Miyawaki showed that natural Japanese temperate forest should be mainly composed of deciduous trees – while in practice conifers often dominate. Deciduous trees are still present around tombs and temples, where they have been protected from exploitation for religious and cultural reasons.
The more his research progressed, the more he found that the current forest vegetation of Japan (24.1 million hectares, or 3.5 billion cubic meters of timber on more than 64% of the country) had moved away from potential natural vegetation, due to the introduction of alien species by man. He noted that conifers (still considered in the 1970s as indigenous by many Japanese, including botanists), which became dominant in many forests, are actually an introduced species, and were only naturally present at high altitudes and in extreme environments (such as mountain ridges and steep slopes). They have for centuries been planted there to produce timber faster, and they acclimated. This led Miyawaki to think about forest other than as a source of greenery, recreation or timber. He became interested in the functions of allelopathy and complementarity of species in naturally wooded areas.
"Rather than scrap them, I want to bring memory objects back to life as earth resources - for the sake of repose of souls, and for the future."