Effect of biotic and abiotic factors on composition and foraging intensity of subterranean termites

Elucidating the influence of ecological factors on composition and foraging intensity of subterranean termites is critical in development of sustainable termite management strategies. Our aim was therefore to analyze the effect of selected biotic and abiotic factors on composition and foraging intensity of termites. We used principal component and canonical correspondence analysis to select appropriate factors and to model relationships respectively. Macrotermes species occurred in sites where the quantity of litter was generally above the mean. However, Macrotermes herus (Rambur) and Macrotermes spp.4 occurred in sites where the litter quantity was below the mean. Trinervitermes oeconomous (Tragardh) and Odontoremes spp.1 were noted to occur in the direction of increasing quantity of biomass. Generally, most species occurred in sites where soil pH was above or slightly below the mean (4.8). Majority of the species were also noted to occur in sites where bulk density was below or slightly above the mean (1.55 g/cm3). Highest bait consumption (95%) occurred within a range of 55 to 60% basal cover beyond which the amount of bait consumed reduced. Litter and biomass quantity, pH and bulk density were noted as the most influential environmental variables determining composition of termites while basal cover was the major determinant of foraging intensity.Key words: Rangelands, Macrotermes, rangelands, vegetation, litter, biomass, basal-cover

Drought Adaptation and Coping Strategies Among the Turkana Pastoralists of Northern Kenya

This study highlights drought characteristics and the many responses to drought stresses employed by Turkana pastoralists of northwestern Kenya. Multiple data sources, including socioeconomic interviews with 302 households, focus group discussions, and informal interviews with pastoralists were used to capture various aspects of drought and drought adaptation and coping practices. Standardized precipitation index derived from long-term rainfall data obtained from the Kenya Meteorological Service was used to quantify different degrees of drought intensity between 1950 and 2012. Results revealed that extreme drought events were increasingly frequent, and have impacted negatively on pastoral livelihoods. In order to adapt to or cope with climatic anomalies, households are using a variety of strategies. In addition to the traditional short-term coping mechanisms, the long-term adaptation strategies used include diversification of livelihood sources; livestock mobility to track forage and water resources; diversification of herd composition to benefit from the varied drought and disease tolerance, as well as fecundity of diverse livestock species; and sending children to school for formal education as a long term investment expected to pay back through income from employment. Policies and development interventions that reduce risks, diminish livelihood constraints, and expand opportunities for increased household resilience to drought are critical complements to the existing pastoral strategies

Effects of Agroforestry Practices on Soil Properties in the Drylands of Eastern Kenya

Drylands, which are home to about 2 billion people face a myriad of problems among them low land productivity. Agroforestry is one of the land use practices that is perceived to be sustainable with beneficial effects on soil properties. However, the effects of agroforestry practices on soils especially in the drylands have rarely been quantified and studied in details. The study determined the effects of selected agroforestry practices on soil properties in Makueni County of Kenya where agroforestry has been promoted by various organizations. Four soil samples were collected at 0-15cm, 15-30cm, 30-45cm and 45-60cm depths in a zigzag pattern at each 10 x 10m plots established along line transects laid in woodlots established in 2007, 2010 and 2013 and their adjacent parkland and grazing land. Seven randomly selected farms were sampled. The samples were analyzed using laboratory methods for soil nutrients and physical properties. Density of tree species in these established plots were also determined using quadrat technique. Tree density was higher in woodlots followed by grazing area and parkland .Soil samples showed that Soil Organic Carbon and Total Nitrogen were significantly higher in the woodlots than in the parkland and grazing lands ((p≤0.05). Soil Organic Carbon was significantly higher in woodlots established in 2007 than those established in 2013. Phosphorus was significantly higher in cropland compared to woodlots and grazing land. Phosphorus and Potassium were significantly higher at 0-15 cm depth compared to other soil depths. Bulky density was significantly higher with a corresponding lower total porosity in grazing lands than in the woodlots and parklands. The results suggest that different agroforestry practices contribute differently to soil properties. Mixed tree woodlots contributed significantly to improving soil properties and could be considered as a strategy to sustainably restore degraded and infertile soils in the drylands

Large herbivores maintain a two‐phase herbaceous vegetation mosaic in a semi‐arid savanna

1. Many arid and semi‐arid rangelands exhibit distinct spatial patterning of vegetated and bare soil‐dominated patches. The latter potentially represent a grazing‐induced, degraded ecosystem state, but could also arise via mechanisms related to feedbacks between vegetation cover and soil moisture availability that are unrelated to grazing. The degree to which grazing contributes to the formation or maintenance of degraded patches has been widely discussed and modeled, but empirical studies of the role of grazing in their formation, persistence, and reversibility are limited. 2. We report on a long‐term (17 years) grazing removal experiment in a semi‐arid savanna where vegetated patches composed of perennial grasses were interspersed within large (>10 m2) patches of bare soil. 3. Short‐term (3 years) grazing removal did not allow bare patches to become revegetated, whereas following long‐term (17 years) grazing removal, bare soil patches were revegetated by a combination of stoloniferous grasses and tufted bunchgrasses. In the presence of grazers, stoloniferous grasses partially recolonized bare patches, but this did not lead to full recovery or to the establishment of tufted bunchgrasses. 4. These results show that grazers alter both the balance between bare and vegetated patches, as well as the types of grasses dominating both patch types in this semiarid savanna. 5. Synthesis: Large herbivores fundamentally shaped the composition and spatial pattern of the herbaceous layer by maintaining a two‐phase herbaceous mosaic. However, bare patches within this mosaic can recover given herbivore removal over sufficiently long time scales, and hence do not represent a permanently degraded ecosystem state

Dry matter yields and hydrological properties of three perennial grasses of a semi-arid environment in east Africa

Enteropogon macrostachyus (Bush rye), Cenchrus ciliaris L. (African foxtail grass) and Eragrostis superba Peyr (Maasai love grass) are important perennial rangeland grasses in Kenya. They provide an important source of forage for domestic livestock and wild ungulates. These grasses have been used extensively to rehabilitate denuded patches in semi-arid environment of Kenya. This study investigated the dry matter yields and hydrological properties of the three grasses under simulated rainfall at three phenological stages; early growth, elongation and reproduction. Laboratory seed viability tests were also done. Hydrological properties of the three grasses were estimated using a Kamphorst rainfall simulator. Results showed that there was a significant difference (p > 0.05) in dry matter yields and soil hydrological properties at the different grass phenological stages. Generally, all the three grasses improved the soil hydrological properties with an increase in grass stubble height. C. ciliaris gave the best soil hydrological properties followed by E. macrostachyus and E. superba, respectively. E. macrostachyus recorded the highest seed viability percentage. C. ciliaris and E. superba were ranked second and third, respectively. C. ciliaris yielded the highest biomass production at the reproductive stage followed by E. superba and E. macrostachyus, respectively. (Résumé d'auteur

Economic Valuation of Grazing Management Practices: Discrete Choice Modeling in Pastoral Systems of Kenya

This study estimates the economic contribution of grazing management practices in pastoral systems by specifically undertaking an economic analysis of pastoralists’ preferences for grazing management practices and the economic value pastoralists place on them. The study applied the discrete choice experiment technique using a D-optimal design, a multi-attribute preference elicitation method to evaluate the economic value of grazing management options practiced in pastoral areas of Kenya. The results show that pastoral communities derive positive utility in connected systems that enable reciprocal access to resources in both wet and dry seasons. Pastoralism adapts to spatial–temporal variability of pasture and water through herd mobility; hence the positive utility derived from practices that contribute to the availability of adequate water and pasture across the seasons. These findings provide empirical evidence on the social and economic net benefits of rangeland management practices that should be enhanced to promote sustainable management of rangeland resources

The role of drought among agro-pastoral communities in a semi-arid environment: The case of Botswana

Agro-pastoral livelihoods in semi-arid Botswana have evolved and adapted to recurrent droughts endemic to the region. Droughts, more than any other phenomena, have shaped and influenced rural communities' interaction with their environment on which they eke a living. The physical aspect of droughts and their effects are well known, but the often subtle and complex dynamics emanating from drought outbreaks are less understood among communities. A study was conducted during the 2009/2010 season to investigate how communities in Kgalagadi North and Bobonong Sub-districts perceive droughts, anticipate droughts and which sections of the respective communities were most vulnerable to drought shocks. An extensive agro-ecological knowledge base, in form of environmental indicators, was used by communities to predict imminent droughts. Preparations included storing excess crop harvests during good years, storing crop residues for livestock, buying commercial feed to supplement livestock and seeking alternative sources of income outside the agricultural sector. In spite of these efforts, drought still affected the communities negatively mainly through increased livestock mortalities and crop failure-especially among poorer households. Subsequently, it is recommended that any effective aid interventions ought to understand and appreciate these dynamics to enhance resilience to future droughts and ensure sustainable rural development

Hydrologic properties of grazed perennial swards in semiarid southeastern Kenya

Identification of plant resources that persist under grazing pressure, support desirable levels of production and at the same time protect the grazing environment is central to sustainable livestock production. This study assessed the infiltration capacity and soil loss associated with perennial swards subjected to different levels of utilization using simulated rainfall. The hypothesis was tested that grazed perennial swards have similar hydrologic properties and threshold removal levels below which runoff increases markedly. Infiltration capacity for the perennial swards increased with increasing stubble height before leveling off towards the highest stubble height. A 50% removal of current growth was the upper limit above which runoffs from the swards increased rapidly. Aggregate stability, organic carbon and percent ground plant cover were the most significant attributes that influenced infiltration capacity. Panicum maximum and Enteropogon macrostachyus were the most suitable perennial swards with favourable soil physical properties and infiltration capacities in the study area. The results support the existence of a threshold level of sward stubble height for minimizing runoff

Range Use and Trophic Interactions by Agropastoral Herds in Southeastern Kenya

Habitat utilization patterns and feeding interaction of free ranging agropastoral herds were investigated in two cycles of four consecutive grazing periods, in a semiarid environment, southeastern Kenya. The bites count and herd locations per area methods were used. During the dry season, areas of concentrated drainage; river valleys, bottomlands and ephemeral drainage ways absorbed a greater feeding load, taking 57.1 to 60% of the grazing time by the animals. In contrast, areas of limited moisture concentration, the open sandy/clay plains, were mainly exploited in the wet season and accounted for 52.6 to 55.6% of the grazing time. The trophic interaction patterns indicated that goats and cattle had a seasonal mean diet overlap index of less than 0.5 for all forage classes. Sheep and cattle, and sheep and goats had a seasonal mean diet overlap index of greater than 0.5 on grass and forbs, and browse and forbs, respectively. This indicated that during periods of resource scarcity, sheep and cattle or sheep and goats could become competitive feeders for same feed resources. Grazing management strategies aimed at even distribution of grazing pressure and enhancing complementary trophic interactions could be central to sustainable livestock production in such environment