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The normalised difference vegetation index (NDVI) has evolved as a primary tool for monitoring continental‐scale vegetation changes and interpreting the impact of short to long‐term climatic events on the biosphere. The objective of this research was to assess the nature of relationships between precipitation and vegetation condition, as measured by the satellite‐derived NDVI within South Australia. The correlation, timing and magnitude of the NDVI response to precipitation were examined for different vegetation formations within the State (forest, scrubland, shrubland, woodland and grassland). Results from this study indicate that there are strong relationships between precipitation and NDVI both spatially and temporally within South Australia. Differences in the timing of the NDVI response to precipitation were evident among the five vegetation formations. The most significant relationship between rainfall and NDVI was within the forest formation. Negative correlations between NDVI and precipitation events indicated that vegetation green‐up is a result of seasonal patterns in precipitation. Spatial patterns in the average NDVI over the study period closely resembled the boundaries of the five classified vegetation formations within South Australia. Spatial variability within the NDVI data set over the study period differed greatly between and within the vegetation formations examined depending on the location within the state. ACRONYMS AVHRR Advanced Very High Resolution Radiometer ENVSAEnvironments of South Australia EOS Terra‐Earth Observing System EVIEnhanced Vegetation Index MODIS Moderate Resolution Imaging Spectro‐radiometer MVC Maximum Value Composite NDVINormalised Difference Vegetation Index NIRNear Infra‐Red NOAANational Oceanic and Atmospheric Administration SPOT Systeme Pour l’Observation de la Terre 相似文献
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Loren G. Davis Shane J. MacfarlanCeleste N. Henrickson 《Journal of archaeological science》2012,39(3):663-671
Correlating archaeological finds with their associated stratigraphic context is elementary to modern excavation methods. Although micro-contextual approaches can provide invaluable perspectives, ascribing primary depositional status and associative context has traditionally been a qualitative exercise. To improve the empirical nature of this process as part of new excavations at the Cooper’s Ferry site in western Idaho, we established a chemostratigraphic framework that enables us to quantitatively relate the elemental geochemistry of sediments associated with artifacts and other samples back to a master lithostratigraphic sequence. We subjected a total of 151 PXRF readings from six lithostratigraphic units to multiple discriminant function analysis, which led to the identification of characteristic elements. To test the site’s chemostratigraphic framework, we collected PXRF readings from an infilled rodent burrow, which visually appeared to contain mixed sediments from multiple lithostratigraphic units. Statistical analysis could not relate the rodent burrow’s sedimentary geochemistry well to any of the known lithostratigraphic units, thus marking it as potentially disturbed. This methodological approach allows us to make quantitative correlations between stratigraphic units across the site and most importantly, enables us to independently evaluate whether objects from any part of the site are in direct association with “anomalous” or “regular” sediments. 相似文献
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Patrick De Deckker 《Alcheringa: An Australasian Journal of Paleontology》2013,37(4):249-274
Two spring-fed swamp deposits in northwestern Tasmania which contain non-marine ostracods are characterized by an alternation of marl, peaty marl and peaty layers: the Pulbeena Swamp deposit (4.80 m thick) was formed over approximately the last 80,000 years, and Mowbray Swamp (2 m thick) over about the last 110,000 years. Fifteen ostracod species have been recovered from 179 samples: three are new, three are in open nomenclature and the others have living representatives. The ostracod data compared with pollen curves for both sites demonstrate, for most levels, a good correlation between the abundance of ostracods and that of Cyperaceae and Potamogeton-Triglochin pollen. This implies that ostracods can be successfully used as indicators of different water regimes for spring-fed swamps. Comparison of the ostracod fauna from the two Tasmanian sites is also made with that of other known Australian and New Zealand swamp deposits. 相似文献