青藏高原东缘几种树苗对增强紫外线-B和氮供应的响应

大气臭氧的损耗导致了地球表面具有生物学效应的紫外线-B(UV-B)辐射增强。同时，大气成分变化中除了UV-B辐射增强外，氮沉降是一个新近出现而又令人担忧的环境问题，其来源和分布正在迅速扩展到全球范围，并不断向陆地和水生生态系统沉降。本试验在四川省境内的中国科学院茂县生态站内进行，以云山、冷杉、色木槭和红椋子幼苗为模式植物，从生长形态、光合作用、抗氧化能力和矿质营养等方面研究了青藏高原东缘4种树苗对全球变化－增强UV-B辐射和氮供应(氮沉降)的响应。该试验为室外盆栽试验，包括四个处理：(1)大气UV-B辐射+无额外的氮供应(C)；(2)大气UV-B辐射+额外的氮供应(N)；(3)增强UV-B辐射+无额外的氮供应(UV-B)；(4)增强UV-B辐射+额外的氮供应(UV-B+N)。其目的：一方面有助于丰富我国对全球变化及区域响应研究的全面认识，进一步完善在全球气候变化条件下臭氧层削减和氮沉降对陆地生态系统影响的内容；另一方面，在一定程度上有助于我们更好的理解在全球变化下森林更新的早期过程。具体结果如下： 增强的UV-B辐射在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有显著的影响。UV-B辐射增强对幼苗的影响不仅与物种有关，而且，还与氮营养水平相关。总体表现为，高的UV-B辐射导致了色木槭和红椋子幼苗叶片的皱缩和卷曲，并降低了色木槭幼苗的叶片数和叶重，在额外的氮供应下，云杉、冷杉和红椋子的叶重也显著地降低了；色木槭和红椋子幼苗叶片的解剖结构受到了增强的UV-B辐射的影响，增强的UV-B辐射显著地降低了色木槭叶片的栅栏组织厚度，提高了红椋子叶片的厚度；增强的UV-B辐射显著地降低了4种幼苗的单株总生物量、植物地下部分的生长、总叶绿素含量 [Chl (a + b)]、净光合速率和最大量子产量(Fv/Fm)，提高了4种幼苗叶片的膜脂过氧化(MDA含量)，改变了植物体不同器官中的矿质元素含量；增强的UV-B辐射提高了冷杉、色木槭和红椋子叶片中的过氧化氢含量(H2O2)、超氧负离子(O2-)生成速率，在额外的氮供应下，云杉叶片中的活性氧含量也显著地提高了；在无额外的氮供应条件下，增强的UV-B辐射显著地提高了4种幼苗叶片中的UV-B吸收物质、脯氨酸含量和抗氧化酶的活性(SOD、POD、CAT、GR和APX)。在额外的氮供应条件下，UV-B辐射的增强却显著地降低了冷杉叶片中脯氨酸含量和红椋子叶片中UV-B吸收物质含量，但是，在4种幼苗叶片中，5种抗氧化酶的活性对UV-B辐射的增强没有明显的规律性，增强的UV-B辐射显著地提高了云杉叶片中的POD、SOD和GR的活性，提高了冷杉叶片中的POD和GR活性，提高了色木槭叶片中的POD、SOD和CAT活性和红椋子幼苗叶片中的POD和SOD活性。从这些结果可知，植物在遭受高的UV-B辐射导致的过氧化胁迫时，植物体内形成了一定的保护机制，但是，这种保护不能抵抗高的UV-B辐射对植物的伤害。 额外的氮供应在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有一定的影响，不同幼苗对额外的氮供应响应不同，并且受到UV-B辐射水平的影响。在当地现有的UV-B辐射水平下，额外的氮供应显著地提高了幼苗的单株总生物量、植物地下部分的生长、Chl (a + b)、净光合速率(红椋子除外)、UV-B吸收物质(冷杉除外)、脯氨酸含量(红椋子除外)和部分抗氧化酶的活性，降低了H2O2的含量、O2-的生成速率和MDA含量(红椋子除外)，改变了植物体内部分矿质元素含量，显著地提高了云杉和冷杉叶片中的Fv/Fm。这些指标总体表明，在当地现有大气UV-B辐射水平下，额外的氮供应对植物的生长和发育是有利的。在增强的UV-B辐射水平下，4种幼苗的生长形态和光合大部分指标都没有受到额外氮供应的影响，额外的氮供应提高了红椋子幼苗的单株总生物量和Chl (a + b)含量，提高了冷杉和色木槭叶片中的活性氧含量和MDA含量，却降低了红椋子叶片中的活性氧含量；额外的氮供应也提高了云杉、色木槭和红椋子叶片中UV-B吸收物质和脯氨酸含量，降低了冷杉叶片中UV-B吸收物质和脯氨酸含量；在抗氧化酶活性方面，额外的氮供应降低了云杉、冷杉叶片中5种抗氧化酶的活性和红椋子叶片中POD和GR的活性，提高了色木槭叶片中的POD和SOD的活性；4种幼苗植物体内的矿质元素含量对额外的氮供应没有显著的规律性。从这些结果可知，在高的UV-B辐射下，额外的氮供应提高了云杉、冷杉和色木槭幼苗对高的UV-B辐射的敏感性，然而，额外的氮供应却促进了红椋子幼苗的生长，原因可能是，在高的UV-B辐射下，额外的氮供应增加了红椋子叶片的厚度、叶重和叶片数，降低了叶片中活性氧含量的结果。表明在高的UV-B辐射水平下，额外的氮供应降低了红椋子幼苗对高的UV-B辐射的敏感性。 在全球变化的趋势下，UV-B辐射增强和氮沉降可能同时存在，我们的研究表明，与大气UV-B辐射+无额外的氮供应处理相比，增强UV-B辐射+额外的氮供应处理显著地降低了幼苗的单株总生物量(红椋子除外)、Chl (a + b)、净光合速率、Fv/Fm(冷杉除外)和MDA含量(红椋子除外)，提高了活性氧含量 (云杉除外)、UV-B紫外吸收物质含量(冷杉除外)、脯氨酸含量和部分抗氧化酶的活性，改变了植物体不同器官中的矿质元素含量。结果表明，在当地现有条件下，全球变化(UV-B辐射增强和氮沉降)对云杉、冷杉和色木槭幼苗的生长是不利，尽管植物体内一些抗氧化性指标提高了，然而，却对红椋子幼苗的单株总生物量的累积没有显著的影响。 The depletion of the ozone led to the increase of ultraviolet-B (UV-B) with biological effects in the earth’s surface. At the same time, except for enhanced UV-B radiation, nitrogen deposition was an anxious environmental problem at present, rapidly expanding to the global scope and continuously depositing to land and aquatic ecosystem. The experiment was conducted in Maoxian Ecological Station of Chinese Academy of Sciences, Sichuan province, China. Picea asperata, Abies faxoniana, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings were selected as model plants to assess the effects of enhanced UV-B radiation and supplemental nitrogen supply on growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings in east Qinghai-Tibetan Plateau. The experiment was potted outdoor, including 4 treatments: (1) ambient UV-B without supplemental nitrogen (control, C); (2) ambient UV-B with supplemental nitrogen (N); (3) enhanced UV-B without supplemental nitrogen (UV-B); (4) enhanced UV-B with supplemental nitrogen (UV-B+N). One hand, it was helpful for enriching our country to comprehensive understanding of the researches in the global change and the region response, further perfecting the effects of the depleted ozone layer and nitrogen deposition on land ecosystem under the global change; the other hand, it was favorable for us to better understanding of the early process of forest renews under the global change. The results were as follows: Enhanced UV-B radiation had significant effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings. The effects of enhanced UV-B on plants were not only related with species, but also related with nitrogen nutrient level. Generally, the increase of UV-B radiation led to the shrinkage and curl of leaves in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, and reduced the number of leaf and leaf weight of Acer mono Maxim seedlings, under supplemental nitrogen supply, leaf weight of Picea asperata, Abies faxoniana and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings significantly also reduced; the anatomical features of leaf in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings affected by enhanced UV-B radiation, the increase of UV-B radiation markedly reduced the palisade tissue thickness of Acer mono Maxim leaf and enhanced the leaf thickness of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings; the enhanced UV-B radiation significantly reduced total biomass per plant of 4 species seedlings, the growth of the underground parts, Chl (a + b), net photosynthetic rate and maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA content) and changed the content of mineral elements in different parts of plants; the enhanced UV-B radiation also increased the rate of superoxide radical (O2-) production and hydrogen peroxide (H2O2) content in leaves of Abies faxoniana, Acer mono Maxim, Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, under supplemental nitrogen supply, the reactive oxygen species in leaves of Picea asperata seedlings also significantly increased by enhanced UV-B radiation; under without supplemental nitrogen supply, enhanced UV-B radiation evidently induced an increase in UV-B absorbing compounds, proline content and the activities of antioxidant enzymes (SOD, POD, CAT, GR and APX) of leaves in 4 species seedlings. Under supplemental nitrogen supply, enhanced UV-B radiation induced a decrease in proline content of leaves in Abies faxoniana seedlings and UV-B absorbing compounds of leaves in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, but, there were no obvious rules in the activities of five antioxidant enzymes of 4 species seedling leaves to enhanced UV-B radiation, enhanced UV-B radiation significantly increased the activities of POD, SOD and GR in Picea asperata leaves, the activities of POD and GR in Abies faxoniana leaves and the activities of POD, SOD and CAT in Acer mono Maxim leaves. The results indicated that some protective mechanism was formed when plants were exposed to enhanced UV-B radiation, but the protection could not counteract the harm of high UV-B radiation on plants. Supplemental nitrogen supply had some effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits. The response of 4 species seedlings was different to supplemental nitrogen supply, and was affected by UV-B levels. Under local ambient UV-B radiation, supplemental nitrogen supply significantly increased the total biomass per plant, the growth of underground parts, Chl (a + b), net photosynthetic rate (except for Acer mono Maxim seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and the activities of some antioxidant enzymes, and reduced H2O2 content, the rate of O2- production and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and changed the content of mineral elemental in different parts; supplemental nitrogen supply also evidently increased Fv/Fm in Picea asperata and Abies faxoniana seedlings. These results indicated that supplemental nitrogen supply was favorable for the growth of plants under local ambient UV-B radiation. Under enhanced UV-B radiation, mostly parameters in growth and morphology of 4 species seedlings were not affected by supplemental nitrogen supply. Supplemental nitrogen supply increased the total biomass per plant and Chl (a + b) of Swida hemsleyi (Schneid. et Wanger.) Sojak seedling, increased the reactive oxygen species and MDA content in Abies faxoniana and Acer mono Maxim leaves, and reduced the reactive oxygen species in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves; supplemental nitrogen supply also increased UV-B absorbing compounds and proline content in Picea asperata, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, decreased UV-B absorbing compounds and proline content in Abies faxoniana leaves; in the activities of antioxidant enzymes, supplemental nitrogen supply significantly reduced the activities of antioxidant enzymes in Picea asperata and Abies faxoniana leaves and the activities of POD and GR in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, and increased the activities of POD and SOD in Acer mono Maxim leaves; the content of mineral elements in 4 species seedlings was no significantly rule to supplemental nitrogen supply. We knew from the results, under enhanced UV-B radiation, supplemental nitrogen supply made Picea asperata, Acer faxoniana and Acer mono Maxim seedlings more sensitivity to enhanced UV-B radiation, however, accelerated the growth of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings. The reason was probably that supplemental nitrogen supply increased the leaf thickness, leaf weight and leaf number, reduced the reactive oxygen content of leaf in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings grown under high UV-B radiation. This showed that supplemental nitrogen supply reduced the sensitivity of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings to high UV-B radiation. Under the tendency of the global change, enhanced UV-B radiation and nitrogen deposition may probably coexist. The results showed, compared with the treatment of ambient UV-B radiation without supplemental nitrogen supply, the treatment of enhanced UV-B radiation with supplemental nitrogen supply significantly reduced the total biomass per plants (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), Chl (a + b), net photosynthetic rate, Fv/Fm and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), and increased reactive oxygen content (except for Picea asperata seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content and part antioxidant enzymes, and changed the content of mineral elements of different parts. The results indicated that the global change (enhanced UV-B and nitrogen deposition) were not favorable for the growth of plants under local ambient UV-B radiation and nitrogen nutrient level,, though increased some antioxidant indexes, however, the treatment of enhanced UV-B with supplement nitrogen supply did not significantly affect on the biomass accumulation of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings.

黄龙世界自然遗产地岷江冷杉原始林群落结构与植物多样性：生境差异性研究

黄龙世界自然遗产地岷江冷杉林(Abies faxoniana)生境类型多样，群落结构复杂，群落植物种类组成多样性丰富。揭示不同生境的生物多样性及其差异是认识生物多样性格局、形成及维持机制的前提和进行多样性保育的基础。本文采用样方法对黄龙钙化滩生境、阴坡非钙化生境及半阳坡非钙化生境的岷江冷杉原始林植物群落结构及植物多样性进行了研究。结果表明： 黄龙岷江冷杉林具有明显的复层异龄结构，垂直结构明显，乔木、灌木、草本、苔藓层次分明。共发现高等植物386 种，其中维管植物46 科103 属163 种，苔藓植38 科83 属物223 种。各层片结构及物种组成如下: (1)钙化滩生境、阴坡非钙化生境、半阳坡非钙化生境分别发现乔木18 种、13种、8 种。乔木层均可分为两个亚层，第一亚层优势种均为岷江冷杉，第二亚层主要为岷江冷杉异龄树或其它大高位芽物种。钙化滩生境第一亚层除优势种岷江冷杉外混生有巴山冷杉(Abies fargesii)、粗枝云杉(Picea asperata)以及阔叶树种白桦(Betula platyphylla)等，第二亚层主要为岷江冷杉异龄树；阴坡非钙化生境第一亚层除优势种岷江冷杉外间有巴山冷杉和白桦，第二亚层物种主要为川滇长尾槭(Acer caudatum var. prattii)；半阳坡非钙化生境第一亚层除优势种岷江冷杉外混生有巴山冷杉，第二亚层主要为岷江冷杉异龄树。依乔木层优势种的差异，钙化滩生境及半阳坡非钙化生境为岷江冷杉纯林，阴坡非钙化生境为岷江冷杉－川滇长尾槭混交林。不同生境乔木层郁闭度、乔木密度、树高结构、直径结构均存在差异。 (2)钙化滩生境发现灌木41 种，平均盖度为18.49±1.72(％)，平均高度为52.12±4.45(cm)，优势种为直穗小檗(Berberis dasystachya)；阴坡非钙化生境发现灌木30 种，平均盖度为29.33±2.56 (％)，平均高度为119.55±8.01 (cm)，优势种为箭竹 (Fargesia spathacea) 、唐古特忍冬(Lonicera tangutica) 和袋花忍冬(Lonicera saccata)；半阳坡非钙化生境发现灌木29 种，平均盖度为31.35±1.93 (％)，平均高度为107.55±4.24 (cm)，优势种为箭竹(Fargesia spathacea)。不同生境灌木层结构和物种组成多样性差异显著，钙化滩生境的灌木盖度、高度总体上较非钙化的坡地生境低, 钙化滩生境灌木以小型叶的落叶灌木为主，沟两侧非钙化的坡地生境上则发育了丰富箭竹。 (3)钙化滩生境发现草本46 种，平均盖度为7.18±0.79 (％)，平均高度为5.04±0.26(cm)，以山酢浆草(Oxalis griffithii)为优势种；阴坡非钙化生境发现草本物种71 种，平均盖度达29.04±2.31(％)，平均高度为9.08±0.52(cm)，以钝叶楼梯草(Elatostema obtusum)、山酢浆草为优势种；半阳坡非钙化生境草本物种50 种，平均盖度为以8.79±0.82(％)，平均高度为7.67±0.43 (cm)，以扇叶铁线蕨(Adiantum flabellulatum)、双花堇菜(Viola biflora)、华中蛾眉蕨(Lunathyrium shennongense)、山酢浆草为优势种。阴坡非钙化生境草本层片发育良好，多样性最为丰富，盖度和物种丰富度均显著高于钙化滩生境和半阳坡非钙化生境。 (4)钙化滩生境发现苔藓物种140 种，平均盖度达84.25±1.30 (％)，以仰叶星塔藓(Hylocomiastrum umbratum) 等大型藓类为优势种；阴坡非钙化生境发现苔藓物种115 种，平均盖度为79.29±1.64 (％)，以刺叶提灯藓(Mnium spinosum)、大羽藓(Thuidium cymbifolium)、毛尖燕尾藓(Bryhnia trichomitra)等个体较小的物种为优势种；半阳坡非钙化生境发现苔藓物种91 种，平均盖度为60.64±1.93 (％)，也以刺叶提灯藓为优势种。 (5)钙化滩生境、阴坡非钙化生境、半阳坡非钙化生境的物种数分别为234 种、221 种、175 种。乔木层的Shannon-Wiener 指数分别为0.75 ±0.12、1.87±0.12、1.78±0.07（灌木层，0.44±0.08、1.71± 0.15、2.49±0.06；草本层，0.33±0.13、1.31±0.15 、2.15±0.08； 苔藓层1.30±0.11、2.08±0.04、1.73±0.11，）；Pielou 均匀度指数分别为0.45±0.05、0.29±0.06、0.28±0.08（灌木层，0.75±0.03、0.68±0.05、0.52±0.06；草本层，0.68±0.02、0.77±0.02、0.74±0.02；苔藓层，0.40±0.03、0.63±0.02、0.52±0.03）；Simpson's 优势度指数分别为0.63±0.06、0.78±0.04、0.83±0.07（灌木层，0.21±0.03、0.28±0.05、0.45±0.06；草本层，0.25±0.02、0.12±0.01、0.17±0.01；苔藓层，0.45±0.04、0.18±0.01、0.31±0.04）。三种生境间乔木层、草本层的Sorenson 群落相似性系数较低, 灌木层、苔藓层的的Sorenson 群落相似性系数较高。 综上所述，黄龙岷江冷杉林的群落结构、植物多样性在三种生境间存在差异性，这将意味着我们在进行黄龙世界自然遗产地的森林经营管理时要较多地关注岷江冷山林群落在不同生境中的差异性。 There were multiplex habitat types, complicated community structure and abundant species composition in the Huanglong World Natural Heritage Site. Uncovering the differences of biodiversity among different habitats was a precondition to understand the distribution, formation and sustaining mechanism of the biodiversity, and the foundation of biodiversity conservation. In the present study, using plenty of quadrants, we investigated the community structure and the biodiversity of the primitive Abies faxoniana forest in different habitats (travertine bottomland, semi-sunny-slope non-calcified habitat and shady-slope non-calcified habitat) in the Huanglong World Natural Heritage Site. The main results are as follows: All the primitive Abies faxoniana forests in the three habitats were uneven-aged with obvious vertical structure including tree layer, shrub layer, herb layer and bryophyte layer. A total of 386 higher plants including 163 vascular plant species (103 generic, 46 families) and 223 bryophyte species (83 generic, 38 families) were investigated. The structure and species composition of each layer are as follows: (1) There were 18, 13 and 8 tree species in travertine bottomland, shady-slope non-calcified habitat and semi-sunny-slope non-calcified habitat, respectively. The tree layers in all habitats can be divided into two clear sub-layers. The upper tree layers were dominated by Abies faxoniana, and the lower tree layers were dominated by uneven-aged Abies faxoniana or other phanerophytes species. There were Abies fargesii , Picea asperata and Betula platyphylla besides the dominated species (Abies faxoniana) in the upper tree layer in travertine bottomland, and the lower tree layers were dominated by uneven-aged Abies faxoniana; There were Abies fargesii and Betula platyphylla besides the dominated species (Abies faxoniana) in the upper tree layer in shady-slope non-calcified habitat, and the lower tree layers were dominated by Acer caudatum var. prattii; There was Abies fargesii besides the dominated species (Abies faxoniana) in the upper tree layer semi-sunny-slope non-calcified habitat, and the lower tree layers were dominated by uneven-aged Abies faxoniana. According to composition percentage of dominate species in tree layer, both the forest in travertine bottomland and in semi-sunny-slope non-calcified habitat could be ranked as pure forest, and the forest in shady-slope non-calcified habitat could be ranked as mingled forest. There were significant differences in crown density, plant density, height structure and diameter structure among the three habitats. (2) A total of 41 shrub species (average coverage 18.49±1.72％; average height 52.12±4.45 ㎝)were found in travertine bottomland, and the dominate species was Berberis dasystachya; A total of 30 shrub species (average coverage 29.33±2.56 ％;average height 119.55±8.01 ㎝)were found in shady-slope non-calcified habitat, and the dominate species was Fargesia spathacea, Lonicera tangutica and Lonicera saccata. A total of 29 shrub species (average coverage 31.35±1.93％; average height 107.55±4.24 ㎝) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Fargesia spathacea. There were significant differences in structure and species diversity of the shrub layers among the three habitats. The coverage and height of shrub had lower value in travertine bottomland than in two non-calcified habitats. Moreover, travertine bottomland was dominated by deciduous shrub species with microphyll and non-calcified habitats developed abundant Fargesia spathacea species. (3) A total of 46 herb species (average coverage 7.18±0.79％;average height 5.04±0.26 ㎝)were found in travertine bottomland, and the dominate species was Oxalis griffithii; A total of 71 herb species (average coverage 29.04±2.31％;average height 9.08±0.52 ㎝)were found in shady-slope non-calcified habitat, and the dominate species was Elatostema obtusum and Oxalis griffithii. A total of 50 herb species (average coverage 8.79±0.82％;average height 7.67±0.43 ㎝) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Adiantum flabellulatum, Viola biflora, Lunathyrium shennongense and Oxalis griffithii. Herb layers developed well in shady-slope non-calcified habitat and had the higher species richness and coverage than travertine bottomland and semi-sunny-slope non-calcified habitat. (4) A total of 140 bryophyte species (average coverage 84.25±1.30％)were found in travertine bottomland, and the dominate species was big bryophyte species such as Hylocomiastrum umbratum and so on; A total of 115 bryophyte species (average coverage 79.29±1.64％)were found in shady-slope non-calcified habitat, and the dominate species was small bryophyte species such as Mnium spinosum, Thuidium cymbifolium, Bryhnia trichomitra and so on. A total of 91 bryophyte species (average coverage 60.64±1.93％) were found in semi-sunny-slope non-calcified habitat, and the dominate species was Mnium spinosum. (5) There were 234, 221 and 175 plant species in travertine bottomland, shady-slope non-calcified habitat and semi-sunny-slope non-calcified habitat, respectively. Shannon-Wiener index of the tree layer was 0.75 ±0.12, 1.87±0.12 and 1.78±0.07 (the shrub layer, 0.44±0.08, 1.71± 0.15 and 2.49±0.06; the herb layer, 0.33±0.13, 1.31±0.15 and 2.15±0.08; the bryophyte layer, 1.30±0.11, 2.08±0.04 and 1.73±0.11.) for the three habitats, respectively; Pielou index of the tree layer was 0.45±0.05, 0.29±0.06 and 0.28±0.08 (the shrub layer, 0.75±0.03, 0.68±0.05 and 0.52±0.06; the herb layer, 0.68±0.02, 0.77±0.02 and 0.74±0.02; the bryophyte layer, 0.40±0.03, 0.63±0.02 and 0.52±0.03.) for the three habitats, respectively. Simpson's index of the tree layer was 0.63±0.06, 0.78±0.04 and 0.83±0.07 (the shrub layer, 0.21±0.03、0.28±0.05、0.45±0.06; the herb layer, 0.25±0.02, 0.12±0.01 and 0.17±0.01; the bryophyte layer, 0.45±0.04, 0.18±0.01 and 0.31±0.04.) for the three habitats, respectively. There were low Sorenson index both in the tree layer and in the herb layer among the three habitats, whereas, high Sorenson index occurred both in the shrub layer and in the bryophyte layer. To sum up, there were differences both in community structure and plant diversity among the three different habitats, which means that we should pay more attention to habitats heterogeneities of the primitive Abies faxoniana forest when we take action to manage the forest in the Huanglong World Natural Heritage Site.

SULFUR IX TO XIII SPECTRAL MEASURMENTS BETWEEN 170 AND 500Å

This paper reports laboratory measurements of the spectrum of highly ionized sulfur. The spectrum of S Ⅸ–S ⅩⅢ has been observed in the wavelength range 170–500 Å. A total of 54 lines have been measured. Forty-two of them have been classified as 2s22pk–2s2pk+1and 2s2pk–2pk+1 transitions. Twelve other lines have been ascribed to 2s–2p,4p–5s,5p–6s,5d–6p, and 6p–8d transitions. These spectral lines have been identified, among which 22 are new and accurately measured. The analysis of the spectra was based on a comparison with other experimental results and calculated values.

铀矿坑水样中铀电沉积层的表征

描述了硫酸铵溶液中铀矿坑水样品中铀的电沉积层特性。电沉积液为10ml0.8M的硫酸铵溶液,电流密度0.6A/cm2,pH值为2.5,电镀1h。电沉积经化学分离后的水样品和电沉积的纯硝酸铀酰样品进行了比较,并对二者分别做了红外(IR)光谱、扫描电镜(SEM)、元素分析以及α能谱测量。IR谱上铀酰离子的反对称伸缩振动峰在887cm-1附近,使电沉积在不锈钢片上的铀主要以铀酰离子水合物的形式存在,有一部分NH4+以NH3的形式替代水合物中的水,使电沉积层中铀的化合物形式为UO2(OH)2.xNH3.yH2O或者UO2(OH)2-x.(ONH4)x.yH2O,铀酰离子通过链的形式形成聚合结构。SEM照片显示电沉积层均匀,没堆积成团现象出现。α谱表明电沉积层中铀的同位素主要是238U和234U,相应的α能量峰4198和4773keV很显著,没其它峰的干扰。

电子辐照PVA/CMC共混水凝胶的成胶研究

本试验利用电子辐照PVA/CMC共混水凝胶,通过外观透明度、凝胶分数、溶胀度和红外光谱分析,研究了样品中结构的变化与外观透明度、凝胶分数和溶胀度的关系,以及辐照剂量对样品中结构和性能的影响。结果表明,不同比例的PVA与相同比例的CMC组成的共混水凝胶,经电子辐照后呈现不同的宏观特性。辐照样品萃取后得到的凝胶比萃取前的混合凝胶拥有更强的吸水性,表明辐照PVA/CMC共混凝胶形成了网状结构凝胶。几种竞争反应导致不同辐照剂量下混合凝胶中凝胶含量随PVA含量的变化变得复杂。辐照后样品的红外光谱分析显示,辐照使凝胶中部分仲醇中C上链接的H原子被取代而转变为叔醇,从而产生交联。

Mid-Holocene climate variations recorded by palaeolake in marginal area of east Asian monsoon: A multi-proxy study

IEECAS SKLLQG

Late Neogene rock magnetic record of climatic variation from Chinese eolian sediments related to uplift of the Tibetan Plateau

IEECAS SKLLQG

~(265)Bh(Z=107)同位素的首次观测

在兰州的重离子加速器上用 2 6Mg离子束轰击 2 43 Am靶 ,产生了新同位素 2 65Bh .通过观测新同位素 2 65Bh和它的已知子核 2 61Db和 2 57Lr之间的α衰变的关联 ,实现了对新核素的鉴别 .实验中使用了一套新建立的具有数个探测器对的转轮收集探测系统 .将该系统用于特殊的母 -子核搜索模式 ,从而大大减少了本底 .共测得了 8个 2 65Bh的α衰变关联事件 ;同时 4个已知核 2 64Bh的衰变关联事件也被鉴别出来 .实验测得 2 65Bh的α衰变能量为 (9.2 4± 0 .0 5 )MeV ,半衰期为 0 .94 + 0 .70-0 .3 1s .

自旋极化的对称核物质和中子物质的性质

利用Skyrme有效相互作用对自旋极化的同位旋对称核物质和中子物质的特性进行了研究 .用 4种核子 -核子相互作用参数SⅢ ,SKM ,SLy2 30a和SLy2 30b ,分别描绘了核物质状态方程曲线 .可以发现不论使用哪一种参数 ,在自旋极化的同位旋对称核物质和中子物质中都存在着磁化相变转换点 .另外还对磁化系数进行了计算 ,给出了磁化系数比率随密度的变化关系 ,由于无限不连续点的存在 ,进一步肯定了在Skyrme Hartree Fock理论框架内两种物质会出现磁化相变转换点