Koyama Kohei Specially Appointed Assistant Professor

ThemeShape and function of plants

My DreamNobel Prize Winner
  • Plant ecology laboratory


Research Department/Department of Agro-environmental Science/Division of Ecology and Environmental Science/Section of Ecology and Environmental Science
Field Plant ecology, especially plant physiological ecology
Keyword Allometry, Scaling theory, Plant physiological ecology


The animal body consists of organs with different shapes and roles, such as arms, legs and the head. In contrast, as seen in trees outside your window, the plant body is made of branches and leaves from top to bottom. In other words, plants are made of similar repeated structures. Insects usually have six legs, but there's no set number of branches or leaves. The plant body is a collection of numerous branches and leaves, like a village. The photosynthesis of a forest is the aggregate of the photosynthesis of individual leaves. I study theories—scaling theory and allometry—that are necessary to address plants and forests as groups of branches and leaves.

When living organisms or their organs are examined in great numbers, we tend to find many small ones, only a few large ones and even fewer very large ones. Such data are said to have a “lognormal distribution.” The sizes of new twigs are also approximated by a lognormal distribution, with many small ones and very few large ones. We're trying to elucidate the mechanism whereby such a distribution emerges from the shapes of trees. A branch that's part of a tree has a very similar shape to the whole tree. Patterns like this, where a smaller portion is similar to the whole, are called fractals. We're examining the relationship between this form and the lognormal distribution.

Regularity in ramification and growth of branches, Regularity in growth of frondage
Academic degree D.Agr.
Self introduction

I like math and Chinese. I had a high enough level on the HSK test of Chinese language proficiency to be admitted to university, but I let that certification lapse. I'm not good at sports, but I contribute to society by learning things. During my school days, I took a one-year leave of absence to train on a farm.

Room addressGeneral Research Building 2
Room number206
Mail address koyama atmark obihiro.ac.jp