NET PRODUCTION AND CARBON CYCLING IN A BAMBOO PHYLLOSTACHYS PUBESCENSSTAND

Phyllostachys pubescens Mazel ex Houzeau de Lehaie is one of the large st bamboo species with a leptomorph root system in the world. The spec ies originates in China and has been naturalized in the neighboring co untries. It was introduced in 1746 into Japan because of the economic value of the young sprouts and culm woods. It escaped from the planted areas and expanded by invading the original vegetation. In order to c larify the basic ecological characteristics of the species, carbon fix ation and cycling were determined in a stand of Phyllostachys pubescen s. The standing culm density and average DBH in 1991 were 7100 ha(-1) and 11.3 cm, respectively. The above-ground biomass was 116.5 t ha(-1) for culms, 15.5 t ha(-1) for branches, 5.9 t ha(-1) for leaves and 13 7.9 t ha(-1) in total. The total above-ground biomass was one of the l argest among the world's bamboo communities. The biomasses of rhizomes and fine roots were 16.7 t ha(-1) and 27.9 t ha(-1), respectively. An nual soil respiration was 52.3 t CO2 ha(-1) yr(-1), the highest among those determined in Japan. The gross production was high: 32.8 t C ha( -1) yr(-1). Allocation of the products to its root system was also hig h: 34% to gross production and 46% to the fluxes out of the leaves int o other compartments of the ecosystem. This resulted in the reduced ab ove-ground net production of 18.1 t ha(-1) yr(-1), which fell within t he average range of productivity of forests under similar climate cond itions. This paper discusses the correspondence of the allocation patt ern with the successful range expansion.