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1.
Oak (Quercus spp.) regeneration is an important forest management goal in the central hardwood forest region of the United States. Silvicultural methods that target oak regeneration, such as the creation of canopy openings and removal of shade-tolerant midstory trees, are complicated by the impact of pre- and post-dispersal predators of oak acorns like acorn weevils (Curculio spp.) and granivorous small mammals. Understanding the effects of forest disturbance created by silviculture on these predators is important to promote successful oak regeneration. We conducted a 6-year study of acorn production, weevil infestation, and acorn removal at 113 black (Q. velutina) and white oak (Q. alba) trees impacted by three types of silvicultural treatments: adjacent to harvest openings, midstory removal (first-stage shelterwood harvest), and control (no harvest) in south-central Indiana, USA. We observed highly variable acorn production across years, but minimal impact of silvicultural treatments. Levels of weevil infestation and acorn removal by small mammal seed predators also varied greatly, and predation pressure was highest in years when acorns were scarce. Weevil infestation was reduced following midstory removal in shelterwood harvests, but probability of acorn removal by small mammals was unchanged following harvest. Damaged, germinated, and weevil-infested acorns were less likely to be removed by seed predators, suggesting additive effects of pre- and post-dispersal predators. This study emphasizes the importance of considering acorn predators in oak regeneration silviculture, and timing harvests to follow large acorn crops in order to reduce predation pressure and generate a high number of seedlings. 相似文献
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Riegel CM Stockham SL Patton KM Thomas CL 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2008,37(3):353-356
Pleural effusion was examined from a 5-year-old, female Brittany Spaniel with a 7-day history of dyspnea, anorexia, and diarrhea. The fluid was yellow, cloudy, and slightly gelatinous, and had a total protein concentration of 2.8 g/dL, a total nucleated cell concentration of 1.1 x 10(3)/muL, and a triglyceride concentration of 177 mg/dL. A cytocentrifuged preparation contained a mixed inflammatory cell population with a predominance of small lymphocytes and abundant mucinous material in the background. The dog died 3 days later and a mass was found within the lumen and wall of the right auricle of the heart at necropsy. Histopathologic sections of the mass contained a population of anaplastic spindle cells diffusely suspended in a pale basophilic matrix, consistent with myxosarcoma. The cells were positive for vimentin and negative for cytokeratin, desmin, and von Willebrand factor VIII-related antigen. A myxoid matrix was confirmed by positive staining with Alcian blue. Myxosarcoma is a rare cardiac tumor in dogs that should be considered, along with mucus-producing carcinomas and bile, as a cause of muculent effusion. 相似文献
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ABSTRACT The epidemiology and control of black rot (Guignardia bidwellii) was studied from 1995 to 1999 in vineyards in Dresden and Naples, NY, where disease pressure was moderate and extreme, respectively. The efficacy of serial applications of myclobutanil, provided at 2-week intervals and varied with respect to their number and time of initiation, was examined within the context of host phenology, inoculum availability, and sanitation. At Dresden, sprays applied over 4 weeks through the immediate prebloom stage provided only 13 to 91% control of diseased clusters, despite the release of 95% of the season's ascosporic inoculum during the period of fungicidal protection. However, applications immediately prior to bloom plus 2 and 4 weeks later, which afforded protection while fruit are highly susceptible to infection, provided virtually complete control. At Naples, where mummified berries were retained in the canopy after mechanical pruning, this same regime provided only approximately 80% disease control, but applying a fourth spray 2 weeks prebloom generally improved control. Hand-pruning mummies to the ground in selected plots significantly (P 相似文献
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The rapid and early detection of autotetraploid individuals is a fundamental requirement in genetic improvement programmes based on chromosome duplication. Counting chromosomes provides certainty of the ploidy level of an individual, however, it is very laborious. In this work, image cytometry is proposed as an easy alternative method to detect tetraploid individuals. Plantlets of the species Rhodophiala montana treated with colchicine were karyomorphologically analysed. Based on the Feulgen stain, chromosomes were counted and the integrated density value of interphase nuclei was determined. The average DNA content measured with image cytometry for the polyploid individuals was 1.88 times more than that for the diploid individuals. With this methodology, 100% effectiveness in the selection was achieved, rapidly identifying all autotetraploid individuals. 相似文献
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Riegel KW 《Science (New York, N.Y.)》1973,179(4080):1285-1291
There have been major qualitative and quantitative changes in outdoor lighting technology in the last decade. The level of skylight caused by outdoor lighting systems is growing at a very high rate, about 20 percent per year nationwide. In addition, the spectral distribution of man-made light pollution may change in the next decade from one containing a few mercury lines to one containing dozens of lines and a significantly increased continuum level. Light pollution is presently damaging to some astronomical programs, and it is likely to become a major factor limiting progress in the next decade. Suitable sites in the United States for new dark sky observing facilities are very difficult to find. Some of the increase in outdoor illumination is due to the character of national growth and development. Some is due to promotional campaigns, in which questionable arguments involving public safety are presented. There are protective measures which might be adopted by the government; these would significantly aid observational astronomy, without compromising the legitimate outdoor lighting needs of society. Observatories should establish programs to routinely monitor sky brightness as a function of position, wavelength, and time. The astronomical community should establish a mechanism by which such programs can be supported and coordinated. 相似文献
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David A. Perry Paul F. HessburgCarl N. Skinner Thomas A. SpiesScott L. Stephens Alan Henry TaylorJerry F. Franklin Brenda McCombGreg Riegel 《Forest Ecology and Management》2011,262(5):703-717
Forests characterized by mixed-severity fires occupy a broad moisture gradient between lower elevation forests typified by low-severity fires and higher elevation forests in which high-severity, stand replacing fires are the norm. Mixed-severity forest types are poorly documented and little understood but likely occupy significant areas in the western United States. By definition, mixed-severity types have high beta diversity at meso-scales, encompassing patches of both high and low severity and gradients in between. Studies of mixed-severity types reveal complex landscapes in which patch sizes follow a power law distribution with many small and few large patches. Forest types characterized by mixed severity can be classified according to the modal proportion of high to low severity patches, which increases from relatively dry to relatively mesic site conditions. Mixed-severity regimes are produced by interactions between top-down forcing by climate and bottom-up shaping by topography and the flammability of vegetation, although specific effects may vary widely across the region, especially the relation between aspect and fire severity. History is important in shaping fire behavior in mixed-severity landscapes, as patterns laid down by previous fires can play a significant role in shaping future fires. Like low-severity forests in the western United States, many dry mixed-severity types experienced significant increases in stand density during the 20th century, threatening forest health and biodiversity, however not all understory development in mixed-severity forests increases the threat of severe wild fires. In general, current landscapes have been homogenized, reducing beta diversity and increasing the probability of large fires and insect outbreaks. Further loss of old, fire tolerant trees is of particular concern, but understory diversity has been reduced as well. High stand densities on relatively dry sites increase water use and therefore susceptibility to drought and insect outbreaks, exacerbating a trend of increasing regional drying. The need to restore beta diversity while protecting habitat for closed-forest specialists such as the northern spotted owl call for landscape-level approaches to ecological restoration. 相似文献
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Solís J. L. Muth J. Canales J. Lizana C. Pruefer D. Riegel R. Behn A. 《Genetic Resources and Crop Evolution》2022,69(1):297-314
Genetic Resources and Crop Evolution - The potato (Solanum tuberosum L.) is the fourth most important crop for global food security. Its tubers contain high concentrations of antioxidants,... 相似文献
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Revierförfter Riegel 《European Journal of Forest Research》1857,1(8):333-336
Ohne Zusammenfassung 相似文献
10.
A single dilution enzyme-linked immunosorbent assay for the quantitative detection of antibodies to bovine herpesvirus type 1 总被引：1，自引：0，他引：1
Three serological assays were compared for detection of antibodies to bovine herpes-virus type 1. These were virus neutralization (VN), enhanced complement fixation (CF) and enzyme-linked immunosorbent assay (ELISA). The ELISA was developed using an infected cell lysate antigen and purified virus and was optimized in relation to antigen and antisera dilutions. The CF assay was enhanced by the addition of bovine complement. These 3 assays were compared for detection of: specific virus antibody titers; sero-conversions; early antibody response in experimentally-infected cattle. Both ELISA end-point titers and single dilution values were found to be more sensitive than the CF or VN assays for specific antibody level quantitation. With a single dilution ELISA test procedure a correlation was obtained between ELISA values and VN titers. Using the single dilution ELISA test the assay also detected antibodies in experimentally-infected cattle before either the VN or CF assays, and agreed with the VN test in 35/38 seroconversions found by 4-fold or more VN changes between acute and convalescent paired sera from naturally-infected animals. The single dilution ELISA was a rapid and sensitive test for routine antibody detection in bovine sera. 相似文献