FINE-ROOT VERTICAL PROFILE, PRODUCTION, MORTALITY AND DECOMPOSITION IN AN <em>ACACIA</em> PLANTATION IN NORTH-EAST VIETNAM

Abstract

Fine-roots drive plant growth and influence the global carbon cycle. Thus understanding their production and distribution is useful for plantation management. Therefore, in the present study, the vertical distribution and production of fine-roots were investigated in a 2-year-old Acacia plantation in Vietnam that had a planting density of 1100 trees ha^-1. A 30 m × 30 m plot was established in the plantation and field data were collected using sequential soil core sampling and the litter bag technique. The continuous inflow method was used to estimate fine-root production, mortality and decomposition during spring, summer, fall and winter. More than 78.0% of the fine-roots were distributed in the 0–20 cm soil layer while less than 4.0% were distributed in the 50–80 cm later. The proportion of fine-roots in the 0–20 cm layer was greater in summer (81.0%) than in winter (78.0%), while the reverse was true in the 50–80 cm layer (summer 2.3%, winter 3.6%). The total fine-root production, mortality and decomposition in the study area were 9.90, 8.39 and 7.07 tonnes ha^-1 year^–1 respectively and all three of these parameters were seasonally dependent, being higher in summer (> 2.5 g m–2 day–1) than in winter (< 1.5 g m^–2 day^–1).