A re-assessment of effects of fire on miombo regeneration in the Zambian Copperbelt

Abstract

In 1933/34 eight coppice plots were established in Brachystegia-Julbemardia (miombo) woodland at Ndola in the Copperbelt area of Zambia by the Forestry Department. These plots have been maintained under fire protection, annual early or late dry season burning since 1934/35. Before establishment stems over 20.3 cm girth at breast height were enumerated. Three of the eight plots (one fire protected and two annually early burnt) were enumerated in 1982, 48–49 years after establishment. In addition, a coppice plot at Chitwi, 16 km southwest of the Ndola plots, cleared in 1972 and left to regenerate naturally was enumerated in May 1982 and August 1986 to assess woody plant growth.The density of stems over 20.0 cm girth in the 13-year-old coppice at Chitwi was 2.5 times that in an adjacent shelterbelt woodland. The stem density in the fire protected plot at Ndola in 1982 was 86% of the pre-felling density while in one of the early burnt plots it was 95% of the pre-felling density. The protected plot had the lowest species diversity after 49 years, largely because of the loss of 11 understorey species that were present before felling.There were no significant differences in stem mean girth at breast height (gbh) of canopy species in the Ndola plots under fire protection and early burning regimes. Mean annual gbh increments of abundant species were estimated at 1.17–2.21 cm yr⁻¹ and 0.59–1.42 cm yr⁻¹ during 0–9 and 0–49 year age-periods, respectively. Estimated mean annual basal area increments for stems over 30 cm gbh were 0.35 m² ha⁻¹ for the 13-year-old coppice and 0.24–0.27 m² ha⁻¹ for the 49-year-old coppice. These results indicate a decrease in both gbh and basal area increment with increasing age of miombo coppice