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41.
We conducted a microcosm experiment with monocultures and all possible combinations of four aquatic hyphomycete species, Articulospora tetracladia, Flagellospora curta, Geniculospora grandis and Heliscus submersus, to examine the potential effects of species richness on three functional aspects: leaf litter decomposition (leaf mass loss),
fungal production (ergosterol buildup) and reproductive effort (released spores). Both species richness and identity significantly
affected fungal biomass and conidial production (number and biomass of released spores), whereas only species identity had
a significant effect on leaf mass loss. In mixed cultures, all measures of fungal functions were greater than expected from
the weighted performances of participating species in monoculture. Mixed cultures outperformed the most active monoculture
for biomass accumulation but not for leaf mass loss and conidial production. The three examined aspects of aquatic hyphomycete
activity tended to increase with species richness, and a complementary effect was unequivocally demonstrated for fungal biomass.
Our results also suggest that specific traits of certain species may have a greater influence on ecosystem functioning than
species number. 相似文献
42.
Most methods of analyzing intracellular metabolites require extraction of metabolites from the cells. A concern in these methods is underestimation of metabolite levels due to incomplete extraction. In comparing extraction methods, then, it would seem that the best method for extracting a particular metabolite is the one that gives the largest yield. In extracting Escherichia coli with different methanol:water mixtures, we observed that >or=50% water gave an increased yield of nucleosides and bases compared with 相似文献
43.
Fitzgerald J Xu X Pepper N Easterbrook M Solomon M 《Experimental & applied acarology》2008,44(4):293-306
Extensive sampling of strawberry plants in everbearing and June-bearing strawberry plantations and on potted plants showed
that different species of mites were spatially separated. Of the two phytophagous species recorded, Tetranychus urticae was most abundant on old leaves and Phytonemus pallidus on folded leaves and flower/fruit clusters. Predatory phytoseiid mites were found on all plant parts but different species
were spatially separated; Neoseiulus cucumeris and N. aurescens were found mostly on folded leaves and clusters, and N. californicus and Phytoseiulus persimilis on old and medium aged leaves. No Typhlodromus pyri were found in the field plantations. These patterns of distribution did not change over sampling dates in summer and early
autumn. An understanding of this within-plant zonation of mite species is important when studying predator–prey interactions
and when designing sampling strategies for strawberry. A programme to sample the entire mite system on strawberry should be
stratified to include all the above mentioned parts of the plant. Different sampling protocols, as appropriate, are required
for sampling different pest species and their associated predators. 相似文献
44.
Gustavo M. Martins Francisco F. M. Wallenstein Nuno V. Álvaro Ana I. Neto Ana C. Costa 《Helgoland Marine Research》2005,59(3):219-223
Azorean rocky shores are mainly characterized by patchy algae-based communities with variable associated macrofauna. Characterization studies should therefore include quantitative information for both algae and macroinvertebrates. Unlike for the algae, minimal sampling areas are undefined for macroinvertebrates in the Azores. The present study defines the minimal area to be used for the assessment of the abundance of conspicuous benthic macroinvertebrate abundance. This study proposes methodologies to be used for a selected group of invertebrates when simultaneously undertaking quantifications of macroalgae. 相似文献
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基因检测是遗传工程的重要技术之一,基因检测技术的自动化对工程的研究具有重要意义,而自动进样控制系统是基因快速检测仪的重要组成部分。该系统的硬件部分主要由液位检测电路及其接口电路组成;软件部分主要由VisualC 6.0编程对硬件实现其自动控制功能。该系统主要包括:控制清洗通道流程、排除废流流程和进样流程等功能,工作模式可根据人机对话方式设定,并能将扩增反应后的试样自动送到基因检测池中进行检测。系统具有快速、操作方便、智能化程度高、准确性高等特点。 相似文献
49.
Abstract. Plant cover was visually estimated by five observers, independent of each other, in a species‐rich grassland in the Bílé Karpaty Mts., southeastern Czech Republic, in seven plots ranging from 0.001 to 4 m2. Variation of total plant cover among the observers was high at small scales: 0.001–0.016 m2; coefficient of variation, CV = 35 to 45%, but much lower at larger scales: 0.06–4 m2; CV = 7 to 15%. Differences between visual estimates of plant cover of individual species made by different observers were affected by plot size, total cover and morphology of particular plants. CV of the cover of individual species ranged from 0 to 225% and decreased with increasing plot size. For abundant plants the CV attained ca. 50%, independent of plot size. In spite of a very high number of sterile plants with similar leaf morphology and colour, the observed variation in cover estimates in the studied grassland was comparable with results reported from other vegetation types. Differences between estimates by individual observers were often larger than usual year to year changes in undisturbed grasslands. Therefore, I suggest that to avoid difficulties in the interpretation of results based on plant cover data obtained from visual estimates, several observers should always work together, adjusting their extreme estimates. 相似文献
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