Acacia mollissima and A. dealbata was sown and planted in spring 1956 at the Experimental Forest of Shimane Agr, Coll. near Matsue-si. They have grown well in spite of snow damage in Dec. 1959. But they were severely injured by the extraordinary cold weather in Jan.-Feb. 1963. The study was made of their growth and cold injury. The results are as follows.
1. A. mollissima grew more rapidly in height and diameter than A. dealbata.
2. The rate of height growth in both species decreased since 1960, but the rate of diameter growth increased since then.
3. The low temperture, the wind velocity, the height of maximum snow cover and the duration of snow coverage in 1963 marked the new records since 1926.
4. By the effects of such cold weather, all trees of A. mollissima were killed, some of A. dealbata were injured, but none of the latter was killed.
5. As it is said, that water of Lake Sinziko has never frozen for about 100 years except 1963, the cold weather of this year may be said to be very extraordinary. Consequently it seems not unreasonable to plant A. mollissima on this area.