Biodeterioration of natural stone with special reference to nitrifying bacteria

An evaluation of field data from historical buildings in Germany showed that chemoorganotrophic bacteria are the most numerous microorganisms in building stones, followed by fungi and nitrifying bacteria. Chemoorganotrophic bacteria and fungi were present in almost every sample. Ammonia and nitrite oxidizers were found in 55 and 62% of the samples, respectively. Within months, natural stone was colonized by chemoorganotrophic microorganisms. The highest cell numbers were usually found near the surface. The colonization of natural stone by nitrifying bacteria took several years. The highest cell numbers were in some cases found underneath the surface. Nitrifying bacteria showed a preference for calcareous material with a medium pore radius between 1 and 10 m. Cell numbers of nitrifying bacteria did not correlate to the nitrate content of the stone material. We demonstrated that the stone inhabiting microflora can cause significant loss of nitrate by denitrification. Our data strongly suggested that microbial colonization of historical buildings was enhanced by anthropogenic air pollution. Samples taken from stone material with a pore radius 1 m had significantly higher cell numbers when they were covered with black crusts. A comparison of samples taken between 1990–1995 from buildings throughout Germany showed that in eastern Germany a significantly stronger colonization with facultatively methylotrophic bacteria and nitrifying bacteria existed. The same was true for natural stone from an urban exposure site when compared to material from a rural exposure site. Data from outdoor exposure and laboratory simulation experiments indicated that the colonization of calcareous stone by nitrifying bacteria was enhanced by chemical weathering.     

Structural damage to oak leaves alters natural enemy attack on a leafminer

A field experiment was conducted to test the role of structural changes in oak leaves caused by folivory on natural enemy attack of leafmining larvae and pupae of Cameraria sp. nov., while controlling for induced chemical responses. Damaged and intact leaves of Quercus emoryi were sealed with a fluorocarbon telomer in 1988–1989 to prevent release of long-range or contact chemical cues that might be perceived by searching parasitoids and predators. These leaves were attached to Q. emoryi leaves harboring first instars of Cameraria, but otherwise were undamaged. Rates of attack by natural enemies of leafminers in leaves with sealed, damaged leaves attached were significantly greater than those in control leaves, indicating that structural damage alone influences attack by natural enemies. Survival of leafminers in leaves with attached damaged leaves was significantly less than that of controls, suggesting that structural changes in leaves due to folivore feeding affect population dynamics of Cameraria via increased attack by the third trophic level.

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Résumé Des expériences ont été faites dans la nature pour évaluer l'influence des modifications structurales provoquées par la défoliation sur les attaques des ennemis naturels des chenilles mineuses et des chrysalides de Cameraria sp. nov. En 1988–89 des feuilles saines et endommagées de Quercus emoryi ont été enduites de télomère de fluorocarbone pour empêcher l'émission d'indicateurs chimiques à distance ou de contact pouvant être utilisés par les parasitoïdes et les prédateurs lors de leur prospection. Ces feuilles ont été attachées à des feuilles apparemment intactes de Q. emoryi mais hébergeant des Cameraria du premier stade. Les attaques par les ennemis naturels des mineuses étaient plus importantes sur feuilles associées à des feuilles endommagées mais enduites de fluorocarbone que sur feuilles témoins, ce qui montre que les dégâts structuraux seuls influent sur les attaques par les ennemis naturels. La survie des mineuses dans les feuilles associées à des feuilles endommagées était plus faible que chez les témoins, ce qui suggère des changements structuraux dans les feuilles provoqués par les phytophages affectant la dynamique de population de Cameraria via une attaque accrue par le troisième niveau trophique.

     

Leaf nutrient dynamics and nutrient resorption: a comparison between larch plantations and adjacent secondary forests in Northeast China

Aims Conversion of secondary forests to pure larch plantations is a common management practice driven by the increasing demand for timber production in Northeast China, resulting in a reduction in soil nutrient availability after a certain number of years following conversion. Nutrient resorption prior to leaf senescence was related to soil fertility, an important nutrient conservation strategy for plants, being especially significant in nutrient-poor habitats. However, the seasonal dynamics of leaf nutrients and nutrient resorption in response to secondary forest conversion to larch plantations is not well understood.Methods A comparative experiment between larch plantations (Larix spp.) and adjacent secondary forests (dominant tree species including Quercus mongolica, Acer mono, Juglans mandshurica and Fraxinus rhynchophylla) was conducted. We examined the variations in leaf nutrient (macronutrients: N, P, K, Ca and Mg; micronutrients: Cu and Zn) concentrations of these tree species during the growing season from May to October in 2013. Nutrient resorption efficiency and proficiency were compared between Larix spp. and the broadleaved species in the secondary forests.Important findings Results show that the seasonal variation of nutrient concentrations in leaves generally exhibited two trends, one was a downward trend for N, P, K, Cu and Zn, and another was an upward trend for Ca and Mg. The variations in foliar nutrient concentrations were mainly controlled by the developmental stage of leaves rather than by tree species. Resorption of the observed seven elements varied among the five tree species during leaf senescence. Nutrient resorption efficiency varied 6–75% of N, P, K, Mg, Cu and Zn, while Ca was not retranslocated in the senescing leaves of all species, and Mg was not retranslocated in Larix spp. Generally, Larix spp. tended to be more efficient and proficient (higher than 6–30% and 2–271% of nutrient resorption efficiency and resorption proficiency, respectively) in resorbing nutrients than the broadleaved species in the secondary forests, indicating that larch plantations had higher leaf nutrient resorption and thus nutrient use efficiency. Compared with Larix spp., more nutrients would remain in the leaf litter of the secondary forests, indicating an advantage of secondary forests in sustaining soil fertility. In contrast, the larch plantation would reuse internal nutrients rather than lose nutrients with litter fall and thus produce a positive feedback to soil nutrient availability. In summary, our results suggest that conversion from secondary forests to pure larch plantations would alter nutrient cycling through a plant-mediated pathway.     

山楂绢粉蝶的生物学及防治

山楂绢粉蝶在陇东各地每年发生 1代 ,以 3龄幼虫群集于树冠上吐丝缀叶成巢 ,并在其中越冬。幼虫共 5龄 ,幼虫食叶为害 ,每年 4月中下旬是猖獗为害期。天敌优势种是菜粉蝶绒茧蜂和白头小食虫虻等。     

生态系统服务与自然资本价值评估

生态系统服务是生态系统提供的商品和服务,是人类生态和发展的物质基础和基本条件,是人类拥有的关键自然资本。概述了生态系统服务的内涵及类型,介绍了当前国内外有关生态系统服务及自然资本的价值理论、价值评估的各种方法及其类型;评述了研究的主要进展,存在的主要问题、难点和研究的主要趋向。认为生态系统服务及自然资本的价值评估研究是建立生态－环境－经济综合核算体系（可持续发展核算体系）的重要内容和关键环节,完善价值评估的理论与经济技术方法是生态系统服务价值评估研究亟待解决的问题。     

天然产物Combretastatins的研究进展

Combretum caffrum是南非的一种具有很强抗肿瘤活性的植物,80年代开始,一系列化合物（combretastatins）从这种植物中被分离、鉴定出来,它们大多具有较强的抑制微管聚合和有丝分裂的活性。本文综述了对这类天然产物combretastatins的全合成、药理作用机理及结构修饰等方面的研究进展。     

Darwin and palaeontology: a re-evaluation of his interpretation of the fossil record

Charles Darwin's empirical research in palaeontology, especially on fossil invertebrates, has been relatively neglected as a source of insight into his thinking, other than to note that he viewed the fossil record as very incomplete. During the Beagle voyage, Darwin gained extensive experience with a wide diversity of fossil taxa, and he thought deeply about the nature of the fossil record. That record was, for him, a major source of evidence for large-scale transmutation, but much less so for natural selection or single lineages. Darwin's interpretation of the fossil record has been criticised for its focus on incompleteness, but the record as he knew it was extremely incomplete. He was compelled to address this in arguing for descent with modification, which was likely his primary goal. Darwin's gradualism has been both misrepresented and exaggerated, and has distracted us from the importance of the fossil record in his thinking, which should be viewed in the context of the multiple, sometimes competing demands of the multifaceted argument he presented in the Origin of Species.     

Dynamics of the silver fir (Abies alba Mill.) natural regeneration in a mixed forest in the Central Apennine

The dynamics of the silver fir represent an important topic for researchers across Europe. Following its decline, which occurred in Europe after the last glaciation, the remaining relict areas became a very important laboratory for studying its conservation. The Central Apennine chain, particularly in Molise, represents one unique case where silver fir, Turkey oak and beech can be found within the same forest. This study focused on the forest structure of the Bosco Monteluponi where the closeness with Collemeluccio Man and Biosphere reserve has affected the diffusion of conifer within the forest. Consequently, the forest structure has shifted from even aged to uneven aged. The resulting complex forest structure offers new challenges for forest practitioners in the identification of silvicultural treatments, which identify and maintain the balance among the three species within the same forest. Particular importance was given to the silver fir natural regeneration in order to assess the forest suitability for conifer expansion. Results demonstrated that Monteluponi is strongly suitable for the in situ conservation of silver fir and offers a great opportunity for its diffusion.     

Parasitoids and hyperparasitoids of Mythimna convecta (Walker) (Lepidoptera: Noctuidae) larvae infesting late-maturing maize in southern New South Wales

Abstract  After several reports of late-maturing maize in Murrumbidgee valley, southern New South Wales, Australia, being severely damaged by armyworm, five crops were surveyed for the presence of larvae in April 2003. Mythimna convecta Walker (Lepidoptera: Noctuidae) was the only species successfully reared from armyworm larvae collected in the field. Ninety-six per cent of armyworm larvae collected were parasitised. Five parasitoid species, Cuphocera sp. nr pilosa (Malloch), Ceromya horma (Malloch), Tritaxys scutellate (Macquart), Chaetophthalmus sp. (Diptera: Tachinidae) and Netelia sp. (Hymenoptera: Ichneumonidae) were reared from M. convecta larvae. Cuphocera sp. nr pilosa was the most frequently encountered parasitoid being reared from 83% of M. convecta larvae collected. Examination of maize plants at each collection site showed high numbers of tachinid puparia adhering to plants. Cuphocera sp. nr pilosa was the only species reared from these puparia. Of the Cu . sp. nr pilosa puparia collected, 23–83% were parasitised by five parasitoid wasps: Trichomalopsis sp. Crawford (Hymenoptera: Pteromalidae), Brachymeria sp. Westwood, Eupelmus sp. Dalman (Hymenoptera: Chalcididae), Perilampus sp. Latreille (Hymenoptera: Perilampidae) and a species belonging to the family Diapriidae.