Forma, Vol. 8 (No. 2), pp. 245-253, 1993

The Evolutionarily Ecological Viewpoint on the Diversity in the Above-Ground Architecture of Herbs

Satoki Sakai

Department of Ecology, National Grassland Research Institute, Nishinasuno, Tochigi 329-27, Japan

(Received March 29, 1993; Accepted June 25, 1993)

Keywords: above-ground architecture of herbs, leaf phenology, photosynthetic capacity, evolutionarily stable strategy, mathematical model

Abstract. Two models on the diversity in the above-ground architecture of herbs were illustrated, which models predicted whether which above-ground architecture is favored by natural selection in a given habitat. The first model predicted that 1) a herb forms a rosette in scarce and open habitats, 2) a herb creeps on the ground in scarce and closed habitats, 3) a herb grows gregariously in dense and open habitats, and 4) a herb grows both vertically and horizontally in dense and closed habitats. Moreover, the second model predicted that 1) a herb with a very large leaf biomass emerges early and sheds late in a growing season, and photosynthesizes for a long period, 2) a herb with a large leaf biomass also emerges early but sheds at the leaf expansion of canopy trees, and photosynthesizes for a short but sunny spring period, and 3) a herb with a small leaf biomass emerges late and sheds early, and photosynthesizes for the most period under shading by canopy trees.