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121.
To facilitate future carbon and nutrient inventories, we used mixed-effect linear models to develop new generic biomass functions for Norway spruce (Picea abies (L.) Karst.) in Central Europe. We present both the functions and their respective variance-covariance matrices and illustrate their application for biomass prediction and uncertainty estimation for Norway spruce trees ranging widely in size, age, competitive status and site. We collected biomass data for 688 trees sampled in 102 stands by 19 authors. The total number of trees in the "base" model data sets containing the predictor variables diameter at breast height (D), height (H), age (A), site index (SI) and site elevation (HSL) varied according to compartment (roots: n = 114, stem: n = 235, dry branches: n = 207, live branches: n = 429 and needles: n = 551). "Core" data sets with about 40% fewer trees could be extracted containing the additional predictor variables crown length and social class. A set of 43 candidate models representing combinations of lnD, lnH, lnA, SI and HSL, including second-order polynomials and interactions, was established. The categorical variable "author" subsuming mainly methodological differences was included as a random effect in a mixed linear model. The Akaike Information Criterion was used for model selection. The best models for stem, root and branch biomass contained only combinations of D, H and A as predictors. More complex models that included site-related variables resulted for needle biomass. Adding crown length as a predictor for needles, branches and roots reduced both the bias and the confidence interval of predictions substantially. Applying the best models to a test data set of 17 stands ranging in age from 16 to 172 years produced realistic allocation patterns at the tree and stand levels. The 95% confidence intervals (% of mean prediction) were highest for crown compartments (approximately +/- 12%) and lowest for stem biomass (approximately +/- 5%), and within each compartment, they were highest for the youngest and oldest stands, respectively. 相似文献
122.
Fumonisin B2 production by Aspergillus niger 总被引:1,自引:0,他引:1
Frisvad JC Smedsgaard J Samson RA Larsen TO Thrane U 《Journal of agricultural and food chemistry》2007,55(23):9727-9732
The carcinogenic mycotoxin fumonisin B2 was detected for the first time in the industrially important Aspergillus niger. Fumonisin B2, known from Fusarium verticillioides and other Fusaria, was detected in cultures of three full genome sequenced strains of A. niger, in the ex type culture and in a culture of F. verticillioides by electrospray LC-MS analysis of methanolic extracts from agar plugs of cultures grown on several substrates. Whereas F. verticillioides produced fumonisins B1, B2, and B3 on agar media based on plant extracts, such as barley malt, oat, rice, potatoes, and carrots, A. niger produced fumonisin B2 best on agar media with a low water activity, including Czapek yeast autolysate agar with 5% NaCl. Of the media tested, only rice corn steep agar supported fumonisin production by both F. verticillioides and A. niger. However, A. niger had a different regulation of fumonisin production and a different quantitative profile of fumonisins, producing only B2 as compared to F. verticillioides. Fumonisin production by A. niger, which is a widely occurring species and an extremely important industrial organism, will have very important implications for biotechnology and especially food safety. A. niger is used for the production of citric acid and as producer of extracellular enzymes, and also as a transformation host for the expression of heterologous proteins. Certain strains of A. niger produce both ochratoxin A and fumonisins, so some foods and feeds may potentially contain two types of carcinogenic mycotoxins from this species. 相似文献
123.
Desmedipham, phenmedipham and a 50% mixture of the two decreased the maximum quantum efficiency of photosystem II (F(v)/F(m)) and the relative changes at the J step (F(vj)) immediately after spraying in both sugar beet and black nightshade grown in the greenhouse. Sugar beet recovered more rapidly from phenmedipham and the mixture than from desmedipham. Desmedipham and the mixture irreversibly affected F(v)/F(m) and F(vj) in black nightshade at much lower doses than in sugar beet. Black nightshade recovered from phenmedipham injury at the highest dose in the first experiment (120 g AI ha(-1)) but not in the second experiment (500 g AI ha(-1)). The dry matter dose-response relationships and the energy pipeline presentation confirmed the same trend. There was a relatively good correlation between F(vj) taken 1 day after spraying and dry matter taken 2 or 3 weeks after spraying. The differential speed of herbicide metabolism between weed and crop plays an important role in herbicide selectivity and can be studied by using appropriate chlorophyll a fluorescence parameters. 相似文献
124.
Jens Gebauer Eike Luedeling Karl Hammer Maher Nagieb Andreas Buerkert 《Genetic Resources and Crop Evolution》2007,54(3):465-481
Several botanical studies have been conducted in different parts of Oman, but knowledge about agro-biodiversity in the rapidly decaying ancient mountain oases of this country remains scarce. To fill this gap we assessed the genetic resources of three mountain oases in the al-Hajar range using a GIS-based field survey and farmer interviews. While arid conditions prevail throughout the mountain range, the different elevations of Balad Seet (950–1020 m a.s.l.), Maqta (930–1180 m a.s.l.) and Al Jabal al Akhdar (1750–1930 m a.s.l.) provide markedly differing agro-climatic conditions. Overall, 107 different crop species were identified belonging to 39 families. Species number was highest among fruits (33 spp.), followed by vegetables (24 spp.). Intensive irrigation allows cultivation of a broad range of species at all oases. However, the number of species varied significantly between sites. Fruit species diversity and homogeneity of distribution of individual fruit species was highest at Balad Seet and lowest at Maqta as indicated by respective Shannon indices of 1.00 and 0.39 and evenness values of 32% and 16%. Century plant (Agave americana L.), faba bean (Vicia faba L. var. minor Peterm. em. Harz) and lentil (Lens culinaris Medik.) were identified as relict crops, supporting oral reports of past cultivation and providing evidence of genetic erosion. Some species, such as the temperate fruits of Al Jabal al Akhdar, were exclusively found at the coolest site, while others only occurred at the hotter locations. Overall greatest species similarity was found between Balad Seet and Al Jabal al Akhdar as indicated by a Sørensen coefficient of similarity of 67%. At all oases a multilayered vegetation structure dominated with a canopy, an understory and a ground layer. Greatest species richness was recorded in the lowest stratum. Overall the study shows a location-specific but surprisingly diverse mosaic of crops in Omani mountain oases which merits further studies and conservation efforts. 相似文献
125.
Egenvall A Bonnett BN Häggström J 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2006,20(4):894-903
BACKGROUND: Population-based information on disease occurrence is paramount in clinical decision making and in designing preventative measures, but such information is scarce. HYPOTHESIS: The risk of cardiac death is higher in certain breeds and mortality varies by age and sex. DOGS: Dogs that were life insured by an animal insurance company between 1995 and 2002. METHODS: The mortality pattern for heart disease in insured dogs up to 10 years of age was studied. The influences of sex, age, breed, month, and geographic location were investigated by means of incidence rates, proportions, and survival proportions. Cox proportional hazards regression was used to model time to heart disease. RESULTS: 405,376 dogs contributed to a denominator of 1,431,933 dog-years at risk (DYAR) and 3,049 dogs had been assigned a cardiac-related diagnosis as cause of death. The cardiac-related mortality for dogs <10 years of age, was 21.3 deaths per 10,000 DYAR. This mortality in males and females was 27.3 deaths and 15.4 deaths per 10,000 DYAR, respectively. Twelve of 54 breeds had a point estimate above the overall rate. The 3 breeds with the highest point estimates were: Irish Wolfhounds, Cavalier King Charles Spaniels, and Great Danes (rates of 356, 247, and 179 deaths per 10,000 DYAR, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Breed, age, and sex affect cardiac mortality in certain breeds of dogs, but no effects of month and geographic location were identified. These findings can assist clinicians in establishing diagnoses, and can assist breeders in defining priorities for preventative measures. 相似文献
126.
Jens Peter Vesterager Kasper Teilmann Henrik Vejre 《European Journal of Forest Research》2012,131(1):95-107
The lack of generic methods to assess the environmental consequences of agricultural practices and the lack of consensus on
monitoring and evaluation of environmental, agricultural and socio-economic effects of agri-environment schemes (AES) in EU
Member States call for better evaluation methods. The ‘Agri-environmental Footprint’ project proposed to deal with these problems
by establishing a new evaluation method, the Agri-Environmental Footprint Index (AFI). The AFI is an index customised to local
stakeholder preferences, using expert knowledge for assessment of impacts and sensitivity, and indicators of the environmental
state at farm level. In a Danish test case, agricultural practices at twenty-five farms in two groundwater protection zones
were assessed. Data was collected from databases, registers, maps and interviews with farmers. The index was calculated for
1996/7 and 2006/7 to track temporal development and effects of entering an agri-environmental scheme. The Danish case demonstrated
that the index can be used to track changes in environmental impacts and that entering agri-environmental scheme had a positive
impact on the index value. However, the index should be used with caution. It is important to consider the robustness of each
indicator: to assess whether changes will occur over time; whether changes are linked to management practices or external
factors; and whether data are available up to date. Indicators dependent upon uptake data from agri-environmental schemes
should be used with great caution. Retrospective use of stakeholder preferences is subject to uncertainty because preferences
may have changed over time. 相似文献
127.
Kreysing M Pusch R Haverkate D Landsberger M Engelmann J Ruiter J Mora-Ferrer C Ulbricht E Grosche J Franze K Streif S Schumacher S Makarov F Kacza J Guck J Wolburg H Bowmaker JK von der Emde G Schuster S Wagner HJ Reichenbach A Francke M 《Science (New York, N.Y.)》2012,336(6089):1700-1703
Despite their diversity, vertebrate retinae are specialized to maximize either photon catch or visual acuity. Here, we describe a functional type that is optimized for neither purpose. In the retina of the elephantnose fish (Gnathonemus petersii), cone photoreceptors are grouped together within reflecting, photonic crystal-lined cups acting as macroreceptors, but rod photoreceptors are positioned behind these reflectors. This unusual arrangement matches rod and cone sensitivity for detecting color-mixed stimuli, whereas the photoreceptor grouping renders the fish insensitive to spatial noise; together, this enables more reliable flight reactions in the fish's dim and turbid habitat as compared with fish lacking this retinal specialization. 相似文献
128.
Behrens M Studt F Kasatkin I Kühl S Hävecker M Abild-Pedersen F Zander S Girgsdies F Kurr P Kniep BL Tovar M Fischer RW Nørskov JK Schlögl R 《Science (New York, N.Y.)》2012,336(6083):893-897
One of the main stumbling blocks in developing rational design strategies for heterogeneous catalysis is that the complexity of the catalysts impairs efforts to characterize their active sites. We show how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al(2)O(3) methanol synthesis catalyst by using a combination of experimental evidence from bulk, surface-sensitive, and imaging methods collected on real high-performance catalytic systems in combination with density functional theory calculations. The active site consists of Cu steps decorated with Zn atoms, all stabilized by a series of well-defined bulk defects and surface species that need to be present jointly for the system to work. 相似文献
129.
130.
BACKGROUND: Bifora radians, an annual weed in winter wheat, is distributed mainly in the Mediterranean area, Asia Minor and the Caucasus. It infests winter-sown crops of the Central Anatolia and Middle Black Sea regions of Turkey. Field experiments in heavily B. radians-infested fields were conducted over 3 years in Samsun, Turkey, to determine the response of B. radians to ALS-inhibiting herbicides, because growers had complained of a decrease in herbicide effect. RESULTS: The efficacy of ALS inhibitors on a putatively tolerant population sprayed annually with ALS inhibitors and an adjacent allegedly sensitive population was estimated at the ED50 and ED90 response levels. The recommended rates of herbicides controlled 90% of the weed (ED90) in the sensitive population at the early stage of B. radians development, but not in the tolerant population. The relative potencies (EDx(tolerant)/EDx(sensitive)) of herbicides on the two populations were estimated by assuming years as being random effects. The relative potency was on average about 1.7, irrespective of the EDx levels. CONCLUSION: Although the relative potencies were not large, they were large enough to be noted by growers. In field experiments it would be important to establish tools demonstrating when farmers recognise loss of herbicide efficacy. There has been no indication of evolution of resistant biotypes so far, but continuous spraying favours biotypes with increased levels of tolerance. Copyright © 2011 Society of Chemical Industry 相似文献