Bark removal for medicinal use predisposes indigenous forest trees to wood degradation in Zambia

Abstract

Bark harvesting for medicinal purposes has become widespread in Zambia, mainly due to the high levels of poverty among the population. The injury caused to trees leads to wood deterioration as a result of insect damage and fungal infection. This study aimed to ascertain the effects of different bark harvesting practices on the quality of wood of selected indigenous tree species often used as medicinal plants. The bark of these trees, which included Julbernardia paniculata, Isoberlinia angolensis, Brachystegia longifolia, Albizia adianthifolia and Parinari curatellifolia, was removed by (1) stripping bark on the side of the tree facing the sun, (2) on the shaded side of the tree, (3) covering the wound with mud immediately after harvesting, (4) stripping at night and (5) no wounding as control. Wood of J. paniculata and I. angolensis was severely deteriorated, displaying extensive tissue discolouration, increased insect infestation and profuse gum exudation, especially when the wound was not covered with mud. Covering the wound site with mud considerably protected the trees from wood deterioration and insect damage and this constitutes the best and most sustainable bark harvesting prescription for biodiversity conservation.

Keywords: Africa, Albizia adianthifolia, bark harvesting, Brachystegia longifolia, Isoberlinia angolensis, Julbernardia paniculata, Parinari curatellifolia, tree wounds, wood deterioration

Southern Hemisphere Forestry Journal 2007, 69(3): 157–163