To role of morphological characteristics in adaptation : in a case of evergreen shrubs to snow stress

• Project/Area Number: 06640824
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: 生態
• Research Institution: Waseda University
• Principal Investigator: INO Yoshio Waseda University School of Education Professor, 教育学部, 教授 (30063697)
• Project Period (FY): 1994 – 1995
• Project Status: Completed (Fiscal Year 1995)
• Budget Amount: ¥2,000,000 (Direct Cost: ¥2,000,000); Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000); Fiscal Year 1994: ¥1,200,000 (Direct Cost: ¥1,200,000)
• Keywords: Adaptation / Snow stress / Morphological characteristics / Evergreen shrubs / Plasticity / Carbon content

Research Abstract

Aucuba japonica var. borealis, Camellia japonica var. rusticana and Daphniphyllum macropodum var. humile grow in heavy snow areas, Hokuriku and Tohoku regions in Japan. Their relatives, A.japonica, C.japonica and D.macropodum var. macropodum and D.teijsmanni grow in little or no snow areas. In winter, the three species in heavy snow area are laid down on the ground surface by heavy snow. When the snow pressure becomes lower in spring, their shoots spring up and their evergreen leaves begin matter production. Therefore, their shoots must have both pliability and elasticity, or pliability in autumn and elasticity in spring.
Twenty to thirty shoots of these three species were sampled at the floor of beech forest in Matsudai, Niigata Pref. in November and December, 1965 and in May and September, 1995. The maximum snow depth was over 2m in this area.
The shoot was fixed horizontally at the point of 20cm from the top, then 50g weight was attached to the top. The deflectio of the stem from hori zontal line was measured at the top and the relationship between the deflection and the fresh weight of the stem was taken. The shoots of A.japonica and C.japonica were sampled at Yokosuka, Kanagawa Pref., where it seldom snows and the same measurement was done for the comparison with the shrubs in deep snow area. The deflection of these stems could not be compared with that of the stem of D.macropodum var. humile, dwarf shrub, because D.macropodum var. macropodum and D.teijsmanni are trees.
In A.japonica var. borealis and C.japonica var. rusticana, , decrease of the flexibility with the increase of age was smaller than those in A.japonica and C.japonica. It shows that these two species in little snow area lost the flexibility of the stems with the agin. In D.macropodum var.humile, the flexibility of the stems was large in December but small in May. Large flexibility is advantageous when the stems begin to be buried deep in snow and small flexibility is advantageous when the stems spring up snow.