Baum D A (1995) The comparative pollination and floral biology of baobabs (Adansonia-Bombacaceae). Annals of the Missouri Botanical Garden, 82(2): 322-348
The baobabs comprise eight species with large, spectacular, nocturnal flowers. The African baobab, Adansonia digitata, has long been known to be bat-pollinated. In this paper I document the floral biology and pollination systems of the remaining seven species. The two species in section Brevitubae, both endemic to Madagascar, are pollinated by nocturnal mammals (fruit bats and lemurs). In contrast, the five species in section Longitubae, four endemic to Madagascar and one to Australia, are pollinated by long-tongued hawkmoths. In all cases, animals besides the legitimate pollinators also exploited nectar and pollen. The two pollination systems occurring in the genus correlate closely with differences in the floral morphology, phenology, and nectar production.
Belsky A J, Mwonga S M, Amundson R G, Duxbury J M and Ali A R (1993) Comparative Effects of Isolated Trees on their Undercanopy Environments in High-rainfall and Low-rainfall Savannas. Journal of Applied Ecology, 30(1): 143-155
1. To determine whether agroforestry and silvopastoralism might be introduced more successfully into xeric or into mesic environments, the effects of isolated, mature trees of Acacia tortilis (acacia) and Adansonia digitata (baobab) on herbaceous-layer composition and productivity, soil properties, and microclimate in a moderately mesic savanna (c. 750 mm annual rainfall) were investigated and compared with an earlier study of the effects of the same two species in a more xeric savanna (c. 450 mm annual rainfall) in Tsavo National Park (West), Kenya. 2. Similar to the more xeric site, solar radiation was reduced by 45-65% and soil temperatures were reduced by 5 - 12oC under both tree species. Except for early in the growing season, soil-moisture values were similar under tree canopies and in open grasslands. 3. Compared to the more xeric site, where herbaceous-layer productivity was 95% higher under trees than in the open, productivity in the mesic site was 52% higher under acacia canopies (a mean of 808 g m-2) than in the open (533 g m-2), but only 18% higher under baobab canopies (569 g m-2) than in the open (484 g m-2). 4. Concentrations of organic matter, total N, N-15, P, K and Ca were significantly higher, and C:N ratios and soil bulk density significantly lower under tree canopies than in the open at both sites. Mg concentrations were significantly higher in the open than under tree canopies at the mesic, but not the xeric, site. 5. The contrast noted in 3 above between the herbaceous layer productivity below tree canopies and that in areas beyond them was attributed higher soil-N concentrations and to reduced evapotranspiration in these N- and water-limited systems. 6. The contrast in forage production under tree canopies between xeric and mesic sites may be due to the greater importance of shade in reducing temperatures and evapotranspiration in more arid environments.
Belsky A J, Mwonga S M and Duxbury J M (1993) Effects of Widely Spaced Trees and Livestock Grazing on Understorey Environments in Tropical Savannas. Agroforestry Systems, 24(1): 1-20
The effects of widely spaced trees of Acacia tortilis and Adansonia digitata on their understory environments were investigated in four savannas located along a gradient of increasing livestock utilization in Tsavo National Park (West), Kenya. Plant species composition and biomass and the physical and chemical properties of soils that occur below tree crowns were compared to open grasslands. The tree-crown zones at lightly and moderately grazed sites had a unique understory flora and higher plant biomass, lower temperatures and bulk densities, and higher levels of P, K, Ca, and mineralizable N than their associated open-grassland zones. In the heavily grazed savanna, few differences between tree-crown and grassland zones were found. The beneficial effects of savanna trees on their understory environments appear to diminish with increasing livestock utilization.
Belsky A J (1992) Effects of Trees on Nutritional Quality of Understorey Gramineous Forage in Tropical Savannas. Tropical Grasslands, 26(1): 12-20
The effects of isolated savanna trees on nutrient concentrations, total nutrient content, cell-wall fibre content, and digestibility of gramineous forage growing in three zones (canopy, tree-root, and grassland) surrounding individual trees of Acacia tortilis (acacia) and Adansonia digitata (baobab) were compared in low- and high-rainfall sites in Tsavo National Park, Kenya. The two tree species had similar effects on forage quality except that tissue-N was higher around the leguminous acacia trees. Concentrations of N, P, K, Ca, B, and Cu in the forage tended to increase from open grassland to tree understorey while concentrations of Mn, Zn, and Mo decreased. Since forage yield also increased from grassland to the canopy zone, total content of all nutrients per unit area increased towards the tree base. Concentrations of the forage fibres - neutral detergent fibre, acid detergent fibre and cellulose - and of SiO2 decreased, while lignin increased, from grassland to canopy zone, but the digestibility of dry matter was slightly lower in the canopy zone. Trees in Kenyan savannas, therefore, increase the availability of nutrients in the herbaceous forage, but this is offset by a slight drop in digestibility.
Belsky A J, Amundson R G, Duxbury J M, Riha S J, Ali A R and Mwonga S M (1989) The effects of trees on their physical, chemical, and biological environments in a semi-arid savanna in Kenya. Journal of Applied Ecology, 26(3): 1005-1024
Isolated mature trees of Acacia tortilis and Adansonia digitata in Tsavo National Park were studied for herbaceous-layer composition and productivity, site microclimate, and soil fertility under the canopy, in the rooting zone, and in surrounding grasslands. Compared to open grassland, tree canopies of both species reduced solar irradiance by 45-65%, soil temperatures by 5-11oC and rainfall by 50%. Soil water content was higher in open grassland immediately after the start of the two rainy seasons, higher under tree canopies during the first rainy season, but equal in the two areas during the second rainy season. Patterns of herbaceous-layer composition and above-ground net primary productivity (ANPP) under and near trees of the two species were similar. ANPP was significantly greater in their canopy zones (705 plus or minus 39 g/m
Berghen C vanden (1984) Observations on the vegetation of the Kalounayes forest, Casamance, southern Senegal. Part 1. Original Title: Observations sur la vegetation du massif forestier des Kalounayes (Casamance, Senegal meridional). 1e partie. Bulletin de la Societe Royale de Botanique de Belgique, 117(2): 359-381.
Four forest associations, stages of a degradation process, are identified and defined: a closed forest with Khaya senegalensis and Cola cordifolia, an open forest with Daniellia oliveri and Pterocarpus erinaceus, a thicket with Combretum nigricans, and a very open forest with Adansonia digitata and Strychnos spinosa on former clearings.
Guy R D (1972) The Gorongosa bee tree. African Wildlife, 26(4): 160-161.
A specimen of baobab tree Adansonia digitata containing 3 nests of Apis mellifera adansonii is described. Numerous pegs and peg sockets in the trunk of the tree showed that it had been visited regularly by honey-hunters for centuries. Many old peg sockets were occupied by nests of stingless bees, probably Trigona gribodoi; other sockets had become filled with rain water and bees drank from these. Forktailed drongos, greater honeyguides and flocks of bee-eaters were often found around the tree.
Igboeli L C, Addy E O H and Salami L I (1997) Effects of some processing techniques on the antinutrient contents of baobab seeds (Adansonia digitata). Bioresource Technology, 59(1): 29-31
The effect of different processing techniques on the antinutritional factors inherent in the seeds of baobab (Adansonia digitata) was investigated. The processing methods, which included dehulling, cold-water, hot-water hot- alkali and acid treatments, revealed that the concentration of tannic acid was reduced significantly by all the processing techniques except for dehulling. The activity of the amylase inhibitors in the seeds was also reduced significantly by dehulling, cold-water and hot-alkali treatments while the hot- water and hot-acid treatments increased the activity of the amylase inhibitors.
Koop K and Velimirov B (1981) Field observations on activity and feeding of bat-eared foxes (Otocyon megalotis) at Nxai Pan, Botswana. African Journal of Ecology, 20(1): 23-27.
A short study was made on 5 pairs of bat-eared foxes (Otocyon megalotis) at Nxai Pan on the Kalahari plain of Botswana. The study area was on grassland with many Acacia copses forming islands in the pan surrounded by Mopane woodland giving way towards the edge of the pan to shrubby Acacia vegetation scattered with baobab trees (Adansonia digitata). O. megalotis appeared to be diurnally active although nocturnal activity could not be excluded. Activity seemed to be closely related to availability of insects, particularly termites which were most abundant on the surface of the pan around noon. Analysis of scats showed that termites were the main food item, comprising about 89% of the dry weight of scats. O. megalotis did not appear to be territorial and intolerance among pairs was not observed.