森林溪流倒木生态学研究进展

溪流倒木是指在河流中长度大于1 m、直径大于10 cm的死木。溪流倒木在森林河流中(特别是较小的河流中)是一个常见且重要的结构成分。该文综述了近30年溪流倒木的研究成果(主要来自北美),总结溪流倒木在河流形态、碳循环、泥沙与养分拦截、水生生境的形成、水生生物多样性等方面的生态功能,倒木的时间动态性与空间变异性,以及干扰(包括自然干扰与人为干扰)与倒木存留量及分布的关系。此外,该文也探讨了溪流倒木的生态管理模式及未来研究方向。大量的研究证明,溪流倒木对森林水生生态系统具有重要的生态功能,但它的存留量、分布以及它的生态意义因所研究的森林生态系统、河流大小不同而异。随着河流宽度的增加, 倒木的存留量及它对河流的影响减少,并且倒木的分布以单个为主变为聚集体为主。单个倒木的直径则随河流宽度增加而增大。倒木也呈现十分明显的时间动态性,而这种动态往往是由大规模毁灭性的森林干扰(火、风倒等)所驱动的。研究倒木的时空变异性及自然干扰与人为干扰对倒木的不同影响对于保持倒木的生态功能是十分必要的。该文还对中国开展溪流倒木的生态研究提出一些建议。     

大小兴安岭针叶树倒木上木腐真菌的物种多样性

木腐真菌在森林生态系统中具有丰富的物种多样性, 并在倒木的降解过程中发挥重要的生态功能。针叶树是大小兴安岭森林生态系统的优势树种, 因此研究针叶树倒木木腐真菌物种多样性和影响其物种分布的相关环境因子有助于揭示大小兴安岭森林生态系统物质循环的机理。本研究收集了近16年对大小兴安岭地区冷杉属(Abies)、落叶松属(Larix)、云杉属(Picea)和松属(Pinus) 4类针叶树倒木上1,561份木腐真菌标本的采集信息, 统计了物种种类及其腐朽类型, 并选取具有代表性的地点开展木腐真菌群落多样性及其与环境因子的相关性分析。结果显示, 大小兴安岭针叶树倒木木腐真菌有166种, 隶属于70属, 其中白腐真菌有111种, 占所有种类的66.9%, 褐腐真菌为55种, 占所有种类的33.1%。在4类针叶树倒木上均能生长的真菌种类有19种, 占所有种类的11.5%, 其中柔丝干酪孔菌(Oligoporus sericeomollis)是各类倒木上木腐真菌群落中的优势种。大兴安岭地区落叶松属为优势寄主, 其倒木上生长的木腐真菌种类数和个体数在4类倒木中均为最高; 而小兴安岭地区松属倒木上木腐真菌种类数和个体数比其他3类倒木高, 是该地区的优势寄主。对6个代表性地区木腐真菌群落的研究显示, 有11种真菌在6个地区均有分布, 小兴安岭地区木腐真菌多样性普遍高于大兴安岭地区; 聚类分析显示树种比地理位置对木腐真菌物种分布的影响更大。     

粗木质物残体生态研究历史、现状和趋势

粗木质物残体(Coarse Woody Debris,简称CWD)是森林生态系统或溪流生态系统中残存的一定直径大小的站杆(snag)、倒木、枝桠及根系等死木质物的总称,倒木往往是     

强度干扰后退化森林生态系统中保留木的生态效应研究综述

保留木是指森林生态系统受到强度干扰后所存留的树木,保留木对退化森林生态系统结构与功能的维持和恢复具有多方面的生态效应。在生态系统的尺度上总结了退化森林生态系统中保留木的各种生态效应,主要包括保留木对非生物因子和生物因子(附生生物多样性、动物活动和动物多样性、树木更新、空间结构)的影响。森林生态系统经营中,"绿树保留"的经营方式是基于保留木生态效益的实践应用,它可有效减少采伐对生态系统结构和功能所造成的损失。并将有助于深入理解受到强度干扰后森林生态系统中保留木的多种生态效应,可为退化森林生态系统的恢复与重建提供理论依据。     

森林生态系统中木腐真菌群落形成机理及生态功能

在森林生态系统中,枯死木是一个重要的组成部分,为很多生物提供栖息地,有助于养分循环以及碳和水的储存.木材分解是森林生态系统养分循环、土壤形成和碳收支的决定性过程,越来越受到森林生态学家、病理学家和管理者的重视.在此过程中,木腐真菌通过分泌多种酶降解木材主要成分,实现生态系统中的物质循环,具有极为关键和重要的作用.木腐真...     

溪流粗木质残体的生态学研究进展

粗木质残体（CWD）是森林或溪流生态系统中残存的超过一定直径大小的站杆、倒木、枝桠及根系等死木质物的总称,溪流CWD对于溪流生态系统的稳定,水生生物多样性,河槽形态及其变化过程有着重要的作用。对溪流CWD的产生和分类,溪流CWD对于溪流生态系统的稳定,水生生物多样性,河槽形态及其变化过程有着重要的作用。对溪流CWD的产生和分类,溪流CWD贮量,分布和动态,以及溪流CWD的功能和管理分别进行了总结,并指出应尽快在国内开展溪流CWD的研究和管理。     

天宝岩长苞铁杉林倒木接触处土壤酶活性变化及其环境效应

倒木是森林生态系统中重要的结构性和功能性成分,但分解过程十分缓慢,目前有关土壤生物学特性对其分解影响机制的研究甚少。通过分析环境因子对选择天宝岩国家级自然保护区长苞铁杉林内倒木接触处土壤酶活性的影响,探讨酶活性对倒木分解机制、土壤进程的影响及特定酶活性的时空分布格局。研究结果表明:天宝岩长苞铁杉林内倒木接触处土壤酶活性的变异系数属中高等变异程度,纤维素分解酶活性受环境影响最大,蛋白酶受影响最小;倒木的覆盖有利于提高土壤酶活性,尤其是显著地提高了纤维素酶活性,蛋白酶及脲酶活性随腐烂等级升高而降低,纤维酶活性呈升高趋势;在所有环境因子中,土壤基质环境对土壤酶活性的解释量最大,表明化学基质环境对土壤酶活性的影响不容忽视,土壤酶活性随土壤SOC、TN含量的增加而升高,随海拔升高而降低,越往南坡,土壤酶活性越高。研究揭示倒木分解与土壤酶活性之间相互促进、相互制约,倒木的存在对驱动森林生态系统的碳循环有重要意义。     

青藏高原东缘高寒森林小型兽类地表洞穴选择与生境特征

高寒森林地表的小型兽类洞穴是生态系统重要的景观特征,对于认识小型兽类的分布格局及其生态功能具有重要意义.为此,以青藏高原东缘典型高寒森林生态系统小型兽类洞穴为对象,于2015年夏季(7—9月)研究了其地表分布与生境特征.结果表明: 小型兽类洞穴平均洞口密度为182.8个·hm^-2,不同森林植被类型显著影响洞穴密度,表现为针叶林(328.6个·hm^-2)>针阔混交林(160.0个·hm^-2)>灌木林(125.0个·hm^-2)>阔叶林(81.5个·hm^-2)>竹林(66.7个·hm^-2). Mann-Whitney U Test和主成分分析表明,小型兽类栖息样地的乔木郁闭度、乔木均高、乔木胸径、乔木密度、地表植被盖度、倒木密度、倒木覆盖度、灌木均高都显著大于非栖息样地;乔木因子是决定小型兽类生境选择的首要因子,贡献率最大(44.8%),其次是倒木因子(23.2%)和灌草丛因子(13.9%).说明高寒森林地表有明显的小型兽类洞穴分布,其分布格局主要受植被和倒木的影响.     

高山森林林窗和生长基质对苔藓植物氮和磷含量的影响

苔藓在森林生态系统养分富集和循环方面有重要作用,苔藓植物在氮磷循环中的作用可能受到森林更新和生长基质的影响.为理解苔藓在森林生态系统养分循环中的作用,研究了高山森林不同位置(林窗中心、林窗边缘、林下)和不同生长基质(活立木、倒木、枯立木、大枯枝、根桩、地表)上的苔藓植物氮磷含量.结果表明:地表苔藓氮含量(3.12 mg·g^-1)显著低于其他生长基质上的苔藓,尽管枯立木附生苔藓氮含量高达17.41 mg·g^-1,但倒木、大枯枝、枯立木和活立木苔藓氮含量差异不显著;最高(1.09 mg·g^-1)和最低(0.61 mg·g^-1)的磷含量分别出现在森林地表和枯立木的苔藓,且森林地表的苔藓磷含量显著高于其他生长基质上的苔藓,但倒木、大枯枝、根桩和活立木上的苔藓磷含量差异不显著.林窗位置显著影响了倒木和大枯枝上的苔藓氮、磷含量,林窗内倒木和大枯枝上的苔藓氮、磷含量显著高于林窗边缘.粗木质残体的类型、腐烂等级对苔藓氮、磷含量的影响存在差异,两者交互作用的影响显著;第Ⅴ腐烂等级倒木上的苔藓氮含量显著高于其他腐烂等级;第Ⅲ腐烂等级大枯枝上的苔藓氮含量显著高于其他腐烂等级;第Ⅱ腐烂等级倒木上的苔藓磷含量显著高于其他腐烂等级;第Ⅳ腐烂等级枯立木上的苔藓磷含量显著高于其他腐烂等级.可见,森林林窗更新和粗木质残体腐解过程会影响苔藓植物的氮、磷含量,同时影响森林生态系统的养分循环过程.     

丰林国家级自然保护区木腐真菌多样性与寄主倒木的关系

木腐真菌是一类以木材为生长基质的大型真菌, 通过分泌各种水解酶全部或部分降解木材中的木质素、纤维素和半纤维素, 促进森林生态系统的物质循环, 具有重要的生态功能。本研究调查了丰林国家级自然保护区固定样地中木腐真菌的多样性和倒木特征, 并进行了木腐真菌的物种多样性和数量与倒木的种类、数量、腐朽程度、直径大小等的相关性分析。结果显示: 在样地内共采集木腐真菌标本295份, 经鉴定为93种, Shannon多样性指数为3.86, Simpson指数为0.96。相关性分析发现木腐真菌的数量和种类与直径为2-5 cm和5-10 cm的倒木、2级腐烂的倒木和红松倒木均显著相关。样地中优势倒木寄主分别为槭属(Acer)、榛属(Corylus)、云杉属(Picea)和松属(Pinus), 这4类倒木上生长的木腐真菌种类组成具有明显的差异, 槭属和榛属倒木上的共有优势种主要是三色拟迷孔菌(Daedaleopsis tricolor)、云芝(Trametes versicolor)和桦附毛孔菌(Trichaptum pargamenum), 而松属和云杉属的共有优势种主要有白囊耙齿菌(Irpex lacteus)、云芝、冷杉附毛孔菌(Trichaptum abietinum)和褐紫附毛孔菌(T. fuscoviolaceum)。倒木产生真菌子实体的概率研究表明, 同一类寄主倒木上发生木腐真菌子实体的概率在调查面积增加到0.36 ha后趋于一个定值, 松属倒木中仅有10.2%产生真菌子实体, 槭属和云杉属分别是12.9%和13.4%, 榛属最高, 达到53.7%。本研究结果对于预测森林生态系统中木腐真菌的发生具有重要理论意义。     

白蚁与动物及微生物的共生类型及其机制

综述了白蚁螱客的主要种类、共生关系及相关机制的研究进展。白蚁螱客中,已报道的动物种类达170种。在与动物的共生关系中存在偏利共生（宾主共栖和异种共栖）、互利共生和无关共生三种;在与微生物的共生关系中,存在与内生菌（原生动物、细菌、真菌和放线菌）和外生菌（蚁巢伞菌等）间的互利关系。指出了白蚁与螱客研究中存在的问题,给出了解决方案,并提出了今后可能的研究热点或方向,为白蚁的综合利用（如纤维素酶）及今后研究物种间的协同进化提供了基础资料。     

New amino-dithiaphospholanes and phosphoramidodithioites and their rhodium and iridium complexes

New sulfur derivatives of phosphoramidite ligands were synthesized and the impact of the sulfur unit on the spectroscopic properties of their rhodium and iridium complexes was investigated. The new ligands Bn₂NPSCH₂CH₂S^a(P-S^a) (Bn = benzyl, 4), Bn₂NPSCHCHS^a(CH₂)₃C^aH₂(P-S^a)(C^a-S^a) (6) and Bn₂NP(4-XC₆H₄OMe)₂ (X = S, 7a; X = O, 7b) were converted to the rhodium and iridium complexes trans-[Rh(CO)Cl(L)₂] (L = 4, 6, 7), [RhCl(COD)(L)] (L = 4, 6, 7), [IrCl(COD)(7a)] and [IrCl₂Cp∗(6)]. For comparison, some phosphoramidite complexes of these formulations also were synthesized. The new metal complexes were spectroscopically analyzed. For the carbonyl complexes, the ν_CO IR stretching frequencies were lower than for the corresponding phosphite and phosphoramidite ligands. The ¹J_PRh coupling constants for the rhodium complexes with the new ligands were also smaller than for the respective phosphoramidite and phosphite complexes. Finally, the ¹J_PSe coupling constants of the selenides of the new ligands were lower than those of the phosphoramidite ligands but higher than for PPh₃. The spectroscopic data reveal that the new thio ligands 4, 6 and 7a are more electron donating than phosphites and phosphoramidites but less electron donating than PPh₃.     

Astrocytes and Synaptosomes Transport and Metabolize Lactate and Acetate Differently

Astrocytes transport the monocarboxylate acetate, but synaptosomes do not. The reason for this is unknown, because both preparations express monocarboxylate transporters (MCT). The transport and metabolism of lactate, another monocarboxylate, was examined in these two preparations, and the results were compared to those for acetate. Lactate transport is more rapid in astrocytes than in synaptosomes, but of lower affinity (Kms of 17 and 4 mM, respectively). Lactate (0.2 mM) is metabolized to CO2 more rapidly in synaptosomes than in astrocytes (rates of 0.37 and 0.07 nmol x mg protein(-1) x min(-1), respectively). The reason for this is unclear, but cellular differences in lactate dehydrogenase isotype expression may be involved. Acetate is metabolized to CO2 more rapidly in astrocytes than in synaptosomes (rates of 0.43 and 0.02 nmol x mg protein(-1) x min(-1), respectively). This is likely due to cellular differences in the expression of monocarboxylate transporter subtypes.     

Rapporteur report: Basics and technology and metrology and standards

The first and second sessions of the Workshop focussed on the basics of ultrasound and infrasound, their applications in both industry and medicine, and metrology and protection standards for ultrasound applications.     

Relative and combined effects of ethanol and protein deficiency on strontium and barium bone content and fecal and urinary excretion

To elucidate accumulation of minerals in human iliac arteries with aging, the content of minerals was analyzed by inductively coupled plasma atomic emission spectrometry. Bilateral common, internal, and external iliac arteries of 16 men and 8 women, ranging ages from 65 to 93 yr, were examined. It was found that an extremely high accumulation of calcium and phosphorus occurred in the common iliac artery at old age, being higher than that of the internal and external iliac arteries. It should be noted that the accumulation of calcium and phosphorus is the highest in the common iliac artery among the human arteries examined to date. Regarding sexual differences, the content of calcium and phosphorus in the common and internal iliac arteries was higher in women than in men, whereas their content in the external iliac artery was lower in women than in men.     

Prostaglandin and thromboxane production by human and guinea-pig macrophages and leucocytes

The ability of partially purified human and guinea-pig haematogenous cell populations, when cultured in vitro, to metabolise arachidonic acid (AA) has been studied. Supernatants from 24 hour cell culture have been subjected to analysis for products of AA metabolism by gas chromatography with electron-capture detection.The cell types studied were human peripheral blood monocytes (both glass adherent and non-adherent), neutrophils, eosinophils and leukemic leucocytes; thoracic duct lymphocytes and lung alveolar macrophages. From the guinea-pig, induced and non-induced macrophage or neutrophil enriched peritoneal exudate populations, lymph node cells, peritoneal eosinophils and peripheral blood platelets were examined. Supernatants were assayed for the presence of PGE₂, PGD₂, PGF_2α, TXB₂ and 6-keto-PGF_1α. In all types studied PGE₂ and TXB₂ were the major products formed. The identification of PGE₂ and TXB₂ was confirmed by GC/MS with multiple ion monitoring.The results have been compared with other reports and their possible significance discussed in relation to the proposed role of prostaglandins as mediators and modulators in immunopathology.     

Chemokines and cytokines: axis and allies in asthma and allergy

Allergic asthma can be precipitated by many factors. For the atopic person, fungus, pollen, dust mites, cockroach antigens, and diesel exhaust are all agents that may trigger an allergic attack. Cytokines and chemokines are integral mediators of fungal asthma. From the earliest time points, they recruit and activate the cells required for the clearance of fungus as well as being critical factors involved in the immunopathology of this disease. In the final analysis, it is clear that these mediators can act to the benefit or the detriment of the host.     

Oxidation and nitration of ribonuclease and lysozyme by peroxynitrite and myeloperoxidase

In spite of the many studies on protein modifications by reactive species, knowledge about the products resulting from the oxidation of protein-aromatic residues, including protein-derived radicals and their stable products, remains limited. Here, we compared the oxidative modifications promoted by peroxynitrite and myeloperoxidase/hydrogen peroxide/nitrite in two model proteins, ribonuclease (6Tyr) and lysozyme (3Tyr/6Trp). The formation of protein-derived radicals and products was higher at pH 5.4 and 7.4 for myeloperoxidase and peroxynitrite, respectively. The main product was 3-nitro-Tyr for both proteins and oxidants. Lysozyme rendered similar yields of nitro-Trp, particularly when oxidized by peroxynitrite. Hydroxylated and dimerized products of Trp and Tyr were also produced, but in lower yields. Localization of the main modified residues indicates that peroxynitrite decomposes to radicals within the proteins behaving less specifically than myeloperoxidase. Nitrogen dioxide is emphasized as an important protein modifier.