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Review of ground-based methods to measure the distribution of biomass in forest canopies 总被引：1，自引：0，他引：1
Dominik Seidel Stefan Fleck Christoph Leuschner Tom Hammett 《Annals of Forest Science》2011,68(2):225-244
? Context
Ecological research and an effective forest management need accurate information on the structure of the forest canopy to understand the biochemical, physiological and biogeochemical processes within a forest.? Research question
This paper reviews the currently available instruments for measuring the distribution of biomass within forest canopies. We compare the most well-established approaches and present the different measurable parameters. A special focus lies on the resolution of the obtained data.? Results
It was found that only 3D laser scanners offer data with the resolution required by ecologists, private landholders, the forest industry and the public to detect trends in tree growth patterns and canopy interactions in all three spatial dimensions. But data validation, data analysis and parameter extraction are still under development, and the price of the instrument is quite high.? Conclusion
Research should focus on the parameter extraction from terrestrial laser scanner data as this could allow the calculation of functional attributes for different sections of a canopy on a high spatial resolution. It could also help ecologists characterize the structure of forest stands in a quick and precise way. 相似文献2.
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ULTRASONOGRAPHIC EVALUATION OF THE FETUS AND INTRAUTERINE ENVIRONMENT IN HEALTHY MARES DURING LATE GESTATION 总被引：3，自引：0，他引：3
Virginia B. Reef DVM Wendy E. Vaala VMD Leila T. Worth VMD PhD Pamela A. Spencer ScM Barbara Hammett 《Veterinary radiology & ultrasound》1995,36(6):533-541
Mares with uncomplicated pregnancies (n = 33) underwent transabdominal sonography to evaluate fetal well-being, obtain measurements of fetal size and characterize the intrauterine environment. Data from the last examination obtained prior to parturition were used for statistical analysis. All mares had one active fetus with good fetal tone. The maximal vertical depth of amniotic fluid (7.9 ± 3.5 cm) was less than allantoic (13.4 ± 4.4 cm) and fewer echogenic particles were detected in amniotic fluid. The maximal uteroplacental thickness was 1.38 ± 0.23 cm (retrospective) and 1.15 ±± 0.24 cm (propspective). In 3 mares small anechoic spaces were imaged between the uterus and placenta. Fetuses had a regular cardiac rhythm with a mean heart rate of 75 ± 7 beats/minute and breathing movements. The diameter of the fetal aorta (mean = 22.8 ± 2.15 mm) was significantly correlated with neonatal foal weight (P<0.0008, r = 0.72) and maternal prepartum weight (P<0.002, r = 0.86). This information of the normal intrauterine environment and fetal well-being can be used to develop a biophysical profile specific for the equine fetus. 相似文献
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N. Feau D. I. Ojeda S. Beauseigle G. J. Bilodeau A. Brar S. Cervantes-Arango A. L. Dale B. Dhillon C. Hammett P. Herath S. F. Shamoun C. K. M. Tsui P. Tanguay R. C. Hamelin 《Plant pathology》2019,68(5):878-888
Early detection provides the best way to prevent introduction and establishment of alien plant pathogens. Amplification of DNA by PCR has revolutionized the detection and monitoring of plant pathogens. Most of those assays rely on the amplification of a fraction of the genome of the targeted species. With the availability of whole genomes for a growing number of fungi and oomycetes it is becoming possible to compare genomes and discover regions that are unique to a target organism. This study has applied this pipeline to develop a set of hierarchical TaqMan real-time PCR detection assays targeting DNA of all four Phytophthora ramorum lineages, and a closely related species, P. lateralis. Nine assays were generated: three targeting DNA of all P. ramorum lineages, one for each lineage of P. ramorum, one for P. lateralis and one targeting DNA of P. ramorum and P. lateralis. These assays were very accurate and sensitive, ranging from 98.7% to 100% detection accuracy of 2–10 gene copies of the targeted taxa from pure cultures or inoculated tissues. This level of sensitivity is within the lowest theoretical limit of detection of DNA. It is expected that these assays will be useful because of their high level of specificity and the ease with which they can be multiplexed because of the inherent flexibility in primer and probe design afforded by their lack of conservation in non-target species. 相似文献
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The ability of 13 Nemesia species (six annual and seven perennial) to sexually hybridize was investigated. Six of the perennial Nemesia species investigated were inter-fertile with one another. Two of the annual species, N. macroceras and N. strumosa, were inter-fertile. Thirty three crosses were successful and resulted in viable seeds. The analysis of meiotic chromosome behaviour in interspecific hybrids indicated that Nemesia chromosomes in different parental species were homeologous. No evidence of chromosome inversions or chromosome translocations was observed during meiosis in interspecific hybrids between the six perennial Nemesia species. In the hybrids produced between N. macroceras and N. strumosa, a quadrivalent was observed during meiotic metaphase I, indicating that these two species differ by a reciprocal translocation. A successful hybridization was made between N. anisocarpa (annual) and N. foetans (perennial), producing two triploid hybrids. In the unsuccessful crosses, pollen tubes were observed entering ovaries and ovules, suggesting that post-fertilization barriers were preventing sexual hybridization. Many of these crosses produced nonviable, shrunken, empty seeds, suggesting that endosperm breakdown and embryo abortion prevent interspecific hybridization in unsuccessful crosses. The manipulation of ploidy levels in N. fruticans and N. strumosa and tissue culture of N. strumosa × N. fruticans ovules failed to overcome post-fertilization barriers between these species. 相似文献