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LORI D. DANIELS MARIKO YANAGAWA KARI L. WERNER LUKE VASAK JESSICA A. PANJER REBECCA A. KLADY JANNEKE LADE BOB BRETT 《The Canadian geographer》2008,52(3):367-379
This paper explores the concepts of old‐growth forests, preservation and natural disturbance and demonstrates how contemporary biogeographic theory contributes to successful preservation of old‐growth forests. The case study analyzes the composition, structure, age and growth histories of trees in Big Timber Park, Whistler, British Columbia. Composition. The structure of the forest was diverse and tree ages ranged from 122 to 305 years. The densities of large old Douglas‐fir, shade‐tolerant trees and all snags are indicative of old‐growth forests; however, maximum tree diameters and densities of large snags and logs do not meet quantitative criteria for old‐growth forests. The abundance of tree regeneration and understory vegetation are relatively low. We conclude that some aspects of Big Timber Park are transitional between the mature and old‐growth stages of forest development. In the future, fine‐scale canopy gaps caused by tree senescence and interactions among insects, pathogens and wind are expected to dominate stand dynamics. Forest structure will become increasingly complex, exemplifying the dynamic nature of old‐growth forests. To successfully preserve Big Timber Park and La préservation des forêts other old‐growth forests in Canada requires understanding of natural disturbances. Preservation and the criteria and indicators used to measure successful preservation must explicitly include elements of natural change. 相似文献
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Petrography, Eh‐pH calculations and the stable isotope composition of oxygen are used to interpret geochemical processes that occurred during iron oxide mineralization and dolomitization along the Menuha Ridge segment of the Paran Fault, southern Israel, adjacent to the Dead Sea Transform (DST). Iron mineralization is strongly localized in the fault zone as ferruginous lenses, whereas Fe dolomitization spreads laterally into the Cenomanian‐Turonian carbonate host rock as stratabound beds. The average oxygen isotope fractionation between syngenetic quartz and iron oxides in the ferruginous lenses gives a temperature of 50 ± 10°C and δ18O SMOW water = ?3.5‰; consistent with an origin from metalliferous groundwater flow in the sedimentary basin. Ferroan dolomite initially formed under strongly reducing conditions, but this was followed by oxidation and pseudomorphic replacement of the dolomite by a mesh of fine‐grained iron oxides (simple zoned dolomites). This cycle of ferroan dolomite formation and replacement by iron oxides was repeated in complex zoned dolomites. Dolomite oxygen isotope compositions fall into two groups: a high δ18O group corresponding to the simple zoned dolomites and non‐ferroan dolomites and a low δ18O group corresponding to the complex zoned dolomites. Water‐rock calculations suggest that the epignetic dolomites formed under fluid‐buffered conditions: the high δ18O group are indicated to have formed at temperatures of ca. 25°C for waters with δ18O = ?4 to 0‰; the low δ18O complex zoned dolomites at 50–75°C for waters with the same isotopic composition. A kinetic calculation for a complex zoned dolomite‐bearing bed indicates that dolomitization must have occurred at high values of the dolomite saturation index. This requirement for high Mg supersaturation and the indication that epigenetic dolomitization is more protracted in stratigraphically deeper formations located closer to the DST is consistent with models proposing that Mg‐rich solutions originated in the Dead Sea Rift. 相似文献
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THE OLIVE IN THE PREHISTORIC AEGEAN: THE EVIDENCE FOR DOMESTICATION IN THE EARLY BRONZE AGE 总被引:1,自引:0,他引:1
Summary. In 1972 Colin Renfrew suggested that the rise of Mycenaean civilization may have been made possible by the development of a polycultural triad of wheat, vine and olive in the Early Bronze Age. A careful examination of the botanical and archaeological evidence for the domestication of the olive lends little support to this aspect of the thesis. The palynological evidence from various points in Greece is inconclusive, but for most areas it would seem to suggest that the intensive cultivation of olive began in the Late Bronze Age or even later.
No conclusive archaeological evidence for processing or storage of olive oil exists for any period in the Bronze Age. The question of when olive domestication took place must remain unanswered until more data are available from Early and Middle Bronze Age contexts and more conclusive botanical data have been collected. 相似文献
No conclusive archaeological evidence for processing or storage of olive oil exists for any period in the Bronze Age. The question of when olive domestication took place must remain unanswered until more data are available from Early and Middle Bronze Age contexts and more conclusive botanical data have been collected. 相似文献
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THEORY AND ESSENTIALISM IN MARXIST GEOGRAPHY 总被引:1,自引:0,他引:1
JULIE GRAHAM† 《对极》1990,22(1):53-66
Many Marxist geographers are involved in the current attempt within human geography to create nonessentialist forms of social explanation. This project has been carried forward with great, though uneven, success. I argue that the concept of ‘theory’ is an area of our discourse where essentialism tenaciously persists. I explore some essentialist meanings of ‘theory’ in Marxist geography and offer a nonessentialist alternative meaning, embedded within an explicitly nonessentialist Marxism. 相似文献
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Neutron activation analyses of the body fabric of celadons from the main production sites of the Koryǒ period have shown differences in composition between kilns. Comparison of over 50 celadon objects in the collections of the British Museum with this data base from the production sites has permitted the assignment of over 40 of the pieces to their kiln of origin The majority show the trace element pattern of the Sadangri kilns, a smaller proportion are assigned to Yuchǒnri, while others are assigned to the kilns at Chinsanri (underglaze iron) and Kyǒngsǒ-dong (unglazed). A representative group of Chinese Yue wares arc clearly different from Koryǒ celadons in trace element composition. 相似文献
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JANE MOON SHAHINA FARID ALISON HICKS MARTIN HICKS JENNIFER KIELY BRIAN IRVING WENDY MATTHEWS CHARLES FRENCH 《Arabian Archaeology and Epigraphy》1995,6(3):139-156
During 1993, the London-Bahrain Archaeological Expedition conducted a fourth season of excavations at the early second millennium settlement of Saar, Bahrain. A lower level of the temple was cleared, and a range of buildings to its north-west discovered. A new street was found opposite the temple entrance, and several of the buildings along the main street were further investigated. Further environmental research included a new programme of micromorphology and the start of research into the fish remains. 相似文献