Abstract:
Miombo woodland and dambo grassland soils were selected to study the effect of soil transfer on early growth of B. petersiana, C. spectabilis, and C. calothyrsus on degraded sites in northern Zambia. The experiment was conducted on previously slash and burned, cultivated, and abandoned sites. Both sterile and unsterile miombo and dambo soils were used to determine whether the possible effects of soil transfer might result from biotic or abiotic soil factors. Seedlings were harvested three months after sowing and dry weights, heights, root lengths, and root collar diameter were determined. Ectomycorrhiza formation by B. ietersiana was also determined (Mycorrhizae were not determined for the other two species which are vesicular arbuscular mycorrhizae). Nonsterile miombo soil stimulated C. calothyrsus seedling growth and increased the number of B. Ietersiana seedlings with ectomycorrhizal roots. Soil transfer did not affect growth of other species. The three tree species differed widely in early growth but somewhat less in survival. B. petersiana had three times greater aboveground biomass than the other two species, and five to ten times greater belowground biomass. Q. calothyrsus had higher shoot:root ratio than the other two species. Results showed that increased C. calothyrsus seedling growth and increased mycorrhizal formation in B. petersiana using unsterilized miombo soil was probably the result of soil biotic factors. Soil transfer from appropriate sources can stimulate growth and encourage mycorrhizal formation with some tree species on some sites. Soil transfers from mature miombo forest can stimulate C. calothyrsus growth and B. petersiana mycorrhizal formation. Beneficial effects of soil transfer on C. calothyrsus may be due to the large shoot biomass relative to roots in seedlings of this species.
