氮沉降增加对森林土壤碳氮过程影响的试验研究

化石燃料的燃烧、农业施肥及森林破坏等人类活动引起了大气CO2浓度和氮沉降量的增加。研究发现氮沉降的增加使一些森林生态系统结构和功能发生改变，甚至衰退。全球氮沉降、CO2浓度升高的背景下，氮素对生态系统碳氮周转过程的影响开始越来越引起人们的关注，同时作为陆地生态系统碳库和氮库重要组成部分的森林土壤，也逐渐成为全球变化研究的重点。 本研究以长白山原始阔叶红松林和杨桦次生林为研究对象，自2006年起，采用人工施氮方式，实地模拟氮沉降增加对森林土壤碳氮元素周转过程的影响，其试验研究结果能够为系统评估区域森林生态系统对氮沉降增加的响应提供科学依据。主要试验研究结果如下： （1）氮沉降增加促进了杨桦次生林叶和根的初期分解，对后期分解的影响则不显著。 （2）氮沉降增加促进了阔叶红松林和杨桦次生林的土壤呼吸，主要源于根呼吸对氮沉降增加的响应。不同氮处理下土壤呼吸速率与5 cm地温均呈显著幂指数相关关系。 （3）氮沉降增加提高了土壤氮素转化速率，不仅显著增加了土壤氮矿化量、硝化量及N2O的释放，也显著增加了土壤铵态氮和硝态氮的含量，且随氮处理水平的增加促进效果更加显著。 （4）树干径流中铵态氮、硝态氮、DON、DOC的含量高于穿透雨和大气降水，氮沉降增加对土壤溶液和地表径流的影响不显著，因土壤溶液和地表径流对氮沉降的响应还受降水强度、降水水量及施氮时间等影响，变异性较大。 （5）氮沉降增加使阔叶红松林微生物生物量增加，而使杨桦次生林微生物生物量减少。氮沉降增加均提高了两种林型土壤微生物的C/N。 （6）不同氮处理均使阔叶红松林纤维素酶和蔗糖酶活性升高，多酚氧化酶活性降低；低氮处理使杨桦次生林多酚氧化酶、纤维素酶和蔗糖酶活性升高，但高氮处理随施氮时间的延长有降低3种酶活性的趋势。

林木及林下土壤N<,2>O排放的研究

N<,2>O是一种重要的温室气体.该研究以中国长白山典型的森林生态系统——阔叶红松林为研究对象，采用空气样品同步采样法和封闭罩法首次对几种主要树木——水曲柳、红松、赤杨（阳生树木）和椴树（阴生树木）的N<,2>O释放进行了较为系统的研究，同时对林下土壤N<,2>O排放进行了实验室模拟实验.获得以下主要研究结果：1.首次确证在自然状态下，林木是森林生态系统中除土壤外的另一重要N<,2>O排放源.2.首次发现光照对阴生树木与阳生树木N<,2>O释放的调节作用不同.3.首次在野外自然条件下，对林木的N<,2>O排放通量进行了测定，并估算了其年排放总量.4.发现在一定条件下，土壤N<,2>O排放和CH<,4>吸收与土壤pH和温度呈正相关.

Effect of Nozzle Temperature on the Performance of a 1 kW H2-N2 Arcjet Thruster

A 1 kW-class arcjet thruster was ¯red in a vacuum chamber at a pressure of 18 Pa. A gas mixture of H2 : N2 = 2.8 : 1.5 in volume at a total °ow rate of 4.3 slm was used as the propellant with an input power ¯xed at 860 W. The time-dependent thrust, nozzle temperature and inlet pressure of the propellant were measured simultaneously. Results showed that with the increase in nozzle temperature the thrust decreased and various losses increased. The physical mechanisms involved in these effects are discussed.

禄春安息香种子和攀援孔药花全草的化学成分研究

本文对禄春安息香（Styrax macranthus）种子和攀援孔药花（Porandra scandens）全草的化学成分进行了研究，共获得30个化合物，其中2个为新化合物。 从禄春安息香种子95%乙醇提取物中分离并鉴定了12个化合物，其中2个新化合物鉴定为3-[7-methoxy-2-(3,4-methylenedioxy phenyl) benzofuran-5-yl] propyl 3-[7-methoxy-2-(3,4-methylenedioxyphenyl)benzofuran-5-yl] propanoate (1) 和去甲氧基-egonol-龙胆双糖甙 (2)；已知化合物分别为2-(3,4-二氧亚甲基苯基)-5-甲酰基-7-甲氧基-苯并呋喃 (3)、egonol (4)、去甲氧基-egonol (5)、去甲基-egonol (6)、egonol-葡萄糖甙 (7)、egonol-龙胆双糖甙 (8)、egonol-龙胆三糖甙 (9)、豆甾醇 (10)、二十四烷酸 1-甘油酯 (11) 和胡萝卜甙 (12)。生物活性测试发现，化合物2具有促进雌激素E2合成的作用。 从攀援孔药花全草95%乙醇提取物中分离并鉴定了19个化合物：(2S,3S,4R)-2-[(2R)-2-羟基-二十一烷酰基氨基]-二十一烷-1,3,4-三醇 (13)、(2S,3S,4R)–2–二十四烷酰基氨基-十八烷-1,3,4-三醇 (14)、胡萝卜甙 (12)、β-谷甾醇 (15)、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇 (16)、6β-羟基-豆甾-4-烯-3-酮 (17)、十六烷酸 1-甘油酯 (18)、桦木酸 (19)、大黄素 (20)、二十二烷酸 1-甘油酯 (21)、对羟基苯甲醛 (22)、十七烷酸 1-甘油酯 (23)、金色酰胺醇乙酸酯(24)、十九烷酸 1-甘油酯 (25)、棕榈酸 (26)、(E)-p-香豆酸 (27)、(22E,24S)-24-麦角甾醇-7,22-二烯-3β,5α,6β-三醇 (28)、2-去氧-β-蜕皮激素 (29)和auranamide (30)。 综述了近十年来发现的2－芳基苯并呋喃类新木脂素的结构特征、来源、生物活性和化学全合成。 Phytochemical investigation on the seeds of Styrax macranthus and the whole plants of Porandra scandens led to the isolation of thirty compounds, two of which were new ones. Two new 2-aryl benzofuran derivatives, 3-[7-methoxy-2-(3,4-methylenedioxy phenyl) benzofuran-5-yl]propyl 3-[7-methoxy-2-(3,4-methylenedioxyphenyl)benzo furan-5-yl]propanoate (1) and demethoxy egonol gentiobioside (2), were isolated from the 95% aqueous ethanolic extract of the seeds of Styrax macranthus, together with 7-methoxy-2-(3,4-methylenedioxyphenyl) benzofuran-5-carbaldehyde (3), egonol (4), demethoxy egonol (5), demethyl egonol (6), egonol glucoside (7), egonol gentiobioside (8), egonol gentiotrioside (9), stigmasterol (10), 2,3-dihydroxypropyl tetracosoate (11), and daucosterol (12). In vitro test, compound 2 promote the synthesis of estrogen E2. Nineteen compounds were isolated from the 95% aqueous ethanolic extract of the whole plant of Porandra scandens for the first time. Their structures were identified as (2S,3S,4R)-2-[(2R)-2-hydroxy-heneicosanoylamino]-1,3,4- heneicosanetriol (13), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (14), daucosterol (15), β-sitosterol (12), (20S,22E,24R)-5α,8α-epidioxy-ergosta-6,22-diene- 3β-ol (16), 6β-hydroxylstigmast-4-en-3-one (17), 1-glycerol-1-hexadecoate (18), betulinic acid (19), emodin (20), 1-glycerol-1-docosoate (21), p-hydroxybenzaldehyde (22), 1-glycerol-1-heptadecoate (23), aurantiamide acetate (24), 1-glycerol-1- nonadecoate (25), palmatic acid (26), (E)-p-coumaric acid (27), (22E,24S)- 24-metbylcbolesta-7,22-diene-3β,5α,6β-triol (28), 2-deoxycrustecdysone (29), and auranamide (30). The characteristic, natural resource, bioactivity, and the total synthesis of 2-aryl benzofurans were reviewed.

钮子瓜和袋花忍冬的化学成分研究

钮子瓜（Zehneria maysorensis Arn.）是一种常用的中草药，其性味苦、凉，主要功效为清热利湿、散风止痛，主治膀胱炎、头痛。体外活性筛选实验表明，袋花忍冬（Lonicera saccata Rehd.）95%乙醇提取物的乙酸乙酯部分对血管紧张素转化酶显示较强的抑制活性。为明确钮子瓜的药用物质基础和袋花忍冬中具有ACE抑制活性的成分，首次对两个植物的成分进行了研究。 1. 从钮子瓜95%乙醇提取物中主要通过色谱方法首次分离了14个化合物，通过波谱方法鉴定为(2S,3S,4R,10E)-2-[(2R)-2-羟基二十四烷酰基氨基]-10-十八烷-1,3,4-三醇（1）、(2S,3S,4R)-2-二十四烷酰基氨基-十八烷-1,3,4-三醇 （2）、胡萝卜苷（3）、swertish （4）、苯甲酸（5）、水杨酸（6）、loliolide （7）、胸腺嘧啶（8）、尿嘧啶（9）、(23Z)-9,19-环阿尔廷-23-烯-3β,25-二醇（10）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、大豆脑苷Ⅰ（13）和(22E,24S)-24-甲基-5α-胆甾-7,22-二烯-3β,5α,6β-三醇（14）。其中化合物4为一黄酮碳苷，具有旋转异构现象，有止痛作用；化合物6具有抗炎、镇痛、减热的活性，它们可能是钮子瓜药用物质基础的一部分。 2. 从袋花忍冬95%乙醇提取物中首次分离并鉴定了16个已知化合物：胡萝卜苷（3）、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇（11）、十六烷酸 1-甘油酯（12）、E-p-coumaryl behenate (15)、谷甾醇（16）、2,6-dihydroxyhumula-3(12), 7(13),9(E)-triene (17)、环阿尔廷-25-烯-3β,24ξ-二醇 (18)、二十四烷酸 (19)、2,4-二羟基-3,6-二甲基苯甲酸甲酯 (20)、乌苏酸 (21)、柚皮素 (22)、木犀草素 (23)、柏双黄酮（24）咖啡酸 (25)、洋芹素（26）和木犀草素-7-O-β-D-葡萄糖苷 (27)。其中木犀草素（23）和咖啡酸（25）含量较高，它们为抑制ACE活性的成分。 3．综述了黄酮碳苷的旋转异构现象。 Zehneria maysorensis is a folk medicine for the treatment of cystitis and headache. The ethyl acetate soluble fraction of the 95% ethanol extract of Lonicera saccata showed obvious ACE inhibitory activity in vitro. To reveal their active constitutents, they were subjected to chemically study. From the 95% ethanol extract of the whole plants of Zehneria maysroensis fourteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were characterized to be (2S,3S,4R,10E)-2-[(2R)-2-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (1), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (2), daucosterol (3), swertish (4), benzoic acid (5), salicylic acid (6), loliolide (7), thymine (8), uracil (9), (23Z)-9,19-cycloart-23-ene-3β,25-diol (10), (20S,22E,24R)-5α,8α-epidioxy-ergosta- 6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), soya-cerebroside (13) and (22E,24S)-24-methyl-5α-cholesta-7,22-diene-3β,5α,6β-triol (14). Compound 4, a C-glycosylflavone, showed a very interesting rotational isomerism. Compounds 4 and 6 may be the active constituents of Zehneria maysorensis considering their sedative and anti-inflammation activity, respectively. From the whole plants of Lonicera saccata, sixteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were identified to be daucosterol (3), (20S,22E,24R)-5α,8α-epidioxy- ergosta-6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), E-p-coumaryl behenate (15), β-sitosterol (16), 2,6-dihydroxyhumula-3(12),7(13),9(E)-triene (17), cycloart-25-ene-3β,24ξ-diol (18), tetracosanoic acid (19), methyl 2,4-dihydroxy- 3,6-dimethylbenzoate (20), ursolic acid (21), naringenin (22), luteolin (23), cupressuflavone (24), caffeic acid (25), apigenin (26) and luteolin-7-O-β-D- glucopyranoside (27). Luteolin (23) and caffeic acid (25) were the ACE inhibitory active constituents. Rotational isomerism for C-glycosylflavonoid was reviewed.

川西亚高山云杉人工林天然更新与生境异质性研究

川西亚高山针叶林是四川森林的主体，是长江上游重要的生态屏障。云杉作为亚高山针叶林人工更新的主要树种，已经在该地区形成了大面积的人工纯林。目前，许多云杉人工林分已经进入更新成熟龄，而这些人工林的持续更新却成为日益凸现的问题。探讨这些云杉人工林的自我更新潜力及云杉种子种群更新特点，可为培育后续森林资源提供科学依据。 本文以川西米亚罗亚高山60a云杉人工林为研究对象，并以该区域内相对稳定的植被群落——天然林为对照，采用种子收集器、土壤种子库筛选、室内外种子萌发实验及野外幼苗调查等方法，从异质性微生境的角度研究了种子雨下落之后，不同微生境对种子库、种子萌发、幼苗建立及分布这一前期更新过程的影响，得出如下结果： 1、通过对川西亚高山60a云杉人工林和天然林6年内种子雨雨量、形态特征、散步动态等的持续观测和综合比较可以发现，云杉林结实特点由于林木自身的特征存在着巨大的变动，2002年和2006年两个种子结实大年内，60a人工林种子雨强度分别达到1088.2 ± 52.3粒/m2和704.3 ± 48.9粒/m2，远大于天然林579.9 ± 28.9粒/m2 和507.5± 30.7粒/m2；且云杉林结实质量优于天然林。60a人工林结实量大，种子质量也最好，相对天然林来说对种群的天然更新以及群落的演替都有最大的贡献潜力。应该说，在川西亚高山云杉人工林的天然更新过程中，种源不是影响天然更新的因素。在种子结实大年里，达到更新成熟的云杉人工林有着优于该地区相对稳定植被群落——天然林的种源优势。至少在种子结实大年，种子供应不是该区域人工林天然更新的限制因子。 2、相对于天然林种子库，人工林种子库在种子萌发前能够有较多的有活力种子。虽然这其中有种子雨输入量有差别的因素存在，但两种林分种子库对种子的保存率的不同才是造成这种差异的主要因素。在人工林中，不同地被类型形成的微生境显著地影响了种子库中种子的密度、垂直分布。有地被物存在的微生境能够将种子雨的大部分截留在地被层中，成为幼苗出现的主要场所；同时不同的地被物对种子的保存情况存在显著的差异，苔藓和凋落物层能都较好地保持其中的种子，到种子萌发前，这两种种子库类型能分别为天然更新提供366.1粒/m2和302粒/m2的有效种子。从这点来看，林下地被物上的种子库能够为天然更新萌发阶段提供数量可观的物质基础。 3、种子的萌发和幼苗的定居是天然更新过程中种子库向幼苗库转化的关键环节。总的说来，米亚罗人工林区60a云杉人工林种子向幼苗的转化率十分低下，凋落物、苔藓、草本、裸地四种主要地被物以及天然林内种子/幼苗的转化率分别仅为2.22%、2.14%、0.57%、0.67%、1.05%。这种低的转化率成为云杉林天然更新的限制性因子。但在现有更新条件下，微生境对这一环节仍然显示出十分显著的影响，表现为凋落物和苔藓对现有更新的新幼苗的保存率高于其它类型及天然林。苔藓和凋落物在种子萌发，幼苗保存，以及幼苗分布上都要优于其它地被物类型；另外，微地形对天然更新过程的影响也很显著，凹立地上更适宜于种子的汇集、萌发和定居。 Subalpine coniferous forests dominate most parts of the forested areas in western Sichuan, and they are important ecological barriers in the upper reaches of the Yangtze River. Picea asperata is one of the keystone spruce species for re-afforestation after felling of the natural forests and there have been a total of ca. 13 000 ha of plantations dominate by this species established. Nowadays, many P. asperata plantations have reached reproductive maturity. However, continued regeneration becomes to an important problem in these plantations. Understanding their self-regeneration potential and the regeneration characteristics of seed populations in spruce plantations of these plantations can have some insights on the management of these plantations and the establishment of following forest resources. A subalpine 60a P. asperata plantation distributed in Miyaluo artificial forest area was studied in this paper, at the same time. Synchronously, a 150a natural spruce forest was studied as comparison. Using seed collecting traps, sieving method for soil seed bank, seed germination experiments and seedling investigations in the field, the effects of heterogeneous microsites on early natural regeneration processes after seed rain were studied, which included seed banks, seed germination, seedling establishment and distribution. The main results are as follows. 1. Through a 6-year long term investigation of seed rain intensities, characteristic, dispersal dynamics of 60a P. asperata plantation, we could concluded that the seed setting properties of 60a P. asperata plantation have a great variation for the characteristics trees. In the mast seed year of 2002 and 2006, the seed rain intensities of plantation was 1088.2 ± 52.3 seeds/m2 and 704.3 ± 48.9 seeds/m2 respectively, which were much greater than that of natural spruce forest (579.9 ± 28.9 seeds/m2 in 2002, and 507.5± 30.7 seeds/m2 in 2006). Furthermore, the quality of seed rain in P. asperata plantation was better than that of natural spruce forest. Contrasting with natural spruce forest, 60a P. asperata plantation has a greater potential on natural regeneration of P. asperata population and succession of community for the reason of greater seed rain intensities and better seed quality. We can confirm that seed source was not a limiting factor which influences the natural regeneration progress of P. asperata population distributed in subalpine mountain zone, at least in the mast seed year. 2. Contrasting with natural spruce forest, P. asperata population had more viable seeds in seed bank before the germination. Although the difference of seed rain intensities of two forests has effect on this phenomenon, the difference of seed conservation ability in two forests was the main factor. In the P. asperata plantation, the seed densities and seed vertical distribution pattern were significant effected by the microsites, which posed by different ground cover types. In other word, Microsite with ground covers can obstruct most seeds and keep them in ground cover layer from seed rain, and these ground covers would be the main site for seed occurrence. There was a significant difference about seeds conservation ability among these ground covers. Litter and moss could better conserve P. asperata seeds which distributed in this two covers. Seed banks exist in litter and moss ground cover types could respectively provide 302seed/m2 and 366.1seed/m2 for natural regeneration before the seed germination. From this point of view, we could conclude that ground covers can ensure considerable numbers of seeds for the germination process. 3. Seed germination and seed establishment are key steps that the seeds invert to seedlings in natural generation process. In sum, the seed/seeding transform rate in 60a P. asperata plantation distributed in Miyaluo artificial forest area is very low. the seed/seeding transform rates in litter, moss, herb, soil surface and natural spruce forest were 2.22%、2.14%、0.57%、0.67%、1.05%, respectively. The low transform rate become to a limiting factor of P. asperata natural regeneration process. However, under the existing conditions of natural regeneration, microsit still had significant effect on this transform. The states of Seed germination, new seedling conservation, and older seedling distribution in litter and moss were better than in any other ground cover type or natural spruce forest. In addition, the micro-relief has significant effect on natural regeneration process. Concave site was more suitable for seed collection, seed germination and seedling distribution.