Development of plantation techniques of dipterocarp trees for reforestation

本研究旨在寻找在野外耐受多种环境胁迫的龙脑果树种，并提出育苗和育苗的方法，以期为亚洲热带草原或退化土地的环境造林提供参考。根据在泰国那拉提瓦退化沙土上建立的试验地的田间研究和实验室工作，获得了以下结果：(1)利用各种环境传感器和数据记录仪在试验地建立的相思林内和开阔地进行连续测量，结果表明，相思树冠遮荫改善了苗木的微环境；(2)光硬化，种植前在苗圃将遮荫的苗木暴露在充分的阳光下，提高了六种龙胆树种的苗木存活率，它们分别是金缕梅、金合欢、金合欢树。(3)通过对6种相思树种的光合作用特性进行耐高温评价，探讨了其作为育苗树种的可能性；(4)在退化沙地上栽植耐寒树种，使其具有良好的生长和良好的光合作用能力；(5)育苗，在栽植目标树种前种植耐逆树种，提高了龙脑果幼苗的成活率。

The present study was aimed at finding out dipterocarp species tolerating multiple environmental stresses in the field and at suggesting ways of nursing and planting seedlings, supposing to use the species for environmental reforestation of grasslands or degraded lands in tropical Asia. According to the field study at an experimental planting site established on degraded sandy soils in Narathiwat, Thailand and to laboratory works, the following findings were obtained : (1) Continuous measurements at open site and within an Acacia mangium stand established in the experimental site using a variety of environmental sensors and data loggers revealed that canopy shading by Acacia mangium ameliorated the microenvironment for seedlings, (2) Light hardening, exposing the shaded seedlings to full sunlight at nursery before planting, improved seedling survival of six dipterocarp species, Dipterocarpus obtusifolius, Hopea odorata, Shorea leprosula, S.roxburghii, Shorea sp., Neobalanocarpus heimii, (3) Possibility as an candidate for nurse tree was examined according to an evaluation of high temperature tolerance of six Acacia species in terms of photosynthetic characteristics, (4) Dipteocarpus obtusifolius showed good growth and excellent photosynthetic capacity when planted on degraded sandy soils, and (5) Nurse tree planting, planting stress-tolerant tree species as nurse tree in prior to planting the target species, improved the survival of dipterocarp seedlings