Endogeic earthworms alter carbon translocation by fungi at the soil-litter interface     

Olaf Butenschoen  Christian Poll  Ellen Kandeler  Stefan Scheu 《Soil biology & biochemistry》2007,39(11):2854-2864

The effect of endogeic earthworms (Octolasion tyrtaeum (Savigny)) on the translocation of litter-derived carbon into the upper layer of a mineral soil by fungi was investigated in a microcosm experiment. Arable soil with and without O. tyrtaeum was incubated with ¹³C/¹⁵N-labelled rye leaves placed on plastic rings with gaze (64 μm mesh size) to avoid incorporation of leaves by earthworms. The plastic rings were positioned either on or 3 cm above the soil surface, to distinguish between biotic and chemical/physical translocation of nutrients by fungi and leaching.Contact of leaves to the soil increased ¹³C translocation, whereas presence of O. tyrtaeum reduced the incorporation of ¹³C into the mineral soil in all treatments. Although biomass of O. tyrtaeum decreased during the experiment, more ¹³C and ¹⁵N was incorporated into earthworm tissue in treatments with contact of leaves to the soil. Contact of leaves to the soil and the presence of O. tyrtaeum increased cumulative ¹³CO₂-C production by 18.2% and 14.1%, respectively.The concentration of the fungal bio-indicator ergosterol in the soil tended to be increased and that of the fungal-specific phospholipid fatty acid 18:2ω6 was significantly increased in treatments with contact of leaves to the soil. Earthworms reduced the concentration of ergosterol and 18:2ω6 in the soil by 14.0% and 43.2%, respectively. Total bacterial PLFAs in soil were also reduced in presence of O. tyrtaeum, but did not respond to the addition of the rye leaves. In addition, the bacterial community in treatments with O. tyrtaeum differed from that without earthworms and shifted towards an increased dominance of Gram-negative bacteria.The results indicate that litter-decomposing fungi translocate litter-derived carbon via their mycelial network in to the upper mineral soil. Endogeic earthworms decrease fungal biomass by grazing and disruption of fungal hyphae thereby counteracting the fungal-mediated translocation of carbon in soils.  相似文献   

Anconeus muscle injury in a juvenile greyhound     

Olaf R. Schaaf BVSc  MANZCVS  DECVS  Tyler Roennfeldt-Philp BSc  DVM  Natalie S. Webster BVSc  CertVDI  DipECVDI  MANZCVS 《Veterinary surgery : VS》2020,49(8):1648-1657

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The feeding ecology of earthworms – A review     

James P. Curry  Olaf Schmidt 《Pedobiologia》2007,50(6):463-477

Current knowledge of earthworm feeding ecology is reviewed, with particular reference to food selection, ingestion, digestion and assimilation, and the use of novel techniques to advance understanding of the functional significance of these processes.

Traditional research methods including direct observation of feeding behaviour, gut content analysis, choice tests, and litter bags have provided a wealth of information on earthworm feeding. However, there is a lack of the mechanistic, quantitative information required to characterise adequately their functional role in soil ecosystem processes such as soil C sequestration and loss, decomposition of organic residues, the maintenance of soil structure and trophic interactions with plants and microorganisms.

Stable isotope ratio analysis of light elements (C, N, and S) offers a powerful research tool to reveal and quantify trophic relationships of earthworms in soil food webs, while molecular techniques can further enhance understanding of the interactions between earthworms and microorganisms and their functional significance.  相似文献   

如何在花卉产销中增加产品附加值     

Olaf Van Kooten  王丽勉 《中国花卉园艺》2007,(21):48-49

超市的出路现在许多人都在满怀希望地关注着花卉零售连锁产业的发展,这个市场越来越大,参与的人们都希望能分得一杯羹。但是英国的经营模式告诉我们,在花卉贸易中,连锁经营中供应商的选择相当重要。  相似文献   

Hydroelectric reservoir inundation (Rio Madeira Basin, Amazon) and changes in traditional lifestyle: impact on growth and neurodevelopment of pre-school children     

Marques RC  Dórea JG  McManus C  Leão RS  Brandão KG  Marques RC  Vieira IH  Guimarães JR  Malm O 《Public health nutrition》2011,14(4):661-669

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Livelihoods and agro-ecological gradients: A meso-level analysis in the Indo-Gangetic Plains, India     

Olaf Erenstein  William Thorpe 《Agricultural Systems》2011,104(1):42-53

Rice-wheat systems in the Indo-Gangetic Plains (IGP) have long exemplified South Asia’s agricultural transformation through the Green Revolution. The same systems now also typify the post-Green Revolution stagnation and equity challenges, despite receiving considerable attention from the research and development (R&D) community. The apparent homogeneity of vast irrigated plains masks significant diversity in assets, livelihood strategies and livelihood outcomes. The paper analyzes the rural livelihoods and underlying agro-ecological gradients in the IGP drawing on village surveys and secondary data as characterization tools. The contribution of the paper is twofold: (i) new knowledge of the socio-economic circumstances in farming communities across the Indian IGP to enhance the effectiveness and efficiency of R&D interventions and particularly poverty alleviation; and (ii) an illustration of a novel approach to operationalize livelihood analysis at the meso-level so as to address spatial scale issues and link micro-level contextual realities across a vast geographical area. The agricultural R&D community needs to incorporate this socio-economic diversity more proactively into its R&D agenda if it is to succeed in sustaining productivity gains, improving rural livelihoods equitably, and securing environmental sustainability in this important eco-region.  相似文献   

Bluetongue virus seropositivity in sheep flocks in North West Frontier Province, Pakistan     

Saeed Akhtar  Nakiri Djallem  Gul Shad  Olaf Thieme 《Preventive veterinary medicine》1997,29(4):293-298

The objectives of this study were to describe the prevalence and distribution of serum antibodies to Bluetongue virus (BTV) in a sample of 38 sheep flocks in northern areas of the North West Frontier Province of Pakistan and to identify demographic and productivity variables that are associated with BTV seropositivity. Blood samples were taken from a random sample of ewes in each flock in April 1995. The owners of the flocks were interviewed regarding some demographic, husbandry and productivity variables of the flocks on the day of blood sampling. A competitive enzyme-linked immunosorbent assay was conducted to test the serum samples for BTV group-specific antibodies. BTV seropositive reactions were obtained in 184 (48.4%) out of 380 tested sera, and in 89.5% (34/38) of the flocks. In the 34 seropositive flocks, the prevalences ranged from 12.5 to 100% (median = 47). A multivariable logistic analysis was carried out to study the influence of demographic and productivity variables on the BTV serological status of the sheep flocks. Abortion risk in the previous lambing season was mildly associated with the serological status of the flock (adjusted odds ratio = 1.16, P = 0.07). For the seropositive flocks, a linear multiple regression showed that distance travelled by the flock during transhumant movement was significantly associated with percent seropositivity (partial regression coefficient (± SE) = − 0.091 ± 0.045).  相似文献   

Letters to the Editor ◆ Lettres À La Rédaction: Prescribing and selling pharmaceuticals          下载免费PDF全文

Olaf Swarbrick 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(1):5

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INFLUENCE OF ORGANIC AND MINERAL FERTILIZATION ON GERMINATION,LEAF NITROGEN,NITRATE ACCUMULATION AND YIELD OF VEGETABLE AMARANTH     

Cecilia M. Onyango  Jeremy Harbinson  Jasper K. Imungi  Solomon S. Shibairo  Olaf van Kooten 《Journal of plant nutrition》2013,36(3):342-365

The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination, leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus hypochondriacus) was investigated. Field trials were set up at the University of Nairobi Field Station at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials were laid out as complete randomized block design with four fertilization treatments: 20, 40, and 60 kg nitrogen (N) ha^?1 supplied by DAP (18:46:0), 40 kg N ha^?1 supplied by cattle manure and an unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8 weeks after planting. Results indicated that there were significant differences between treatments in germination percentage, leaf nitrogen content, nitrate accumulation and vegetable yield. Plants that received manure had a higher germination percentage than those that received the same amount of N supplied by the chemical fertilizer DAP. The yields generally increased from week 6 to week 8. The highest yield was recorded in plots receiving 40 kg N ha^?1 from DAP at eight weeks after planting. Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was supplied by DAP fertilizer. The leaf nitrogen content decreased with increasing age of the plants. The leaf nitrate content increased with increase in DAP application rate. Results indicate that manure application produced quality vegetables in terms of low nitrate levels, but leaf nitrogen and vegetable yields were low. DAP application effected higher yields, but the vegetables had high though acceptable nitrate levels.  相似文献   

Respiratory chlamydial infection based on experimental aerosol challenge of pigs with Chlamydia suis     

Sachse K  Grossmann E  Berndt A  Schütt C  Henning K  Theegarten D  Anhenn O  Reinhold P 《Comparative immunology, microbiology and infectious diseases》2004,27(1):7-23

An experimental study of aerogeneous challenge in pigs was conducted in order to reveal characteristic features of porcine respiratory chlamydiosis. Eight conventionally raised pigs were exposed to a pathogenic strain of Chlamydia (C.) suis, four controls were mock infected. Besides pathological changes, the acute-phase and humoral immune responses, as well as the dissemination and transmission of the challenge strain was monitored in the course of infection. The data from clinical investigations, LPS-binding protein assay, antibody ELISAs, confocal laser scanning and light microscopy, immunohistochemical staining and PCR provided extensive evidence of the pathogenic potential of C. suis for the porcine respiratory system. This model appears suitable for further pathophysiological and immunological investigations of chlamydial respiratory infections and can also be recommended for studies of Chlamydia-associated infections of the human lung.  相似文献