济南市发展现代都市农业的主要模式与对策建议

都市农业是发展现代农业的重要载体。本课题在研究国内外都市农业发展趋势、深入调查分析济南市发展都市农业的优势条件及制约因素的基础上,提出了加快农业结构调整步伐、建立济南特色都市农业体系的政策建议。     

Modeling Landscape Vegetation Pattern in Response to Historic Land-use: A Hypothesis-driven Approach for the North Carolina Piedmont,USA

Current methods of vegetation analysis often assume species response to environmental gradients is homogeneously monotonic and unimodal. Such an approach can lead to unsatisfactory results, particularly when vegetation pattern is governed by compensatory relationships that yield similar outcomes for various environmental settings. In this paper we investigate the advantages of using classification tree models (CART) to test specific hypotheses of environmental variables effecting dominant vegetation pattern in the Piedmont. This method is free of distributional assumptions and is useful for data structures that contain non-linear relationships and higher-order interactions. We also compare the predictive accuracy of CART models with a parametric generalized linear model (GLM) to determine the relative strength of each predictive approach. For each method, hardwood and pine vegetation is modeled using explanatory topographic and edaphic variables selected based on historic reconstructions of patterns of land use. These include soil quality, potential soil moisture, topographic position, and slope angle. Predictive accuracy was assessed on independent validation data sets. The CART models produced the more accurate predictions, while also emphasizing alternative environmental settings for each vegetation type. For example, relic hardwood stands were found on steep slopes, highly plastic soils, or hydric bottomlands – alternatives not well captured by the homogeneous GLM. Our results illustrate the potential utility of this flexible modeling approach in capturing the heterogeneous patterns typical of many ecological datasets.     

Evaluation of environmental and management-related risk factors associated with chronic mastitis in sows

OBJECTIVE: To evaluate environmental and management-related risk factors associated with chronic mastitis in sows. ANIMALS: 1,254 sows from 76 herds. PROCEDURE: Prevalence of chronic mastitis was determined by a veterinarian who performed clinical examinations at the time of weaning and approximately 1 week later in a sample of the sow population on each farm. Information concerning environmental factors and management practices was collected. In addition, the herd veterinarian made an assessment of the farmer's skills in swine production. RESULTS: Use of partly slatted floors in the farrowing pens, use of disinfectants between batches in the farrowing and breeding areas, feeding lactating sows whey, and avoiding cutting or grinding of the piglets' teeth were significantly associated with a decreased risk of chronic mastitis. A high hygienic standard on the farm, as determined by the herd veterinarian, was associated with a significant reduction in the prevalence of mastitis. CONCLUSIONS AND CLINICAL RELEVANCE: Chronic mastitis in sows is a common disease that has a negative influence on productivity. Results indicate that certain management practices and environmental factors influenced the development of mastitis, which may contribute to the development of methods useful for controlling the disease.     

Environmental and personal risk factors for toxocariasis in children with diagnosed disease in urban and rural areas of central Poland

To investigate the epidemiology of human toxocariasis a field survey was carried out at homes of 194 children (80 of rural and 114 of urban origin) with diagnosed disease from central Poland. A questionnaire referring to the possible risk factors was directed to their parents. Overall contamination rate of soil by Toxocara eggs was 27.5% in rural and 21.1% in urban environment in the households examined, with difference not significant (chi2=1.08, p=0.2986). In rural settlements 29.3% of yards surrounding houses were found contaminated, whereas in urban 25.0% of family gardens, 26.4% of private yards and 10.7% of public sandpits were positive. Frequency of positive samples differs only for rural yards and urban sandpits (chi2=3.85, p=0.0499). The study showed a high risk of reinfection for the ill children in sites of their residence. Despite diagnosed toxocariasis kids were not adequately supervised by their parents with no measures undertaken to avoid further infection. These data present strong need for educational programs which should be implemented for prevention of Toxocara infections in children.     

分子证据表明苏拉威西岛特有鸟种苏拉山鸫(Geomalia heinrichi)属于地鸫属(Zoothera)(鸫科,鸟纲)(英文)

苏拉威西地区特有鸟种苏拉山鸫(Geomalia heinrichi)的分类地位,是属于画眉科还是鸫科,长期以来一直备受争议。基于线粒体细胞色素 b 基因、细胞核肌红蛋白内含子 2 以及鸟氨酸脱羧酶内含子 6–7 基因,我们估计了鸫科 43 个分类群的系统发育关系。结果表明,苏拉山鸫是地鸫属的一个分支,并具有较高的支持率。我们建议将 Geomalia 并入地鸫属(Zoothera),并命名为 Zoothera heinrichi。     

Chilling stress tolerance of two soya bean cultivars: Phenotypic and molecular responses

Chilling stress is a major factor limiting the yield of soya bean [Glycine max (L.) Merr.] on a global scale. However, the regulatory network that controls the chilling response of soya bean remains unclear. In the present study, phenotyping and quantitative analyses of miRNAs in soya bean under chilling stress were carried out to determine the impact of environmental constraints on soya bean productivity. Measurements done during soya bean growth in chilling along with the results of field trials indicated that the cultivars Augusta and Fiskeby V responded differently to low temperatures. Although chilling affected the reproductive development of both cultivars, the final seed output remained unchanged. The differential expression of miR169, miR319, miR397 and miR398 under cold stress was detected using ddPCR. Upon chilling in the reproductive stage, we found that these miRNAs had contrasting expression profiles in Augusta and Fiskeby V. A set of candidate target genes was predicted based on degradome sequencing data. A negative correlation was found between the expression of miR169, miR319 and miR398 and their targets in the roots of both cultivars. Our work elucidates the impact of chilling stress on the productivity of two soya bean cultivars and reveals the importance of miRNA involvement in the low temperature response.     

The relevance of marine chemical ecology to plankton and ecosystem function: an emerging field

Marine chemical ecology comprises the study of the production and interaction of bioactive molecules affecting organism behavior and function. Here we focus on bioactive compounds and interactions associated with phytoplankton, particularly bloom-forming diatoms, prymnesiophytes and dinoflagellates. Planktonic bioactive metabolites are structurally and functionally diverse and some may have multiple simultaneous functions including roles in chemical defense (antipredator, allelopathic and antibacterial compounds), and/or cell-to-cell signaling (e.g., polyunsaturated aldehydes (PUAs) of diatoms). Among inducible chemical defenses in response to grazing, there is high species-specific variability in the effects on grazers, ranging from severe physical incapacitation and/or death to no apparent physiological response, depending on predator susceptibility and detoxification capability. Most bioactive compounds are present in very low concentrations, in both the producing organism and the surrounding aqueous medium. Furthermore, bioactivity may be subject to synergistic interactions with other natural and anthropogenic environmental toxicants. Most, if not all phycotoxins are classic secondary metabolites, but many other bioactive metabolites are simple molecules derived from primary metabolism (e.g., PUAs in diatoms, dimethylsulfoniopropionate (DMSP) in prymnesiophytes). Producing cells do not seem to suffer physiological impact due to their synthesis. Functional genome sequence data and gene expression analysis will provide insights into regulatory and metabolic pathways in producer organisms, as well as identification of mechanisms of action in target organisms. Understanding chemical ecological responses to environmental triggers and chemically-mediated species interactions will help define crucial chemical and molecular processes that help maintain biodiversity and ecosystem functionality.     

Stand density and fertilization effects on aboveground allocation patterns and stem form of Pinus sylvestris in young stands

The increasing demand for forest biomass for energy generation could be partially met by growing denser stands and use of fertilizer. Before this is done at large scale, more knowledge of the effects of stand density and fertilization on aboveground allocation patterns and stem form is needed. Therefore, effects of pre-commercial thinning (PCT) to 3000 stems ha^?1, an unthinned dense control (C), and PCT combined with two levels of fertilization (100 kg ha^?1 of nitrogen applied either during the establishment of the field experiment (F1) or annually (F2)) were examined in 23- to 26-year-old Scots pine (Pinus sylvestris L.) stands six years after the establishment of the field experiment. In total, 114 sample trees were harvested using destructive biomass sampling. The growth allocation and stem form of trees with diameter at breast height (DBH; 1.3 m height) >5.0 cm were not affected by either the PCT or fertilization. Small trees (DBH < 5 cm) in denser, unthinned control plots had more slender stems (lower DBH/height ratios) and allocated less growth to branches and foliage than trees in PCT plots. Fertilization had little effect on the stem form and growth allocation of the smallest trees. Therefore, effects of stem density and fertilization on stem form and growth allocation to foliage were only found for small suppressed trees, and the treatments had very little influence on dominant and codominant trees.