DO FOREST-FLOOR WOOD RESIDUES IN PLANTATIONS INCREASE THE INCIDENCE OF TERMITE ATTACK?— TESTING CURRENT THEORY

Abstract

The incidence of attack by the termite, Coptotermes curvignathus Holmgren, in four- to eight-year-old Acacia mangium forest plantations is examined and discussed in relation to 1) the occurrence of the termite on wood material on the forest floor of plantations and dipterocarp forest, and 2) the severity of attack reported in four-year-old conifer plantations. Although A. mangium plantations had a much greater number of large stumps and logs on the forest floor than dipterocarp forests, due to incomplete clearing and burning of the original forest, numbers of forest floor wood material in which the termite occurred averaged 5.3 per ha and 8.0 per ha respectively for these habitats. The number of living A. mangium trees with infestations averaged 13.3 per ha, while there were no infestations of living trees sampled in dipterocarp forests. The incidence of attack on A. mangium trees was greater than that reported for Pinus caribaea, P. merkusii, P. oocarpa and Agathis macrophylla, but lower than that reported for Araucaria cunninghamii and A. hunsteinii However, reported rates of mortality among these conifers in plantations greatly exceeded that of A. mangium. The results of the study suggest that, although populations of the termite C. curvignathus are neither eliminated nor greatly reduced by the practice of clear felling and burning of wood debris, contrary to current theory, large stumps and logs left behind by this site preparation practice do not contribute much to increases in the termite population. Susceptibility of the tree species appears, therefore, to be the major factor affecting the incidence of attack and mortality in plantations. It is suggested that this pest be managed by selection of plantation tree species which are less susceptible to attack and planting of susceptible species, such as conifers, at low-risk sites.