THE INFLUENCE OF TREE THINNING ON THE REPRODUCTION DYNAMICS OF COLOPHOSPERMUM MOPANE

The reproduction dynamics of Colophospermum mopane, including flowerin g, fruit bearing, the germination potential of the seed and seedling e stablishment were studied over a period of three years on six plots wh ere the trees were thinned to the approximate equivalents of 75%, 50%, 35%, 20% and 10% of the tree density of the control plot (2 711 trees ha(-1)). Thinning of C. mopane reduced inter-tree competition which r esulted in marked increases in the flowering and fruit bearing of the remaining trees. Though the percentage reproductive trees were higher in the low tree density plots, the greater number of trees in the high tree density plots ensured that the total number of trees that flower ed and produced fruit were of the same order of those in the low tree density plots. The fruit (seed with and without their pod covers) from trees within the low tree density plots were larger and heavier than those from the plots with a high tree density, but this did not have a marked effect an their potential to germinate. Since the greatest ger mination was achieved from fresh seeds, no dormancy appears to exist i n C. mopane seeds. Seedling numbers were low in all plots and a specif ic pattern of seedling establishment was lacking. At high tree densiti es severe competition from the established C. mopane trees could accou nt for the low rate of seedling establishment. while in the low tree d ensity plots competition from newly established herbaceous plants, mai nly grasses, could account for the tree seedling absence in these plot s.