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首頁> 美國政府科技報告 >Seedling Response to CO sub 2 Enrichment under Stressed and Non-Stressed Conditions.
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Seedling Response to CO sub 2 Enrichment under Stressed and Non-Stressed Conditions.

機譯：脅迫和非脅迫條件下幼苗對CO 2富集的響應。

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Loblolly pine and sweetgum seedlings were obtained from a Duke University phytotron study, where three groups were grown in different atmospheres of CO2 (i.e., 350, 500, 650 ppmv). Seedlings were grown over three growing seasons, and included a set of water-stressed and non-stressed individuals. X-ray densitometry was used to evaluate growth and density characteristics of the wood samples. Cross-sectional discs of these samples were radiographed and scanned with a microdensitometer to determine ring width, area, density and mass for each growth year. Results indicated significant differences in wood production (ring width, area and mass) between the lowest treatment of CO2 (350 ppmv) and the higher concentration (500 and 650 ppmv) treatments. While only a few density parameters demonstrated significant changes with increasing CO2 , almost all showed a systematic increase in density with increasing CO2 concentration. Ring area and mass displayed the greatest degree of change between treatments. Induced drought effects appeared only to strengthen the CO2 -growth association. These findings suggest that naturally stressed trees are also likely to exhibit some growth effect with increasing atmospheric CO2 . And because the greatest margin of response existed between 350 and 500 ppmv, this study emphasizes the importance and need to determine growth responses at preindustrial era CO2 concentrations in order to more accurately identify the postulated ''fertilizer'' effect on modern forests. 10 refs., 4 tabs. (ERA citation 13:057606)

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