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  • Lignification of latewood tracheids in silver fir - a comparison of healty and declining trees
    Gričar, Jožica ...
    From 1960 up to the late 80s silver fir trees in Slovenia showed distinct decline symptoms such as severe needle loss and reduced wood formation. Subsequently, many of these trees began to recover, ... but some still appear affected. According to transmission electron microscopy (TEM) and UV-microspectrophotometry of current year latewood tracheids of such affected trees the secondary wall deposition as well as lignification were completed in samples taken in middle of October. Unexpectedly, in samples taken at the same date from healthy looking silver firs the S3 and also the warty layer, which are normally developed in mature tracheids, were not yet present in the cambium-adjacent latewood tracheids. In addition, the innermost S2 of these tracheids did not show lignin deposition, whereas the middle lamella and outer secondary wall were distinctly lignified. That means, these youngest tracheids of healthy trees still undergo lignification or remain partly unlignified, while the cambium appeared dormant. From these observations we conclude that the cambial activity appears to end later in healthy trees than in declining trees. Consequently, declining trees exhibit a distinct reduction of the duration of wood formation representing one of the reasons responsible for reduced tree-ring widths.
    Vir: Proceedings of the Fifth International Conference on the Development of Wood Science, Wood Technology and Forestry, ICWSF 2001, 5th - 7th September 2001, Ljubljana, Slovenia (Str. 341-346)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2001
    Jezik - angleški
    COBISS.SI-ID - 803209

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