主要造林樹種의 凍害의 原人과 그의 Mechanism에 關한 硏究

Studies on the Frost Damage and their Mechanism of some Principal Forest Trees

The stem temperature, cold damage, frost damage of tissues and seasonal variation of sugars in cortex were measured on Populus alba × glandulosa, Populus × euramericana, Alnus inokumai, Pinus rigida ×taeda and Cryptomeria japonica, The results abtained are as follows. 1. In Populus alba × glandulosa, Populus × euramcricana and Alnus inokumai, the lowest minimum temperature and the highest maximum temperature occurred in cortex of 20cm above soil surface. 2. Super cooling in cortex of Populus alba × glandulosa, Populus × euramericana and Alnus inokumai was broken at 0~-2℃, at -2℃, and at -1~-2℃, respectively. 3. The minimum temperature in cortex of Populus alba × glandulosa and Populus × euramericana occurred early in the morning and its maximum temperature occurred early in the afternoon. This was not related to either season or direction. 4. The stem frost damage of Populus alba × glandulosa occurred mostly in the lower part of stems and to the south. Its damage rate shown below 30cm of stem height amounted to 42 percent. 5. Alnus inokumai and Pinus rigida × taeda showed weak frost hardiness in stems while Populus alba × glandulosa and Populus × euramericana showed strong frost hardiness. 6. All trees used in this study showed greater frost hardiness in stems than that in buds. 7. The stem cold-damage of Populus alba × glandulosa and Populus × euramericana increased with increasing wind velocity and with increasing length of treatment time at the same low temperature. 8. The amount of total or reduced sugars in cortex increased with decreasing temperature.