A re-assessment of a fire protection experiment in north-eastern Ghana savanna.
Abstract
Three plots in northern Ghana savanna were enumerated and then clearfelled in 1950. Since then one plot has been completely protected, a second has been burnt annually early in the dry season, and a third plot has been burnt annually late in the dry season. In 1976-77 there were 202 trees ha-1 ( more than or equal to 30 cm girth) on the protected plot, forty-two trees ha-1 on the early burnt plot and twenty trees ha-1 on the late burnt plot. Corresponding figures for basal area are 3.43, 0.51, 0.24 m2 ha-1. The basal area of grass on both the burnt plots has remained constant at about 13% since 1960 whereas the basal area of grass on the protected plot has continued to decline and was 6.3 in 1976. Grass biomass at the end of the growing season in 1976 was 182 g m-2 on the protected plot, and 260 g m-2 and 144 g m-2 on the early and late burnt plots respectively. There were seventy-three species of vascular plants on the protected plot in 1977, and fifty-three and forty-four repectively on the early and late burnt plots. Only slight differences in the soils were observed, though the protected plot had significantly more organic matter and total nitrogen. The results are compared with those of similar experiments elsewhere in Africa, and recommendations are made for improved experimental design.