Aboveground Net Primary Productivity in Grazed and Ungrazed pastures: Grazing Optimisation Hypothesis or Local Extinction of Vegetation Species

The controversy that has surrounded herbivory studies in the last few decades prompted our investigation to establish the extent to which herbivore optimisation hypothesis or compensatory growth evidence is real. We used the traditional movable cage method to collect primary productivity data on herbage, functional groups and key individual grass species in various controlled large herbivore treatments in an east African savanna. The herbivore treatments in triplicate blocks included cattle, wild herbivores with and without mega herbivores and combinations of cattle and wild herbivores also with and without mega herbivores. The findings revealed that at herbage level, most grazed treatments (four out of five) had higher productivity than the ungrazed control and three showed grazing optimisation curve at sixth polynomial degree between monthly productivity and grazing intensity (1-g/ng). At functional group level forbs productivity was higher in the ungrazed control than in any of the grazed treatments while at individual grass species level _Themeda triandra_ productivity was higher in all grazed treatments than in ungrazed control. We conclude against presence of herbivore optimisation hypothesis at herbage, functional group and species level because of lack of attributable grazing effect in grazed treatments that matches complex ecological effects in the ungrazed treatment

The canopy effects of Prosopis juliflora (DC) and Acacia tortilis (Hayne) trees on herbaceous plants species and soil physico-chemical properties in Njemps Flats, Kenya

The canopy effects of an exotic and indigenous tree species on soil properties and understorey herbaceous plant species were investigated on the Njemps Flats, Baringo district, Kenya. Samples of soil and herbaceous plant species were obtained within the canopies of systematically selected P. juliflora (exotic) and A. tortilis (indigenous) trees, and from adjacent open areas. Standing biomass, frequency and cover of understorey plant species were significantly (P<0.05) higher in the open area than under the canopies. Cover for herbaceous plant species was 63% under P. juliflora, 82% under A. tortilis and 90% in open areas. All forbs occurred under the canopies indicating that they are more adapted to the shaded micro environments than grasses. Soils under the tree canopies had significantly (P<0.05) higher organic carbon and total nitrogen than those in adjacent open areas. Soils under A. tortilis had significantly (P<0.05) higher organic carbon and total nitrogen than soils from under P. juliflora. The results suggested that A. tortilis trees are more beneficial to soil physical and chemical properties than P. juliflora. Accordingly, the common practice of clearing woody trees indiscriminately to improve grassland for livestock production or for crop cultivation should not be recommended

Climate forecast information : the status, needs and expectations among smallholder agro-pastoralists in Machakos District, Kenya

The potential use of seasonal climate forecasts in farm and resource management has been studied in a number of cultural contexts around the world. Many of these studies reveal difficulties that smallholders encounter in accessing, interpreting and applying forecasts for their own benefit. This study looked at the awareness of and usage of climate forecast information in central Kenya in the aftermath of the 1997/98 El Niño event. Household surveys were conducted in Machakos District, Kenya, in January 2001. Retrospective and concurrent awareness and application of seasonal forecast information was assessed for 240 households across a range of agro ecological zones. The results show high degree of awareness and use of forecasts. Farmers discussed both actual and potential application of forecasts for both above-normal and below-normal rainfall. The influence of the El Niño tendency to increase the rainfall as in the case of 1997/98 El Niño was clear from their emphasis on strategies to mitigate the impacts of above-or below-normal rainfall. Applications of information in both crop and livestock management are documented. Constraints still exist, such as interpretation of information, relevance of the variables forecast to the management decisions of concern, confidence in the forecasts, and timely and affordable access to resources such as seeds. We suggest that collaborative efforts between the forecast providers and the users of information may be directed towards addressing these constraints. For instance in case of abnormal phenomenon such as droughts or floods, forecasts can be closely followed by early warning campaigns with clear guidelines of how to prepare, distributed through the FM radio in local languages order to abate human suffering

The influence of water availability on pastoralist's resource use in Mwingi and Kitui districts in Kenya

Understanding where pastoral livestock grazing takes place and how water availability and distribution influences resource use, is critical in planning and management of arid and semi -arid lands. This study was carried out in Mwingi and Kitui districts in Eastern Kenya. Semi-structured questionnaires were used for data collection for five months. Watering points were established through cluster sampling by considering each administrative sub- location with the help of topographical maps. Three ethnic communities, namely ,the Akamba, Oroma and Somali, utilize resources in the area. The distribution of dry season water in the area influence the distances livestock herds traveled from their homelands. There was a significant difference between number of wells and the number of households, with an overall mean number of five to eight households per well. The population of goats and camels was highest for the area, and that they walked longer and their watering frequency was low. However, diseases, predators and frequent droughts occasioned animal’s losses, with goats having the highest death (6.0%) and birth (44.8%) rates. The dry season water availability may explain why livestock routes changed over the seasons and highlight the importance and ubiquity of common utilization of the range by these communities. Therefore, common rights of access prevail, although the control and organization of shallow wells is the responsibility of the Akamba ‘well owner’. Water constraints and property right issues in the study area limit exploitation of the resources for livestock production. This paper highlights the need to integrate water development and improved livestock management in the arid and semi- arid areas to reduce poverty

THE CANOPY EFFECTS OF Prosopis juliflora (DC.) AND Acacia tortilis (HAYNE) TREES ON HERBACEOUS PLANTS SPECIES AND SOIL PHYSICO-CHEMICAL PROPERTIES IN NJEMPS FLATS, KENYA

The canopy effects of an exotic and indigenous tree species on soil properties and understorey herbaceous plant species were investigated on the Njemps Flats, Baringo district, Kenya. Samples of soil and herbaceous plant species were obtained within the canopies of systematically selected P. juliflora (exotic) and A. tortilis (indigenous) trees, and from adjacent open areas. Standing biomass, frequency and cover of understorey plant species were significantly (

Seasonal botanical and chemical composition of sheep and goat diets on a common range in eastern Africa

The botanical and chemical composition, intake and digestibility of local sheep (Ovis aries) and goat (Capra hirtus) diets were evaluated over the wet (growing) and dry (dormant) seasons. Diet botanical composition was related to the vegetation composition on the range. Commiphora riperia and Acacia tortilis were the most dominant tree species, while Duosperma kilimandscharicum and Premna hildebrandtii were the most dominant shrub species. Enteropogon macrostachyus, Cenchrus ciliaris and Chloris roxburghiana were the most abundant grass species, while Brepharis integriifolia, Commelina benghalensis and Macrotylomma axillare were the most dominant forb species. Grasses increased towards the end of the wet season and the beginning of the dry season, while the forbs decreased. Eragrostis caespitosa, Cenchrus ciliaris, Eragrostis superba, Enteropogon macrostachyus and Themeda triandra were the most dominant grass species in sheep diets during both seasons, accounting for over 82% of the diet. Acalypha fruticosa, Grewia similis and G. bicolor were the most important browse species in goat diets in both seasons, while Eragrostis caespitosa and E. superba were the most common grass species during both seasons. Overall, goat diets comprised 81% browse, 17% grass and 2% forbs during the wet season; and 82% browse, 15% grass and 3% forbs during the dry season. Whilst the goat diets had higher (P < 0.05) crude protein (CP) content than sheep diets during both seasons, the sheep diets were lower in lignin content than goat diets during the wet season. Overall, the goat diets were lower in neutral detergent fibre (NDF) and acid detergent fibre (ADF) than sheep diets during both seasons. There was no difference (P < 0.05) in digestibility between the two animal species. However, it was higher (P < 0.05) during the dry than the wet season. Although sheep and goats are commonly herded together in east African rangelands, they have differing abilities to utilise forages. These differences must be taken into consideration in grazing management decisions, and selected grazing areas should be able to cater for the forage requirements of both species. Keywords: diet selection, forage, free-grazing, Kenya, range herbivores,, rangeland, seasonal variation African Journal of Range & Forage Science 2004, 21(1): 11–1

Effect of Acacia tortilis pods on intake, digestibility and nutritive quality of goat diets in southwestern Eritrea

Fresh Acacia tortilis pods were mixed with low quality native grass hay to form the following five rations: 100% hay (T1), 25% pods and 75% hay (T2), 50% pods and 50% hay (T3), 75% pods and 25% hay (T4) and 100% pods (T5) on ‘as fed' weight basis. Fifteen male Barka goats, approximately one year old and 10–15kg body weight, were randomly assigned to the five rations and fed in individual pens. Chemical composition, dry matter intake (DMI), in vitro dry and organic matter digestibility and body weight changes of the animals were evaluated. The average crude protein content of the pods was about 47% higher than the 7% minimum required for normal rumen function, while that of the hay was about 13% below. Percent ash, neutral detergent fibre (NDF), acid detergent fibre (ADF), hemi-cellulose (HC), cellulose (CL) and acid detergent lignin (ADL) contents were higher in the hay than in the pods. The pods were, however, generally higher in Ca, P, Mg and Na than the hay. Average DMI (g d-1 and g kg-1 LBW), percent in vitro dry and organic matter digestibility and body weight gains (total kg and gd-1) increased with an increase in A. tortilis pods, up to 75% level and then begun to decline. However, despite the decrease, T5 still had significantly (P < 0.05) higher feed digestibility and body weight gains than T2 and T3. Thus, supplementing low quality range herbage with Acacia pods can considerably improve the nutritive value of range livestock diets, particularly during the dry season when other types of fodder are of extremely low quality. Keywords: Acacia pods, Barka goat diet, range forage, pastoralists, semi-arid EritreaAfrican Journal of Range & Forage Science 2003, 20(1): 59–6