Vegetation structure and composition in the semi-arid Mapungubwe Cultural Landscape

Mapungubwe Cultural Landscape (MCL) woody vegetation was characterized to establish structural and compositional attributes. Stratified random sampling based on major soil types was used and nine plant variables were measured in 137(20x30) m(2) sampling plots; these being genera, species and family names; basal circumference; plant height; depth and diameter of tree canopy; number of stems per plant; plant life status; number of trees and shrubs; and number of saplings. A total of 3114 woody plants were sampled, comprising an assemblage of 28 families, 63 genera and 106 species. The results suggest alluvial floodplain flanking the Limpopo River is a biodiversity hotspot with high plant species diversity (H'= 1.8-2.2) 1/ha, taller trees (P< 0.05) with median height per plot ranging between 6.1-10 m, high canopy volume at 105783 (443155m(3)/ha) and basal area (16.9-111m(2)/ha). The Arenosols-Regosol stratum had significantly shorter trees (P< 0.05) with median height per plot between 3-4 m, low species diversity (H'= 0.8-2.3) 1/ha, low basal area (3.23-48.2m(2)/ha) and low canopy volume (6687.08(155965.00) m(3)/ha. The Cambisol-Luvisol stratum in the western section of MCL had high number of stems/plant at 1.65 (1.40), high woody plant density 483.33 (900.00) 1/ha, F-3,F-137 = 19.07, P< 0.05), high density of dead plants 16.67 (133.30) 1/ha and high sapling density 208.33 (850.00) 1/ha. The present study suggests soil type is a key determinant of woody vegetation structure and composition. The study recommends regular vegetation monitoring, periodic update of plant species inventories in protected areas, control of exotic invasive woody plant species found along the Limpopo river floodplain within the biodiversity management framework of Greater Mapungubwe Transfrontier Conservation Area initiative.