Department of Biological and Environmental Sciences

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    African knowledge on Endod (phytolaccadodecandra) and its potential for medicinal uses in Kenya
    (University of British Columbia, Vancouver, BC, Canada, 2014) Ooko, SA.; Nashon, S.; Anderson, D.; Okeyo, JB.; Beru, F.; Okemwa, P.
    The majority of people in Africa use plant based traditional medicines for their care. Demand for medicinal plants is increasing in Africa as the population grows. The threat posed by over-exploitation of medicinal plants has serious implications on the survival of several plant species, many of which are faced with extinction. The pharmaceutical potentials of African medicinal plants are immense. But constraints and challenges exist at all levels. This paper discusses these constraints and challenges in relation to conservation, science and technology, use of medicinal plants at the local level, the domestic drug production sector, marketing, safety and efficacy requirements. Measures and strategies for enhancing the development of a medicinal and aromatic plants industry in Africa are suggested.
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    Ecological Manipulation of Psidium guajava to Facilitate Secondary Forest Succession in Tropical Forests
    (Journal of Ecological Engineering, 2020-10-01) Otuoma, John; Nyongesah, John Maina; Owino, Jesse; Onyango, Alice Adongo; Okello, Victor Samuel
    Psidium guajava L. has been documented as an exotic invasive species in many parts of the world, but little is known about its interactions with native woody species during secondary forest succession in tropical forests. Its invasion and interactions with native species in different stages of secondary forest succession were assessed in Kakamega Rainforest in western Kenya. The study covered three forest blocks each with five different forest types, namely: open fields, young secondary forest, middle-aged secondary forest, old-growth secondary forest and disturbed primary forest, which served as the control. Open fields that were subjected to frequent clearing to control the spread of Psidium guajava remained under a thicket of the species two decades later. On the other hand, open fields where Psidium guajava was ignored, either due to lack of resources or sheer neglect, transformed into young secondary forest stands within a decade. The transformation increased woody species richness from 2.0±0.0 to 5.0±0.0 ha-1, and the Shannon diversity index from 0.30±0.33 to 1.10±0.01. It reduced the dominance of Psidium guajava from 80.5±22.7 to 62.26±0.84% and changed the canopy structure. The change in canopy structure led to the mortality of Psidium guajava stems in the sub-canopy and understory layer, which significantly reduced its stem density from 1,111±313 to 639.4±45 stems ha-1. The pattern was repeated in middle-aged secondary forest stands with woody species richness increasing to 26.0±8.2 ha-1, and Shannon index to 2.72±0.32. Psidium guajava’s dominance and stem density decreased further to 30.44% and 400.57 stems ha-1, respectively, due to mortality attributed to shading by native tree species. In the old-growth secondary forest, only snags of Psidium guajava were recorded. The species was not represented in the disturbed primary forest. The results indicate that Psidium guajava facilitates secondary forest succession by allowing shade-tolerant native tree species to recruit and grow in its shade. It is thereafter eliminated when the native species close the forest canopy. The species can be ecologically manipulated to facilitate post-disturbance forest regrowth and thereafter removing it when the forest canopy begins to close.
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    Exploratory study on the impact of woodfuel use and planning strategies for its sustainability in Western Kenya
    (University of British Columbia, Vancouver, BC, Canada, 2014) Beru, F.; Nashon, S.; Anderson, D.; Opata, P.; Ooko, S.; Okemwa, P.; Wafula, SS.
    The impact of woodfuel collection on forests has been controversial and its role in rural livelihoods and deforestation is the subject of considerable debate. This study reviews the main dimensions of this discourse and the resulting responses form the forestry sector. It assesses new information that has come to light over the past decade, looking at national and global trends on woodfuel production and use and the evolution of patterns of urban and rural demand and supply. It examines livelihood and environmental dimensions of relevance to forestry and outlines some of the main issues that warrant additional attention. It is thus intended more as a foundation for further discussion, rather than being a set of prescriptions for action by forestry, though where these are evident they are identified. "The available evidence does not substantiate earlier concerns that woodfuel demand has been outpacing sustainable supply on a scale that makes it a major cause of deforestation. It appears the balance between the two seldom an issue requiring forestry intervention on a national scale. However, the rapid rise in charcoal production and its concentration, to supply large urban markets, certainly warrants further investigation. Overall, the woodfuels situation is an important consideration for particular areas within a country and for particular groups of users and suppliers. Globally, fuelwood consumption appears to have peaked (although charcoal consumption is continuing to rise) and in some developing countries, it now appears to be in decline. However, the total quantities of woodfuels being used, and the number of people using them, are still huge. In poor households almost everywhere, woodfuels are among the main forest related inputs, although the level of attention they receive does not currently reflect this, despite the growing focus on giving forestry a stronger livelihood orientation. Forestry initiatives need to be compatible with the energy sector’s objective of helping poor users move up the energy ladder to greater fuel efficiency and alternative fuels. The main task though, is likely to be facilitating access to supplies for those who continue to depend on biomass fuels, for their own use or as an important source of income. Forestry measures will need to integrate meeting this demand into wider forestry objectives, rather than, as in the past, developing responses focusing on the fuelwood issue alone."