baumzaehlen - Primeval Forests & Their Trees

Yakushima Wilderness Area, Japan

Yakushima is an island south of Kyushu, the southernmost of the four main islands of Japan. A large part of it has been nominated as a World Heritage Site. Wood has been extracted throughout most of the WH site, but in the small (12 km²) Wilderness Area on the western slopes of the island, there has been no tree cutting¹. The Wilderness Area comprises a mountain valley with very steep slopes.

On the lower slopes, forests are composed of evergreen angiosperms, most notably Castanopsis cuspidata (Japanese chinquapin). Higher, at an altitude of 1000 metres, annual precipitation is a tremendous 8000 mm, and the most important tree species are evergreens, either the conifers Cryptomeria japonica (Japanese cedar) and Tsuga sieboldii (southern Japanese hemlock) or the angiosperm Trochodendron aralioides (wheel tree), though a few deciduous tree species also occur, e.g. Kalopanax septemlobus (prickly castor-oil tree) ². Trochodendron most commonly regenerates on living and dead trees³, often called “nurse logs”. These higher altitude species are easy to identify but generally tree identification is challenging, particularly because for most westerners, Japanese identification guides are unreadable. However they have superb photos (better than in any western book I have seen), and identification is often possible simply by comparing photos. J. Ohwi’s old “Flora of Japan” (in English) helps, too.

The canopy is relatively open and the shrub layer dense. Leeches abound.

References:

1        http://whc.unesco.org/archive/advisory_body_evaluation/662.pdf

2        Suzuki, E. & Tsukahara, J. (1987): Age structure and regeneration of old growth Cryptomeria japonica forests on Yakushima Island. Bot. Mag. Tokyo 100: 223-241.

3        Suzuki, E. (1997): The Dynamics of Old Cryptomeria japonica Forest on Yakushima Island. Tropics 6(4), 421-428.