Studies on biomass and production of the lower subtropical evergreen broad-leaved forest in Heishiding Nature Reserve, China. VI. Distribution, biomass and production of roots

Abstract

Heishiding Nature Reserve is located on the Tropic of Cancer (1 110 53' E, 230 27' N, 150-930 m altitude), and on the west of Guangdong Province, China. The climate is lower subtropical moist monsoon, with an annual mean temperature of 19.60C (1971-1975) , ranging from 10.60C in January, to 28.40C in July. The minimum and maximum temperatures were respectively -6.1? and 38.80C. Annual rainfall during this period was 1744 mm; the rainy season occurring from April to September (79% annual rainfall) and a pronounced dry season from October to March. Mean relative humidity was generally higher than 80%. The soil of the study area developed from granite and is deep, frequently >1 m but reaching in places 4-5 m; rock emergences are rare. The A horizon, usually 20-40 cm in thickness, is characterized by its dark colour and fine texture, a pH value of 4-5, a bulk density of 0.66 g dry weight cm-3, and an organic carbon content of 2.66% (Table 1). The B horizon, usually 100-150