Agroforestry Systems 60: 77–91, 2004. © 2004 Kluwer Academic Publishers. Printed in the Netherlands. 77 Leafing, flowering and fruiting of Vitellaria paradoxa subsp. nilotica in savanna parklands in Uganda J.B.L. Okullo 1 , John B. Hall 2,∗ and J. Obua 1 1 Department of Forest Biology and Ecosystems Management, Faculty of Forestry and Nature Conservation, Ma- kerere University, P.O. Box 7062, Kampala, Uganda (e-mail: Okullo@forest.mak.ac.ug; obua@forest.mak.ac.uk); 2 School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd LL57 2UW, UK ∗ Author for correspondence (e-mail: j.b.hall@bangor.ac.uk) Key words: Environmental cues, Karit´ e, Phenophases, Shea butter, Tree phenology Abstract Vitellaria paradoxa leafing, flowering and fruiting patterns were monitored in Otuke county (Lira district), northern Uganda, over a period of 25 months. The monitoring revealed that leaf shedding takes place in the middle of the dry season and the trees are in full leaf by the onset of the wet season. New leaves continue to appear on the new shoots while old leaves persist during the leaf-fall period. The pattern of leafing and leaf loss, flowering and fruiting are unimodal with major peaks in flowering and fruiting, although in the study area rainfall is bimodal. Flowering was concentrated in months when the atmospheric relative humidity begins to rise from an initially low value (around November), peaks three months later and usually ends when rainy conditions persist. Flowers produced during the rainy season usually abort. Fruiting starts at the end of the dry season (December/January) and peaks from February to April. Seed matures during the rainy season (March to May) and fruit harvesting occurs mainly from May to August, when the soil is well supplied with plant available water but coinciding with high pre-growing season famine risk in the community. Introduction Indigenous woody plants of savanna parklands such as the sapotaceous Vitellaria paradoxa C.F.Gaertn. subsp. nilotica (Kotschy) A.N. Henry et al., the shea butter, yao (Lango) or karité (French) tree, with edible fruits, play important roles in household consumption for rural people. Apart from providing a food supple- ment, Vitellaria has cash importance in local econom- ies and international trade. In Uganda, the primary traditional role arises from the oil present in the ker- nels being a source of vegetable fat. Other uses range from the household production of cheese through the industrial production of cosmetics and medicines, and wood and soap production to illumination (Hall et al. 1996). In a broad belt of Africa, extending from Senegal through the Sahel, savanna parklands are the modified communities that have replaced “Sudanian Isober- linia” and related woodlands (White 1983). Vitellaria paradoxa is a dominant species of these parklands; the range of the best production has been described as ran- ging from 11 ◦ to 14 ◦ N, in West Africa (Bonkoungou 1987). In contrast to the permanently cultivated Faid- herbia albida (Delile) A.Chev. parkland systems, Vi- tellaria parklands pass through alternating cultivation and fallow phases. The fallow periods offer oppor- tunities for regeneration but are continuously being shortened because of pressure for land (Boffa 1999; Lovett & Haq 2000). Typical Vitellaria parklands have ageing and thinning tree populations (Hall et al. 1996). Initiation of viable local conservation strategies based on reproductive processes for Vitellaria is re- quired before ecological integrity is lost, since the success of any plant species depends on its ability to realise its vegetative and reproductive potential,. To develop a viable conservation strategy for Vitel- laria, formal studies of the reproductive processes and phenological patterns are vital. In view of the