放牧侵蚀研究回顾与展望

纵观土壤侵蚀研究的历史,风蚀和水蚀被认为是土壤侵蚀的主要形式。尽管近年来耕作侵蚀研究取得了巨大进展, 但迄今放牧侵蚀研究较少。本文探讨了放牧侵蚀研究的意义,回顾了国内外研究现状和存在的问题,提出放牧侵蚀是由于草原动物的直接作用而导致在过牧草地上土壤物质的重新分配。放牧侵蚀作为过度放牧的指示向量,是一个今后值得大力研究的领域,这不仅有益于草地载畜量评定、碳素减源增汇研究,而且在草地退化程度诊断和退化草地治理中具有重要指示意义。     

食根动物与植物的相互关系

食根动物是植物的主要危害者,植物与食根动物之间的相互作用一直备受关注.本文从食根动物与异质性土壤、根系的关系,以及食根动物对植物的影响等方面,探讨了食根动物与根系生物量的变化、再生能力、存活,植物化学物质与其他有机体之间的作用机理和食根动物对植物生理、种群动态、植物结构的影响.建议加强对植物控制食根动物取食时采取的对策、食根动物改变生态系统C、N循环的机制以及植物寄生性线虫存在的生态系统养分的动态变化等方面的研究.     

中华山蓼化学成分研究

bk中华山蓼(Dxyria sinensis Hemsl.)全草中首次分离得到十四个化合物,通过波谱学方法分别鉴定为(-)-表没食子儿茶素(1)、(-)-儿茶素没食子酸酯(2)、(-)-表儿茶素(3)、(-)-表儿茶素-3-没食子酸酯(4)、槲皮素-3-O-α-L-鼠李糖苷(5)、tiliroside(6)、山萘酚-3-O-β-D-吡喃葡萄糖苷(7)、桷皮素(8)、2,4-二羟基-6-甲氧基-乙酰基苯-4-O-β-D-吡喃葡萄糖苷(9)、反-N-(4-羟基苯乙基)阿魏酸酰胺(10)、顺-N-(4-羟基苯乙基)阿魏酸酰胺(11)、icariol A2(12)、(+)-松脂素(13)、Helonioside B(14).     

狸藻属中国一新记录种及芋兰属中国大陆一新记录种

报道了狸藻科中国分布一新记录种--叉状挖耳草Utricularia furcellata, 并对该种花的颜色进行了补充描述.同时报道了兰科中国大陆一新分布种--台湾芋兰N. nipponica,该种叶五角形或七角形,花序仅生一朵花.     

THE LATE TRIASSIC BLACK SHALES OF THE GUANLING AREA, GUIZHOU PROVINCE, SOUTH-WEST CHINA: A UNIQUE MARINE REPTILE AND PELAGIC CRINOID FOSSIL LAGERSTÄTTE

Abstract:  Black shales of the lower member of the Carnian Xiaowa Formation (previously known as the Wayao Member of the Falang Formation or as the Wayao Formation) in the Guanling area, Guizhou Province, south-west China, are yielding a rich marine reptile fauna and exceptional remains of pelagic crinoids. The black shales represent deposition on the drowned southern margin of the Yangtze Platform during a Maximum Flooding Interval. The relatively reduced sedimentation rates led to the formation of the Lagerstätte through the accumulation of fossils in the anoxic bottom sediments over a prolonged period of time. Invertebrate fossils represent almost exclusively pelagic forms, such as a diverse ammonite fauna and halobiid bivalves. The spectacular finds of colonies of large (stem lengths > 11 m) crinoids of the genus Traumatocrinus attached to driftwood prove that this crinoid was the first to evolve a pseudoplanktonic life style. The other crinoid is the planktonic roveacrinid Osteocrinus . The marine reptile fauna, represented by probably hundreds of skeletons, is numerically dominated by three species of ichthyosaurs and four species of thalattosaurs. The thalattosaurs fill a palaeobiogeographic gap between the Alpine thalattosaur faunas and those from western North America. Two species of placodonts are rare finds. As for the thalattosaurs, the placodont occurrences greatly expand the geographic range of the group because placodonts have been known previously only from the Mediterranean region, the Alps and the Muschelkalk Basin. The unique abundance of thalattosaurs contrasts with a scarcity of fishes. Although we suggest that the fauna is authochthonous and inhabited surface waters, it must have represented an unusual ecosystem. However, the possibility remains that both the marine reptiles and the Traumatocrinus colonies were concentrated in the region by currents and do not reflect the biocoenosis.     

ABA诱导基因及其与逆境胁迫的关系(综述)

本文介绍 ABA 诱导基因的类型、结构、功能,并对其表达与逆境胁迫的关系进行综述。     

MRSA感染性创面菌群结构分析

目的探究耐甲氧西林金黄色葡萄球菌(MRSA)感染性创面与创面旁菌种组成的差异并寻找可能的有益菌,为从皮肤微生态角度治疗MRSA感染性创面提供理论依据。方法采集湖南省人民医院MRSA感染性创面及创面旁的皮肤样本,其中创面部位样本22份为D组,创面旁样本11份为N组,提取样本DNA,采用高通量测序技术对16S rRNA基因V3-V4区测序并进行生物信息学分析。结果根据Alpha多样性分析,D组的Chao1指数、Ace指数和Shannon指数明显低于N组(Z=62, P=0.023 8；Z=66, P=0.035 9；Z=30, P=0.000 2),而Simpson指数明显高于N组(Z=211, P=0.000 3)。Beta多样性分析显示2组皮肤菌群组成具有差异,表明分组合理(R=0.584 3、0.467 3, P=0.001 0)。D组葡萄球菌属(Staphylococcus)及韦荣球菌属(Veillonella)丰度显著性升高(Z=213, P=0.000 5；Z=48.5, P=0.004 8),其他常驻菌群均下降。N组的乳杆菌属(Lactobacillus)相对丰度均值较D组高(Z=38, P=0.000 8)。结论MRSA感染性创面的菌群结构较创面旁组具有一定变化,Lactobacillus为皮肤有益菌,可能对创面的恢复有益。     

Ocean acidification and warming will lower coral reef resilience

Ocean warming and acidification from increasing levels of atmospheric CO₂ represent major global threats to coral reefs, and are in many regions exacerbated by local‐scale disturbances such as overfishing and nutrient enrichment. Our understanding of global threats and local‐scale disturbances on reefs is growing, but their relative contribution to reef resilience and vulnerability in the future is unclear. Here, we analyse quantitatively how different combinations of CO₂ and fishing pressure on herbivores will affect the ecological resilience of a simplified benthic reef community, as defined by its capacity to maintain and recover to coral‐dominated states. We use a dynamic community model integrated with the growth and mortality responses for branching corals (Acropora) and fleshy macroalgae (Lobophora). We operationalize the resilience framework by parameterizing the response function for coral growth (calcification) by ocean acidification and warming, coral bleaching and mortality by warming, macroalgal mortality by herbivore grazing and macroalgal growth via nutrient loading. The model was run for changes in sea surface temperature and water chemistry predicted by the rise in atmospheric CO₂ projected from the IPCC's fossil‐fuel intensive A1FI scenario during this century. Results demonstrated that severe acidification and warming alone can lower reef resilience (via impairment of coral growth and increased coral mortality) even under high grazing intensity and low nutrients. Further, the threshold at which herbivore overfishing (reduced grazing) leads to a coral–algal phase shift was lowered by acidification and warming. These analyses support two important conclusions: Firstly, reefs already subjected to herbivore overfishing and nutrification are likely to be more vulnerable to increasing CO₂. Secondly, under CO₂ regimes above 450–500 ppm, management of local‐scale disturbances will become critical to keeping reefs within an Acropora‐rich domain.