Growth Mechanism of Fast Grown Species in Tropical Forest

恢复热带森林的努力逐年增加，被称为速生树种的树木种植在印度尼西亚和马来西亚蓬勃发展。但目前对其材性的掌握尚不深入，需要了解材性，制定树种选择方法和营林技术。另一方面，了解生长速度对树木生长应力水平的影响，对于阐明生长应力产生的机理具有重要意义。在这次联合研究中，上述两项研究的目的与茂物大学的印度尼西亚研究人员一致，并实现了。通过田间测量，以马占相思、鹰嘴豆、木棉和松凯为试材，对每棵立木进行了8-12个部位的应变测量，砍伐后收集含有测量点的圆盘，送往名古屋大学进行质量分析。在…上此外，还测量了样品的纵切向杨氏模数和泊松比，并计算了生长应力。其他测量项目包括风干条件下比重的径向分布、微纤丝角和结晶度，α-纤维素含量和Klason木质素含量。将这些值与生长应力进行比较。以各测点距髓的距离作为生长速率指标。(A)所有被测树木的生长应力水平与直径均未发现相关关系。这与目前已有的关于Sugi的研究结果是一致的。也就是说，生长应力并不依赖于树木的生长速度。这一结果表明，加速生长条件并没有使树木的生长应力变大。(B)生长应力与微纤丝角呈负相关。生长应力与α-纤维素含量呈正相关关系，这种趋势与温带树种的趋势一致，说明树种间只要不具备在营林过程中产生反应木材的条件，就具有一定的生长应力值。(3)树种间的比重分布存在差异。例如，马占相思的比重在心材和汁液木材交界处突然发生变化，这一事实得出了从工业角度来看，马占相思是一种劣质材料的结论。更有必要阐明比重的产生机制。如上所述，即使是有限的数据，也给出了一些关于热带速生物种的重要结果。增加测量对象的种类和个体数量，应验证这一结论的可靠性，并提出使速生树种质量更好的营林条件。较少

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