Seedling Growth Form of Oaks

Growth forms of recently-established oak seedlings were comparedamong five species from California and three species from Japan.Evergreen and deciduous species were included, native to a varietyof habitats. Each seedling was grown in a tall tube in orderto measure main root length and was harvested when leaf expansionhad ceased. The effects of light intensity reduced to 5% onseedling growth form were not strong enough to overcome theinnate differences between species. Shoot/root and leaf area/rootweight ratios were smaller in the species from drier environmentswithin each region, though all Californian oaks showed muchgreater root elongation than did the Japanese oaks. Extensiveroot systems combined with small leaf areas would help seedlingssurvival in xeric and open sites. Large leaf areas combinedwith small roots would be profitable for surviving in shadeunder canopy. In oaks of both regions, xeromorphic evergreengrowth forms are clearly distinguished from hygromorphic evergreengrowth forms. Seedling growth form, habitat moisture gradient, California oaks, Japanese oaks, shoot/root ratio