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Japanese cedar (Cryptomeria japonica) preheated at 700°C was subsequently heated to 1800°C and characterized by electron microscopy, X-ray diffraction, and micro-Raman spectroscopy. The degree of disorder of carbon crystallites and the amount of amorphous phase decreased considerably with an increase in heat treatment temperature to 1400°C, while carbon crystallites clearly developed above this temperature, showing that the microstructure of carbonized wood undergoes drastic changes around 1400°C. Besides showing the bands for sp 2 -bonded carbon, the Raman spectra showed a shoulder near 1100 cm −1 assigned to sp 3 -bonded carbon. With an increase of heat treatment temperature, the peak position of the Raman sp 3 band shifted to a lower frequency from 1190 to 1120 cm −1 , which is due to the transformation of sp 3 -bonded carbon from an amorphous phase to a nanocrystalline phase. These data showed that the microstructure of carbonized wood from 700° to 1800°C consisted of the combination of sp 2 -and sp 3 -bonded carbon, which is probably due to the disordered microstructure of carbonized wood. It is suggested that the sp 3 -bonded carbon is transformed from an amorphous structure to a nanocrystalline structure with the growth of polyaromatic stacks at temperatures above 1400°C.

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Japanese cedar was preheated at 5008C and subsequently mixed with 40 mm Al 2 O 3 particles. A pulse current heating method was used for a 5-min carbonization step under a pressure of 50 MPa in order to promote the graphitization at temperatures between 2000 and 22008C. The samples were analyzed in an analytical transmission electron microscope equipped with a GATAN Imaging Filter, in a high resolution transmission electron microscope and in a scanning electron microscope. Transformation into well-ordered graphite could be enforced by the intermediate reaction of Al 2 O 3 and carbon to plate-like Al 4 C 3. This latter compound dissociates under the proper CO pressure and temperature into Al vapor and solid graphite. The addition of Al 2 O 3 and the pressurized heating device improve the graphitization in comparison with the effect of temperature alone. The electron microscopic observations are supported by XPS and XRD spectra.

Information on primary growth behavior after planting is required for mixed-plantation revegetation using broad-leaved species. To estimate primary growth, especially from the perspective of crown coverage and changing growth rates, we examined the growth and survival of four broad-leaved species that are frequently used in erosioncontrol plantations in Japan. The species studied were Myrica rubra Sieb. et Zucc., Alnus pendula Matsum., Quercus glauca Thunb., and Q. serrata Thunb. The survival, height, and basal diameter of planted trees were measured over a 4-year period, and crown area was calculated over a 3-year period. We found a negative relationship between relative growth rate (RGR) and survival rate, suggesting that fast growth may be fatal when resources are severely limited. The relative height growth rate (RHGR) of A. pendula was especially high during the early period of the study (1997)(1998)(1999) and then drastically declined, whereas the opposite tendency was observed in Q. glauca. The results of stem allometry analyses conformed to the specific relationships between height growth and diameter growth of the four species; increases in stem thickness based on height increments were smaller in the pioneer species A. pendula. Between-species differences in coverage per planted tree (mean crown area multiplied by survival rate) were small as a result of the negative relationship between coverage area and survival rate.