Model simulation output data (CCSM3) related to uplift of Africa and Himalaya/Tibet Plateau and the influence on tropical African vegetation

Hominid evolution in the late Miocene has long been hypothesized to be linked to the retreat of the tropical rainforest in Africa. One cause for the climatic and vegetation change often considered was uplift of Africa, but also uplift of the Himalaya and the Tibetan Plateau was suggested to have impacted rainfall distribution over Africa. Recent proxy data suggest that in East Africa open grassland habitats were available to the common ancestors of hominins and apes long before their divergence and do not find evidence for a closed rainforest in the late Miocene. We used the coupled global general circulation model CCSM3 including an interactively coupled dynamic vegetation module to investigate the impact of topography on African hydro-climate and vegetation. We performed sensitivity experiments altering elevations of the Himalaya and the Tibetan Plateau as well as of East and Southern Africa. The simulations confirm the dominant impact of African topography for climate and vegetation development of the African tropics. Only a weak influence of prescribed Asian uplift on African climate could be detected. The model simulations show that rainforest coverage of Central Africa is strongly determined by the presence of elevated African topography. In East Africa, despite wetter conditions with lowered African topography, the conditions were not favorable enough to maintain a closed rainforest. A discussion of the results with respect to other model studies indicates a minor importance of vegetation-atmosphere or ocean-atmosphere feedbacks and a large dependence of the simulated vegetation response on the land surface/vegetation model.

长花马先蒿的居群遗传变异与生物地理学

青藏高原地区是我国植物物种多样性和特有性最高的地区，且作为东亚植物区系的一个现代分化中心受世人瞩目。长花马先蒿是青藏高原高山草甸的广布种，其地理分布格局的形成与高原的隆升和气候变迁有着密切关系。因此，对长花马先蒿进行谱系生物地理学研究，有助于探讨青藏高原地区物种快速分化的机制和群体建立过程。 本研究对长花马先蒿11个居群、188个个体的叶绿体DNA trnT-trnF区进行了序列分析，发现该片段的长度变异范围为1441-1472bp。对位排列后的矩阵（含外类群）长1534bp，内类群中含33个碱基替换和 17 个插入/缺失,可分为20种单倍型。11个地理居群的总核苷酸多态性（π）为0.00468，单倍型多态性（Hd）为0.853，居群间的遗传变异（FST）高达88.2％，说明长花马先蒿具有很高的遗传多样性，且居群间发生了强烈遗传分化。 系统发育和遗传多样性分析发现长花马先蒿的20种叶绿体单倍型可归于四个地理单元——川西高海拔地区、川北地区、云南德钦地区及川藏地区。进一步分析发现：4个地理单元间存在着显著的遗传分化, 说明长花马先蒿具有明显的谱系地理分布格局。其中川西高海拔地区的四种主导单倍型构成了系统发育树最基部的一支，而以川西地区为中心、向南扩展至云南的两个居群所包含的几种单倍型均属于比较进化的类型。单倍型的网络关系(Network) 显示出西藏、青海、云南及四川北部的一些单倍型间遗传差异很小，亲缘关系很近。上述结果表明：长花马先蒿群体在冰期后的重新扩张过程主要表现为由南往北的递进式扩散，第四纪冰期气候的反复波动导致了该物种居群随生境变化而不断扩张或收缩,形成了现今的分布格局。初步推测川西地区很可能曾是长花马先蒿在第四纪冰期时的重要避难所，瓶颈效应和奠基者效应对其遗传多样性分布格局有重要影响。

苍山冷杉复合体的居群遗传变异与谱系地理学

青藏高原为冷杉属(Abies)的多度中心，共分布有10种，9变种和4亚种。其中苍山冷杉复合体(Abies delavayi complex)包括3种，5变种和2亚种。它们的形态性状变异较小，且分布区重叠。迄今对该复合体的遗传多样性水平、分化程度以及进化历史仍缺乏了解。 本研究对苍山冷杉复合体的14个居群、302个个体进行取样，并对193个个体的母系遗传线粒体DNA nad1 intron2区和276个个体的父系遗传的叶绿体DNA trnS-trnG区进行了序列分析。该复合体的线粒体DNA nad1 intron2区的序列为675bp，其中有4个单碱基变异和1个插入/缺失，可分为6种线粒体单倍型。这14个居群的线粒体总核苷酸多态性(π)为0.00114，单倍型多态性(Hd)为0.627，居群间的遗传变异(FST)高达84.034%。叶绿体DNA trnS-trnG区的序列排列后为718bp，共有8个单碱基变异和4个插入/缺失，可分为12种叶绿体单倍型。这14个居群的总核苷酸多态性(π)为0.00116，单倍型多态性(Hd)为0.590，居群间的遗传变异(FST)为65.830%。以上结果显示苍山冷杉复合体居群间已经产生了强烈的遗传分化。叶绿体的3种主导单倍型(H1、H2和 H3)在YLXS、SKXS、GS和WX 4个居群中都有分布;而其它居群则只有主导单倍型(除SJLS外)中的1种或2种。造成边缘居群(如JZS)多样性较低的主要原因是冰期后群体在迁移过程中的遗传漂变和奠基者效应。根据谱系关系线粒体H1型和叶绿体H3型均为较古老的单倍型，线粒体和叶绿体的谱系关系均支持上述分析。 本研究初步推测青藏高原的东南部—横断山区(包括YLXS、SKXS、GS、WX、BMXS、ELS和EMS)可能为苍山冷杉复合体的冰期避难所，群体存在冰期后向西和向南扩张的过程。间冰期群体隔离和扩张过程中的奠基者效应是形成目前居群分化和遗传多样性分布格局的重要因素。

青藏高原紫花针茅与青藏苔草的遗传多样性及克隆格

青藏高原是世界上最高的高原，被称为“地球第三极”，环境条件相当严酷。本研究通过ISSR标记的方法研究青藏高原两种相对克隆构型的克隆植物紫花针茅（Stipa purpurea Griseb.）和青藏苔草（Carex moorcroftii Falc. ex Boott）不同种群的遗传多样性及克隆格局，在分子水平上揭示两种植物对极端环境适应的机理。主要结果如下： 与其它针茅属植物相比，紫花针茅各种群平均遗传多样性相对较低，其遗传变异主要存在于种群之内;与其它苔草属植物相比，青藏苔草各种群平均遗传多样性也较低，而总的遗传多样性较高，其遗传变异主要存在于种群之间。紫花针茅各种群平均遗传多样性高于青藏苔草各种群平均遗传多样性，尽管差异不显著。紫花针茅和青藏苔草各种群间具有较高的遗传分化。 紫花针茅具有与其它分蘖型克隆植物相当的克隆多样性，说明有性生殖在其生活史中起着重要作用。青藏苔草具有与其它克隆植物相当的克隆多样性，而与北极地区苔草属植物相比，其克隆多样性则较低。 Pearson相关显示，紫花针茅遗传多样性与纬度、经度均成显著负相关，而与海拔高度相关关系不显著;青藏苔草克隆多样性及遗传多样性与纬度、经度、海拔高度均不相关，而克隆多样性与遗传多样性的比值则与纬度显著相关。唐古拉山对紫花针茅遗传格局未产生显著影响，山南北地区遗传多样性无显著差别;唐古拉山对青藏苔草遗传格局产生了重要影响，唐古拉山南北地区基因交流有显著隔离，唐古拉山以北地区种群遗传多样性显著高于以南地区，推测其种群自北向南迁移过程中的瓶颈效应起着重要作用。青藏苔草种群的克隆多样性与遗传多样性成显著正相关。Mantel test检验显示，紫花针茅和青藏苔草的地理距离与遗传距离间的关系均不显著。 紫花针茅以分蘖生长的方式由源株向外扩展，有明确、致密的边界，野外观察和室内检测的结果显示其环上其它基株也可进行生长成活，可形成一种克隆环镶嵌格局，克隆环或其边界可能是幼苗定居有利的生境;空间自相关也显示在较小的尺度内紫花针茅遗传相关性强，推测克隆繁殖在其中也起重要作用。青藏苔草种群不同尺度的取样其克隆多样性不同，小面积（1 × 1 m2）的克隆多样性均小于大面积的（10 × 10 m2），空间自相关也显示克隆生长在其中起重要作用;尽管青藏苔草有较强的克隆生长能力，在环境条件较好时其呈密集分布，表现出较强的可塑性。 总之，尽管青藏高原环境非常严酷，紫花针茅与青藏苔草仍有较高水平的克隆多样性和一定的遗传多样性;高原严酷的环境造成了两种植物较大的遗传隔离。紫花针茅环状结构对其有性更新有重要作用，青藏苔草克隆生长具有较大可塑性，这些都是植物对高原严酷环境的适应形式。

青藏高原几种植物的光合特性研究

通过气体交换、荧光猝灭动力学以及反射光谱等技术研究了两个青稞（Hordeum vulgare L.）品种的光合特性及激发能分配。结果表明，青稞的光饱和点1000 μmol m-2 s-1左右。在0～500 μmol m-2 s-1的光强范围里，青稞叶片的光呼吸(Pr)随着光强升高而增加;光强超过500 μmol m-2 s-1以后，光呼吸变化不明显。光呼吸占总光合的比例(Pr/Pm)随光强增强下降。随着光强增强，PSⅡ有效光化学量子效率（Fv′/Fm′），PSⅡ反应中心的实际光化学量子效率（ΦPSⅡ），光化学猝灭系数（qP）不断降低而青稞叶片的非光化学猝灭(NPQ)不断升高，说明越来越多的光能以热耗散的形式耗散掉。光谱分析表明△PRI 随着青稞叶片暴露于光下的时间迅速增大。因此，我们认为光呼吸不是青稞主要的光破坏防御机制，依赖叶黄素循环的热耗散可能是田间青稞耗散过剩光能的主要途径。 通过气体交换、荧光猝灭动力学等技术研究了四种乔木在拉萨和那曲的光合特性及激发能分配。结果表明，四种乔木藏川杨（Populus szechuanica var. tibetica schneid.），银白杨（Populus alba L.），左旋柳(Salix paraplesia var. subintegra C. Wang et P. Y. Pu)，墨竹柳(Salix maizhokunggarensis N. Chao)在拉萨市的光合速率（Pn），叶片气孔导度（Gs），蒸腾速率（Tr）均显著高于那曲。藏川杨和墨竹柳的光下实际光化学效率（ΦPSⅡ）在拉萨显著高于那曲，银白杨和左旋柳的光下实际光化学效率在拉萨和那曲没有显著差异。四种乔木开放反应中心激发能捕获效率（Fv′/Fm′）和天线热耗散（1－Fv′/Fm′）在拉萨和那曲的差异不显著。测量光合时的气温（Tair）拉萨显著高于那曲，除墨竹柳外叶温（Tleaf）也显著高于那曲，墨竹柳的上述两参数在两地间无显著差异。除藏川杨外其余三种乔木在拉萨的胞间二氧化碳浓度（Ci）显著高于那曲，气孔限制值(Ls)显著低于那曲，藏川杨的上述两指标在两地间无显著差异。除墨竹柳外，其余三种乔木在两地的光合（Pn）与叶温（Tleaf）成显著正相关。对银白杨和左旋柳来说，低叶温通过降低气孔导度（Gs）从而降低胞间二氧化碳浓度（Ci）是造成那曲光合低的主要因素之一。对于墨竹柳来说，可能有其他非温度的环境条件影响其气孔导度进而造成气孔限制。此外，叶温可能主要通过非气孔限制来影响藏川杨的光合速率。因此，我们认为在西藏地区不同乔木对海拔高度的响应机制可能不同，但具体机制还需要进一步研究。

Genetic diversity and taxonomic implication of Cordyceps sinensis as revealed by RAPD markers

Random amplified polymorphic DNA (RAPD) markers are used to investigate genetic variation and evolutionary relationships of 29 samples of Cordyceps sinensis from different geographical populations on the Qinghai-Tibet plateau. Out of 137 RAPD bands scored, 100 are polymorphic. A correlation is revealed between geographical distance and genetic distance. The molecular phylogenetic tree suggests that the 29 samples are divided into three notable clusters, corresponding to the geographical populations, i.e., the north population (NP), middle population (MP), and south population (SP). The NP consists of 7 northern samples from Menyuan, Maqu, and Luqu, the MP consists of 8 samples from Yushu and Chengduo, and the SP consists of 14 samples from Byma Snow Mountain, Renzhi Snow Moutain, Chongcaoxiwa, and Dacaodi. It is demonstrated that extensive genetic diversity is found among different geographical populations of C. sinensis. The genetic diversity pattern of C. sinensis may be caused by the founder effects. The taxonomic status of NP, MP, and SP populations should be that they are different subspecies rather than different species.

Molecular phylogeny and biogeography of woolly flying squirrel (Rodentia : Sciuridae), inferred from mitochondrial cytochrome b gene sequences

To investigate the genetic diversity between the populations of woolly flying squirrels (Eupetaurus) from the eastern and western extremes of the Himalayas, partial mitochondrial cytochrome b gene sequences (390-810bp) that were determined from the museum specimens were analyzed using maximum parsimony (MP) and maximum likelihood (ML) methods. The molecular data reveal that the two specimens that were collected in northwestern Yunnan (China) are members of the genus Eupetaurus. Reconstructed phylogenetic relationships show that the populations of Eupetaurus in the eastern and western extremes of the Himalayas are two distinct species with significant genetic differences (12%) and diverged about 10.8 million years ago. Eupetaurus is significantly different from Petaurista and Pteromys. The level of estimated pairwise-sequence divergence observed between Eupetaurus and Petaurista or Pteromys is greater than that observed between Eupetaurus and Trogopterus, Belomys, Glaucomys, or Hylopetes. Considering the divergence time of the two Eupetaurus groups, the glaciations and the uplift of the Himalayas and Qinghai-Tibet plateau during the Pliocene-Pleistocene period might be the major factors affecting the present distribution of Eupetaurus along the Himalayas. (C) 2004 Elsevier Inc. All rights reserved.

Speciation and Phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: Analysis of the Cytochrome b Gene of mtDNA from Diverse Populations

Gao-Yan Li, Xu-Zhen Wang, Ya-Hui Zhao, Jie Zhang, Chun-Guang Zhang, and Shun-Ping He (2009) Speciation and phylogeography of Opsariichthys bidens (Pisces: Cypriniformes: Cyprinidae) in China: analysis of the cytochrome b gene of mtDNA from diverse populations. Zoological Studies 48(4): 569-583. The cyprinid fish Opsariichthys bidens Gunther is distributed in all major river systems of continental East Asia, and represents an attractive model for phylogeographic studies among cyprinid species or within a given species. In this study, we investigated the phylogeographic and demographic history of this species, using partial sequences of the cytochrome (cyt) b gene in mitochondrial (mt)DNA. Fish samples were collected from almost all major river systems where O. bidens is distributed in China. Sequence analysis showed remarkably high polymorphism, with 125 haplotypes in the 234 specimens examined, and with 89.8% of haplotypes occurring in only 1 specimen. A neutrality test indicated that some groups were not at mutation-drift equilibrium, suggesting a past population expansion. These results were supported by a mismatch distribution analysis. Based on our analysis, O. bidens consists of 4 groups belonging to 2 clades. The divergence time of the 2 clades was estimated to be 11.06-8.04 my. This value corresponds to the time of the 2nd uplift of the Qinghai-Tibet Plateau, the emergence of the East Asian monsoon, and the Epoch-6 Event. A two species scheme is proposed. http://zoolstud.sinica.edu.tw/Journals/48.4/569.pdf

次生植被土壤碳、氮养分季节动态及凋落物输入与温度的影响

土壤微生物量、可溶性有机碳与氮虽然只占土壤有机碳、氮总量的较小部分，但可以在土壤全碳、氮变化之前反映土壤微小的变化，又直接参与土壤生物化学转化过程，因而在植被恢复过程中，较其它土壤理化性质等能够更好地指示土壤恢复情况。在青藏高原东缘存在大面积的次生人工林替代灌丛或采伐迹地，而关于这些人工林替代后的生态效果和生态过程的评估却十分缺乏，本研究通过评估岷江上游植被恢复重建过程中典型人工替代次生植被凋落物层与土壤碳、氮等养分大小，动态监测土壤微生物生物量、水溶性碳、氮等指标，结合温度与凋落物输入等影响土壤活性有机碳、氮因子的控制试验，系统分析不同人工替代次生植被土壤碳、氮等养分的差异原因，试图寻找低效人工林优化调控与持续管理技术，为区域生态公益林持续管理提供理论和技术依据。主要结论如下： 1. 通过对不同人工替代次生植被凋落物层和土壤碳、氮分析发现，油松和华山松人工林替代次生灌丛后土壤碳、氮含量较灌丛和阔叶人工林低，主要原因可能为凋落物质量(C/N)较差，而引起碳、氮等元素难以归还土壤。进而通过对不同人工替代次生植被凋落物层和土壤微生物生物量、水溶性有机碳、氮等指标的季节性动态模式的分析，发现各次生植被土壤微生物生物量C、N，P以及土壤水溶性碳、氮含量均呈明显季节性动态，呈现秋季明显大于其它季节，冬季最低，在表层土壤最为明显。 2. 油松、华山松人工林凋落物层和土壤水溶性有机碳(WDOC)、土壤水溶性有机氮(WDON)明显低于灌丛和连香树，土壤微生物生物量C、N也以油松和华山松人工林最低，而落叶类植被，如灌丛、连香树和落叶松之间没有明显差异，说明可利用底物的数量和质量差异是影响各次生植被凋落物分解和土壤微生物活性的主要原因。MBC/OC和MBN/ON能较好地指示土壤微生物活性的变化，MBC/OC凋落层总体以灌丛和连香树人工林最高，油松和华山松人工林最低；而土壤中MBC/OC连香树人工最高，华山松人工林最低。说明以油松和华山松为主的人工造林替代乡土阔叶灌丛造成土壤C、N等养分严重匮乏，微生物活性低下是影响其养分周转的主要原因。 3. 从各次生植被凋落物产生看，凋落物年归还量最大的为华山松人工林(5.1×103 kg ha-1)，其次为落叶松人工林(4.8×103 kg ha-1)，阔叶灌丛林地凋落物产生总量(4.4×103 kg ha-1)略大于油松人工林(4.2×103 kg ha-1)，最小的为连香树人工林(3.6×103 kg ha-1)；叶是凋落物的主体，落叶类树种月动态表现为单峰型，高峰主要在10-11月，如落叶松、连香树和灌丛林；常绿的松类月动态不明显，各月基本相同，最为明显地为油松林，华山松人工林略有二个小峰，分别出现在11月和5月。落叶阔叶灌丛的凋落物分解速率大于常绿针叶林，如油松和华山松。结合凋落物的产生量和分解速率，不同树种人工林替代次生阔叶灌丛后，人工油松和华山松林枯落物总贮量和厚度明显大于落叶松人工林、灌丛林和连香树人工林，说明以油松和华山松为主的人工造林替代乡土阔叶灌丛延缓了有机物向土壤的顺利归还，不利于土壤C、N等养分循环。 4. 通过控制地面凋落物和地下根系输入有机物对土壤碳、氮的影响研究发现，(1) 单独去除根系以及根系与地面凋落物同时去除处理1年后对表层(0-10cm)土壤WDOC均没有显著影响，而土壤WDON显著增加，油松人工林土壤微生物生物量C、N显著降低，人工落叶松林没有显著差异，说明油松人工林土壤微生物活性对地下碳输入的依赖大于其它次生植被，而落叶松土壤微生物活性对地下碳输入依赖性较小；去除地面凋落物，明显降低了落叶松人工林土壤WDOC，华山松和连香树土壤WDON均较对照显著减少，油松人工林土壤微生物量C较对照显著减少；双倍增加地面凋落物处理对土壤微生物生物量、WDOC和WDON没有明显地增加，相反，连香树、华山松和油松人工林土壤WDON较对照减少。说明油松人工林微生物活性不仅依赖于地下碳输入，而且对地上有机物输入的依赖性也较大；连香树、落叶松和华山松人工林土壤微生物生物量并没有因地面凋落物的去除减少可能与土壤总有机碳含量及活性均较高有关，而双倍增加地面凋落物反而降低了土壤微生物生物量，说明凋落物覆盖后改变了土壤微气候。 5. 碳矿化累积量与有机碳含量和活性有机碳含量之间存在显著地正相关关系。凋落物碳累积矿化量、矿化速率以连香树最高，油松和华山松人工林次之，落叶阔叶灌丛低于常绿针叶纯林，导致其差异的主要原因可能为凋落物产生的时间动态模式不一样，致使凋落物起始分解时间不一致。而土壤层有机碳矿化速率和矿化量以阔叶落叶灌丛和连香树最高，油松和华山松人工土壤最低，再次证实利用针叶纯林恢复植被阻碍了有机质周转与循环。 6. 凋落物累积矿化量与C/N值呈显著地相关关系，并随着温度的升高而明显增加，而土壤累积矿化量与C/N值没有显著相关关系，说明土壤有机碳质量(C/N)对温度的响应不十分明显。通过双指数模型对不同温度下碳矿化过程进行模拟和计算出活性有机碳与惰性有机碳比例，发现温度升高促进了惰性有机碳向活性有机碳的转化，增加了活性有机碳含量，说明温度升高可促进次生植被凋落物与土壤有机质的分解，进而可影响到林地碳源/汇关系的变化。 综上，通过对不同人工替代次生植被凋落物与土壤C、N大小、以及土壤微生物生物量、水溶性C、N等指标动态变化模式研究，结合温度与凋落物数量输入等影响土壤活性C、N因子的综合分析，以油松和华山松人工纯林对山地植被恢复，延缓或阻碍了有机质周转与循环，造成了土壤肥力退化。对现有低效人工纯林改造，应为地面大量有机物分解创造条件。 Although soil microbial biomass, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are a small part of total soil organic carbon and nitrogen, they can directly participate in the process of soil biochemical translation and indicate the fine changes before changes of soil total organic carbon and nitrogen occur. So, they are good indexes to indicate soil restoration condition during the process of vegetation rehabilitation. There are large areas of secondary vegetations which substitute for indigenous shrubs in the eastern fringe of Qinghai-Tibet Plateau. However, it is not well known that the ecological effect and process after substitution by different secondary plantations. Based on comparison of soil organic and nitrogen contents in litter layer and soil under different secondary vegetations in upper reaches of Minjiang River, soil microbial biomass, DOC and DON in litter layer and soil were investigated in order to analyze the seasonal dynamic. Combining the effects of temperature, litter input and root exclusion on soil microbial biomass, DOC and DON, we also aim to understand the reason and mechanism of difference in soil carbon and nitrogen contents among different secondary vegetations. The study would contribute to comprehensively understanding C and N cycling processes and provide optimal control and sustainable technology of low-effect plantations in these regions. The results are as follows: (1) Organic carbon and nitrogen in litter layers and soil under different substitution plantations were investigated. The results showed that contents of soil organic carbon and nitrogen were lower in P. tabulaeformis (PT) and P. armandi Franch(PA) than those in native broad-leaf shrub and broad-leaf plantation. The low quality (C/N) of litter in PT and PA plantations caused carbon and nitrogen returning to soil difficultly. Seasonal dynamic of soil microbial carbon (MBC),-nitrogen (MBN),-phosphor (MBP), and WDOC and WDON showed similar pattern, which had the highest values in autumn and the lowest values in winter. (2) WDOC and WDON in litter layers and soil under PT and PA plantations were significantly lower than those in native broad-leaf shrub and Cercidiphyllum japonicum Sieb. et Zucc.(CJ). Soil MBC and MBN were also the lowest, while there were no significant differences among deciduous vegetations, i.e. native broad-leaf shrub, CJ and Larix kaempferi Lamb.(LK) plantation. The results suggested that difference in quantity and quality of available substance was main reason that affected the activity of microbe in soil and litter layer. MBC/OC and MBN/ON were good indexes to indicate the change of soil microbial activity. MBC/OC of litter had the highest value under native broad-leaf shrub and CJ plantation, and had the lowest value in PT and PA plantations, while MBC/OC of soil was the highest under CJ plantation, and was the lowest in PT and PA plantations. These results indicated that PT and PA plantations substituting for native broad-leaf shrub caused deficit of carbon and nitrogen in soil, low microbial activity was a main reason influencing the cycling and turnover of carbon and nitrogen in soil. (3) The annual litter fall production, composition, seasonal dynamic and decomposition of five typical secondary stands in upper reaches of Minjiang River were studied in this paper. The annual litter productions were: PA (5.1×103 kg ha-1), LK(4.8×103 kg ha-1), native broad-leaf shrub (4.4×103 kg ha-1), PT(4.2×103 kg ha-1)，CJ(3.6×103 kg ha-1). The litter production of leaves in five secondary vegetations occupied a higher percentage in the annual total litter production than those of other components. The litterfall was mostly producted in the cool and dry period (October-November) for deciduous vegetations and relatively equably producted in every season for evergreen coniferous vegetations. The decomposition rate of leaf litter in the broad-leaf stand was higher than those in evergreen coniferous stand. Combined with annual litter fall production and decomposition rate of leaf litter, we found that stock and depth of litter layer were significantly larger in PT and PA plantations than those in native broad-leaf shrub, LK and CJ plantations. The results confirmed that PT and PA plantations substituting for native broad-leaf shrub delayed organic matter returning to soil and hindered cycling of carbon and nitrogen again. (4) We explored plant litter removal, double litter addition, root trenching, and combining root trenching and litter removal treatments to examine the effects of above- and belowground carbon inputs on soil microbial biomass, WDOC and WDON in four secondary plantations. During the experimental period from June 2007 to July 2008, 1 year after initiation of the treatments, WDOC in soil did not vary in root trenching, and combining root trenching and litter removal treatments, while WDON in soil significantly increased compared with CK treatment. Root trenching reduced soil MBC and MBN in PT plantation, while MBC and MBN in soil did not vary in LK plantation. The rasults implied that soil microbial activity was more dependent on belowground carbon input in PT plantation than those in other secondary plantations, on the contrary, soil microbial activity in LK plantation was not dependent on belowground carbon input. Plant litter removal significantly decreased soil WDOC in LK plantation, decreased WDON in PA and CJ plantations, and also significantly reduced soil MBC in PT plantation. However, double litter addition did not increase soil microbial biomass, WDOC and WDON, on the contrary, soil WDON in CJ, PA and PT plantations were decreased. These suggested that soil microbial activity was not only dependent on belowground carbon input, but also on aboveground organic material input. Double litter addition could change the microclimate and result in the decrease of soil microbial activity in CJ, PA and PT plantations. (5) We measured carbon mineralization in a 107 days incubation experiment in 5℃,15℃ and 25℃. Carbon cumulative mineralization was positively correlated with organic matter and labile organic carbon in litter layer and soil. Cumulative carbon mineralization and mineralization rate of litter layers in PT and PA plantations were higher than that in native broad-leaf shrub. This difference between native broad-leaf shrub and coniferous plantations in cumulative carbon mineralization and mineralization rate of litter layers could be attributed to the initiating time of decomposition due to the difference in seasonal dynamic of litter fall production between two types of secondary plantations. However, cumulative carbon mineralization and mineralization rate in soil were the highest in native broad-leaf shrub and CJ plantation, and were the lowest in PT and PA plantations. This also confirmed that PT and PA plantations substituting for native broad-leaf shrub hindered the cycling and turnover of organic matter again. (6) Carbon cumulative mineralization was positively correlated with C/N in litter layer and increased with temperature increasing, while carbon cumulative mineralization was not correlated with C/N in soil. This indicated that soil organic matter quality (C/N) was insensitive to temperature. Applying bi-exponential model, we computed the percent of labile and stable carbon in different temperature incubation and found that temperature increasing would accelerate the transform from stable carbon to labile carbon and increase the percentage of labile organic carbon. This illuminated that temperature incraesing could facilitate the decomposition of litter and soil organic matter in secondary vegetations and hence affect the relationship between carbon source and sink.

川西亚高山人工针叶林下11种植物对两种光生境的适应性研究

青藏高原东缘的亚高山针叶林是长江上游重要的生态屏障，经过近六十年的采伐后，取而代之的是大量人工种植的云杉纯林。目前，这些人工林已经表现出树种单一，结构层次简单等生态问题，其物种多样性及生态效益与同地带天然林相比差距较明显。如何丰富该地区物种多样性，完善人工林生态系统的生态功能是一个十分重要的课题。林下植物是人工林群落的重要组成部分，对维持群落的生物多样性及完善生态系统功能具有明显的作用。因此，研究该地区人工针叶林的林下植被对不同生境的适应性对于理解人工林生态系统物种多样性的形成和维持机制都具有重要的意义。 本文以青藏高原东部亚高山针叶林的主要森林类型----云杉人工林为研究对象，选择林下11种具有不同喜光特性的常见植物，分别设置人工林林冠下及成熟林窗为研究样地，通过对各种植物叶片形态与物质分配特征、叶片解剖学特征、叶片光合生理特性、植物自然分布特征等方面的比较分析，研究林下植物对不同光生境的适应策略及其适应能力，揭示不同物种对人工林生境的适应共性，为西南亚高山地区植被恢复及人工林的经营管理提供科学依据。具体研究结果如下： 在叶片形态和物质分配特征方面：在林窗光生境中，11种林下植物叶片比叶重(LMA)显著高于林下光生境的同种植物。同时，林窗下生长的植物叶片叶片厚度及栅栏细胞长度显著增加，这是影响叶片比叶重变化的直接原因。而多数植物叶重比在两种生境中无明显变化。说明在长期适应自然生境之后，植物可能更多地采取调节叶片组织细胞水平（即叶片功能细胞形态）及叶片器官水平（即单个叶片形态）特征的策略来适应各类生境，而非整株水平上的叶片总比重的增减。 在叶片解剖结构特征方面：多数阔叶物种栅栏组织厚度(PT)、栅栏组织厚度/海绵组织厚度(PT/ST)、栅栏细胞层数及近半数种的气孔密度(SD)在林窗生境中更大或更多，而叶片表皮细胞厚度(UET、LET)气孔长径(SL)及海绵组织厚度(ST)受两种生境影响不大。喜光特性相似的物种在生境适应策略上具有一定的趋同性。 在光合生理特征方面：在林窗生境中多数种植物的最大光合速率(Amax)、暗呼吸速率(Rd)及喜光植物光补偿点(LCP)显著或极显著高于林内生境同种植物。且在同一生境条件下，多数深度耐荫植物比喜光及轻度喜光植物有稍低的Rd和LCP。各植物在林内低光生境中具有更大的内禀光能转化效率，并在中午12:00～14:00之间光强最大的时刻发生了的最深程度的光抑制。多数种能通过调节自身某种光合素含量或色素之间的比例来适应不同的光生境，即通过增加叶绿素含量或降低Chla/b值来适应林内弱光生境，通过提高类胡萝卜素含量或单位叶绿素的类胡萝卜素含量降低强光带来的伤害。绝大多数物种并不采取调节叶片C、N含量的策略来适应不同的光生境。总之，植物部分光合参数(Amax、Rd、LCP)受生境的影响与其自身喜光特性有关，但另一些参数（Fv/Fm日变化、色素含量及比例、叶氮相对含量）受生境影响与其自身喜光特性无明显关联。 在表型可塑性方面：在叶片各表型参数中，器官水平及细胞水平的形态特征参数平均可塑性大于整株水平形态和物质分配特征参数可塑性；叶片光合组织的可塑性大于非光合组织可塑性；反映植物光合能力的参数可塑性大于叶片色素含量参数可塑性。植物叶片形态和物质分配、解剖学特征参数平均可塑性大小与其自身喜光特性基本吻合，即喜光种及轻度耐荫种各参数可塑性最高，深度耐荫种可塑性最小，而这种规律并未在光合生理参数的可塑性大小上体现出来。但是叶片形态和物质分配参数、光合生理参数的平均可塑性水平却大于叶片解剖学参数。 在植物自然分布特征方面：喜光物种云杉幼苗及歪头菜在林内生境中分布密度明显降低，深度耐荫种疏花槭却恰恰相反，更多数物种（7种植物）在两种生境中密度变化趋势不明显。从分布格局来看，7种植物在两种生境中均为聚集分布，但聚集强度为林窗>林内；少数物种桦叶荚迷、直穗小檗、冰川茶藨、黄背勾儿茶在林窗中为聚集型，在林内生境中的分布型发生改变而成为随机型，说明光生境的差异能影响到植物种群的分布特征。但这种影响程度与植物自身的喜光特性无关，同时与各物种叶片表型平均可塑性的大小也无明显关联。 The subalpine coniferous forest area in eastern Qinghai-Tibet Plateau is important ecology-barrier of upriver Yangtze. In past sixty years, those forests had been cut down and replaced with a lot of spruce plantations. At now, there are many ecology problems presenting to us such as singleness species, simple configuration, lower species diversity and ecological benefit than natural forests at the same belt. How to restore the species diversity and enhance the eco-function of the plantations is a very important issue. The understory plants are important part of plantation community, which improved the bio-diversity and eco-function distinctly of forests. So, it is very significance to study the adaptation of understory plants to different environment in plantation, and this study would helping us to understand how plantations to develop and remain their biodiversity. This study was conducted in a 60a spruce plantation in Miyaluo located in western Sichuan, China, and spruce plantation is major types of subalpine coniferous forest in eastern Qinghai-Tibet Plateau. In this paper, the leaf morphological and biomass-distributed characteristics, the anatomical characteristics, the photosynthetic characteristics and the distribution patterns characteristics of eleven different light-requirement understory species grown in two different environments (forest gaps and underneath close canopy) were studied and compared. The purpose of this study was to analyze the adaptation of this forest understory plants, to show up the commonness of these different light-requirement understory species in light acclimation, and to provide some scientific reference to manage and restore the vegetation of subalpine plantation of southwest China. The results were as follows: The leaf morphological and biomass-distributed characteristics: These eleven species in forest gaps had significantly higher dry weight per leaf area (LMA) than those under close canopy. The palisade parenchyma cells of the broad-leaved species in gaps were significantly longer than those grown under the canopy, which been a directed factor for the change of leaf mass per unit area (LMA) in different environment. But the leaf weight ratio (LWR) of most plants species were not evidently changed by the contrasted environments in our study. It was shown the morphological characteristics changing been adopted as a strategy of light acclimation for plants wasn’t on whole plant level (leaf weight ratio) but cellular level (the function cells morphological characteristics) and organic level (the leaf morphological and biomass-distributed characteristics) mostly. The leaf anatomical characteristics: Most broad-leaved plants in gaps increased palisade parenchyma thickness (PT), the palisade parenchyma cell layers and the ratio of palisade to spongy parenchyma (PT/ST). So did as almost about half species in this study in stomatal density (SD). No significant differences in thickness of leaf epidermal cells (UET, LET), stomatal length (SL) and spongy parenchyma (ST) between two environments of most species were observed. The results suggested that species with light-requirement approximately had convergent evolution on adaptation to light condition. The leaf photosynthetic characteristics: The dark respiration rate (Rd) of most plants species, the light compensation point (LCP) of light-demanding plants species in gaps were significantly increased than under close canopy in this study. In a same habitat, most deep-shade-tolerant plants had lower Rd and LCP than those light-demanding plants and slight-shade-tolerant plants. Each species has bigger inherent electron transport rate under close canopy than in gaps, and the greatest photoinhibition happened during 12 to 14 in the daytime. Most species could adapt different light environment by the way of changing their photosynthetic pigments content or the ratio of pigments content. For example, some plants under close canopy increased chlorophyll (Chl) or reduced the values of the ratio Chla/b to adapted the low light condition, some plants in gaps increased carotenoid (Car) or reduced the weight ratio CarChl to avoid been hurt in high light. For most plants, changing the content of C and N in leaf wasn’t a strategy of light acclimation. In conclusion, the variation of some leaf photosynthetic parameters in different light environment such as Fv/Fm, pigments, C and N in leaf related with the light-requirmnet of species, but the others such as Amax, Rd, LCP did not. The leaf plasticity indexes: Among those leaf plasticity indexes, the leaf morphological and biomass-distributed parameters on cellular and organic level were greater than on whole plant level for same species, and the photosynthetic parenchyma parameters were greater than non-photosynthetic parenchyma parameters in same leaf, and photosynthetic capability parameters were greater than photosynthetic pigments content parameters for same species. The average plasticity indexes of leaf morphological and biomass-distributed and anatomical parameters were accordant with plants’ light-requirement approximately: those light-demanding plants and slight-shade-tolerant plants had bigger plasticity indexes than deep-shade-tolerant plants. But this regular wasn’t observed in physiological plasticity indexes for most plants, though the average leaf plasticity indexes of leaf morphological and biomass-distributed, photosynthetic characteristics parameters was greater than the anatomical characteristics parameters. The distribution patterns characteristics: Oppositely to the deep-shade-tolerant specie Acer laxiflorum Pax., the density of light-demanding species Picea asperata Mast. and Vicia unijuga A. Br. in gaps was bigger than under close canopy. Each of the other species has the approximately density in two different environment. The spatial patterns of seven species were aggregated distribution in two environments, but the trend of aggregation of population under close canopy was decrease from in gaps. A few species such as Viburnum betulifoium Batal., Berberis dasystachya Maxim., Ribes glaciale Wall. and Berchemia flavescens Brongn. were aggregated distribution in gaps while random distribution under close canopy. It was shown that the difference between two light environments could affect the distribution pattern of plant population, and the effect didn’t relate with the light-requirement or plasticity indexes of species.

水分亏缺和凋落物水浸液对云杉幼苗生长和种子萌发的影响

在人类活动导致全球变暖的前提下，由于全球气温的升高，地表水分加速向空中蒸发。从20世纪70年代至今，地球上严重干旱地区的面积几乎扩大了一倍。这一增长的一半可归因于气温升高而不是降雨量下降，因为实际上同期全球平均降水量还略有增长。干旱对陆地植物和农林生态系统产生深远影响，并已成为全球变化研究的一个重要方面。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、人工林下和林窗环境作为目前该区人工造林和森林更新的重要生境，其截然不同的光环境对亚高山针叶林更新和森林动态有非常重要的影响。凋落物产生的化感物质可通过影响种子萌发和早期幼苗的定居而影响种群的建立和更新，而人工林和自然林物种以及更新速度的差异性也都受凋落物的影响。 云杉是川西亚高山针叶林群落的重要树种之一,在维持亚高山森林的景观格局和区域生态安全方面具有十分重要的作用，其自然更新能力及其影响机制一直是研究的热点问题。本试验以云杉种子和2年生幼苗为研究对象，从萌发、根尖形态、幼苗生长、光合作用、渗透调节和抗氧化能力等方面研究了不同光环境下水分亏缺和凋落物水浸液对云杉种子和幼苗生长的影响。旨在从更新的角度探讨亚高山针叶林自然更新的过程，其研究成果可在一定程度上为川西亚高山针叶林更新提供科学依据，同时也可为林业生产管理提供科学指导。主要研究结论如下： 水分亏缺在生长形态、光合作用、抗氧化能力、活性氧化对云杉幼苗都有显著影响。总体表现为，水分亏缺导致了云杉幼苗的高度、地径、单株总生物量降低，增加了地下部分的生长；水分亏缺显著降低了云杉叶片中相对含水量、光合色素、叶氮含量，净光合速率和最大量子产量(Fv/Fm)，提高了幼苗叶片中膜脂过氧化产物（MDA）的含量；水分亏缺提高了幼苗叶片中过氧化氢(H2O2)含量，超氧荫离子（O2-）生成速率以及脯氨酸和抗氧化系统的活性（ASA, SOD, CAT, POD, APX和GR）。从这些结果可知，植物在遭受水分亏缺导致的伤害时，其自身会形成防御策略，并通过改变形态和生理方面的特性以减轻害。但是，这种自我保护机制依然不能抵抗严重水分亏缺对植物的伤害。 模拟林下低光照条件显著增加单株植物的地上部分生长，尤其是其叶片的比叶面积（叶面积/叶干重），同时其光合色素含量和叶片相对含水量也显著增加，这些改变直接导致植株光合速率和生物量的增加。同时，与高光照水平相比，低光照幼苗的膜脂过氧化产物（MDA）和活性氧物质均较低，显示出低光照比高光照水平对植物的更低的氧化伤害。尽管低光照也导致大部分抗氧化酶活性降低，但这正显示出植物遭受低的氧化伤害，更印证了前面的结论。 凋落物水浸液影响了云杉种子的萌发和根系的生长，更在形态、光合作用、抗氧化能力、活性氧物质以及叶氮水平上显著影响了云杉幼苗，其中，以人工纯林凋落物的影响更有强烈。具体表现在，种子萌发速率和萌发种子幼根的长度表现为对照>自然林处理>人工纯林；凋落物水浸液抑制种子分生区和伸长区的生长，人工林处理更降低了根毛区的生长，使根吸水分和养分困难。对2年生幼苗的影响主要表现在叶绿素含量、光合速率以及叶氮含量的降低；膜脂过氧化产物、活性氧物质和抗氧化酶系统的显著增加。同样的，人工纯林处理对云杉幼苗的影响显著于自然林处理。 在自然生态系统中，由于全球变暖气温升高导致的水分亏缺和森林凋落物都存在森林的砍伐迹地，林窗和林下环境中。我们的研究表明，与迹地或林窗强光照比较，林下的低光照环境由于为植物的生长营造了较为湿润的微环境，因此水分亏缺在林下对云杉幼苗造成的影响微弱。这可以从植物的形态、光合速率以及生物量积累，过氧化伤害和抗氧化酶系统表现出来。另一方面，凋落物水浸液在模拟林下低光照环境对植物的伤害也微弱于强光照环境，这与强光照环境高的水分散失导致环境水分亏缺有关；而人工纯林处理对云杉幼苗的伤害比对照和自然林处理显示出强烈的抑制作用。 Under the pre-condition of global warming resulted from intensive human activities, water in the earth’s surface rapidly evaporates due to the increase of global air temperature. From 1970s up to now, the area of serious drought in the world is almost twice as ever. This increase might be due to the increasing air temperature and not decreasing rainfall because global average rainfall in the corresponding period slightly is incremental. Drought will have profound impacts on terrestrial and agriculture-forest system and has also become the important issue of global change research. The subalpine coniferous forests in the eastern Qinghai-Tibet Plateau provide a natural laboratory for the studying the effects of global warming on terrestrial ecosystems. The light environment significantly differs among cutting blanks, forest gap and understory, which is particularly important for plant regeneration and forest dynamics in the subalpine coniferous forests. Picea asperata is one of the keystone species of subalpine coniferouis forests in western China, and it is very important in preserving landscape structure and regional ecological security of subalpine forests. The natural regeneration capacities and influence mechanism of Picea asperata are always the hot topics. In the present study, the short-term effects of two light levels (100% of full sunlight and 15% of full sunlight), two watering regimes (100% of field capacity and 30% of field capacity), two litter aqueous extracts (primitive forest and plantation aqueous extracts) on the seed germination, early growth and physiological traits of Picea asperata were determined in the laboratory and natural greenhouse. The present study was undertaken so as to give a better understanding of the regeneration progress affected by water deficit, low light and litter aqueous extracts. Our results could provide insights into the effects of climate warming on community composition and regeneration behavior for the subalpine coniferous forest ecosystem processes, and provide scientific direction for the forest production and management. Water deficit had significant effects on growth, morphological, physiological and biochemical traits of Picea asperata seedlings. Water deficit resulted in the decrease in height, basal diameter, total biomass and increase in under-ground development; water deficit significantly reduced the needle relative water content, photosynthetic pigments, needle nitrogen concentration, net photosynthetic rate and the maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA) in Picea asperata seedlings; water deficit also increased the rate of superoxide radical (O2-) production, hydrogen peroxide (H2O2) content, free proline content and the activities of antioxidant systems (ASA, SOD, POD, CAT, APX and GR) in Picea asperata seedlings. These results indicated that some protective mechanism was formed when plants suffered from drought stress, but the protection could not counteract the harm resulting from the serious drought stress on them. Low light in the understory significantly increased seedling above-ground development, especially the species leaf area (SLA), and photosynthetic pigments and relative needle content. These changes resulted in the increase in net photosynthetic rate and total biomass. Moreover, the lower MDA content and active oxygen species (AOS) (H2O2 and O2-) in low light seedlings suggested that low light had weaker oxidative damage as compared to high light. Lower antioxidant enzymes activities in low light seedlings indicated the weaker oxidative damage on Picea asperata seedlings than high light seedlings, which was correlative with the changes in MDA and AOS. Litter aqueous extracts affected seed germination and root system of Picea asperata seedlings. Significant changes in growth, photosynthesis, antioxidant activities, active oxygen species and leaf nitrogen concentration were also found in Picea asperata seedlings, and plantation treatment showed the stronger effects on these traits than those in control and primitive forest treatment. The present results indicated that seed germination and radicle length parameters in control were superior to those in primitive forest treatment, and those of primitive forest treatment were superior to plantation treatment; litter aqueous extracts inhibited the meristematic and elongation zone, and plantation treatment caused a decrease in root hairs so as to be difficult in absorbing water and nutrient in root system. On the other hand, litter aqueous extracts significantly decreased chlorophyll content, net photosynthetic rate and leaf nitrogen concentration of Picea asperata seedlings; MDA, AOS and antioxidant system activities were significantly increased in Picea asperata seedlings. Similarly, plantation treatment had more significant effect on Picea asperata seedlings as compared to primitive forest treatment. In the nature ecosystem, water deficit resulted from elevating air temperature and litter aqueous extract may probably coexist in the cutting blank, forest gap and understory. Our present study showed that water deficit had weaker effects on low light seedlings in the understory as compared to high light seedlings in the cutting blank and forest gap. The fact was confirmed from seedlings growth, gas exchange and biomass accumulation, peroxidation and antioxidant systems. This might be due to that low light-reduced leaf and air temperatures, vapour-pressure deficit, and the oxidative stresses can aggravate the impact of drought under higher light. On the other hand, litter aqueous extracts in the low light had weaker effects on the Picea asperata seedlings than those at high light level, which might be correlative to the water evapotranspiration under high light. Moreover, plantation litter aqueous extracts showed stronger inhibition for seed germination and seedling growth than control and primitive forest treatments.

岷江冷杉林群落几种树苗对光强的响应与适应

在青藏高原东部的亚高山针叶林区，如何尽快恢复这一生态脆弱地区的植被，改变生态环境恶化的趋势，是一个十分重要的课题。光一直被认为是植物种间相互替代，尤其是森林演替过程中植物相互替代或植被恢复中的关键环境要素之一。植物能否适应林冠下或林窗中异质的、或多变的光照条件，对其在林中的生存、分布、更新以及森林动态都是非常重要的。 本文以青藏高原东部亚高山针叶林的主要森林类型——岷江冷杉林群落的几种树苗为研究对象，采用实验生态学、生理及生物化学等方法，通过模拟针叶林不同大小林窗内光照强度的变化，在中国科学院茂县生态站内采用遮荫处理设置6个光照梯度（100、55、40、25、15与7%全光照），来研究具有不同喜光特性的植物对光强的响应与适应机制，其研究结果可为揭示亚高山针叶林的演替规律、以及人工林下幼苗的存活与定居提供科学依据，也能为苗木的生产与管理提供科学指导，尤其是对针阔树种在不同光强下的响应与适应的比较研究，能为如何将阔叶树种整合到人工针叶林中提供新的思路。 光强对植物生长的影响 光强对植物的生长具有重要作用，不同植物在各自适宜的光强梯度下才能生长良好。通过一个野外盆栽实验，来研究不同光强对植物生长的影响（第三章）。主要研究结果如下，低光强下植物株高/茎生物量增加，说明植物会将生物量更多用于高生长，以便有效地拦截光资源；在强光下，植物将生物量更多地向根部分配，使得植物在强光下能够吸收更多的水分，而避免干旱胁迫。 在第一个生长季节，以相对生长速率（RGR）表示，红桦和青榨槭在100%全光照下RGR最大，粗枝云杉在55%最大，岷江冷杉在25-40%下较好；然而，在第二个生长季节，2种阔叶树的相对生长速率（RGR）的适宜光强则变为25-55%，云杉为55-100%，而冷杉为25-100%。可见，从第一年到第二年，2种阔叶树苗更适宜在部分荫蔽的条件下生长；而2种针叶树苗对光的需求则逐渐增加，这可能是增加对根生物量相对投资的结果，因为以这种方式，强光下生长的针叶树幼苗更能保持其内部水分平衡，其生长不会因干旱胁迫而受到严重影响。另外，严重遮荫会引起冷杉幼苗死亡。 植物对光强的生理适应 植物可以通过自身形态和生理特征的调整，来发展不同的光能利用策略从而能够在林中共存。通过一个野外盆栽实验，研究了不同光强下生长的几种树苗的生理特征（第四章）对不同光强的响应与适应。结果显示：强光下，粗枝云杉和红桦的光合能力增加，而岷江冷杉和青榨槭在中度遮荫（25-55%）的条件下光合能力最大。植物叶氮和叶绿素含量增高，而光补偿点和暗呼吸速率降低，这些都是植物对低光环境的适应性反应；而强光下植物叶片和栅栏组织变厚，是对强光的一种保护性反应。 植物对光的可塑性反应 不同植物会表现出对光适应有利的生理和形态可塑性反应。本文对第三章、第四章的实验数据进行可塑性指数分析，来研究植物对光强的表型可塑性反应（第五章）。结果显示，生理特征调整是植物对不同光环境的主要适应途径。红桦和青榨槭的可塑性指数平均值要大于粗枝云杉和岷江冷杉，充分表明这2种阔叶树在生理和形态上较强的可塑性更有利于对光环境的适应，而具有比耐荫树种更强的适应能力。另外，2种针叶树相比，云杉的适应性更强。本研究结果支持树种的生理生态特性决定了其演替状况和生境选择的假说。 植物的光抑制与防御 当植物叶片吸收了过多光能，会发生光抑制现象。植物对光抑制的敏感性及防御能力对其生长具有重要意义。本文通过两个野外盆栽实验，研究了生长在强光下（第六章）和变化光强下（第八章）植物的光抑制现象及其防御策略。结果表明，在强光下或从遮荫状态转入强光下，植物都会发生光抑制，其对光抑制的敏感性与植物的耐荫性（或喜光）和演替状态有密切联系。长期生长在强光下的植物受到光抑制是可恢复的，而当处于荫蔽环境的植物突然暴露于强光下时，受到的光抑制不能完全恢复，可能是（部分）光合机构受到破坏的缘故。粗枝云杉和青榨槭防御光抑制伤害的能力较强，热耗散是其防御光抑制的主要途径。长期的强光作用能使岷江冷杉和红桦发生严重光抑制，甚至光伤害，而红桦能够通过“凋落老叶，萌发新叶”的途径来适应新的强光环境。 How to restore the vegetation of subalpine coniferous forest in eastern Qinghai-Tibet Plateau, and change the trend of ecological deterioration is a very important issue. Acclimation of tree seedlings to different and varing light environment affects to a great extent the successful regeneration and establishment of subalpine coniferous forests in southwestern China’s montane forest areas, because the ability to respond to such changing resource are commonly assumed to be critical to plant success, and have a growth advantage than others. In this paper, several species seedlings in Abies faxoniana community were chosed to study the response and adaptation to light intensity and the interspecific differences of adaptability in six shaded sheds (100, 55, 40, 25, 15 and 7% of full sunlight) in the Maoxian Ecological Station of Chinese Academy of Sciences. Our results could provide a strong theoretical evidence for understanding the forest succession laws of subalpine coniferous forests, and the survival and settlement of seedlings under plantations, and provide scientific direction for the production and management of seedlings, especially the comparative studies of the acclimation to light between the conifer and broadleaf trees could provide new ideas for how to integrate the broad-leaved trees into the artificial coniferous forest. Growth under different light intensity Light intensity plays an important role on plant growth. One field experiments was conducted to study the growth of tree seedlings of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii under different light intensities. The results showed that plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources, while biomass greater allocation to the roots, could make plants under high light environment absorb more water, and avoid drought stress. During the first growing season, the relative growth rates (RGRs) of Betula albo-sinensis and Acer davidii had the greatest values under the 100% of full light, for 55% of Picea asperata, and for 25-40% of Abies faxoniana. However, in the second growing season the the relative growth rates of the two broad-leaved trees changed and were appropriate for 25-55% of full light, for 55-100% of spruce, and for 25-100% of fir. Thus, from the first year to the second year, two broad-leaved seedlings maybe more suitable to partly shading environment, and two coniferous seedlings would have an increase in light demand, which may be an increased root biomass investment. Because in this way, seedlings grown under high light could better maintain their internal water balance, and thus its growth would not be seriously affected by drought stress. In addition, serious shading would cause fir seedlings to die. Acclimation of physiology to light Plants could coexist in forest ecosystem by forming different strategies of light use. One field experiments was conducted to study the acclimation of tree seedlings to different light intensity of Picea asperata, Abies faxoniana, Betula albo-sinensis and Acer davidii. The results showed that the photosynthetic capacity of Picea asperata and Betula albo-sinensis exhibited a general tendency of increase with more light availability; but for Abies faxoniana and Acer davidii seedlings, their highest values of the same parameters were found under intermediate light regime (i.e. 25-55% of PFD relative to full sunlight). Plants under low light environment could increase the specific stem length (stem length/ stem dry mass), in order to effectively intercept light resources. Leaf nitrogen and chlorophyll content increased, while dark respiration rate and light compensation points decreased, all of which were adaptive response to the low light environment. On the contrary, plants under high light environment had the thicken leaves and palisade tissue, which was a protective response to high light. Phenotypic plasticity to light Phenotypic plasticity can be exhibited in morphological and physiological processes. Physiological characteristical adjustment is the main for plant adaptation to different light environment.The means of plasticity indexes for Betula albo-sinensis and Acer davidii seelings were greater than Picea asperata and Abies faxoniana, amplied that the two broad-leaved trees were much more adaptable to the environment. In addition, spruce had the higher adaptablity than fir. The findings supported the hypothesis that the ecological characteristics of the species determined the biological status and its biological habitat selection. Photoinhibition and photoprotection to light Compared with conifer, broad-leaved trees could better change leaf morphology and adjust biomass allocation to adapt to changing light environment. However, excess light can photoinhibit photosynthesis and may lead to photooxidative destruction of the photosynthetic appatus. Two field experiments were conducted to study the photoinhibition of photosynthesis. The results showed that when plants grown under high light environment or plants transferred from low to high irradiance, the four tree seedlings would undergo a period of photoinhibition. In four species, photoinhibited leaves could recover to initial photosynthetic rates when they were long-term planted under high light environment. However, when plants were suddenly exposed to high irradiance, this photoinhibition could not be reversible, may be the photosynthesis apparatus were (or partly) photooxidatively destructed.

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.

川西云杉(Picea balfouriana)天然群体的遗传变异

青藏高原东南缘由于特殊的生态地理条件，有着丰富的森林资源，这些资源是长江上游涵养水源、保持水土的生态屏障，是生物多样性的资源宝库。但随着过量的森林采伐，使该区曾经丰富的生物多样性资源遭受了前所未有的破坏，天然林的质量严重下降，生态系统退化，功能减弱。与此同时，许多物种的种群规模正在锐减，物种的遗传多样性也严重丧失。川西云杉是西部地区分布最广的云杉树种之一，在较高海拔的地区有着重要的生态学功能，是一种适应性很强的乡土树种。本项目采用简单序列重复标记(SSR)和特定序列位点(STS)研究不同生境条件下川西云杉群体的遗传变异及其时空分布格局，考察遗传变异与复杂的山地生态环境间的潜在联系，系统地揭示川西云杉天然群体与环境系统相互作用的生态适应与分子进化机制。研究成果能有效地为该树种遗传资源的科学保护与合理利用提供理论依据和科学指导，可为中国西南部亚高山天然林的可持续经营及退化生态系统的恢复与重建提供依据。主要研究结果如下： 1 STS和SSR两种分子标记的研究结果表明：川西云杉群体拥有中等水平的遗传多样性(基于SSR标记，平均He = 0.640；基于STS标记，平均He = 0.553)。造成这种中等水平的遗传多样性，可能是由于历史原因，川西云杉天然林被大量采伐，导致了遗传多样性的丧失。两种方法都检测出群体BT有着最高水平的遗传多样性。 2 两种标记的结果都一致说明：检测的10个川西云杉群体间遗传分化比较高，其存在群体间的遗传变异比例要明显地高于广泛分布的挪威云杉、横贯大陆的黑云杉以及兼有连续分布和不连续分布的西加云杉等，但要低于分布范围狭窄且呈不连续分布的粗枝云杉。青藏高原东南部的片段化生境可能是导致高水平遗传分化的主要原因。 3 基于两种标记的UPGMA 聚类和PCA分析结果，以及基于SSR标记的FCA分析结果都显示：群体BY遗传上明显区别于其它群体，其可能原因是青藏高原东南缘山脉阻隔而导致的生殖隔离的结果。 4 根据软件Bottleneck 1.2.02的检测以及不依赖哈迪一温伯格平衡的M比率检测结果：川西云杉种群很有可能经历了近期的遗传瓶颈效应。在本研究中遗传瓶颈效应并没有显著影响到物种的遗传多样性。然而，在这些片断化群体未来的子代群体中很可能出现遗传瓶颈导致的遗传多样性下降的效应。 Due to the extremely complex topography and climatic conditions, the southeast of the Qinghai-Tibet Plateau is region abundant in forest resource, which is benefit to the upper reaches of the Yangtze River water conservation, and protecting natural environment and biodiversity resources. However, by the reason of a plenty of trees were cut in these yeas, the biodiversity resource was destroy with degraded ecosystem and imperfect funcation. Picea balfouriana is one of the regionally distributed conifer species in the southeast of the Qinghai-Tibet Plateau and considered as a constructive species within its distribution area. It is an optimal species for the production of biomass. Moreover, it is well adapted to stressful environments at high altitude, especially to cold and drought conditions which are generally harsh for other trees. In our study, two types of molecular markers (SSR and STS) were used to estimate the genetic diversity and genetic structure of P. balfouriana populations originating from the southeast of the Qinghai-Tibet Plateau with varying climatic and geographical conditions. The results will not only provide a deep insight into its genetic diversity and population genetic structure but also valuable information for further management and breeding programs in P. balfouriana. In summary, the results obtained in this study revealed that: 1 A moderate degree of genetic variation is present in P. balfouriana in the southeast of the Qinghai-Tibet Plateau and it may caused by many trees were cut in the past. Population BT owns the highest level of genetic diversity by both two types of markers. 2 Considerable population differentiation exists among the ten P. balfouriana populations based on both SSR and STS markers, possibly caused by habitat fragmentation and heterogeneous environments. 3 The UPGMA clustering and PCA analyses based on SSR and STS marker, and FCA analyses based on SSR marker congruously separated population BY from other populations, which is likely due to the presence of mountain barriers. 4 The results of bottleneck analysis indicated that P. balfouriana populations that have undergone recent declines. In our research, the bottleneck effect don’t have a significant impact on the genetic diversity of species, however, the level of genetic diversity of P. balfouriana offspring populations growing in the fragmented habitats will decline in the future.