below 2,800 m, but decreased with increasing altitude above 2,800 m. In contrast, leaf nitrogen content per unit area and carbon isotope composition showed opposite change patterns. Specific leaf area seemed to be the most important parameter that determined the carbon isotope composition along the altitudinal gradient. Our results suggest that near 2,800 m in altitude could be the optimum zone for growth and development of Q. aquifolioides, and highlight the importance of the influence of altitude in research on plant physiological ecology. Genetic variation and differentiation were investigated among five natural populations of Q. aquifolioides occurring along an altitudinal gradient that varied from 2,000 to 3,600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (HE) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R2=0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (FIS=0.136) and a low level of differentiation among populations (FST=0.066). The result of the cluster analysis demonstrates that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation. To further elucidate genetic variation pattern of Q. aquifolioides populations under sub-alpine environments, genetic variation and differentiation were investigated along altitudinal gradients using AFLP markers. The altitudinal populations with an average altitude interval of 400 m, i.e. WL1, WL2, WL3, WL4 and WL5, correspond to the altitudes 2,000, 2,400, 2,800, 3,200 and 3,600 m, respectively. Our results were as follows: (i) decreasing genetic variation (ranging from 0.253 to 0.210) and increasing genetic differentiation with altitude were obtained from the WL2 to the WL5 population; (ii) the WL1 population showed the lowest genetic variation (HE = 0.181) and the highest genetic differentiation (average FST = 0.0596) with the other four populations; (iii) the positive correlation was obtained using Mantel tests between genetic and altitude distances except for the WL1 population. Our results suggest that altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides populations to some extent. In addition, habitat environments (unfavorable wet and hot conditions) and human disturbances (burning, grazing and felling) were possible influencing factors, especially to the low-altitude WL1 population. The present study shows that there were close correlations between morphological features and carbon isotope composition in our data. This indicates that a coordinated plant response modified these parameters simultaneously across different altitudes. Around 2,800 m altitude there seems to be an optimum zone for growth and development of Q. aquifolioides, as indicated by thinner leaves, larger stomata and more negative d13C values. All available evidence indicates altitudinal gradients may have influenced the genetic variation pattern of Q. aquifolioides to some extent. Decreasing genetic variation and increasing genetic differentiation with altitude was obtained except for the WL1 population. And the environment of habitats and human disturbances were also contributing factors, which impact genetic variation pattern, especially to the low-altitude WL1 population.