Growth Mechanism of Fast Grown Species in Tropical Forest

恢复热带森林的努力逐年增加，在印度尼西亚和马来西亚各地，被称为快速生长树种的树木的种植已经蓬勃发展。但对其木材品质作为材料的把握几乎没有被调查过。需要了解其质量，并根据木材的性能建立选种方法和造林技术。另一方面，了解生长速率对树木生长胁迫水平的影响，对于阐明生长胁迫产生的机制具有重要意义。在这次的联合研究中，上述两人的研究目标与茂物大学印尼研究员的研究目标一致，并得以实现。通过田间测量，试验树种以相思、金合欢、木棉和松桂为宜。对每棵立木进行8 ~ 12个点的释放应变测量，并在砍伐后收集包含测点的磁盘，送往名古屋大学进行质量分析。在这些样品上，测量了纵向和切向的杨氏模量和毒药比，并计算了生长应力。其他测量项目为空气干燥条件下比重的直径分布，x射线偏转法测定微纤维角度和结晶度，Wise法测定α -纤维素含量和Klason木质素含量。这些数值与生长应力进行了比较。每个测点到髓的距离作为生长率的指标。(a)所有被测树木的生长应力水平与直径没有相关性。这与迄今为止对杉木的研究结果是一致的。换句话说，生长应力不依赖于树木的生长速度。这说明加速生长条件不会使树木的生长应力变大。(b)生长应力与微纤维角呈负相关。生长胁迫与α -纤维素含量之间的正相关关系虽不如苏木明显。这些趋势与温带树种相同，说明在造林过程中，只要没有条件制造反应木材，树种就具有特定的生长应力值。(c)在比重分布上发现了不同物种之间的差异。例如，相思的比重在心材和汁液材的边界上发生了突然的变化。从工业角度来看，这一事实导致了相思是一种劣质材料的结论。更有必要阐明比重的产生机理。如前文所述，在资料有限的情况下，对热带速生种也给出了一些重要的结果。增加测量对象种类和个体数量，进一步确定该结论的可靠性，并提出适宜速生树种质量的造林条件。少

The effort to recovery of tropical forest increases year by year and plantation of trees called fast grown species has been done flourishingly around Indonesia and Malaysia. But the grasp of their wood qualities as materials has not been investigated almost.It is required to know the quality and to establish the ways of species selection and silvicultural technology considering the performance as timber.On the other hand, to know the influence of growth rate to the level of tree growth stress is important to elucidate the mechanism of growth stress generation.In joint study of this time, studies aim of the above two agreed with Indonesian researcher of Bogor university, and came true.By the field measurement, Acacia mangium, Falcataria, Kapok and Sungkai were used for test tree.The released strain was measured 8-12 places for each standing tree, and the disks which contained the measuring points were gathered after felling and dispatched to Nagoya university to analyze the quality. On … More these samples, Young's moduli and Poison's ratios of longitudinal and tangential directions were measured and growth stresses were calculated.Other measured items were diametral distribution of specific gravity at air dry condition, microfibril angle and degree of crystalinity by means of X-ray deflaction method, alpha-cellulose content and Klason's lignin content by Wise's method. These values were compared with the growth stress. The distance of each measuring point from the pith was used for an index of growth rate.(a) As for level of growth stress of all tree measured, the correlation with the diameter wasn't found. This is same as a result provided about Sugi which have been studied up to now. In other words, it is shown that growth stress is not depend on growth rate of tree.This result suggests that the accelerate growth condition does not make tree growth stress large.(b) A negative correlation was found between growth stress and microfibril angle. And a positive correlation between growth stress and alpha-cellulose content was seen even it was not so clear as Sugi.These tendencies are same as the Temperate Zone species, and suggest that species has a particular value of growth stress so long as there is no condition to make a reaction wood during silviculture.(c) A difference between species was found on the distribution of specific gravity. For instance, specific gravity of Acacia mangium changed suddenly in a boundary of heart wood and sap wood.This fact leads the conclusion that Acacia mangium is an inferior materials as industrial point of view. Elucidation of the generation mechanism of specific gravity is more necessary.As mentioned above, even it was limited number of data, some important results were given about tropical fast grown species. Increasing the measurement object species and an individual number, we should identify reliability of this conclusion and suggest silvicultural conditions which make good quality of fast grown species furthermore. Less