Optimum harvesting time and clone choices for eucalyptus growers in Vietnam

This paper investigates the productivity and optimal rotation for economic timber management of Eucalyptus urophylla S.T Blake clones being planted in Northeast Vietnam in Fluvic Gleysol and Ferric Acrisol soils. In the first section of the paper, timber yield functions for all eucalyptus monoculture clones and seedlings are identified. Next, the biological optimum rotation period for maximizing sustained yield is calculated based on the yield functions for each soil type. In the last section, the economically optimal rotation (EOR) lengths for all clones and seedlings planted in the two types of soil are calculated using a modified Faustmann model.The results indicate that eucalypts in Fluvic Gleysol will produce larger timber yields than in Ferric Acrisol. Among the clones commonly planted in Northeast Vietnam, eucalyptus clones U16 and PN14 can yield the largest timber volumes in Fluvic Gleysol and Ferric Acrisol, respectively. Our EOR model reveals that EOR lengths of eucalyptus plantations in Northeast Vietnam are longer than the biological rotation time by 1–3 years under the governmentally subsidized credit scheme for rural households. If growers borrow from commercial and private entities, such rotation period will be substantially shortened and negative site values will appear in a number of cases. Nevertheless, wherever eucalyptus clones are economically qualified, their EOR length is longer than what is currently practiced. To capture the highest profits from eucalypt plantations, growers should extend their current farming business cycle of 7 years to 14–18 years under the subsidized credit scheme and to 10–12 years under the commercial borrowing interest rate. As increasing land use profitability is of great concern across the region, these findings are of practical importance for Vietnamese farmers in choosing clones, land lots, and economic optimal rotation for their farming businesses.