Seasonal changes in water distribution in xylem of trees were visualized at the cellular level using cryo-scanning electron microscopy (cryo-SEM). In a ring-porous tree (Fraxinus mandshurica var. japonica), the large earlywood vessel lumina of the outermost annual ring had maintained water during the period from May to September and disappeared water during the period from October to November. The earlywood vessel lumina of the outermost annual ring had no water during the next growing season. In two diffuse-porous trees (Betula platyphylla var. japonica and Salix sachalinensis), water in the vessel lumina of the outer three annual rings gradually disappeared during the period from January to March. In April, before the leaves had expanded, the lumina of most vessels of both species were refilled with water. Many vessel lumina of both species were filled with water during the period from the subsequent growth season to the beginning of the next winter. In three conifers (Larix kaempferi, Abies sachalinensis, and Picea jezoensis), all tracheid lumina of the outermost annual ring were filled with water during the period from May to August. In September, many tracheid lumina in the transition zone from earlywood to latewood had no water. Some earlywood tracheid lumina of the outermost annual ring lost water during the period from January to March. The second and third annual rings from the bark had a similar water distribution, except that the third annual ring had more cavitated tracheids than the second annual ring. In these two annual rings, most tracheid lumina in the transition zone from earlywood to latewood had no water, and latewood near the annual boundary and many earlywood tracheids kept water in their lumina. The results of this study suggest that the water transport pathway and seasonal changes in water distribution are depending on the xylem structure of the tree species.
|Translated title of the contribution||Seasonal Changes in Water Distribution in Xylem Cells of Trees|
|Number of pages||8|
|Journal||低温生物工学会誌 = Cryobiology and cryotechnology|
|Publication status||Published - Jul 30 2002|