Sugi: recognising a tree, understanding a forest

Small curved leaves spiral around sugi’s twigs. The reddish-brown bark splits into long strips. Pollen-producing male structures and seed cones perform different reproductive roles: the former release pollen, while the cones contain seeds. These details help distinguish the tree from other conifers. Within Japan, its natural range extends from Ajigasawa in Aomori to Yakushima. In natural forests on the Sea of Japan side, including Akita, sugi can grow alongside Japanese beech, mizunara oak and other conifers. These mixed forests differ from evenly planted stands of one tree species.

Layering under snow

Natural regeneration can involve more than seed. Research on Ashiu sugi explains how snow presses low branches to the ground, where they root and form new young trees. This layering occurs in snowy areas on the Sea of Japan side. It differs both from seed germination and from nursery propagation using detached cuttings; separate-looking stems may belong to one clone.

Timber and forestry

Sugi timber is used for buildings, boats and everyday objects. Forestry regions developed methods of raising planting stock, including propagation by cuttings. Natural forests and planted stands have different management histories; cultivars are selected forms of the tree. These categories can overlap with regional timber traditions.

Different tasks in a plantation

A plantation needs years of work between planting and harvest. Nara’s account of Yoshino forestry distinguishes clearing competing vegetation around young trees, pruning branches to produce timber with fewer knots, and thinning whole trees to adjust stand density and light. These operations do different jobs and may recur as a stand develops. Sugi’s light, workable wood serves building and household uses; its bark can also be used in roofing and interior finishes.

Early forestry and postwar recovery

Sugi was used for timber long before modern mass planting. During the Edo period, forestry regions such as Kitayama and Yoshino developed sugi cultivation. Heavy wartime cutting and postwar rebuilding were followed by restoration planting, then expansion during rapid economic growth.

Fuel changes and plantation expansion

Fuel and farming changes helped drive plantation expansion. From the later 1950s, oil and gas displaced firewood and charcoal, while chemical fertilisers reduced demand for woodland resources used in farming. Housing required more timber. Some cleared broadleaf forests were therefore replanted with fast-growing building-timber species such as sugi. Expansion declined around 1970 as suitable land became scarcer, imported timber raised price concerns, and labour and planting-stock costs increased.

Historical evidence from natural forests

Natural forests have another history. Analysis of sediment pollen around Mount Moriyoshi in Akita found a marked decline in sugi from the mid-sixteenth to mid-nineteenth centuries, probably linked to excessive cutting. Human alteration of sugi forests thus predates postwar mass planting.

Postwar sugi plantations matured as timber markets and forest-management conditions changed. Sugi pollinosis was first identified in 1964, and pollen from mature stands became a major management concern. Selection work for low-pollen sugi began in 1991, with low-pollen varieties developed from 1996 onward. Replanting with lower-pollen trees is a gradual response alongside the management of existing forests.