Mapping floristic communities in Southern Africa savannas, Mozambique

The present study was carried out in Limpopo National Park (LNP) with the objective to map floristic communities that occur inside the park. Three (3) Landsat 8 satellite images were obtained by Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) tools and were pre-processed and classified, culminating in six (6) types of land use and cover. The floristic survey consisted of stratified sampling in three (3) main LNP landscapes types, namely landscape of limestone soils, landscape of rhyolite shallow soils and landscape of deep sandy soils. The final map presents 13 floristic communities identified by the names of greatest value of ecological importance (IVI) species. The community of Terminalia sericea / Combretum apiculatum / Guibourtia conjugata / Colophospermum mopane presented a larger occurrence area. Colophospermum mopane was the most representative species among the mapped communities, mostly occurring in association with other species. The overall accuracy was 74% and the Kappa index was 68%, thus giving a good rating. The mapping also showed that human occupied areas are larger than some floristic communities areas, so we suggest that these smaller communities, should be given priority actions for their conservation, especially those without human occupation.

Influence of fire frequency on Colophospermum mopane and Combretum apiculatum woodland structure and composition in northern Gonarezhou National Park, Zimbabwe

We investigated the long-term effects of fire frequency on Colophospermum mopane and Combretum apiculatum woodland structure and composition in northern Gonarezhou National Park (GNP), Zimbabwe. Fire frequency was categorised as high (every 1–2 years), medium (every 3–4 years) and low (every 5–6 years). The following variables were measured or recorded: plant height, species name, canopy depth and diameter, basal circumference, number of stems per plant, plant status (dead or alive) and number of woody plants in a plot. There was a positive correlation (r = 0.55, P = 0.0007) between annual area burnt (total from January to December) and annual rainfall (average over two rain stations per rain year, July to June) between 1972 and 2005. A total of 64 woody species were recorded from C. mopane and C. apiculatum woodlands. Mean plant height increased from 4.5 to 8.2 meters in C. mopane woodland and from 4.5 to 5.1 meters in C. apiculatum woodland in areas subjected to high and low fire frequencies. In C. mopane woodland, low fire frequency was characterised by a significantly low density of woody plants (P < 0.001), however, with a significantly high mean basal area (P < 0.001). Fire frequency had no significant effect on species diversity (P > 0.05). Our results suggest that C. mopane and C. apiculatum woodlands are in a state of structural transformation. Fire frequency effects, however, appear to be woodland specific. Fire management strategies in GNP should take into consideration annual rainfall and the different vegetation types.Conservation implication: This study provides valuable information on fire frequency effects on woody vegetation in northern GNP, which can be used in fire management programmes for the park. The positive relationship between annual rainfall and annual area burnt emphasises the need for wildlife managers to consider annual rainfall in fire management.

The environment and vegetation of the flux measurement site near Skukuza, Kruger National Park

The SAFARI-2000 intensive study site is located 13 km WSW of Skukuza. Detailed measurements of the exchanges of energy, water, carbon dioxide and other substances between the savanna and the atmosphere have been made there since April 2000. This paper provides basic information regarding the climate, soils and vegetation at the site. The site is located near the top of a gentle rise in an undulating granitic landscape. Most of the data were collected within a 300 m square centred on the flux tower situated at [email protected]' S, [email protected]' E and oriented true north. The tower stands exactly on the ecotone between a ridgetop broad-leafed Combretum savanna on sandy soil and a midslope fme-leafed Acacia savanna on clayey soil. The ecotone is marked by a 10 m wide band of sedges. The tree basal area within the sample square was 6.8 mVha (@ 1.0 standard error), the tree density 128 @ 16 plants/ha and the tree crown cover 24 @ 4 . Shrubs, defined as woody plants greater than 0.5 m but less than 2.5 m tall, contributed a further 7.6 crown cover. The basal area weighted mean height of the trees was 9 m, and the maximum height 13m. Nineteen woody plant species were recorded within the square, with 70 of the woody plant basal area dominated by Combretum apiculatum, Sclerocarya birrea and Acacia nigrescens. The rooted basal area of grasses was 7.1 @ 0.6 and in June 2000 the grass standing crop was 400 g DM m2.