Browsing by Author "Dean, Richard"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Open Access
    Effects of pine invasions on ground-dwelling ants on the southern slopes of the Swartberg Mountains
    (1999) Chaane, Lovejoy; Dean, Richard; Richardson, David
    Ant and plant assemblages in patches of Pinus species trees in mountain fynbos and renosterbos (Elytropappus rhinocerotis) shru.bland were investigated in order to detennine whether there were differences in ant and plant species richness, abundance and cover between patches of pines and the surrounding indigenous vegetation. The study was carried out in the Matjiesrivier valley on the southern slopes of the Swartrg mountains in the Oudtshoom district, South Africa. Ants were collected at three sites: one in an older (c. 70 years) pine patch in mesic mountain fynbos at about midslope and two in younger (c. 10 years) pine patches in closed and open remnant renosterbos shrublands respectively on lower slopes. On a per site basis, there were no major differences in ant and plant species richness between the pine and no-pine sites in renosterbos, or (with the exception of plants) the pine and no-pine site in mesic mountain fynbos. A total of 2 539 ants belonging to 37 species, distributed among 15 genera, were collected during the study. Camponotus was most species-rich genus (13 species), followed by Monomorium (7 species), Tetramorium (4 species) and Lepisiota (2 species), with 11 of the 15 genera each represented by a single species. No non-indigenous species were observed during the duration of the study. Camponotus sp.11, Lepisiota sp.1 and Tetramorium quadrispinosum were observed only in the open renosterbos site. Camponotus klugii, Camponotus sp. l, Camponotus sp. 6, Cerapachys sp. l, Meranoplus peringueyi, Monomorium fri.dae, Monomoriu1'Jl sp.3 and Technomyrmex albipes were observed only in the closed renosterbos. Camponotus bayneii, Camponotus sp.5, 7, 8 and 9, Crematogaster peringueyi, Pachycondyla pumicoca, Solenopsis punctaticeps and Tetramorium regulare were recorded only in mesic mountain fynbos The most abundant ant guild was the non-dominant generalist (17 species), particularly Pheidole sp. 1# (48 % of all individual ants) followed by nectar feeders (15 species), dominant generalists (2 species), specialist predators (2 species) and a seed harvester (1 species). In general, the non-dominant generalists preferred no-pine sites to sites invaded by pines. There was very little undergrowth under the pines in mesic mountain fynbos, and Clutia polygonoides, Cymbopogon sp. 1, Erica sp. 1, Metalasia cephalotes, Metalasia muricata, Pelagronium betulinum sp. 1 and Restio sp. 1 were significantly more frequent outside the patch. The two renosterbos sites showed no significant difference in Elytropappus rhinoceroti's cover in and out of pine patches, and only two species at the open rerttsterbos site, Dodonea sp. 1 and Re/hania squarrosa, were more abundant under pines than in the surrounding renosterbos. The most abundant plant life form was the ericoids (37 species) followed by proteiods (11 species), grasses (11 species), forbs (9 species) and succulents (4 species). In general, the five life forms did not show -any exclusive pattern of preference for either the pine or no-pine sites.
  • Thumbnail Image
    Item
    Open Access
    The influence of size and density of the Camelthorn (Acacia erioloba Meyer) on its keystone role in the Xeric Kalahari
    (2006) Seymour, Colleen; Dean, Richard; Midgley, Jeremy J
    Within the savannas of the southern Kalahari, land use practices can change habitat structure profoundly, so that rangelands either became densely wooden through bush thickening or are cleared completely using arboricides or manual tree felling and bush clearance, or are at some stage in between. Demands for the wood of camelthorn trees (Acacia reioloba), (the largest tree species growing on semi-arid and arid Kalahari sands) for firewood has also impacted habitat structure. Large trees are important in the Kalahari ecosystem because they provide shade, nesting and foraging sites for birds and mammals, as well as microhabitats that facilitate the existence of a suite of subcanopy plants. Indeed, large A. erioloba tress have been mooted as a context-depend keystones species, important to other biota and ecological prcesess. The primary aim of this study was to investigate the importance of A. erioloba to biodiversity, focusing on plants and birds.
  • Thumbnail Image
    Item
    Open Access
    The distribution and habitat preferences of wild ungulates and cattle in Lochinvar National Park, Zambia and the use of resources by people living adjacent to the park
    (2000) Lumbwe, Fainess Chaona; Dean, Richard; Milton, Sue
    (1) The distribution and habitat preferences of wild ungulates and cattle were determined from observations and counts in Lochinvar National Park and the Game Management Area (GMA) on the west em part of the park on the Kafue river floodplain of Zambia over five months. Oribi, zebra and lechwe were the most widely distributed wild ungulates using habitat patches inside and outside the park. Although the distribution of buffalo was restricted within the park, the species was found in all the habitat types unlike lechwe and zebra that preferred only the floodplain and termitaria areas. Wildebeest preferred the termitaria and floodplain areas inside the park. The highest lechwe density was in Chunga floodplain with a density of 504.2/km2 followed by Mulindi GMA with 451.9/km2. The lowest lechwe density was in Mulindl termitaria with 0.4/km2. Zebra density was highest in Nampongwe floodplain with 118/km2 while the highest wildebeest density was on Gwisho dambo with 27/km2. Nampongwe floodplain had the highest oribi density with 2.8/km2. There were significant differences in the density of lechwe inside and outside the park in Mulindi. Zebra and oribi densities inside and outside the park in Mulindi were low and no differences could be noted. (2) The biomass production in the different habitats was determined by harvesting the above ground biomass in selected areas in each habitat. The termitaria were the most productive of the three habitat types with an estimated production of 4320kg/ha followed by the woodland with 3200kg/ha and the least production was in the floodplain with 2850kg/ha. Of this total, grasses made up 87.4%, 83. 7% and 72.5% of the production in the floodplain, termitaria and woodland respectively. There were no significant differences in biomass production between different habitat types, however, there were significant differences in biomass production within the same habitat. (3) The species composition of the dominant plants was different in all habitat types. and as a result, the forage availability in the different habitats also differed. The floodplain was dominated by Echinoehloa spp, Panicum repens and Oryza longistaminata whereas the termitaria was dominated by Hyparrhenia rufa, Setaria spp and Echinochloa colonum. The woodland was dominated by Setaria and Digitaria spp. (4) Cover was determined in the different habitat types using the Parker Step Point method. The highest amount of grass cover was in the floodplain with 46.6% followed by termitaria with 45.6% and the woodland with 13.3%. Non grass cover was highest in the termitaria with 15.8°, followed by floodplain with 9.4% and woodland with 0.5%. The woodland had the highest amount of litter with 66.5% followed by the floodplain with 30.7%. The termitaria had the least amount of litter with 24.9%. The highest amount of bare ground was in the woodland with 19.8% followed by termitaria with 13.8% and the floodplain with 13.3%. There were significant differences in the proportion of grass and non-grass cover in all habitat types. There were no significant differences in the proportion of litter and bare ground between the floodplain and tennitaria and between floodplain and woodland however, there were significant differences in the proportion of litter and bare ground between the tennitaria and woodland. (5) A questionnaire survey revealed that game meat and grazing land are the two main resources that are used by people near the park. The main problems faced by people living near the park is destruction of crops by problem animals like baboons and bushpigs and the transmission of diseases like tuberculosis from game to livestock. The survey also revealed that people are forced to travel inside the park because it is the shortest route to various destinations. Others travel inside the park because the main sources of employment in the area are found inside the park. Game seems to be used to the presence of people and will only run away when closely approached or when people are travelling using a vehicle. (6) The results of the study do not support the hypothesis that cattle can be accommodated in Lochinvar National Park with no adverse effect on lechwe and other large herbivores. Cattle and game use the same areas outside the park in Mulindi but the areas are used at different times in the year. (7) Lochinvar National Park needs a clear burning policy to effectively manage the bush encroachment problem and overgrazing in some areas inside the park. The income generated by the park should be ploughed back into the management of the park in order to effectively control poaching, human encroachment into the park and to monitor the activities and movements of people inside the park.