Browsing by Author "Muriuki, John Njagi"

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    Dodder Infestation on Tea in Nandi County, Kenya
    (International Journal of Research in Environmental Science (IJRES), 2024) Mong’o, Faith Jepchirchir; Koske, James Kibii; Muriuki, John Njagi
    Dodders are holoparasites belonging to the family Convolvulaceae of the genus Cuscuta. Globally, about 200 species are reported to be a threat to crops of economic importance. Of major concern in counties of Kenya, are the impacts of parasitic dodder (Cuscuta spp.) on tea cultivation and production. This study aimed to assess the extent of dodder infestation on tea in Nandi County. An exploratory survey design was chosen for this study. The Yamane sampling formula obtained the sample size for the study. A semi-structured questionnaire was administered to 354 respondents from the Kenya Tea Development Agency to represent small-scale and the multinational tea estate to represent large-scale tea farming. Coordinates were captured on the farms with dodder, recorded on an observation checklist, analyzed, and presented on a map. Results obtained showed that 99.4% of the respondents knew about dodder. 205 (58%) respondents didn’t have dodder on their tea farms while 149 (42%) reported the presence of dodder in their tea farms. In the Multinational tea estates, Siret, Chemomi, and Taito reported cases of dodder infestation. Notably, 74.9% of the respondents recorded that children were the major agents of dodder spread. 97.7% of the respondents acknowledged that dodder is a threat to tea farming. In conclusion, dodder has been extensively distributed on tea farms and is a threat to tea farming in the study area. This study recommends further research to develop effective and sustainable dodder control strategies.
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    The potentials of agroforestry in biodiversity conservation and sustainable development; a case of the Mt. Kenya region
    (2011-11-01) Muriuki, John Njagi
    A study on agroforestry systems in agro-ecological zones of the Mt. Kenya region that are suitable for tea and coffee growing was carried out with the aim of establishing their potential for biodiversity conservation and sustainable development. Agroforestry systems and related socioeconomics data was collected using questionnaires and conducting on-farm observations while, biodiversity data was obtained using descriptive vegetational and faunal survey methods in randomly selected farms in each zone.Validity of biodiversity data obtained was determined using the program EstimateS Ver. 7.5. Tree species diversity in different zones was determined using Shannon Diversity Index (SDI) while, Sorensen Index (SI) of similarity was used to compare coffee and tea agro-ecological zones in different districts for biodiversity. Chi-square tests were used to determine site selection tendencies by mammals, birds and herpetofauna within farm sites under different agroforestry practices while, Pearson Correlation was used to establish if relationships existed between agroforestry trees and farmland fauna. Results of the study showed that agroforestry systems in the Mt. Kenya region are largely agrisilvicultural, and are greatly influenced by prevailing socio-economic conditions. The results for species richness estimates showed that biodiversity data obtained on tree species, mammals, birds and herpetofauna had a completeness that was above 50% and was therefore reliable. Out of all agroforestry trees enumerated on farms, 67.4% were exotics while 32.6 % were indigenous, with 56.6% occurring in the tea zone and 43.4% in the coffee zone. Analysis of variance showed that there were no significant differences in the number of indigenous trees in the coffee and tea agro-ecological zones. Comparison of indigenous with exotic species for all zones showed that the indigenous species were more diverse (Shannon Diversity Index 19.99) than exotics (16.11). The Shannon Diversity Index values for agroforestry tree species (indigenous and exotic) were higher in tea zones (18.83) than coffee zones (16.96). Tea zones had also more mammals, birds and herpetofauna species. Kirinyaga tea zone had the highest diversity of agroforestry tree species in the region while Embu coffee zone was the least diverse for both indigenous and exotic species. The ordination of pairing the zones together showed that combinations with the highest SI percentage (i.e. greatest similarity) for agroforestry trees were the Nyeri coffee zone versus Meru tea zone, while combination of zones with the lowest similarity were Nyeri coffee zone versus Kirinyaga tea zone and also Kirinyaga coffee zone versus Kirinyaga tea zone. Sorenson's Similarity Index indicated that there was relatively more similarity in agroforestry trees and faunal biodiversity within a cropping zone than between the zones. Analysis of variance (ANOVA) test results indicated that the tea zones had significantly more mammals (F=7.094, sig.= 0.037), than coffee zones. Site selection tendencies for mammals were low (X2 = 20.75, d.f. = 11, P < 0.005) for most sites, with over 50% of them occurring in farm sites under woodlots. Mammals species richness and abundance increased gradually from the coffee zone towards the tea zone. For birds, analysis of variance (ANOVA) test results revealed no significant differences (F= 0.801, Sig.= 0.405) in the number of birds observed in the tea and coffee zones and that they had strong site selection tendencies (X2 =3.16), d.f. = 11, P < 0.005), suggesting a high degree of specificity within agroforestry sites. A similar pattern was observed with herpetofauna. Pearson Correlation results showed that there was a significant positive correlation between the total number of trees and farmland mammals (r = 0.716, p = 0.05), birds (r = 0.705, p = 0.05) and herpetofauna (r = 0.846, p = 0.01) in the Mt. Kenya region. The study concludes that agroforestry has an ability to raise the capacity of farmlands to conserve more biodiversity. Biodiversity conservation in farmlands however, need planning so as to determine the kind of bioversity (flora and faunal) suitable for each area, and the kind of agroforestry system or tree species that biodiversity requires for longterm conservation and sustainability. This includes decisions on agroforestry trees to plant or retain, management or maintenance of structural and compositional diversity among other factors. This in turn requires cooperation of landowners or farmers.
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    Spatial Ramifications of Dodder Infestation on Urban Ornamentals in Mombasa, Kenya
    (Scientific Research Publishing, 2020-08) Ngare, Innocent Osoro; Koske, James Kibii; Muriuki, John Njagi; Gathuku, George Njagi; Adiel, Ruth Kangai
    Dodders are cosmopolitan generalist holoparasites that forage on a commu nity of plant species ranging from shrubs, trees and herbaceous. In this study, we employ mixed method research design that involved use of questionnaires and dodder host sampling matrix. Host identification and naming was car ried out by ecological Android PlantNet Plant App version 3.0.5. Respon dents sample size was determined by Krejcie and Morgan sampling formula. Results show that dodder was fast spreading through spatial retrospective sat ellite Landsat imagery analysis. Dodder was known by the majority of re spondents (97.1%) where the exploratory analysis score shows that respon dents’ constituency of residence influenced their understanding of dodder (F(5, 361) = 5.329, P = 0.000). The mode of parasitism between dodder & the hosts varied as some ornamental trees, shrubs and herbaceous plants were either affected moderately or extremely. The study recommends use of bio technological dodder control approaches through transgenic plants biotech nology and plant breeding to develop resistance towards dodder plant para sites.
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    Tea Farmers' Perceptions of the Influence of Climate Variability on Dodder Occurrence in Nandi County, Kenya
    (African Journal of Climate Change and Resource Sustainability, 2025-01) Mong’o, Faith Jepchirchir; Koske, James Kibii; Muriuki, John Njagi
    Climate variability continues to adversely impact agricultural systems globally. From the literature, it is reported that there has been an unprecedented emergence of pests and diseases associated with climate change and variability among other factors. In Kenya, crop cultivation and yield are affected primarily by changing climatic conditions, pests, and diseases. Of major concern in counties of Kenya, are the impacts of climate variability and parasitic dodder (Cuscuta spp.) on tea cultivation and production. From the literature, little is reported on the continuing invasion and effects of parasitic dodder on tea farming. This study aimed to assess tea farmer perceptions on the role of climate variability on the occurrence of dodder in Nandi. An exploratory survey design was utilized for this study. Using the Yamane Formula, a sample size of 392 was drawn from the Kenya Tea Development Agency tea farmers to represent the study. Primary data obtained from the administered questionnaires was extracted, collated, classified, and analysed (p≤0.05) with the aid of the Statistical Package of Social Sciences. Rainfall and temperature data for the County was obtained from the Kenya Meteorological Department from 1992 to 2022. Mann-Kendall Trend Analysis showed a significant increase in temperature denoted by a Sen’s slope= 0.031 and a strong positive correlation of Kendall’s Tau 0.554 indicated an increase at p
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    Urban climate variability trend in the coastal region of Mombasa Kenya
    (Academic Journals, 2020) Ngare, Innocent Osoro; Koske, James Kibii; Muriuki, John Njagi; Chitechi, Evelyn Wemali; Gathuku, George Njagi
    The world population in global south countries is increasing. This fast growth has heightened urban ecological footprint that contributes to anthropogenic forcing triggering of the climate system. From this study, climate variability trend dynamics in Mombasa County, a coastal urban area in Kenya was examined. A retrospective study was done (1989-2019) to determine the changes in temperature and rainfall in the area of study. The results show that climate variability was experienced in Mombasa with a maximum temperature t=-5.628, df=23, P:0.000 and a minimum of t= -5.401, df=23, P:0.000, total rainfall t=2.025, df=23, P:0.275. The linear regression analysis shows rainfall variation y = -9.588x + 1217.1 and temperature y =0.0258x + 29.888 with an increase of +0.4°C. The annual maximum temperature averages show heterogeneous distribution from kurtosis coefficient with little observed skewness.