Contents 1 Introduction 1 2 The role of related disciplines and the progress in application 8 3 Experimental measurement and material 23 4 Diagrams of the developmental process of secondary xylem 36 5 Developmental change of fiber morphology in secondary xylem elaboration (Ⅰ)fiber length 43 6 Developmental change of fiber morphology in secondary xylem elaboration (Ⅱ)fiber diameter 58 7 Developmental change of fiber morphology of secondary xylem (Ⅲ) ratio of fiberlength to diameter 78 8 Developmental change of morphological factors of vessel cell during secondaryxylem elaboration 90 9 Developmental change of specific gravity during secondary xylem elaboration 108 10 Developmental changes of wood mechanical properties in secondary xylemelaboration 133 11 Developmental change of wood shrinkage property in secondary xylem elaboration 156 12 Developmental changes of the straticulate thickness of growth sheaths duringsecondary xylem elaboration 174 13 Developmental change of secondary xylem during the height growth of the tree stem 203 14 Developmental changes of green wood volume and oven-dry weight of the stemwood during secondary xylem elaboration 217 15 Comparison on developmental changes among root， branch and stem 230 16 Review and application prospect in rethought 286 Supplemental material Ⅰ 301 Supplemental material Ⅱ 310
摘要
1 Introduction 1.1 A natural phenomenon unknown for long 1.2 The natural process of secondary xylem elaboration 1.3 The wood state in secondary xylem of a living tree 1.4 Academic significance of the wood difference within an individual tree 1.5 Growth sheath and two directional growth ages 1.6 The characteristics and testability of dynamic developmental changes of secondary xylem 1.7 The difference between the development study of secondary xylem and studies related to wood 1.8 Conclusions Abstract Such natural states that provide the basis for discovering the developmental phenomenon of secondary xylem are realized; and it has been found that some special natural factors related to the phenomenon have to be considered in carrying out there search experiment. The demonstration of developmental change controlled by genetic material is the dynamic similarity among different individuals within a species. The great difficulty in proving it by experiment is that the traits in change must correspond one to one with the time when every changeable trait value appears. The special elaboration process in secondary xylem life contributes to the development study on secondary xylem of the tree. It is quite different from other organism， even from other organs or tissues of the same tree. 1.1 A natural phenomenon unknown for long Natural phenomena regularly occur in the universe and the natural environment where human lives. It could be discovered by natural science， but could not be created. It is necessary that the infinity of mystery of nature is looked into from the mathematical point of view， but there are blind spots left over for us forever to explore the absolute comprehension of nature. Height growth and diameter growth have already been known in botany and forestry science， but the understanding of which is limited to the common process of cell division and differentiation in successive height growth and diameter growth， not involving their changes and the woody tissue differences generated in the changes year by year during the life time of the tree. It has been already realized that the wood differences exist within a tree in forestry and wood science， but it has not been deeply explored that how the differences occur. The perennial trees have the main stem and secondary growth. Apart from that the cell division and differentiation should be considered as the common process in secondary xylem elaboration， is not there any difference among them year by year in the whole life course of a tree? If so， is it random or regular? If it is regular， what is its nature? All those are important theoretical problems that have to be recognized further in forestry and wood science. The main theoretical contribution of this project is that the natural source of the regular difference in wood structure and properties within an individual tree has been found to be the developmental process of secondary xylem. Trees grow in the environment where people live and wood is such a universal material， while this natural phenomenon hasn’t been discovered until today， which indicates it has been deeply hidden. If the new knowledge is expected to be universally accepted， it is required to be proven by adequate experiments and strongly supported by the basic theories. 1.2 The natural process of secondary xylem elaboration Height growth and diameter growth of stem have been continuing simultaneously in the long term life of a tree， but not at the same height of stem. Height growth always takes place at the stem apex， whose location moves up constantly together with height growth; diameter growth occurs below the apex， whose height range expands constantly together with height growth， and its height is almost as high as the stem. Transformation of two directional growth of a stem continues unceasingly. Diameter growth of the tree is the result of cambium division between tree bark and xylem. Cambium is generated from the division， differentiation of apical promeristem， and transformed from primary tissue to secondary meristem， which regains the capacity of persistent cell division. Its direction of cell division is different from the apical promeristem. Cambium is a hollow sheath-like shell without the tip in stem， the apex of which is absent. The woody layers generated by cell division from it year by year are also sheath layers， which are compactly stacked in stratification to form secondary xylem. The apex of stem is composed of the meristematic cells， which remain a state of life in cell division or differentiation. After the beginning of diameter growth at the lowest verge of the stem apex， the pith of stem is composed of the tissues generated from cell division and cell differentiation of apical promeristem， which is located at the central position and includes primary xylem and other primary permanent tissues. Pith would ultimately become dead tis
