Abstract
Leaf area index(LAI) of undergrowth larger than 0.3m in stem length was estimated in a natural forest at southwest Kochi, Japan. The forest is characterized by Hinoki cypress (Chamaecyparis obtusa) and Tsuga hemlock (Tsuga sieboldii) mixed with evergreen Quercus spp. and other broadleaved spp. We settled twenty-two small plots along the forested ridge and on slope and a transect across a canopy gap opened by selective logging of Hinoki trees. Size structures were examined for saplings (less than 5cm in DBH and larger than 0.3m in stem length) mostly shared by evergreen broadleaved species. Sample saplings were harvested and measured their stem, branch and leaf weight, and leaf area, to determine their allometric relationships among size parameters. Averaged undergrowth biomass estimated for non-foliage and foliage were 2.00 and 0.62 ton/ha at forested sites, and 5.94 and 2.39 ton/ha at gap site, respectively. LAI estimates for forested sites ranged from 0.08 to 2.18 m^2/m^2 with 0.78 m^2/m^2 as the average, and 0.31 to 7.87 m^2/m^2 for gap with 2.90 m^2/m^2 as the average. Foliage biomass of undergrowth in this stand is large enough as corresponding to about one-fourth in leaf biomass and about 10% in LAI of reviewed values of Japanese evergreen broadleaved forests, hence it is not at the negligibly small level.
