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Javier Gallego Catharina Bamps 《International Journal of Applied Earth Observation and Geoinformation》2008,10(4):467
CORINE land cover 2000 (CLC2000) is a European land cover map produced by photo-interpretation of Landsat ETM+ images. Its direct use for area estimation can be strongly biased and does not generally report single crops. CLC areas need to be calibrated to give acceptable statistical results.LUCAS (land use/cover area frame survey) is a point survey carried out in 2001 and 2003 in the European Union (EU15) on a systematic sample of clusters of points. LUCAS is especially useful for area estimation in geographic units that do not coincide with administrative regions, such as set of coastal areas defined with a 10 km buffer. Some variance estimation issues with systematic sampling of clusters are analysed.The contingency table obtained overlaying CLC and LUCAS gives the fine scale composition of CLC classes. Using CLC for post-stratification of LUCAS is equivalent to the direct calibration estimator when the sampling units are points. Stratification is easier to adapt to a scheme in which the sampling units are the clusters of points used in LUCAS 2001/2003. 相似文献
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Bart E. van Dongen W. Irene C. Rijpstra Catharina J. M. Philippart Jan W. de Leeuw Jaap S. Sinninghe Damst 《Organic Geochemistry》2000,31(12)
Total extracts of sediment cores from five different stations in the North Sea and Wadden Sea were analysed for their biomarker composition. Only sediments of the Skagerrak contained significant amounts of marine biomarkers (mainly alkenones), other sites contained predominantly terrestrial biomarkers. Bioturbation in the Skagerrak is, however, far too high to determine sea surface temperature (SST) changes within short time intervals. These results indicate that biomarkers contained in these sediments are not useful to reconstruct climate fluctuations during the upper Holocene. High amounts of α-, β- and ω-hydroxy fatty acids as well as small amounts of α, β-dihydroxy fatty acids were released from the insoluble organic material of the sediments from the Wadden Sea station, indicating a significant input of the eelgrass Zostera marina. This was confirmed by microscopic observations. This is the first time the α,β-dihydroxy fatty acids have been found in a sediment core and they have proven to be potential biomarkers for these seagrass species. 相似文献
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Long-term fluctuations in fish recruit abundance in the western Wadden Sea in relation to variation in the marine environment 总被引：1，自引：0，他引：1
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Catharina Johanna Maria Philippart Jolanda Martine van Iperen Gerhard Cornelis Cadée Alain François Zuur 《Estuaries and Coasts》2010,33(2):286-294
Analyses of long-term field observations (1974–2007) on chlorophyll-a concentrations in the western Wadden Sea showed no long-term trends in the timing of the wax and wane of phytoplankton spring
blooms. There is weak evidence, however, that the height of the autumn bloom has decreased since the early 1990s. This fading
of the autumn bloom may have had consequences for the carbon transfer to higher trophic levels, currently hampering primary
consumer species that mostly rely on food supply during late summer. Current and other findings suggest a shortening of the
growing season due to the fading of the autumn bloom in the Wadden Sea and a lengthening of the growing season due to an advancement
of the spring bloom in the North Sea. These regionally different changes in seasonality may have contributed to the coinciding
decrease in bivalve filtering capacity in the western Wadden Sea and the large-scale offshore shift of juvenile plaice from
the Wadden Sea to the adjacent North Sea. 相似文献
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