Learn More About Kiri: Paulownia’s Ecology

By Georgia Merritt | April 2nd 2024

#history #science

An overview Kiri-bako’s material, and a few of its ecological traits

Paulownia (Kiri), the wood our objects are made from, is environmentally radical because of the speed at which it grows, and heals the soil it lives in… meaning that it is a form of timber production that doesn’t damage the earth.

Paulowniceae has many species, it is still debated how many (between 6 and 17). Most of the species are traced back as considered to be natives of China, although they have long been cultivated in Japan and Korea as well. The giant trees have deciduous ‘elephantine’ leaves, with a heart like shape, and pretty, trumpet-like flowers.

Paulownia is one of the fastest-growing hardwood trees, reaching 10-20 feet in their first year and fully maturing within 10. After harvest, the tree is able to regenerate from their stump, without replanting, the ability of the tree to replace itself makes it a truly sustainable, self-renewing source of timber. It is one of the most sustainable hard-woods out there, due to its lack of toxic by-products.

The anthropocene continues to demand more of the earth’s natural resources, so it's more useful than ever to further ecologically positive systems of production over reckless ones.

Paulownia is not only sustainable in terms of its water usage per growth cycle, but also in what it gives back to its environment: its enrichment of soil. This 備後国 (Bingo Region) native species is able to heal damaged topsoil: thanks to a richness in nutrients their large, abundant leaves fertilize the earth they fall upon. Today, the earth’s soil is under constant threat from pollution and waste, and our modes of wood production are a large contributor to this issue. One of paulownia’s magical characteristics lie in their leaves: whose nutrients improve soil quality through controlling the pollution caused by heavy metals, chemicals, and animal waste pollutants.

Meanwhile deep under the earth, their roots reach up to 45 feet in length - that’s around 4 storeys. Their root depth means they’re a perfect candidate for intercropping: the practice of growing two or more crops in proximity. It “can strengthen and stabilize agroecosystems under climate change by improving resource use efficiency, enhancing soil water holding capacity, and increasing the diversity and quality of habitat for beneficial insects that provide pollination services and natural pest control.”

Benefits and Risks of Intercropping for Crop
Resilience and Pest Management,
K D Holmes, 2022 (source)

Coincidentally the deep roots of the Paulownia tree mirrors the deep rooted history of its use within Japanese craft: our factory in Fukuyama bears over 300 years of experience of box making with Paulownia wood, which grows naturally in their region: 備後国 (Bingo).

A series of studies carried out at CsHu Carbon farm confirmed Paulownia’s many magical traits, and revealed some incredible statistics. Tested at a carbon farm, “where special technologies increase the absorption of carbon dioxide… to offset greenhouse gas emissions”.1 the results showed that Paulownia excelled in CO2 absorption. Considered to be an “Oxygen Factory”, The paulownia tree’s CO2 absorption capacity is approximately 15-20 times the capacity than that of
pine. The researchers described its growth speed as “cosmic”... as they learned of its ability to grow to a tall, fully-fledged size within only a few years.

1 Rashiya Bekmurzaeva* Kadyrov Chechen
State University, Sheripova Street, 32, 364024,
Grozny, Russia (source)


These environmentally friendly qualities mean Chowa’s practice doesn’t damage the earth, but instead supports modes of sustainable timber production. Paulownia’s positive impact extends beyond the world of kiri-bako: the tree’s characteristics’ effect within our biosphere shows potential for the improvement of our material industries - showing that even the nuance of a choice of timber can make a difference.