Development of plantation techniques of dipterocarp trees for reforestation

本研究的目的是找出龙脑香属植物在野外能耐受多种环境胁迫，并提出育苗和种植的方法，设想将该物种用于亚洲热带草原或退化土地的环境再造林。根据在泰国那拉提瓦府退化桑迪土壤上建立的试验种植点的实地研究和实验室工作，获得了以下结果：（1）利用各种环境传感器和数据记录器在开放场地和在实验场地建立的马占相思林分内进行的连续测量表明，马占相思的冠层遮蔽改善了幼苗的微环境，（2）光炼，即在育苗前将遮荫的幼苗暴露在充足的阳光下，提高了6种龙脑香属植物的幼苗存活率，即：钝叶龙脑香、飞机草、长柄山龙眼、刺梨、山龙眼、（3）通过对6种相思树光合特性的高温耐受性评价，探讨了其作为保育树候选树种的可能性;（4）在退化的桑迪土壤上种植钝叶双果木，表现出良好的生长和优良的光合能力;在栽植目的树种前栽植耐逆树种作为保育树，提高了龙脑香苗木的成活率

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