Aboveground net primary productivity in grazed and ungrazed pastures: Grazing optimisation hypothesis or local extinction of vegetation species. Otieno, S.G., T.J. Njoka, T.P. Young, S.M. Mureithi and Ngugi, R.K.
.". In: Nature Proceedings
. Afr. J. Range For. Sci.; Submitted. Abstract
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 impact of rangeland livestock manure on nutrient depleted soils in highland small-holder croplands in Central Kenya. Kirigia, AK, Njoka, JT, Kinyua PID Young, TP and Mureithi, SM.
". In: Tropical and Sub-tropical Agroecosystems
. Tropical and Sub-tropical Agroecosystems; Submitted. Abstract
Cities around the world are currently facing considerable pressure to cope with infrastructure provision amidst rapid urban development and economic growth. Kenya is also facing an
increasing growth of informal settlements in her urban centres. As rapid urbanization takes its toll, so has the development and growth of slums. More than 34% of Kenya‟s total population lives in urban areas and of this, more than 71% is confined in informal settlements (UN-Habitat, 2009).
This paper presents the result of study to assess the effects of the change in land use in two sub-catchments, in an urban area close to the Nairobi Central Business District (NCBD). The paper compares the change in land use of two regions in Nairobi, Kenya that are slowly changing due to the fast growing population and economy, on urban runoff.