Abstract

The species that were growing on the stands of C. mopane and on open space stands weighed more than those on the stands of A. johnsonii in both loam and sandy soil areas. This is probably an indication that there are some toxic chemicals that are excreted from various parts of A. johnsonii that caused the suffering and hence lesser weights of the understory species of A. johnsonii. The conditions were found to be unfavorable for the majority of the understory species to grow and flourish well under the canopies of A. johnsonii. This therefore, might imply that even though A. johnsonii possess allelochemical materials, some understory species may adapt to such conditions in the proximity of its vicinity. The decomposition of different parts of the plant on the ground surface under A. johnsonii canopies probably results in relatively highest concentration of allelochemical materials in the soil on A. johnsonii stands. Limiting factors like shading, temperature, water availability, and soil type may not necessarily be causes of the observed differences as the investigation was carried out from the same areas. The present investigation revealed that A. johnsonii in woodlands chokes its understory plants and such plants might eventually die out.

Key words: Allelochemical materials, Androstachys johnsonii, Colophospermum mopane, biodiversity, impact.