Some ecological and demographic characteristics of two growth forms of wild soybean (Glycine soja)

Ecological and demographic characteristics of two morphologically distinct forms of Glycine soja, namely, the twining and branching forms, were investigated in a riverbank habitat. Besides the morphological difference, the ecological distribution and reproductive characteristics for the two forms were also distinctive. The branching form occurred on the open riverside, while the twining form was found in shady, moist inland areas. The branching form had a much larger individual plant biomass and produced more pods and seeds than the twining form. However, the branching form occurred less frequently because of the high mortality it suffered after flooding and the high percent dormancy of seed in the unpredictably disturbed riverside conditions. Despite its lower seed productivity, the twining form was dominant in stable and predictable inland habitats because of its high percent germination and its subsequent high percent survival. The two growth forms of G. soja clearly represent reproductive and ecological differentiation in relation to environmental stability. Key words: disturbance, Glycine, growth form, hard-coatedness, mortality.