Search

The woody plant, Colophospermum mopane, occurs as either a shrub or tree in shrublands and woodlands, respectively, in the central Kruger National Park, South Africa. As a first step in identifying which soil properties potentially influence the structure of C. mopane in these landscapes, we investigated the soil chemistry of the pedoderm in shrublands and woodlands. A total of 39 composite pedoderm samples (0–2 cm) were analysed. Relative to the woodlands, the pedoderm of the shrublands had significantly lower mean concentrations of P, K, Ca, Mg, S, Mn, Cu, Na, B and C. Of the nutrients analysed, only B had a mean concentration likely to be constraining the growth of plants (0.16 ± 0.01 vs 0.69 ± 0.05 mg B kg−1 in shrublands and woodlands, respectively). We suggest that the C. mopane shrubs do not establish as trees in the shrublands because deficiency of B limits their growth and increases the competitive strength of the grass sward relative to eudicot plants in the landscape.

We investigated application of MaxEnt, a one-class classifier, in mapping the spatial distribution of Colophospermum mopane, Dichrostachys cinerea and Salvadora persica using drainage, elevation, s...

Although indigenous to southern Africa, Pechuel-loeschea leubnitziae is considered a problematic weed as it forms dense monotypic stands in the grasslands and woodlands of the Okavango Delta, Botswana, and is associated with veld degradation and a dominance of shade-tolerant, poor-quality grass species. Generalised linear modelling was used to determine the effect of the following environmental conditions on the likelihood of occurrence of P. leubnitziae: type of land use, vegetation type, burning history, total woody species density, soil pH and soil texture. There was no difference in P. leubnitziae presence under wildlife, large livestock and small livestock land use (p = 0.227). Only vegetation type (p

In the Mopane Bushveld, Colophospermum mopane is viewed as a threat due to its ability to suppress the herbaceous layer. The objective of this study was to investigate the re-establishment of C. mopane over a 19-year period on seven plots thinned to different tree densities. Thinning was completed during 1989 and measurements done annually from 1990 to 1995 and again during 2008. Absolute tree densities (plants ha−1) increased in the low tree density plots, whereas in the high tree density plots the tree densities declined. Changes in leaf phytomass of the C. mopane trees were more pronounced than changes in absolute tree densities and growth of the remaining trees mainly occurred as increases in canopy diameter, rather than increases in tree height. Growth of established trees displayed an exponential increase in growth with declining tree density demonstrating the suppressive effect of inter-tree competition on the growth of individual trees. A trend towards an equilibrium appears to exist where some se...

This study aimed to quantify and evaluate the effects of heavy land utilisation, mainly grazing, on plant species richness and diversity, species abundance, vegetation structure and soil characteristics in a communal area in Colophospermum mopane dominated savanna in southern Africa. The treatment was benchmarked against a relatively lightly stocked neighbouring farm. An assessment of termite richness across the contrasting land-use areas was also made. Significant differences were found mainly in plant structure, with reduced plant canopy cover and plant height on the communal land, thus transforming a woodland to a predominantly shrubland physiognomy. There was no significant effect of heavy utilisation on richness or diversity of plant or termite taxa. Species compositional shifts were reflected by significant species associations with either land-use type. Forb species formed an important component of the vegetation irrespective of grazing intensity. Cover of annual plants did not increase with heavy ...

The investigation was conducted on an area covered by a dense stand of Colophospermum mopane. Seven plots (65 m × 180 m) were subjected to different intensities of tree thinning, ranging from a totaly cleared plot (0%) to plots thinned to the equivalent of 10%, 20%, 35%, 50% and 75% of the leaf biomass of a control plot (100%)with a tree density of 2 711 plants ha−1. Thinning was completed during 1989 and a study on the establishment of herbaceous plants in response to reduced competition from the woody plants was conducted during the 1989/1990, 1990/1991 and 1991/1992 seasons. A poor ground cover, mainly characterized by bare ground and the dwarf grass Oropetium capensis, existed in the 50%, 75% and 100% plots. This state proved to be relatively independent of rainfall, typical of an induced or pseudo-drought condition. It can be concluded that the tree density of the 50% plot (mean: 3 620 ETTE ha−1, where 1 ETTE = mean leaf volume of a 1.5 m single-stemmed tree = 500 cm3 leaf volume)had already exceeded the critical point of detrimental grass-tree competition. Colonization of bare ground by herbaceous plants increased from increased levels of tree thinning. Annual grasses were the main colonizers of bare ground, while perennial grasses on(v constituted a small proportion of the grass species composition. The successional order of establishing grasses following thinning was Tragus berteronianus, Brachiaria deflexa and Aristida species, terminating in a state where Enneapogon cenchroides predominated. Perennial grasses showed a general lack of successional trends.Keywords: Annual grasses; bush encroachment; competition; Colophospermum mopane; plant successionAfrican Journal of Range and Forage Science 16(1), May 1999, pp. 9–18

Vegetation change on different substrate types was measured over 15 years in semi‐arid Mopani Veld. Baseline data were collected in the terminal year (1982) of a decade of above‐average rainfall, whilst the period of monitoring was characterised by below‐average rainfall, with severe drought years occurring in 1988/1989 and 1991/1992. Grazing pressure was, on average, alleviated over the period of recording so that changes reflect primarily the effect of rainfall. Long‐lived perennial grasses had declined markedly, annual and micro‐perennial grasses had increased markedly, and the proportion of forbs had increased. Despite 7–17 years since the replacement of livestock grazing with wildlife at lower stocking rates, there was no evidence of an improvement in sward or soil condition, owing ostensibly to the effect of drought. The extent of change in botanical composition and in sward condition was influenced by substrate type. The rate of growth of the woody component had been slow: the average per ...

Leaf dry mass (DM) at peak biomass was estimated for different plant communities in a semi‐arid savanna. These estimates included the total leaf DM, as well as estimates of the leaf DM at browsing heights of 1.5 m, 2.0 m and 5.0 m. The total leaf DM in the different plant communities ranged between 1 224 kg ha−1 and 2 672 kg ha−1. The contribution of individual woody species to the total leaf DM ha−1 is presented for each plant community. Colophospermum mopane contributed substantially to the total leaf DM in all communities. Monthly assessments were made of the abundance of leaves in different phonological states for the most important woody species in each plant community. Differences in the leaf carriage patterns and phenological composition of leaves between different plant communities, as well as between the most important woody species, were established. The long leaf‐carriage period of C. mopane, relative to the other represented tree species, underlies its potential importance as a fodder...