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1.
Marko Debeljak Jrme Cortet Damjan Demar Paul H. Krogh Saso Deroski 《Pedobiologia》2007,51(3):229-ECOGEN
The population dynamics of soil organisms under agricultural field conditions are influenced by many factors, such as pedology and climate, but also farming practices such as crop type, tillage and the use of pesticides. To assess the real effects of farming practices on soil organisms it is necessary to rank the influence of all of these parameters. Bt maize (Zea mays L.), as a crop recently introduced into farming practices, is a genetically modified maize with the Cry1Ab gene which produces a protein toxic to specific lepidopteran insect pests. To assess the effects of Bt maize on non-target soil organisms, we conducted research at a field site in Foulum (Denmark) with a loamy sand soil containing 6.4% organic matter. The study focused on populations of springtails (Collembola) and earthworms (Oligochaeta) from samples taken at the beginning and at the end of the maize crop-growing season during 2 consecutive years. Farming practices, soil parameters, the biological structure of soil communities, and the type and age of the crop at the time of sampling, were used as attributes to predict the total abundance of springtails and biomass of earthworms in general and the abundance or biomass for specific functional groups (epigeic, endogeic and anecic groups for earthworms, and eu-, eu to hemi-, hemi-, hemi to epi- and epiedaphic groups for Collembola). Predictive models were built with data mining tools, such as regression trees that predict the value of a dependent variable from a set of independent variables. Regression trees were constructed with the data mining system M5′. The models were evaluated by qualitative and quantitative measures of performance and two models were selected for further interpretation: anecic worms and hemi-epiedaphic Collembola. The anecic worms (r2=0.83) showed preferences for less clay and more silt soil with medium pH but were not influenced directly by farming practices. The biomass of earthworms was greater in early autumn than in spring or late autumn. Biomass of hemi-epiedaphic Collembola (r2=0.59) increased at the end of the maize growing season, while higher organic matter content and pH tended to increase their biomass in spring. Greater abundance of Collembola was also noted in early autumn if the crop was non-Bt maize. The models assessed by this research did not find any effects of the Bt maize cropping system on functional groups of soil fauna. 相似文献
2.
Ebrima S. Dem Beatriz Rodríguez-Labajos Martin Wiemers Jürgen Ott Norbert Hirneisen Jesus Victor Bustamante Marlynne Bustamante Josef Settele 《Paddy and Water Environment》2018,16(4):725-735
This study relies on the Flying Beauties Citizen Science project conducted in the Philippines to assess personal motivations and learning outcomes of volunteers who were involved in documenting butterflies and dragonflies in rice ecosystems. While evaluation of motivations of volunteers in Citizen Science is not new, at least in affluent western countries, little is done in investigating volunteers’ motivations and learning outcomes of Citizen Science projects in low-income countries. Using surveys, we collected data from volunteers that were analysed qualitatively and quantitatively. We adopted a two stages evaluation format—before and after volunteers finished the project exercise. We compared pre-motivations to motivations attained and changes in level of knowledge before and after the project ended. We use Spearman’s Rho, Kendall’s Tau—nonparametric tests to draw correlations between variables. The results showed that key determinants that drove people to volunteer in the project were (a) learning about species and (b) being part of scientific research and the principal learning outcome was improved awareness about ecosystem functions of the species. 相似文献
3.
Carolina Reigada Rafael de Andrade Moral Clarice Garcia Borges Demétrio José Roberto Postali Parra 《Journal of pest science》2018,91(1):121-131
The cotton bollworm Helicoverpa armigera is a destructive pest that affects a variety of crop plants. Because of its polyphagous feeding habit, mobility as adults, and high fecundity, the expanding infestations of H. armigera in different crops have caused economic losses and difficulties for pest population management. In Brazil, a sequence of different crop systems in the same area and crop rotation during the year can create a spatio-temporal mosaic of crops where H. armigera can persist. However, the consequences of the simultaneous and/or alternating presence of host plants for H. armigera populations through generations are unknown. In this study, we simulated, in the laboratory, hypothetical situations for the availability of soybean and cotton crops in the landscape. We evaluated the effects of: (1) the number of generations during which a population feeds on a host-plant species; (2) the succession of host-plant species on which populations have fed for two generations; and (3) the parental host plant on the fitness of H. armigera populations. Only the current host plant on which larvae fed affected the performance of the H. armigera populations. Decrease of mortality rates during the immature period was slowed when the larvae fed on soybean. The lowest value of reproductive potential (R 0) was found for individuals originating from mating between females and males reared in cotton. Our results indicated that pest-management and biological-control plans for H. armigera should be developed on a regional scale rather than for just a specific crop area. 相似文献
4.
Suely Ruiz Giolo Enrico Antonio Colosimo Clarice Garcia Borges Demétrio 《Journal of Agricultural, Biological & Environmental Statistics》2009,14(2):154-169
Interval-censored survival data, in which the event of interest is not observed exactly but is only known to occur within
some time interval, occur very frequently. In some situations, event times might be censored into different, possibly overlapping
intervals of variable widths; however, in other situations, information is available for all units at the same observed visit
time. In the latter cases, interval-censored data are termed grouped survival data. Here we present alternative approaches
for analyzing intervalcensored data. We illustrate these techniques using a survival data set involving mango tree lifetimes.
This study is an example of grouped survival data. 相似文献
5.
C. J. Brien C. G. B. Demétrio 《Journal of Agricultural, Biological & Environmental Statistics》2009,14(3):253-280
Mixed models have become important in analyzing the results of experiments, particularly those that require more complicated
models (e.g., those that involve longitudinal data). This article describes a method for deriving the terms in a mixed model.
Our approach extends an earlier method by Brien and Bailey to explicitly identify terms for which autocorrelation and smooth
trend arising from longitudinal observations need to be incorporated in the model. At the same time we retain the principle
that the model used should include, at least, all the terms that are justified by the randomization. This is done by dividing
the factors into sets, called tiers, based on the randomization and determining the crossing and nesting relationships between
factors. The method is applied to formulate mixed models for a wide range of examples. We also describe the mixed model analysis
of data from a three-phase experiment to investigate the effect of time of refinement on Eucalyptus pulp from four different
sources. Cubic smoothing splines are used to describe differences in the trend over time and unstructured covariance matrices
between times are found to be necessary. 相似文献
6.
Buckwheat is a pseudocereal with a strong characteristic aroma. Compounds responsible for the aroma of buckwheat groats were recently identified, but the distribution of aromatic compounds between different fractions of the buckwheat kernel (flour, bran, and husk) is not yet known. In this study, the composition of aromatic compounds in buckwheat seed fractions was investigated and compared to the composition of aromatic compounds in groats produced from the same batch of buckwheat seeds. Volatiles from each sample were extracted with simultaneous distillation/extraction with a Likens‐Nickerson apparatus. Extracts were analyzed by gas chromatography coupled with mass spectrometry (GC‐MS) with electron ionization. Apart from the aroma molecules present in all fractions, compounds that are present only in flour or bran, but not in groats, were also found. Furthermore, some compounds were identified only in buckwheat groats but not in buckwheat flour or bran [octanal, (E,E)‐2,4‐heptadienal, (E)‐2‐decenal, and (E,E)‐2,4‐decadienal], others were identified only in husks [(E)‐2‐hexenal, heptanal, (E,E)‐2,4‐hexadienal, phenylacetaldehyde, and alpha‐bisabolol]. 相似文献
7.
Evaluation of effects of transgenic Bt maize on microarthropods in a European multi-site experiment 总被引:2,自引:5,他引:2
Jrme Cortet Bryan S. Griffiths Marko Bohanec Damjan Demsar Mathias N. Andersen Sandra Caul Andrew N. E. Birch Cline Pernin Elisabeth Tabone Annette de Vaufleury Xin Ke Paul Henning Krogh 《Pedobiologia》2007,51(3):207-ECOGEN
The effects of maize expressing the Bacillus thuringiensis Cry1Ab protein (Bt maize) on soil microarthropods were assessed in the field at four European locations (two in Denmark and two in France) that differ in their climatic conditions or soil properties. Each site was considered as a separate experiment, with separate statistical comparison. Effects of farming practices using Bt maize were compared with conventional farming practices using near-isogenic non-Bt maize and also (at some of the sites) other conventional varieties. Furthermore, at one field site (Foulum, Denmark), the effects of Bt crops were studied in both conventional tillage and reduced tillage contexts. At another field site (Askov, Denmark), Bt maize effects were also compared to the effects of the chemical insecticide dimethoate. Moreover, at three of the field sites (all except Narbons, France), the possibility of a localised Bt effect around the rhizosphere compared to the bulk soil was assessed by sampling within and between maize rows. There were some significant negative effects of Bt maize on microarthropods in soils with a high clay content. Significant differences of the same magnitude also occurred between different conventional varieties of maize, but the effect of dimethoate appeared clearly greater than Bt effects. It is thus debatable if the Bt maize effect is an effect of the Bt toxin or just an effect of the maize variety. Based on the results, it can be concluded that the effect of Bt maize on soil microarthropods was small and within the normal variation expected in conventional agricultural systems. 相似文献
8.
E. V. Blagodatskaya T. V. Pampura E. G. Dem’yanova T. N. Myakshina 《Eurasian Soil Science》2006,39(6):653-660
The effects of lead oxide and lead nitrate on the growth strategies of microbial communities in the soil and in the rhizosphere of orchard grass (Dactylis glomerata L.) were studied. The maximum specific growth rate of the microorganisms (μm) changed significantly when the concentration of mobile forms of lead in the soil exceeded 170 mg Pb/kg, which corresponded to the addition of 400–1000 mg Pb/kg of soil in the form of lead nitrate. The addition of lead resulted in the suppression of a part of the r-strategists and in the more active development of the K-strategists in the adapted microbial community. It was demonstrated that the community of rhizosphere microorganisms could be a more sensitive indicator of lead pollution than the nonrhizosphere microbial community. The values of the auxotrophy index (the ratio between the μm values upon the growth on glucose and yeast extract) demonstrated a tendency towards a decrease in the metabolic diversity of the soil microbial community under the impact of lead. 相似文献
9.
10.
The surface quality of solid wood is very important for its effective response in manufacturing processes. The effects of feed rate, cutting depth and rake angle on surface roughness and power consumption were investigated and modeled. Neuro-fuzzy methodology was applied and shown that it could be useful, reliable and an effective tool for modeling the surface roughness of wood. Thus, the results of the present research can be successfully applied in the wood industry to reduce time, energy and high experimental costs. 相似文献